Table of Contents

Overview

Configuring QoS

Overview

This document describes how to configure quality of service (QoS) on the Cisco Industrial Ethernet 2000U Series (IE 2000U) and Connected Grid Switches, hereafter referred to as switch . The QoS feature enables you to select specific network traffic, prioritize it according to its relative importance, and use traffic-management techniques to provide preferential treatment. Implementing QoS in your network makes network performance more predictable and bandwidth utilization more effective.

Features

This chapter provides a summary of the following QoS features:

- Modular QoS CLI

- Input and Output Policies

- Classification

- Table Maps

- Policing

- Marking

- QoS Treatment for Performance-Monitoring Protocols

- Congestion Management and Scheduling

- QoS Features for Traffic Between ESM and CGR 2010

Modular QoS CLI

Modular QoS CLI (MQC) is the framework that you use to create traffic policies and attach these policies to interfaces. A traffic policy contains a traffic class and one or more QoS features. You use a traffic class to classify traffic, and the QoS features in the traffic policy determine how to treat the classified traffic.

The MQC structure allows you to create the traffic policy (policy map) once and then apply it to as many traffic classes as needed. You can also attach the traffic policies to as many interfaces as needed. Although you can assign the same traffic policy to multiple interfaces, each interface can have only one traffic policy attached in the input direction and only one traffic policy attached in the output direction.

MQC also supports parent policy levels and child policy levels for traffic shaping. The QoS parent-child structure is used for specific purposes where a child policy is referenced in a parent policy to provide additional control of a specific traffic type.

Related Topics

Modular QoS CLI

Input and Output Policies

Policy maps are either input policy maps or output policy maps, attached to packets as they enter or leave the switch by service policies applied to interfaces. Input policy maps perform policing and marking on received traffic. Policed packets can be dropped or reduced in priority (marked down) if they exceed the maximum permitted rates. Output policy maps perform scheduling and queuing on traffic as it leaves the switch.

Related Topics

Input and Output Policies

Configuring Input Policy Maps

Configuring Output Policy Maps

Classification

Classification distinguishes one kind of traffic from another by examining the fields in the packet header. When a packet is received, the switch examines the header and identifies all key packet fields. A packet can be classified based on an ACL, on the DSCP, the CoS, or the IP precedence value in the packet, or by the VLAN ID.

Related Topics

Classification

Using ACLs to Classify Traffic

Using Class Maps to Define a Traffic Class

Table Maps

You can use table maps to manage a large number of traffic flows with a single command. You can specify table maps in set commands and use them as mark-down mapping for the policers. You can also use table maps to map an incoming QoS marking to a replacement marking without having to configure a large number of explicit matches and sets. Table maps are used only in input policy maps.

Related Topics

Table Maps

Configuring Table Maps

Policing

After a packet is classified, you can use policing to regulate the class of traffic. The policing function limits the amount of bandwidth available to a specific traffic flow or prevents a traffic type from using excessive bandwidth and system resources. A policer identifies a packet as in or out of profile by comparing the rate of the inbound traffic to the configuration profile of the policer and traffic class. Packets that exceed the permitted average rate or burst rate are dropped or modified (marked for further processing), depending on the policer configuration.

Policing is used primarily on receiving interfaces. You can attach a policy map with a policer only in an input service policy.

Related Topics

Policing

Configuring Input Policy Maps

Marking

You can use packet marking in input policy maps to set or modify the attributes for traffic belonging to a specific class. After network traffic is organized into classes, you use marking to identify certain traffic types for unique handling. For example, you can change the CoS value in a class or set IP DSCP or IP precedence values for a specific type of traffic. These new values are then used to determine how the traffic should be treated. You can also use marking to assign traffic to a QoS group within the switch.

Traffic marking is typically performed on a specific traffic type at the ingress port. The marking action can cause the CoS, DSCP, or precedence bits to be rewritten or left unchanged, depending on the configuration. This can increase or decrease the priority of a packet in accordance with the policy used in the QoS domain so that other QoS functions can use the marking information to judge the relative and absolute importance of the packet. The marking function can use information from the policing function or directly from the classification function.

Related Topics

Marking

Configuring Input Policy Maps with Marking

QoS Treatment for Performance-Monitoring Protocols

The QoS treatment for IP-SLA and TWAMP probes must exactly reflect the effects that occur to the normal data traffic crossing the device.

The generating device should not change the probe markings. It should queue these probes based on the configured queueing policies for normal traffic.

You can use QoS marking to set or modify the attributes of traffic from the CPU. The QoS marking action can cause the CoS, DSCP, or IP precedence bits in the packet to be rewritten or left unchanged. QoS uses packet markings to identify certain traffic types and how to treat them on the local switch and the network.

Related Topics

QoS Treatment for Performance-Monitoring Protocols

Configuring QoS Marking and Queuing for CPU-Generated Traffic

Congestion Management and Scheduling

MQC provides several related mechanisms to control outgoing traffic flow. They are implemented in output policy maps to control output traffic queues. The scheduling stage holds packets until the appropriate time to send them to one of the four traffic queues. Queuing assigns a packet to a particular queue based on the packet class, and is enhanced by the Weighted Tail Drop (WTD) algorithm for congestion avoidance. You can use different scheduling mechanisms to provide a guaranteed bandwidth to a particular class of traffic while also serving other traffic in a fair way. You can limit the maximum bandwidth that can be consumed by a particular class of traffic and ensure that delay-sensitive traffic in a low-latency queue is sent before traffic in other queues.

Related Topics

Congestion Management and Scheduling

Configuring Output Policy Maps

QoS Features for Traffic Between ESM and CGR 2010

You can implement high-priority (low-latency) traffic via the internal data path between the Ethernet Switch Module (ESM) and the host CGR 2010 router by configuring these QoS functions:

- Ingress CoS to Generic Data Frame (GDF) queue mapping

- Port shaping to adjust for differences in ingress traffic bandwidth between the the internal data path on the CGR 2010 and the internal EtherChannel on the ESM

- CoS marking for CPU-generated traffic

Related Topics

Implementing High-Priority Traffic to the Host Router

Configuring QoS

This chapter describes how to configure quality of service (QoS) by using the modular QoS command-line interface (CLI), or MQC, commands on the Cisco Industrial Ethernet 2000U Series

(IE 2000U) and Connected Grid Switches, hereafter referred to as switch . With QoS, you can provide preferential treatment to certain types of traffic at the expense of others. When QoS is not configured, the switch offers best-effort service to each packet, regardless of the packet contents or size. It sends the packets without any assurance of reliability, delay bounds, or throughput. MQC provides a comprehensive hierarchical configuration framework for prioritizing or limiting specific streams of traffic.

Note IPv6 QoS is not supported.

For more information about Cisco IOS MQC commands and complete syntax and usage information for the platform-specific commands used in this chapter, see the documents listed in the “Related Documents” section.

For information about using Ethernet terminal loopback to test full-path QoS on an interface, see the chapter “Enabling Ethernet Loopback” in the System Management Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches .

- Information About QoS

- Prerequisites

- Guidelines and Limitations

- Default Settings

- Configuring QoS

- Verifying Configuration

- Configuration Examples for Policy Maps

- Related Documents

- Feature History

Information About QoS

Typically, networks operate on a best-effort delivery basis, which means that all traffic has equal priority and an equal chance of being delivered in a timely manner. When congestion occurs, all traffic has an equal chance of being dropped.

When you configure the QoS feature, you can select specific network traffic, prioritize it according to its relative importance, and use traffic-management techniques to provide preferential treatment. Implementing QoS in your network makes network performance more predictable and bandwidth utilization more effective.

Figure 2-1 shows the MQC model.

Figure 2-1 Modular QoS CLI Model

Basic QoS includes these actions.

- Packet classification organizes traffic on the basis of whether or not the traffic matches a specific criteria. When a packet is received, the switch identifies all key packet fields: class of service (CoS), Differentiated Services Code Point (DSCP), or IP precedence. The switch classifies the packet based on this content or based on an access-control list lookup. For more information, see the “Classification” section.

- Packet policing determines whether a packet is in or out of profile by comparing the rate of the incoming traffic to the configured policer. You can configure a committed information rate (CIR) and peak information rate (PIR) and set actions to perform on packets that conform to the CIR and PIR ( conform-action ), packets that conform to the PIR, but not the CIR ( exceed-action ), and packets that exceed the PIR value ( violate-action ). For more information, see the “Policing” section.

- Packet prioritization or marking evaluates the classification and policer information to determine the action to take. All packets that belong to a classification can be remarked. When you configure a policer, packets that meet or exceed the permitted bandwidth requirements (bits per second) can be conditionally passed through, dropped, or reclassified. For more information, see the “Marking” section.

- Congestion management uses queuing and scheduling algorithms to queue and sort traffic that is leaving a port. The switch supports these scheduling and traffic-limiting features: class-based weighted fair queuing (CBWFQ), class-based traffic shaping, port shaping, and class-based priority queuing. You can provide guaranteed bandwidth to a particular class of traffic while still servicing other traffic queues. For more information, see the “Congestion Management and Scheduling” section.

- Queuing on the switch is enhanced with the weighted tail-drop (WTD) algorithm, a congestion-avoidance mechanism. WTD differentiates traffic classes and regulates the queue size (in number of packets) based on the classification. For more information, see the “Congestion Avoidance and Queuing” section.

This section includes the following topics:

- Modular QoS CLI

- Input and Output Policies

- Classification

- Table Maps

- Policing

- Marking

- QoS Treatment for Performance-Monitoring Protocols

- Congestion Management and Scheduling

- Congestion Avoidance and Queuing

Modular QoS CLI

Modular QoS CLI (MQC) allows users to create traffic policies and attach these policies to interfaces. A traffic policy contains a traffic class and one or more QoS features. You use a traffic class to classify traffic, and the QoS features in the traffic policy determine how to treat the classified traffic.

Modular QoS CLI configuration includes these steps:

Step 1 Define a traffic class.

Use the class-map [ match-all | match-any ] class-map-name global configuration command to define a traffic class and to enter class-map configuration mode. A traffic class contains three elements: a name, an instruction on how to evaluate the configured match commands (if more than one match command is configured in the class map), and a series of match commands.

- You name the traffic class in the class-map command line to enter class-map configuration mode.

- You can optionally include keywords to evaluate these match commands by entering class-map match-any or class-map match-all . If you specify match-any , the traffic being evaluated must match one of the specified criteria. If you specify match-all , the traffic being evaluated must match all of the specified criteria. A match-all class map can contain only one match statement, but a match-any class map can contain multiple match statements.

Note If you do not enter match-all or match-any, the default is to match all.

- You use the match class-map configuration commands to specify criteria for classifying packets. If a packet matches the specified criteria, that packet is considered a member of the class and is forwarded according to the QoS specifications set in the traffic policy. Packets that fail to meet any of the matching criteria are classified as members of the default traffic class.

Step 2 Create a traffic policy to associate the traffic class with one or more QoS features.

You use the policy-map policy-map-name global configuration command to create a traffic policy and to enter policy-map configuration mode. A traffic policy defines the QoS features to associate with the specified traffic class. A traffic policy contains three elements: a name, a traffic class (specified with the class policy-map configuration command), and the QoS policies configured in the class.

- You name the traffic policy in the policy-map command line to enter policy-map configuration mode.

- In policy-map configuration mode, enter the name of the traffic class used to classify traffic to the specified policy, and enter policy-map class configuration mode.

- In policy-map class configuration mode, you can enter the QoS features to apply to the classified traffic. These include using the set , police , or police aggregate commands for input policy maps or the bandwidth , priority , queue-limit or shape average commands for output policy maps.

Note A packet can match only one traffic class within a traffic policy. If a packet matches more than one traffic class in the traffic policy, the first traffic class defined in the policy is used. To configure more than one match criterion for packets, you can associate multiple traffic classes with a single traffic policy.

Step 3 Attach the traffic policy to an interface.

You use the service-policy interface configuration command to attach the policy map to an interface for packets entering or leaving the interface. You must specify whether the traffic policy characteristics should be applied to incoming or outgoing packets. For example, entering the service-policy output class1 interface configuration command attaches all the characteristics of the traffic policy named class1 to the specified interface. All packets leaving the specified interface are evaluated according to the criteria specified in the traffic policy named class1 .

Note If you enter the no policy-map configuration command or the no policy-map policy-map-name global configuration command to delete a policy map that is attached to an interface, a warning message appears that lists any interfaces from which the policy map is being detached. The policy map is then detached and deleted. For example:

Warning: Detaching Policy test1 from Interface GigabitEthernet0/1

Input and Output Policies

Policy maps are either input policy maps or output policy maps, attached to packets as they enter or leave the switch by service policies applied to interfaces. Input policy maps perform policing and marking on received traffic. Policed packets can be dropped or reduced in priority (marked down) if they exceed the maximum permitted rates. Output policy maps perform scheduling and queuing on traffic as it leaves the switch.

Input policies and output policies have the same basic structure; the difference is in the characteristics that they regulate. Figure 2-2 shows the relationship of input and output policies.

You can configure a maximum of 256 policy maps.

The number of configurable policer profiles on the switch is 256. The number of supported policer instances on the switch is 1024 minus 1 more than the number of interfaces on the switch. On a 24-port switch, the number of available policer instances is 999. You can use a policer profile in multiple instances.

You can apply one input policy map and one output policy map to an interface.

When CPU protection is enabled (the default), you can configure 45 ingress policers per port. If you disable CPU protection by entering the no policer cpu uni all global configuration command and reloading the switch, you can configure a maximum of 63 policers per port for user-defined classes and one for class-default. You can enter the show policer cpu uni-eni {drop | rate} privileged EXEC command to see if CPU protection is enabled.

Figure 2-2 Input and Output Policy Relationship

Input Policy Maps

Input policy map classification criteria include matching a CoS, a DSCP, or an IP precedence value or matching an access control list (ACL) or VLAN ID (for per-port, per-VLAN QoS). Input policy maps can have any of these actions:

- Setting or marking a CoS, a DSCP, an IP precedence, or QoS group value

- Individual policing

- Aggregate policing

Only input policies provide matching on access groups or VLAN IDs, and only output policies provide matching on QoS groups. You can assign a QoS group number in an input policy and match it in the output policy. The class class-default is used in a policy map for any traffic that does not explicitly match any other class in the policy map. Input policy maps do not support queuing and scheduling keywords, such as bandwidth , queue-limit , priority , and shape average .

An input policy map can have a maximum of 64 classes plus class-default . You can configure a maximum of 64 classes in an input policy.

Output Policy Maps

Output policy map classification criteria include matching a CoS, a DSCP, an IP precedence, or a QoS group value. Output policy maps can have any of these actions:

- Queuing ( queue-limit )

- Scheduling ( bandwidth , priority , and shape average )

Output policy maps do not support matching of access groups. You can use QoS groups as an alternative by matching the appropriate access group in the input policy map and setting a QoS group. In the output policy map, you can then match the QoS group. See the “Classification Based on QoS Groups” section for more information.

Output policies do not support marking or policing (except in the case of priority with policing). There is no egress packet marking on the switch (no set command in an output policy).

The class class-default is used in a policy map for any traffic that does not explicitly match any other class in the policy map. There can be a maximum of four classes in the output policy map (including class-default) because egress ports have a maximum of four queues.

An output policy map attached to an egress port can match only the packets that have already been matched by an input policy map attached to the ingress port for the packets. You can attach an output policy map to any or all ports on the switch. The switch supports configuration and attachment of a unique output policy map for each port. However, these output policy maps can contain only three unique configurations of queue limits. These three unique queue-limit configurations can be included in as many output policy maps as there are ports on the switch. There are no limitations on the configurations of bandwidth, priority, or shaping.

You can configure the output policy classification criteria for CPU-generated traffic by using the cpu traffic qos [cos value | dscp value | precedence value | qos-group value ] global configuration command.

Classification

Classification distinguishes one kind of traffic from another by examining the fields in the packet header. When a packet is received, the switch examines the header and identifies all key packet fields. A packet can be classified based on an ACL, on the DSCP, the CoS, or the IP precedence value in the packet, or by the VLAN ID. Figure 2-3 has examples of classification information carried in a Layer 2 or a Layer 3 IP packet header, using six bits from the deprecated IP type of service (ToS) field to carry the classification information.

- On ports configured as Layer 2 IEEE 802.1Q trunks, all traffic is in 802.1Q frames except for traffic in the native VLAN. Layer 2 802.1Q frame headers have a 2-byte Tag Control Information field that carries the CoS value, called the User Priority bits, in the three most-significant bits, and the VLAN ID value in the 12 least-significant bits. Other frame types cannot carry Layer 2 CoS values.

Layer 2 CoS values range from 0 to 7.

- Layer 3 IP packets can carry either an IP precedence value or a DSCP value. QoS supports the use of either value because DSCP values are backward-compatible with IP precedence values.

IP precedence values range from 0 to 7. DSCP values range from 0 to 63.

- Output remarking is based on the Layer 2 or Layer 3 marking type, marking value and packet type.

Figure 2-3 QoS Classification Layers in Frames and Packets

These sections contain additional information about classification:

- Class Maps

- The match Command

- Classification Based on Layer 2 CoS

- Classification Based on IP Precedence

- Classification Based on IP DSCP

- Classification Comparisons

- Classification Based on QoS ACLs

- Classification Based on QoS Groups

- Classification Based on VLAN IDs

Class Maps

As explained previously, you use an MQC class map to name a specific traffic flow (or class) and to isolate it from all other traffic. A class map defines the criteria used to match against a specific traffic flow to further classify it. If you have more than one type of traffic that you want to classify, you can create another class map and use a different name. When you enter the class-map command with a class-map name, the switch enters the class-map configuration mode. In this mode, you define the match criterion for the traffic by using the match class-map configuration command. After a packet is matched against the class-map criteria, it is acted on by the associated action specified in a policy map.

You can match more than one criterion for classification. You can also create a class map that requires that all matching criteria in the class map be in the packet header by using the class map match-all class-map name global configuration command to enter class map configuration mode.

Note You can configure only one match entry in a match-all class map.

You can use the class map match-any class-map name global configuration command to define a classification with any of the listed criteria.

Note If you do not enter match-all or match-any, the default is to match all. A match-all class map cannot have more than one classification criterion (match statement). A class map with no match condition has a default of match all.

The match Command

To configure the type of content used to classify packets, you use the match class-map configuration command to specify the classification criteria. If a packet matches the configured criteria, it belongs to a specific class and is forwarded according to the specified policy. For example, you can use the match class-map command with CoS, IP DSCP, and IP precedence values. These values are referred to as markings on a packet. You can also match an access group, a QoS group, or a VLAN ID or ID range for per-port, per-VLAN QoS.

- For an input policy map, you cannot configure an IP classification ( match ip dscp , match ip precedence , match access-group for an IP ACL) and a non-IP classification ( match cos or match access-group for a MAC ACL) in the same policy map or class map.

- When an input policy map with only Layer 2 classification is attached to a routed port or a switch port containing a routed switch virtual interface (SVI), the service policy acts only on switching eligible traffic and not on routing eligible traffic.

- On an 802.1Q tunnel port, you can use only an input policy map with Layer 2 classification based on MAC ACLs to classify traffic. Input policy maps with Layer 3 classification, match Layer 2 CoS classification, or per-port, per-VLAN policies are not supported on tunnel ports.

- In an output policy map, no two class maps can have the same classification criteria, that is, the same match qualifiers and values.

This example shows how to create a class map example to define a class that matches any of the listed criteria. In this example, if a packet is received with the DSCP equal to 32 or a 40, the packet is identified (classified) by the class map.

Switch(config)# class-map match-any example

Switch(config-cmap)# match ip dscp 32

Switch(config-cmap)# match ip dscp 40

Switch(config-cmap)# exit

Classification Based on Layer 2 CoS

You can use the match command to classify Layer 2 traffic based on the CoS value, which ranges from 0 to 7.

Note A match cos command is supported only on Layer 2 802.1Q trunk ports.

This example shows how to create a class map to match a CoS value of 5:

Switch(config)# class-map premium

Switch(config-cmap)# match cos 5

Switch(config-cmap)# exit

Classification Based on IP Precedence

You can classify IPv4 traffic based on the packet IP precedence values, which range from 0 to 7.

This example shows how to create a class map to match an IP precedence value of 4:

Switch(config)# class-map sample

Switch(config-cmap)# match ip precedence 4

Switch(config-cmap)# exit

Classification Based on IP DSCP

When you classify IPv4 traffic based on IP DSCP value, and enter the match ip dscp class-map configuration command, you have several classification options:

- Entering a specific DSCP value (0 to 63).

- Using the Default service, which corresponds to an IP precedence and DSCP value of 0. The default per-hop behavior (PHB) is usually best-effort service.

- Using Assured Forwarding (AF) by entering the binary representation of the DSCP value. AF sets the relative probability that a specific class of packets is forwarded when congestion occurs and the traffic does not exceed the maximum permitted rate. AF per-hop behavior provides delivery of IP packets in four different AF classes: AF11-13 (the highest), AF21-23, AF31-33, and AF41-43 (the lowest). Each AF class could be allocated a specific amount of buffer space and drop probabilities, specified by the binary form of the DSCP number. When congestion occurs, the drop precedence of a packet determines the relative importance of the packet within the class. An AF41 provides the best probability of a packet being forwarded from one end of the network to the other.

- Entering Class Selector (CS) service values of 1 to 7, corresponding to IP precedence bits in the ToS field of the packet.

- Using Expedited Forwarding (EF) to specify a low-latency path. This corresponds to a DSCP value of 46. EF services use priority queuing to preempt lower priority traffic classes.

This display shows the available classification options:

Switch(config-cmap)# match ip dscp ?

<0-63> Differentiated services codepoint value

af11 Match packets with AF11 dscp (001010)

af12 Match packets with AF12 dscp (001100)

af13 Match packets with AF13 dscp (001110)

af21 Match packets with AF21 dscp (010010)

af22 Match packets with AF22 dscp (010100)

af23 Match packets with AF23 dscp (010110)

af31 Match packets with AF31 dscp (011010)

af32 Match packets with AF32 dscp (011100)

af33 Match packets with AF33 dscp (011110)

af41 Match packets with AF41 dscp (100010)

af42 Match packets with AF42 dscp (100100)

af43 Match packets with AF43 dscp (100110)

cs1 Match packets with CS1(precedence 1) dscp (001000)

cs2 Match packets with CS2(precedence 2) dscp (010000)

cs3 Match packets with CS3(precedence 3) dscp (011000)

cs4 Match packets with CS4(precedence 4) dscp (100000)

cs5 Match packets with CS5(precedence 5) dscp (101000)

cs6 Match packets with CS6(precedence 6) dscp (110000)

cs7 Match packets with CS7(precedence 7) dscp (111000)

default Match packets with default dscp (000000)

ef Match packets with EF dscp (101110)

For more information on DSCP prioritization, see RFC-2597 (AF per-hop behavior), RFC-2598 (EF), or RFC-2475 (DSCP).

Classification Comparisons

Table 2-1 shows suggested IP DSCP, IP precedence, and CoS values for typical traffic types.

Table 2-1 Typical Traffic Classifications

Traffic Type

DSCP per-hop

DSCP (decimal)

IP Precedence

CoS

Voice-bearer—Traffic in a priority queue or the queue with the highest service weight and lowest drop priority.

EF

46

5

5

Voice control—Signaling traffic, related to call setup, from a voice gateway or a voice application server.

AF31

26

3

3

Video conferencing—In most networks, video conferencing over IP has similar loss, delay, and delay variation requirements as voice over IP traffic.

AF41

34

4

4

Streaming video—Relatively high bandwidth applications with a high tolerance for loss, delay, and delay variation. Usually considered more important than regular background applications such as e-mail and web browsing.

AF13

14

1

1

Mission critical data (gold data)—Delay-sensitive applications critical to the operation of an enterprise.

Level 1

Level 2

Level 3

AF21

AF22

AF23

18

20

22

2

2

2

2

2

2

Less critical data (silver data)—Noncritical, but relatively important data.

Level 1

Level 2

Level 3

AF11

AF12

AF13

10

12

14

1

1

1

1

1

1

Best-effort data (bronze data)—Other traffic, including all noninteractive traffic, regardless of importance.

Default

0

0

0

Less than best-effort data—Noncritical, bandwidth-intensive data traffic given the least preference. This is the first traffic type to be dropped.

Level 1

Level 2

Level 3

2

4

6

0

0

0

0

0

0

Classification Based on QoS ACLs

Packets can also be classified in input policy maps based on an ACL lookup. The ACL classification is communicated to an output policy by assigning a QoS group or number in the input policy map. To classify based on ACL lookup, you first create an IP or MAC ACL. Configure a class map and use the match access-group { acl-number | acl name } class-map configuration command, and attach the class map to a policy map.

Note You cannot configure match access-group for an output policy map.

You can use IP standard, IP extended, or Layer 2 MAC ACLs to define a group of packets with the same characteristics (a class). You use the access-list global configuration command to configure IP ACLS to classify IP traffic based on Layer 3 and Layer 4 parameters. You use the mac access-list extended global configuration command to configure Layer 2 MAC ACLs to classify IP and non-IP traffic based on Layer 2 parameters.

Note You cannot match IP fragments against configured IP extended ACLs to enforce QoS. IP fragments are sent as best-effort. IP fragments are denoted by fields in the IP header.

You can use only ACLs with a permit action in a match access-group command. ACLs with a deny action are never matched in a QoS policy.

Note Only one access-group is supported per class for an input policy map.

Classification Based on QoS Groups

A QoS group is an internal label used by the switch to identify packets as a members of a specific class. The label is not part of the packet header and is restricted to the switch that sets the label. QoS groups provide a way to tag a packet for subsequent QoS action without explicitly marking (changing) the packet. You can then communicate an ACL match from an input policy map to an output policy map. The switch supports a maximum of 100 QoS groups.

A QoS group is identified at ingress and used at egress; it is assigned in an input policy to identify packets in an output policy. See Figure 2-4. The QoS groups help aggregate different classes of input traffic for a specific action in an output policy.

Figure 2-4 QoS Groups

You can use QoS groups to aggregate multiple input streams across input classes and policy maps for the same QoS treatment on the egress port. Assign the same QoS group number in the input policy map to all streams that require the same egress treatment, and match to the QoS group number in the output policy map to specify the required queuing and scheduling actions.

You can also use QoS groups to identify traffic entering a particular interface if the traffic must be treated differently at the output based on the input interface.

You can use QoS groups to configure per-port, per-VLAN QoS output policies on the egress interface for bridged traffic on the VLAN. Assign a QoS group number to a VLAN on the ingress interface by configuring a per-port, per-VLAN input policy. Then use the same QoS-group number for classification at the egress. Because the VLAN of bridged traffic does not change during forwarding through the switch, the QoS-group number assigned to the ingress VLAN can be used on the egress interface to identify the same VLAN.

You can use the cpu traffic qos [ cos value | dscp value | precedence value | qos-group value ] global configuration command to configure a QoS group number for CPU-generated traffic.

Independently you can assign QoS-group numbers at the ingress to any combination of interfaces, VLANs, traffic flows, and aggregated traffic. To assign QoS-group numbers, configure a QoS group marking in an input policy map, along with any other marking or policing actions required in the input policy map for the same service class. This allows the input marking and policing functions to be decoupled from the egress classification function if necessary because only the QoS group must be used for egress classification.

To communicate an ACL classification to an output policy, you assign a QoS number to specify packets at ingress. This example identifies specific packets as part of QoS group 1 for later processing in an output policy:

Switch(config)# policy-map in-gold-policy

Switch(config-pmap)# class in-class1

Switch(config-pmap-c)# set qos-group 1

Switch(config-cmap-c)# exit

Switch(config-cmap)# exit

You use the set qos-group command only in an input policy. The assigned QoS group identification is subsequently used in an output policy with no mark or change to the packet. You use the match qos-group in the output policy.

Note You cannot configure match qos-group for an input policy map.

This example creates an output policy to match the QoS group created in the input policy map in-gold-policy . Traffic internally tagged as qos-group 1 is identified and processed by the output policy.

Switch(config)# class-map out-class1

Switch(config-cmap)# match qos-group 1

Switch(config-cmap)# exit

Classification Based on VLAN IDs

With classification based on VLAN IDs, you can apply QoS policies to frames carried on a user-specified VLAN for a given interface. You can use hierarchical policy maps for per-VLAN classification on trunk ports. Per-VLAN classification is not required on access ports because access ports carry traffic for a single VLAN. If you try to attach an input per-port, per VLAN hierarchical policy to a port that is not a trunk port, the configuration is rejected.

The switch supports two policy levels: a parent level and a child level. With the QoS parent-child structure, you can reference a child policy in a parent policy to provide additional control of a specific traffic type. For per-port, per-VLAN QoS, the parent-level class map specifies only the VLAN match criteria, and the child-level class maps provide more detailed classification for frames matching the parent-level class map.You can configure multiple service classes at the parent level to match different combinations of VLANs, and you can apply independent QoS policies to each parent service class using any child policy map.

Note A per-port, per-VLAN parent-level class map supports only a child-policy association; it does not allow any actions to be configured. In addition, for a parent-level class map, you cannot configure an action or a child-policy association for the class class-default.

Per-port, per-VLAN QoS has these limitations:

- You can apply a per-port, per-VLAN hierarchical policy map only to trunk ports.

- You can configure classification based on VLAN ID only in the parent level of a per-port, per-VLAN hierarchical policy map.

- When the child policy map attached to a VLAN or set of VLANs contains only Layer 3 classification ( match ip dscp , match ip precedence , match IP ACL ), you must be careful to ensure that these VLANs are not carried on any port other than the one on which this per-port, per-VLAN policy is attached. Not following this restriction could result in improper QoS behavior for traffic ingressing the switch on these VLANs.

- We also recommend that you restrict VLAN membership on the trunk ports to which the per-port, per-VLAN is applied by using the switchport trunk allowed vlan interface configuration command. Overlapping VLAN membership between trunk ports that have per-port, per-VLAN policies with Layer 3 classification could also result in unexpected QoS behavior.

In this example, the class maps in the child-level policy map specify matching criteria for voice, data, and video traffic, and the child policy map sets the action for input policing each type of traffic. The parent-level policy map specifies the VLANs to which the child policy maps are applied on the specified port.

Switch(config)# class-map match-any dscp-1 data

Switch(config-cmap)# match ip dscp 1

Switch(config-cmap)# exit

Switch(config)# class-map match-any dscp-23 video

Switch(config-cmap)# match ip dscp 23

Switch(config-cmap)# exit

Switch(config)# class-map match-any dscp-63 voice

Switch(config-cmap)# match ip dscp-63

Switch(config-cmap)# exit

Switch(config)# class-map match-any customer-1-vlan

Switch(config-cmap)# match vlan 100

Switch(config-cmap)# match vlan 200

Switch(config-cmap)# match vlan 300

Switch(config-cmap)# exit

Note You can also enter the match criteria as match vlan 100 200 300 with the same result.

Switch(config)# policy-map child policy-1

Switch(config-pmap)# class dscp-63 voice

Switch(config-pmap-c)# police cir 10000000 bc 50000

Switch(config-pmap-c)# conform-action set-cos-transmit 5

Switch(config-pmap-c)# exceed-action drop

Switch(config-pmap-c)# exit

Switch(config-pmap)# class dscp-1 data

Switch(config-pmap-c)# set cos 0

Switch(config-pmap-c)# exit

Switch(config-pmap)# class dscp-23 video

Switch(config-pmap-c)# set cos 4

Switch(config-pmap-c)# set ip precedence 4

Switch(config-pmap-c)# exit

Switch(config)# policy-map parent-customer-1

Switch(config-pmap)# class customer-1-vlan

Switch(config-pmap-c)# service-policy ingress-policy-1

Switch(config-pmap-c)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# switchport mode trunk

Switch(config-if)# service-policy input customer-1-ingress

Switch(config-pmap-c)# exit

Note Each per-port, per-VLAN parent policy class, except class-default, can have a child policy association.

See the “Configuring Per-Port Per-VLAN QoS with Hierarchical Input Policy Maps” section for configuration information, including configuration guidelines and limitations.

Table Maps

You can use table maps to manage a large number of traffic flows with a single command. You can specify table maps in set commands and use them as mark-down mapping for the policers. You can also use table maps to map an incoming QoS marking to a replacement marking without having to configure a large number of explicit matches and sets. Table maps are used only in input policy maps.

Table maps can be used to:

- Correlate specific CoS, DSCP, or IP precedence values to specific CoS, DSCP, or IP precedence values

- Mark down a CoS, DSCP, or IP precedence value

- Assign defaults for unmapped values

A table map includes one of these default actions:

- default default-value —applies a specific default value (0 to 63) for all unmapped values

- default copy —maps all unmapped values to the equivalent value in another qualifier

- default ignore —makes no changes for unmapped values

This example creates a table to map specific CoS values to DSCP values. The default command maps all unmapped CoS values to a DSCP value of 63.

Switch(config)# table-map cos-dscp-tablemap

Switch(config-tablemap)# map from 5 to 46

Switch(config-tablemap)# map from 6 to 56

Switch(config-tablemap)# map from 7 to 57

Switch(config-tablemap)# default 63

Switch(config-tablemap)# exit

The switch supports a maximum of 256 unique table maps. You can enter up to 64 different map from – to entries in a table map. These table maps are supported on the switch:

- DSCP to CoS

- DSCP to precedence

- DSCP to DSCP

- CoS to DSCP

- CoS to precedence

- CoS to CoS

- Precedence to CoS

- Precedence to DSCP

- Precedence to precedence

Table maps modify only one parameter (CoS, IP precedence, or DSCP, whichever is configured) and are only effective when configured with a set command in a policy map or police function. Individual policers also support the violate-action command, but aggregate policers do not support table maps with violate-action .

Table maps are not supported in output policy maps. For more information, set the “Configuring Table Maps” section.

Policing

After a packet is classified, you can use policing as shown in Figure 2-5 to regulate the class of traffic. The policing function limits the amount of bandwidth available to a specific traffic flow or prevents a traffic type from using excessive bandwidth and system resources. A policer identifies a packet as in or out of profile by comparing the rate of the inbound traffic to the configuration profile of the policer and traffic class. Packets that exceed the permitted average rate or burst rate are out of profile or nonconforming . These packets are dropped or modified (marked for further processing), depending on the policer configuration.

Policing is used primarily on receiving interfaces. You can attach a policy map with a policer only in an input service policy. The only policing allowed in an output policy map is in priority classes. See the “Unconditional Priority Policing” section.

Figure 2-5 Policing of Classified Packets

These sections describe the types of policing supported on the switch:

- Individual Policing

- Aggregate Policing

- Unconditional Priority Policing

Individual Policing

Individual policing applies only to input policy maps. In policy-map configuration mode, you enter the class command followed by class-map name, and enter policy-map class configuration mode.

The switch supports 1-rate, 2-color ingress policing and 2-rate, 3-color policing for individual or aggregate policing.

For 1-rate, 2-color policing, you use the police policy-map class configuration command to define the policer, the committed rate limitations of the traffic, committed burst size limitations of the traffic, and the action to take for a class of traffic that is below the limits ( conform-action ) and above the limits ( exceed-action ). If you do not specify burst size (bc), the system calculates an appropriate burst size value. The calculated value is appropriate for most applications. For more information, see the “Attaching a Traffic Policy to an Interface” section.

When you configure a 2-rate policer, in addition to configuring the committed information rate (CIR) for updating the first token bucket, you also configure the peak information rate (PIR) at which the second token bucket is updated. If you do not configure a PIR, the policer is a standard 1-rate, 2-color policer.

For 2-rate, 3-color policing, you can then optionally set actions to perform on packets that conform to the specified CIR and PIR ( conform-action ), packets that conform to the PIR, but not the CIR ( exceed-action ), and packets that exceed the PIR value ( violate-action ).

- If you set the CIR value equal to the PIR, a traffic rate that is less than or equal to the CIR is in the conform range. Traffic that exceeds the CIR is in the violate range.

- If you set the PIR greater than the CIR, a traffic rate less than the CIR is in the conform range. A traffic rate that exceeds the CIR but is less than or equal to the PIR is in the exceed range. A traffic rate that exceeds the PIR is in the violate range.

- If you do not configure a PIR, the policer is configured as a 1-rate, 2-color policer.

Setting the burst sizes too low can reduce throughput in situations with bursty traffic. Setting burst sizes too high can allow too high a traffic rate.

Note The switch supports byte counters for byte-level statistics for conform, exceed, and violate classes in the show policy-map interface privileged EXEC command output.

To make the policy map effective, you attach it to a physical port by using the service-policy input interface configuration command. Policing is done only on received traffic, so you can only attach a policer to an input service policy.

This is an example of basic policing for all traffic received with a CoS of 4. The first value following the police command limits the average traffic rate to 10,000,000 bits per second (b/s); the second value represents the additional burst size (10 kilobytes). The policy is assigned to Fast Ethernet port 1.

Switch(config)# class-map video-class

Switch(config-cmap)# match cos 4

Switch(config-cmap)# exit

Switch(config)# policy-map video-policy

Switch(config-pmap)# class video-class

Switch(config-pmap-c)# police 10000000 10000

Switch(config-pmap-c-police)# exit

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy input video-policy

Switch(config-if)# exit

You can use the conform-action , exceed-action , and violate-action policy-map class configuration commands or the conform-action , exceed-action , and violate-action policy-map class police configuration commands to specify the action to be taken when the packet conforms to or exceeds the specified traffic rates. Conform, exceed, and violate actions are to drop the packet, to send the packet without modifications, to set a new CoS, DSCP, or IP precedence value, or to set a QoS group value for classification at the egress.

You can configure each marking action by using explicit values, table maps, or a combination of both. Table maps list specific traffic attributes and map (or convert) them to other attributes.

You can configure multiple conform, exceed, and violate actions simultaneously for each service class. If you do not configure a violate action, by default the violate class is assigned the same action as the exceed action.

After you create a table map, you configure a policy map policer to use the table map.

Note When you use a table map in an input policy map, the protocol type for the from–action in the table map must be the same as the protocol type of the associated classification. For example, if a class map represents IP classification, the from–type action in the table map must be either dscp or precedence. If the class map represents a non-IP classification, the from–type action in the table map must be cos.

To configure multiple actions in a class, you can enter multiple conform, exceed, or violate action entries in policy-map class police configuration mode, as in this example:

Switch(config)# policy-map map1

Switch(config-pmap)# class class1

Switch(config-pmap-c)# police 100000 500000

Switch(config-pmap-c-police)# conform-action set-cos-transmit 4

Switch(config-pmap-c-police)# conform-action set-dscp-transmit dscp table conform-dscp-to-dscp-mutation

Switch(config-pmap-c-police)# conform-action set-qos-transmit 10

Switch(config-pmap-c-police)# exceed-action set-cos-transmit 2

Switch(config-pmap-c-police)# exceed-action set-dscp-transmit dscp table exceed-dscp-to-dscp-mutation

Switch(config-pmap-c-police)# exceed-action set-qos-transmit 20

Switch(config-pmap-c-police)# exit

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Aggregate Policing

Aggregate policing applies only to input policy maps. An aggregate policer differs from an individual policer because it is shared by multiple traffic classes within a policy map. The switch supports 1-rate, 2-color ingress policing and 2-rate, 3-color policing for aggregate policing.

You can use the policer aggregate global configuration command to set a policer for all traffic received or sent on a physical interface. When you configure an aggregate policer, you can configure specific burst sizes and conform and exceed actions. If you do not specify burst size ( bc ), the system calculates an appropriate burst size value. The calculated value is appropriate for most applications.

When you configure a 2-rate policer, in addition to configuring the committed information rate (CIR) for updating the first token bucket, you also configure the peak information rate (PIR) at which the second token bucket is updated. If you do not configure a PIR, the policer is a standard 1-rate, 2-color policer.

For 2-rate, 3-color policing, you can then optionally set actions to perform on packets that conform to the specified CIR and PIR ( conform-action ), packets that conform to the PIR, but not the CIR ( exceed-action ), and packets that exceed the PIR value ( violate-action ).

Note If the conform action is set to drop, the exceed and violate actions are automatically set to drop. If the exceed action is set to drop, the violate action is automatically set to drop.

- If you set the CIR value equal to the PIR, a traffic rate that is less than or equal to the CIR is in the conform range. Traffic that exceeds the CIR is in the violate range.

- If you set the PIR greater than the CIR, a traffic rate less than the CIR is in the conform range. A traffic rate that exceeds the CIR but is less than or equal to the PIR is in the exceed range. A traffic rate that exceeds the PIR is in the violate range.

- If you do not configure PIR, the policer is configured as a 1-rate, 2-color policer.

Setting the burst sizes too low can result in less traffic than expected. Setting burst sizes too high can result in more traffic than expected.

You can configure multiple conform, exceed, and violate actions simultaneously for each service class. You can use the conform-action , exceed-action , and violate-action policy-map class configuration commands or the conform-action , exceed-action , and violate-action policy-map class police configuration commands to specify the action to be taken when the packet conforms to or exceeds the specified traffic rates. Conform, exceed, and violate actions are to drop the packet, to send the packet without modifications, to set a new CoS, DSCP, or IP precedence value, or to set a QoS group value for classification at the egress.

Note If the conform action is set to drop, the exceed and violate actions are automatically set to drop. If the exceed action is set to drop, the violate action is automatically set to drop.

You can configure each marking conform, exceed, or violate action by using explicit values, using table maps, or using a combination of both. If you do not configure a violate action, by default the violate class is assigned the same action as the exceed action.

Table maps list specific traffic attributes and map (or convert) them to other attributes. Table maps are not supported for violate-action for aggregate policing unless you configure a table map for exceed-action and no explicit action is configured for violate-action .

After you create a table map, you configure a policy map policer to use the table map.

Note When you use a table map in an input policy map, the protocol type for the from–action in the table map must be the same as the protocol type of the associated classification. For example, if a class map represents IP classification, the from–type action in the table map must be either dscp or precedence. If the class map represents a non-IP classification, the from–type action in the table map must be cos.

You can configure multiple conform, exceed, and violate actions simultaneously for an aggregate policer as parameters in the policer aggregate global configuration command, but you must enter the actions in a particular order. See the configuration guideline in the “Configuring Input Policy Maps with Aggregate Policing” section.

After you configure the aggregate policer, you create a policy map and an associated class map, associate the policy map with the aggregate policer, and apply the service policy to a port.

Note Only one policy map can use any specific aggregate policer. Aggregate policing cannot be used to aggregate traffic streams across multiple interfaces. It can be used only to aggregate traffic streams across multiple classes in a policy map attached to an interface and aggregate streams across VLANs on a port in a per-port, per-VLAN policy map.

After you configure the policy map and policing actions, attach the policy to an ingress port by using the service-policy interface configuration command.

The class maps in this example refer to access lists:

Switch(config)# policer aggregate agg1 cir 23000 bc 10000 conform-action set-dscp-transmit 46 exceed-action drop

Switch(config)# class-map testclass

Switch(config-cmap)# match access-group 1

Switch(config-cmap)# exit

Switch(config)# class-map videoclass

Switch(config-cmap)# match access-group 2

Switch(config-cmap)# exit

Switch(config)# policy-map testexample

Switch(config-pmap)# class testclass

Switch(config-pmap-c)# police aggregate agg1

Switch(config-pmap-c)# exit

Switch(config-pmap)# class video-class

Switch(config-pmap-c)# police aggregate agg1

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy input testexample

Switch(config-if)# exit

For configuration information, see the “Configuring Input Policy Maps with Aggregate Policing” section.

You can also use aggregate policing to regulate traffic streams across VLANs, as in this example:

Switch(config)# policer aggregate agg1 cir 23000 bc 10000 conform-action set-dscp-transmit af31 set-cos-transmit 3 exceed-action set-dscp-transmit af11 set-cos-transmit 1

Switch(config)# class-map video-provider-1

Switch(config-cmap)# match access-group 1

Switch(config-cmap)# exit

Switch(config)# class-map video-provider-2

Switch(config-cmap)# match access-group 2

Switch(config-cmap)# exit

Switch(config)# class-map match-any customer1-provider-100

Switch(config-cmap)# match vlan 100

Switch(config-cmap)# exit

Switch(config)# class-map match-any customer1-provider-200

Switch(config-cmap)# match vlan 200

Switch(config-cmap)# exit

Switch(config)# policy-map child-policy-1

Switch(config-pmap)# class video-provider-1

Switch(config-pmap-c)# set dscp af41

Switch(config-pmap-c)# exit

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# police aggregate agg1

Switch(config-pmap-c)# exit

Switch(config)# policy-map child-policy-2

Switch(config-pmap)# class video-provider-2

Switch(config-pmap-c)# set dscp cs4

Switch(config-pmap-c)# exit

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# police aggregate agg1

Switch(config-pmap-c)# exit

Switch(config)# policy-map customer-1-ingress

Switch(config-pmap)# class customer1-provider-100

Switch(config-pmap-c)# service-policy child-policy-1

Switch(config-pmap-c)# exit

Switch(config-pmap)# class customer1-provider-200

Switch(config-pmap-c)# service-policy child-policy-2

Switch(config-pmap-c)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# switchport mode trunk

Switch(config-if)# service-policy input customer-1-ingress

Switch(config-pmap-c)# exit

Unconditional Priority Policing

Priority policing applies only to output policy maps. You can use the priority policy-map class configuration command in an output policy map to designate a low-latency path, or class-based priority queuing, for a specific traffic class. With strict priority queuing, the packets in the priority queue are scheduled and sent until the queue is empty, at the expense of other queues. Excessive use of high-priority queuing can create congestion for lower priority traffic.

To eliminate this congestion, you can use the priority with police feature (priority policing) to reduce the bandwidth used by the priority queue and allocate traffic rates on other queues. Priority with police is the only form of policing supported in output policy maps.

Note You can configure 1-rate, 2-color policers for output policy maps with priority. You cannot configure 2-rate, 3-color policers for output policies.

See also the “Configuring Output Policy Maps with Class-Based Priority Queuing” section.

Note You cannot configure a policer committed burst size for an unconditional priority policer. Any configured burst size is ignored.

This example shows how to use the priority with police commands to configure out-class1 as the priority queue, with traffic going to the queue limited to 20,000,000 b/s so that the priority queue never uses more than that. Traffic above that rate is dropped. This allows other traffic queues to receive some port bandwidth, in this case a minimum bandwidth guarantee of 500,000 and 200,000 kb/s. The class class-default queue gets the remaining port bandwidth.

Switch(config)# policy-map policy1

Switch(config-pmap)# class out-class1

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# police 200000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class out-class2

Switch(config-pmap-c)# bandwidth 500000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class out-class3

Switch(config-pmap-c)# bandwidth 200000

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface gigabitethernet0/1

Switch(config-if)# service-policy output policy1

Switch(config-if)# exit

Marking

You can use packet marking in input policy maps to set or modify the attributes for traffic belonging to a specific class. After network traffic is organized into classes, you use marking to identify certain traffic types for unique handling. For example, you can change the CoS value in a class or set IP DSCP or IP precedence values for a specific type of traffic. These new values are then used to determine how the traffic should be treated. You can also use marking to assign traffic to a QoS group within the switch.

Traffic marking is typically performed on a specific traffic type at the ingress port. The marking action can cause the CoS, DSCP, or precedence bits to be rewritten or left unchanged, depending on the configuration. This can increase or decrease the priority of a packet in accordance with the policy used in the QoS domain so that other QoS functions can use the marking information to judge the relative and absolute importance of the packet. The marking function can use information from the policing function or directly from the classification function.

You can specify and mark traffic by using the set commands in a policy map for all supported QoS markings (CoS, IP DSCP, IP precedence, and QoS groups). A set command unconditionally marks the packets that match a specific class. You then attach the policy map to an interface as an input policy map.

You can also mark traffic by using the set command with table maps.Table maps list specific traffic attributes and maps (or converts) them to another attribute. A table map establishes a to-from relationship for the attribute and defines the change to be made.

You can simultaneously configure actions to modify DSCP, precedence, and COS markings in the packet for the same service along with QoS group marking actions. You can use the QoS group number defined in the marking action for egress classification.

Note When you use a table map in an input policy map, the protocol type of the from-type action in the table map must be the same as the protocol type of the associated classification. For example, if a class map represents an IP classification, the from-type action in the table map must be either dscp or precedence. If the class map represents a non-IP classification, the from-type action in the table map must be cos.

After you create a table map, you configure a policy map to use the table map. See the “Congestion Management and Scheduling” section. Figure 2-6 shows the steps for marking traffic.

Figure 2-6 Marking of Classified Traffic

This example uses a policy map to remark a packet. The first marking (the set command) applies to the QoS default class map that matches all traffic not matched by class AF31-AF33 and sets all traffic to an IP DSCP value of 1. The second marking sets the traffic in classes AF31 to AF33 to an IP DSCP of 3.

Switch(config)# policy-map Example

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# set ip dscp 1

Switch(config-pmap-c)# exit

Switch(config-pmap)# class AF31-AF33

Switch(config-pmap-c)# set ip dscp 3

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy input Example

Switch(config-if)# exit

QoS Treatment for Performance-Monitoring Protocols

- Cisco IP-SLAs

- QoS Treatment for IP-SLA and TWAMP Probes

- QoS Marking for CPU-Generated Traffic

- QoS Queuing for CPU-Generated Traffic

Cisco IP-SLAs

For information about Cisco IP service level agreements (IP-SLAs), see the chapter “Information About Cisco IOS IP SLAs” in the System Management Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches .

QoS Treatment for IP-SLA and TWAMP Probes

The QoS treatment for IP-SLA and TWAMP probes must exactly reflect the effects that occur to the normal data traffic crossing the device.

The generating device should not change the probe markings. It should queue these probes based on the configured queueing policies for normal traffic.

Marking

By default, the class of service (CoS) marking of CFM traffic (including IP SLAs using CFM probes) is not changed. This feature cannot change this behavior.

By default, IP traffic marking (including IP SLA and TWAMP probes) is not changed. This feature can change this behavior.

Queuing

The CFM traffic (including IP SLAs using CFM probes) is queued according to its CoS value and the output policy map configured on the egress port, similar to normal traffic. This feature cannot change this behavior.

IP traffic (including IP SLA and TWAMP probes) is queued according to the markings specified in the cpu traffic qos global configuration command and the output policy map on the egress port. If this command is not configured, all IP traffic is statically mapped to a queue on the egress port.

QoS Marking for CPU-Generated Traffic

You can use QoS marking to set or modify the attributes of traffic from the CPU. The QoS marking action can cause the CoS, DSCP, or IP precedence bits in the packet to be rewritten or left unchanged. QoS uses packet markings to identify certain traffic types and how to treat them on the local switch and the network.

You can also use marking to assign traffic to a QoS group within the switch. This QoS group is an internal label that does not modify the packet, but it can be used to identify the traffic type when configuring egress queuing on the network port.

You can specify and mark traffic CPU-generated traffic by using these global configuration commands:

cpu traffic qos cos { cos_value | cos [ table-map table-map-name ] | dscp [ table-ma p table-map-name ] | precedence [ table-map table-map-name ]}

cpu traffic qos dscp { dscp_value | cos [ table-map table-map-name ] | dscp [ table-map table-map-name ] | precedence [ table-map table-map-name ]}

cpu traffic qos precedence { precedence_value | cos [ table-map table-map-name ] | dscp [ table-map table-map-name ] | precedence [ table-map table-map-name ]}

cpu traffic qos qos-group value

You can mark CoS, IP-DSCP, IP precedence, and QoS group by configuring an explicit value or by using the table-map keyword. Table maps list specific traffic attributes and map (or convert) them to another attribute. A table map establishes a to-from relationship for the attribute and defines the change to be made:

- Marking CoS by using the CoS, or the IP-DSCP, or the IP precedence of IP CPU-packets

- Marking CoS by using the CoS of non-IP CPU-packets

- Marking IP DSCP by using the CoS, or the IP-DSCP, or the IP precedence of the CPU-packet

- Marking IP precedence by using the CoS, or the IP-DSCP, or the IP precedence of the CPU-packet

You can configure either IP-DSCP or IP precedence marking.

You can also simultaneously configure marking actions to modify CoS, IP-DSCP or IP precedence, and QoS group.

The cpu traffic qos command specifies the traffic to which it applies: all CPU traffic, only CPU IP traffic, or only CPU non-IP traffic. All other traffic retains its QoS markings. This feature does not affect CFM traffic (including Layer 2 IP SLA probes using CFM).

Note The switch provides the ability to mark CoS, IP-DSCP and IP precedence of CPU-generated traffic by using table maps.

QoS Queuing for CPU-Generated Traffic

You can use the QoS markings established for the CPU-generated traffic by the cpu traffic qos global configuration command as packet identifiers in the class-map of an output policy map to map CPU traffic to class queues in the output policy map on the egress port. You can then use output policy maps on the egress port to configure queuing and scheduling for traffic leaving the switch from that port.

If you want to map all CPU-generated traffic to a single class in the output policy maps without changing the CoS, IP DSCP, or IP-precedence packet markings, you can use QoS groups for marking CPU-generated traffic.

If you want to map all CPU-generated IP traffic to classes in the output policy maps based on IP-DSCP or IP precedence without changing those packet markings, you can use a table map:

- Configure IP-DSCP or IP precedence marking by using DSCP or precedence as the map from value without a table map.

- Configure IP-DSCP or IP-precedence marking by using DSCP or precedence as the map from value with a table map, using only the default and copy keywords.

If you want to map all CPU-generated traffic to classes in the output policy maps based on the CoS without changing the CoS packet markings, you can use the table map:

- Configure CoS marking by using CoS as the map from value without a table map.

- Configure CoS marking using CoS as the map from value with a table map, using only the default and copy keywords.

For details about table maps, see the “Table Maps” section.

Using the cpu traffic qos global configuration command with table mapping, you can configure multiple marking and queuing policies to work together or independently. You can queue native VLAN traffic based on the CoS markings configured using the cpu traffic qos global configuration command.

The cpu traffic qos command specifies the traffic to which it applies: all CPU traffic, only CPU-IP traffic, or only CPU non-IP traffic. All other traffic is statically mapped to a CPU-default queue on the egress port. All CFM traffic (including Layer 2 IP SLA probes using CFM) is mapped to classes in the output policy map and queued based on their CoS value.

Note The switch provides the ability to queue based on the CoS, IP-DSCP, and IP precedence of CPU-generated traffic.

Congestion Management and Scheduling

Cisco Modular QoS CLI (MQC) provides several related mechanisms to control outgoing traffic flow. They are implemented in output policy maps to control output traffic queues. The scheduling stage holds packets until the appropriate time to send them to one of the four traffic queues. Queuing assigns a packet to a particular queue based on the packet class, and is enhanced by the WTD algorithm for congestion avoidance. You can use different scheduling mechanisms to provide a guaranteed bandwidth to a particular class of traffic while also serving other traffic in a fair way. You can limit the maximum bandwidth that can be consumed by a particular class of traffic and ensure that delay-sensitive traffic in a low-latency queue is sent before traffic in other queues.

The switch supports these scheduling mechanisms:

- Traffic shaping

You use the shape average policy map class configuration command to specify that a class of traffic should have a maximum permitted average rate. You specify the maximum rate in bits per second.

- Class-based-weighted-fair-queuing (CBWFQ)

You can use the bandwidth policy-map class configuration command to control the bandwidth allocated to a specific class. Minimum bandwidth can be specified as a bit rate or a percentage of total bandwidth or of remaining bandwidth.

- Priority queuing or class-based priority queuing

You use the priority policy-map class configuration command to specify the priority of a type of traffic over other types of traffic. You can specify strict priority for the high-priority traffic and allocate any excess bandwidth to other traffic queues, or specify priority with unconditional policing of high-priority traffic and allocate the known remaining bandwidth among the other traffic queues.

– To configure strict priority, use only the priority policy-map class configuration command to configure the priority queue. Use the bandwidth remaining percent policy-map class configuration command for the other traffic classes to allocate the excess bandwidth in the desired ratios.

– To configure priority with unconditional policing, configure the priority queue by using the priority policy-map class configuration command and the police policy-map class configuration command to unconditionally rate-limit the priority queue. In this case, you can configure the other traffic classes with bandwidth or shape average , depending on requirements.

These sections contain additional information about scheduling:

- Traffic Shaping

- Class-Based Weighted Fair Queuing

- Priority Queuing

Traffic Shaping

Traffic shaping is a traffic-control mechanism similar to traffic policing. While traffic policing is used in input policy maps, traffic shaping occurs as traffic leaves an interface. The switch can apply class-based shaping to classes of traffic leaving an interface and port shaping to all traffic leaving an interface. Configuring a queue for traffic shaping sets the maximum bandwidth or peak information rate (PIR) of the queue.

Note You cannot configure traffic shaping (shape average) and CBWFQ (bandwidth) or priority queuing (priority) for the same class in an output policy map. You cannot configure traffic shaping for a traffic class when strict priority (priority without police) is configured for another class within the output policy map.

Class-Based Shaping

Class-based shaping uses the shape average policy-map class configuration command to limit the rate of data transmission as the number of bits per second to be used for the committed information rate for a class of traffic. The switch supports separate queues for three classes of traffic. The fourth queue is always the default queue for class class-default , unclassified traffic.

Note On the switch, configuring traffic shaping also automatically sets the minimum bandwidth guarantee or committed information rate (CIR) of the queue to the same value as the PIR.

This example shows how to configure traffic shaping for outgoing traffic on a Fast Ethernet port so that outclass1 , outclass2 , and outclass3 get a maximum of 50, 20, and 10 Mb/s, respectively, of the available port bandwidth. The class class-default at a minimum gets the remaining bandwidth.

Switch(config)# policy-map out-policy

Switch(config-pmap)# class classout1

Switch(config-pmap-c)# shape average 50000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class classout2

Switch(config-pmap-c)# shape average 20000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class classout3

Switch(config-pmap-c)# shape average 10000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet 0/1

Switch(config-if)# service-policy output out-policy

Switch(config-if)# exit

Port Shaping

To configure port shaping (a transmit port shaper), create a policy map that contains only a default class, and use the shape average command to specify the maximum bandwidth for a port.

This example shows how to configure a policy map that shapes a port to 90 Mb/s, allocated according to the out-policy policy map configured in the previous example. The service-policy policy map class command is used to create a child policy to the parent:

Switch(config)# policy-map out-policy-parent

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# shape average 90000000

Switch(config-pmap-c)# service-policy out-policy

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy output out-policy-parent

Switch(config-if)# exit

Parent-Child Hierarchy

The switch also supports parent policy levels and child policy levels for traffic shaping. The QoS parent-child structure is used for specific purposes where a child policy is referenced in a parent policy to provide additional control of a specific traffic type.

The first policy level, the parent level, is used for port shaping, and you can specific only one class of type class-default within the policy. This is an example of a parent-level policy map:

Switch(config)# policy-map parent

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# shape average 50000000

Switch(config-pmap-c)# exit

The second policy level, the child level, is used to control a specific traffic stream or class, as in this example:

Switch(config)# policy-map child

Switch(config-pmap)# class class1

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# exit

Note The total of the minimum bandwidth guarantees (CIR) for each queue of the child policy cannot exceed the total port-shape rate.

This is an example of a parent-child configuration:

Switch(config)# policy-map parent

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# shape average 50000000

Switch(config-pmap-c)# service-policy child

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy output parent

Switch(config-if)# exit

Class-Based Weighted Fair Queuing

You can configure class-based weighted fair queuing (CBWFQ) to set the relative precedence of a queue by allocating a portion of the total bandwidth that is available for the port. You use the bandwidth policy-map class configuration command to set the output bandwidth for a class of traffic as a rate (kilobits per second), a percentage of total bandwidth, or a percentage of remaining bandwidth.

Note When you configure bandwidth in a policy map, you must configure all rates in the same format, either a configured rate or a percentage. The total of the minimum bandwidth guarantees (CIR) for each queue of the policy cannot exceed the total speed of the parent.

- When you use the bandwidth policy-map class configuration command to configure a class of traffic as an absolute rate (kilobits per second) or a percentage of total bandwidth, this represents the minimum bandwidth guarantee (CIR) for that traffic class. This means that the traffic class gets at least the bandwidth indicated by the command, but is not limited to that bandwidth. Any excess bandwidth on the port is allocated to each class in the same ratio in which the CIR rates are configured.

Note You cannot configure bandwidth as an absolute rate or a percentage of total bandwidth when strict priority (priority without police) is configured for another class in the output policy.

- When you use the bandwidth policy-map class configuration command to configure a class of traffic as a percentage of remaining bandwidth, this represents the portion of the excess bandwidth of the port that is allocated to the class. This means that the class is allocated bandwidth only if there is excess bandwidth on the port, and if there is no minimum bandwidth guarantee for this traffic class.

Note You can configure bandwidth as percentage of remaining bandwidth only when strict priority (priority without police) is configured for another class in the output policy map.

For more information, see the “Configuring Output Policy Maps with Class-Based-Weighted-Queuing” section.

Note You cannot configure bandwidth and traffic shaping (shape average) or priority queuing (priority) for the same class in an output policy map.

This example shows how to set the precedence of output queues by setting bandwidth in kilobits per second. The classes outclass1 , outclass2 , and outclass3 and class-default get a minimum of 40000, 20000, 10000, and 10000 kb/s. Any excess bandwidth is divided among the classes in the same proportion as the CIR rated.

Switch(config)# policy-map out-policy

Switch(config-pmap)# class outclass1

Switch(config-pmap-c)# bandwidth 40000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class outclass2

Switch(config-pmap-c)# bandwidth 20000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class outclass3

Switch(config-pmap-c)# bandwidth 10000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# bandwidth 10000

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet 0/1

Switch(config-if)# service-policy output out-policy

Switch(config-if)# exit

Note When you configure CIR bandwidth for a class as an absolute rate or percentage of the total bandwidth, any excess bandwidth remaining after servicing the CIR of all the classes in the policy map is divided among the classes in the same proportion as the CIR rates. If the CIR rate of a class is configured as 0, that class is also not eligible for any excess bandwidth and as a result receives no bandwidth.

This example shows how to allocate the excess bandwidth among queues by configuring bandwidth for a traffic class as a percentage of remaining bandwidth. The class outclass1 is given priority queue treatment. The other classes are configured to get percentages of the excess bandwidth if any remains after servicing the priority queue: outclass2 is configured to get 50 percent, outclass3 to get 20 percent, and the class class-default to get the remaining 30 percent.

Switch(config)# policy-map out-policy

Switch(config-pmap)# class outclass1

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# exit

Switch(config-pmap)# class outclass2

Switch(config-pmap-c)# bandwidth remaining percent 50

Switch(config-pmap-c)# exit

Switch(config-pmap)# class outclass3

Switch(config-pmap-c)# bandwidth remaining percent 20

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet 0/1

Switch(config-if)# service-policy output out-policy

Switch(config-if)# exit

Priority Queuing

You can use the priority policy-map class configuration command to ensure that a particular class of traffic is given preferential treatment. With strict priority queuing, the priority queue is constantly serviced. All packets in the queue are scheduled and sent until the queue is empty. Priority queuing allows traffic for the associated class to be sent before packets in other queues are sent.

Note You should exercise care when using the priority command. Excessive use of strict priority queuing might cause congestion in other queues.

The switch supports strict priority queuing or priority used with the police policy-map command.

- Strict priority queuing (priority without police) assigns a traffic class to a low-latency queue to ensure that packets in this class have the lowest possible latency. When this is configured, the priority queue is continually serviced until it is empty, possibly at the expense of packets in other queues.

Note You cannot configure priority without policing for a traffic class when traffic shaping or CBWFQ are configured for another class in the same output policy map.

- You can use priority with the police policy-map command, or unconditional priority policing , to reduce the bandwidth used by the priority queue. This is the only form of policing that is supported in output policy maps. Using this combination of commands configures a maximum rate on the priority queue, and you can use the bandwidth and shape average policy-map commands for other classes to allocate traffic rates on other queues.

Note When priority is configured in an output policy map without the police command, you can only configure the other queues for sharing by using the bandwidth remaining percent policy-map command to allocate excess bandwidth.

Priority queuing has these restrictions:

- You can associate the priority command with a single unique class for all attached output polices on the switch.

- You cannot configure priority and any other scheduling action ( shape average or bandwidth ) in the same class.

- You cannot configure priority queuing for the class-default of an output policy map.

For more information, see the “Configuring Output Policy Maps with Class-Based Priority Queuing” section.

This example shows how to configure the class out-class1 as a strict priority queue so that all packets in that class are sent before any other class of traffic. Other traffic queues are configured so that out-class-2 gets 50 percent of the remaining bandwidth and out-class3 gets 20 percent of the remaining bandwidth. The class class-default receives the remaining 30 percent with no guarantees.

Switch(config)# policy-map policy1

Switch(config-pmap)# class out-class1

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# exit

Switch(config-pmap)# class out-class2

Switch(config-pmap-c)# bandwidth remaining percent 50

Switch(config-pmap-c)# exit

Switch(config-pmap)# class out-class3

Switch(config-pmap-c)# bandwidth remaining percent 20

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface gigabitethernet 0/1

Switch(config-if)# service-policy output policy1

Switch(config-if)# exit

This example shows how to use the priority with police commands to configure out-class1 as the priority queue, with traffic going to the queue limited to 20000000 b/s so that the priority queue will never use more than that. Traffic above that rate is dropped. The other traffic queues are configured to use 50 and 20 percent of the bandwidth that is left, as in the previous example.

Switch(config)# policy-map policy1

Switch(config-pmap)# class out-class1

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# police 200000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class out-class2

Switch(config-pmap-c)# bandwidth percent 50

Switch(config-pmap-c)# exit

Switch(config-pmap)# class out-class3

Switch(config-pmap-c)# bandwidth percent 20

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface gigabitethernet 0/1

Switch(config-if)# service-policy output policy1

Switch(config-if)# exit

Congestion Avoidance and Queuing

Congestion avoidance uses algorithms such as tail drop to control the number of packets entering the queuing and scheduling stage to avoid congestion and network bottlenecks. The switch uses weighted tail drop (WTD) to manage the queue sizes and provide a drop precedence for traffic classifications. You set the queue size limits depending on the markings of the packets in the queue. Each packet that travels through the switch can be assigned to a specific queue and threshold. For example, specific DSCP or CoS values can be mapped to a specific egress queue and threshold.

WTD is implemented on traffic queues to manage the queue size and to provide drop precedences for different traffic classifications. As a frame enters a particular queue, WTD uses the packet classification to subject it to different thresholds. If the total destination queue size is greater than the threshold of any reclassified traffic, the next frame of that traffic is dropped.

Figure 2-7 shows an example of WTD operating on a queue of 1000 frames. Three drop percentages are configured: 40 percent (400 frames), 60 percent (600 frames), and 100 percent (1000 frames). These percentages mean that traffic reclassified to the 40-percent threshold is dropped when the queue depth exceeds 400 frames, traffic reclassified to 60 percent is dropped when the queue depth exceeds 600 frames, and traffic up to 400 frames can be queued at the 40-percent threshold, up to 600 frames at the 60-percent threshold, and up to 1000 frames at the 100-percent threshold.

Figure 2-7 WTD and Queue Operation

In this example, CoS values 6 and 7 have a greater importance than the other CoS values, and they are assigned to the 100-percent drop threshold (queue-full state). CoS values 4 and 5 are assigned to the 60-percent threshold, and CoS values 0 to 3 are assigned to the 40-percent threshold.

If the queue is already filled with 600 frames, and a new frame arrives containing CoS values 4 and 5, the frame is subjected to the 60-percent threshold. When this frame is added to the queue, the threshold would be exceeded, so the switch drops it.

WTD is configured by using the queue-limit policy-map class command. The command adjusts the queue size (buffer size) associated with a particular class of traffic. You specify the threshold as the number of packets, where each packet is a fixed unit of 256 bytes. You can specify different queue sizes for different classes of traffic (CoS, DSCP, precedence, or QoS group) in the same queue. Setting a queue limit establishes a drop threshold for the associated traffic when congestion occurs.

Note You cannot configure queue size by using the queue-limit policy map class command without first configuring a scheduling action (bandwidth, shape average, or priority). The only exception to this is when you configure queue-limit for the class-default of an output policy map.

The switch supports up to three unique queue-limit configurations across all output policy maps. Within an output policy map, only four queues (classes) are allowed, including the class default. Each queue has three thresholds defined. Only three unique threshold value configurations are allowed on the switch. However, multiple policy maps can share the same queue-limits. When two policy maps a share queue-limit configuration, all threshold values must be the same for all the classes in both policy maps.

For more information, see the “Configuring Output Policy Maps with Class-Based-Weighted-Queuing” section.

This example configures class A to match DSCP values and a policy map, PM1 . The DSCP values of 30 and 50 are mapped to unique thresholds (32 and 64, respectively). The DSCP values of 40 and 60 are mapped to the maximum threshold of 112 packets.

Switch(config)# class-map match-any classA

Switch(config-cmap)# match ip dscp 30 40 50 60

Switch(config-cmap)# exit

Switch(config)# policy-map PM1

Switch(config-pmap)# class classA

Switch(config-pmap-c)# bandwidth percent 50

Switch(config-pmap-c)# queue-limit 112

Switch(config-pmap-c)# queue-limit dscp 30 32

Switch(config-pmap-c)# queue-limit dscp 50 64

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface gigabitethernet 0/1

Switch(config-if)# service-policy output PM1

Switch(config-if)# exit

You can use these same queue-limit values in multiple output policy maps on the switch. However, changing one of the queue-limit values in a class creates a new, unique queue-limit configuration. You can attach only three unique queue-limit configurations in output policy maps to interfaces at any one time. If you attempt to attach an output policy map with a fourth unique queue-limit configuration, you see this error message:

QoS: Configuration failed. Maximum number of allowable unique queue-limit configurations exceeded.

Note When you configure a queue limit for a class in an output policy map, all other output policy maps must use the same qualifier type and qualifier value format. Only the queue-limit threshold values can be different. For example, when you configure class A queue limit thresholds for dscp 30 and dscp 50 in policy map PM1, and you configure class A queue limits in policy map PM2, you must use dscp 30 and dscp 50 as qualifiers. You cannot use dscp 20 and dscp 40. The threshold values can be different, but different threshold values creates a new queue-limit configuration.

By default, the total amount of buffer space is divided equally among all ports and all queues per port, which is adequate for many applications. You can decrease the queue size for latency-sensitive traffic or increase the queue size for bursty traffic.

Note When you use the queue-limit command to configure queue thresholds for a class, the WTD thresholds must be less than or equal to the queue maximum threshold. A queue size configured with no qualifier must be larger than any queue sizes configured with qualifiers.

When you configure queue limit, the range for the number of packets is from 16 to 544, in multiples of 16, where each packet is a fixed unit of 256 bytes.

Note For optimal performance, we strongly recommend that you configure the queue limit to 272 or less.

Queue bandwidth and queue size (queue limit) are configured separately and are not interdependent. You should consider the type of traffic being sent when you configure bandwidth and queue limit:

- A large buffer (queue limit) can better accommodate bursty traffic without packet loss, but at the cost of increased latency.

- A small buffer reduces latency but is more appropriate for steady traffic flows than for bursty traffic.

- Very small buffers are typically used to optimize priority queuing. For traffic that is priority queued, the buffer size usually needs to accommodate only a few packets; large buffer sizes that increase latency are not usually necessary. For high-priority latency-sensitive packets, configure a relatively large bandwidth and relatively small queue size.

Note These restrictions apply to WTD qualifiers:

- You cannot configure more than two threshold values for WTD qualifiers ( cos , dscp , precedence , qos-group ) by using the queue-limit command. However, there is no limit to the number of qualifiers that you can map to these thresholds. You can configure a third threshold value to set the maximum queue by using the queue-limit command with no qualifiers.

- A WTD qualifier in the queue-limit command must be the same as at least one match qualifier in the associated class map.

This example shows how to configure bandwidth and queue limit so that out-class1 , out-class2 , out-class3 , and class-default get a minimum of 40, 20, 10, and 10 percent of the traffic bandwidth, respectively. The corresponding queue-sizes are set to 48, 32, 16 and 272 (256-byte) packets:

Switch(config)# policy-map out-policy

Switch(config-pmap)# class outclass1

Switch(config-pmap-c)# bandwidth percent 40

Switch(config-pmap-c)# queue-limit 48

Switch(config-pmap-c)# exit

Switch(config-pmap)# class outclass2

Switch(config-pmap-c)# bandwidth percent 20

Switch(config-pmap-c)# queue-limit 32

Switch(config-pmap-c)# exit

Switch(config-pmap)# class outclass3

Switch(config-pmap-c)# bandwidth percent 10

Switch(config-pmap-c)# queue-limit 16

Switch(config-pmap-c)# exit

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# bandwidth percent 10

Switch(config-pmap-c)# queue-limit 272

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface gigabitethernet 0/1

Switch(config-if)# service-policy output out-policy

Switch(config-if)# exit

You can configure and attach as many output policy maps as there are switch ports, but only three unique queue-limit configurations are allowed. When another output policy map uses the same queue-limit and class configurations, even if the bandwidth percentages are different, it is considered to be the same queue-limit configuration.

Prerequisites

- Be familiar with the information in the “Information About QoS” section and “Guidelines and Limitations” section.

- Before configuring QoS, you must have a thorough understanding of these factors:

– The types of applications used and the traffic patterns on your network.

– Traffic characteristics and needs of your network. Is the traffic bursty? Do you need to reserve bandwidth for voice and video streams?

– Bandwidth requirements and speed of the network.

– Location of congestion points in the network.

Guidelines and Limitations

- You can configure QoS only on physical ports.

- On a port configured for QoS, all traffic received through the port is classified, policed, and marked according to the input policy map attached to the port. On a trunk port configured for QoS, traffic in all VLANs received through the port is classified, policed, and marked according to the policy map attached to the port. If a per-port, per-VLAN policy map is attached, traffic on the trunk port is classified, policed, and marked for the VLANs specified in the parent-level policy, according to the child policy map associated with each VLAN.

- If you have EtherChannel ports configured on your switch, you must configure QoS classification, policing, mapping, and queuing on the individual physical ports that comprise the EtherChannel. You must decide whether the QoS configuration should match on all ports in the EtherChannel.

- Control traffic (such as spanning-tree bridge protocol data units [BPDUs] and routing update packets) received by the switch are subject to all ingress QoS processing.

- You are likely to lose data when you change queue settings; therefore, try to make changes when traffic is at a minimum.

- When you try to attach a new policy to an interface and this brings the number of policer instances to more than 1024 minus 1 more than the number of interfaces on the switch, you receive an error message, and the configuration fails.

- When you try to attach new policy to an interface, increasing the number of policer profiles to more than 256, you receive an error message, and the configuration fails. A profile is a combination of commit rate, peak rate, commit burst, and peak burst. You can attach one profile to multiple instances, but if one of these characteristics differs, the policer is considered to have a new profile.

- You can specify 256 unique VLAN classification criteria within a per-port, per-VLAN policy map, across all ports on the switch. Any policy attachment or change that causes this limit to be exceeded fails with a VLAN label resources exceeded error message.

- You can attach per-port and per-port, per-VLAN policy maps across all ports on the switch until QoS ACE classification resource limitations are reached. Any policy attachment or change that causes this limit to be exceeded fails with a TCAM resources exceeded error message.

- When CPU protection is enabled, you can configure only 45 policers per port. Disabling CPU protection allows you to configure up to 64 policers per port. You can enter the show policer cpu uni-eni {drop | rate} privileged EXEC command to see if CPU protection is enabled.

- Note these limitations when you disable CPU protection:

– When CPU protection is disabled, you can configure a maximum of 63 policers per port for user-defined classes, and one for class-default. Any policy attachment or change that causes this limit to be exceeded fails with a policer resources exceeded error message.

– When CPU protection is disabled, you can configure a maximum of 256 policers on the switch. Any policy attachment or change that causes this limit to be exceeded fails with a policer resources exceeded error message.

– If you disable CPU protection and attach a policy map with more than 45 policers, and then enable CPU protection again and reload, 19 policers per port are again required for CPU protection. During reload, the policers 46 and above will reach the policer resources exceeded error condition and no policers are attached to those classes.

- If the number of internal QoS labels exceeds 256, you receive an error message.

- Table maps are not supported for violate-action for aggregate policing unless you configure a table map for exceed-action and no explicit action is configured for violate-action . For both individual and aggregate policers, if you do not configure violate-action , by default the violate class is assigned the same action as exceed-action .

- If double-tagged packets are received on a trunk or 802.1Q tunnel interface, these packets can be classified on DSCP and IP precedence along with other parameters, but you cannot set DSCP or IP precedence on the outgoing packets. You can set CoS on the outgoing packets.

See the configuration sections for specific QoS features for more configuration guidelines related to each feature.

Default Settings

- There are no policy maps, class maps, table maps, or policers configured.

- At the egress port, all traffic goes through a single default queue that is given the full operational port bandwidth.

- The default size of the default queue is 160 (256-byte) packets.

- The packets are not modified (the CoS, DSCP, and IP precedence values in the packet are not changed).

- Traffic is switched in pass-through mode without any rewrites and classified as best effort without any policing.

Configuring QoS

These sections describe how to classify, police, and mark incoming traffic, and schedule and queue outgoing traffic. Depending on your network configuration, you must perform one or more of these tasks.

- Using ACLs to Classify Traffic

- Using Class Maps to Define a Traffic Class

- Configuring Table Maps

- Attaching a Traffic Policy to an Interface

- Configuring Input Policy Maps

- Configuring Output Policy Maps

- Configuring QoS Marking and Queuing for CPU-Generated Traffic

- Implementing High-Priority Traffic to the Host Router

Using ACLs to Classify Traffic

You can classify IP traffic by using IP standard or IP extended ACLs. You can classify IP and non-IP traffic by using Layer 2 MAC ACLs. For more information about configuring ACLs, see the chapter “Configuring Network Security with ACLs” in the Security Software Configuration Guide for

Cisco IE 2000U and Connected Grid Switches .

These sections describe how to create QoS ACLs:

- Creating IP Standard ACLs

- Creating IP Extended ACLs

- Creating Layer 2 MAC ACLs

Creating IP Standard ACLs

BEFORE YOU BEGIN

Follow these guidelines when configuring QoS ACLs:

- You cannot match IP fragments against configured IP extended ACLs to enforce QoS. IP fragments are sent as best effort. IP fragments are denoted by fields in the IP header.

- The switch supports only one access group per class in an input policy map.

- You cannot configure a match-access group in an output policy map.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

access-list access-list-number permit source [ source-wildcard ]

Create an IP standard ACL, repeating the command as many times as necessary.

- For access-list-number , enter the access list number. The range is 1 to 99 and 1300 to 1999.

- Always use the permit keyword for ACLs used as match criteria in QoS policies. QoS policies do not match ACLs that use the deny keyword.

- For source , enter the network or host from which the packet is being sent. You can use the any keyword as an abbreviation for 0.0.0.0 255.255.255.255.

- (Optional) For source-wildcard , enter the wildcard bits in dotted decimal notation to be applied to the source.

or

ip access-list standard name

Define a standard IPv4 access list using a name, and enter access-list configuration mode. The name can be a number from 1 to 99.

In access-list configuration mode, enter permit source [ source-wildcard ]

Step 3

end

Return to privileged EXEC mode.

Step 4

show access-lists

Verify your entries.

Step 5

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To delete an access list, use the no access-list access-list-number global configuration command.

EXAMPLE

This example shows how to allow access for only those hosts on the three specified networks. The wildcard bits apply to the host portions of the network addresses.

Switch(config)# access-list 1 permit 192.5.255.0 0.0.0.255

Switch(config)# access-list 1 permit 128.88.0.0 0.0.255.255

Switch(config)# access-list 1 permit 36.0.0.0 0.0.0.255

Creating IP Extended ACLs

BEFORE YOU BEGIN

Follow these guidelines when configuring QoS ACLs:

- You cannot match IP fragments against configured IP extended ACLs to enforce QoS. IP fragments are sent as best-effort. IP fragments are denoted by fields in the IP header.

- The switch supports only one access group per class in an input policy map.

- You cannot configure a match-access group in an output policy map.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

access-list access-list-number permit protocol { source source-wildcard destination destination-wildcard } [ precedence precedence ] [ tos tos ] [ dscp dscp ]
.

Create an IP extended ACL. Repeat the step as many times as necessary.

- For access-list-number , enter the access list number. The range is 100 to 199 and 2000 to 2699.

- Always use the permit keyword for ACLs used as match criteria in QoS policies. QoS policies do not match deny ACLs.

- For protocol , enter the name or number of an IP protocol. Use the question mark (?) to see a list of available protocols. To match any Internet protocol (including ICMP, TCP, and UDP), enter ip .

- The source is the number of the network or host sending the packet.

- The source-wildcard applies wildcard bits to the source.

- The destination is the network or host number receiving the packet.

- The destination-wildcard applies wildcard bits to the destination.

You can specify source, destination, and wildcards as:

- The 32-bit quantity in dotted-decimal format.

- The keyword any for 0.0.0.0 255.255.255.255 (any host).

- The keyword host for a single host 0.0.0.0.

Other keywords are optional and have these meanings:

- precedence —Enter to match packets with a precedence level specified as a number from 0 to 7 or by name: routine ( 0 ), priority ( 1 ), immediate ( 2 ), flash ( 3 ), flash-override ( 4 ), critical ( 5 ), internet ( 6 ), network ( 7 ).

- tos —Enter to match by type of service level, specified by a number from 0 to 15 or a name: normal ( 0 ), max-reliability ( 2 ), max-throughput ( 4 ), min-delay ( 8 ).

- dscp —Enter to match packets with the DSCP value specified by a number from 0 to 63, or use the question mark (?) to see a list of available values.

or

ip access-list extended name

Define an extended IPv4 access list using a name, and enter access-list configuration mode. The name can be a number from 100 to 199.

In access-list configuration mode, enter permit protocol { source source-wildcard destination destination-wildcard } [ precedence precedence ] [ tos tos ] [ dscp dscp ] as defined in Step 2.

Step 3

end

Return to privileged EXEC mode.

Step 4

show access-lists

Verify your entries.

Step 5

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To delete an access list, use the no access-list access-list-number global configuration command.

EXAMPLE

This example shows how to create an ACL that permits IP traffic from any source to any destination that has the DSCP value set to 32:

Switch(config)# access-list 100 permit ip any any dscp 32

This example shows how to create an ACL that permits IP traffic from a source host at 10.1.1.1 to a destination host at 10.1.1.2 with a precedence value of 5:

Switch(config)# access-list 100 permit ip host 10.1.1.1 host 10.1.1.2 precedence 5

Creating Layer 2 MAC ACLs

Follow this procedure to create a Layer 2 MAC ACL for non-IP traffic.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

mac access-list extended name

Create a Layer 2 MAC ACL by specifying the name of the list and enter extended MAC ACL configuration mode.

Step 3

permit { host src-MAC-addr mask | any | host dst-MAC-addr | dst-MAC-addr mask } [ type mask ]

Always use the permit keyword for ACLs used as match criteria in QoS policies.

- For src-MAC-addr , enter the MAC address of the host from which the packet is being sent. You can specify in hexadecimal format (H.H.H), use the any keyword for source 0.0.0, source-wildcard ffff.ffff.ffff, or use the host keyword for source 0.0.0.

- For mask, enter the wildcard bits by placing ones in the bit positions that you want to ignore.

- For dst-MAC-addr , enter the MAC address of the host to which the packet is being sent. You can specify in hexadecimal format (H.H.H), use the any keyword for source 0.0.0, source-wildcard ffff.ffff.ffff, or use the host keyword for source 0.0.0.

- (Optional) For type mask , specify the Ethertype number of a packet with Ethernet II or SNAP encapsulation to identify the protocol of the packet. For type , the range is from 0 to 65535, typically specified in hexadecimal. For mask , enter the don’t care bits applied to the Ethertype before testing for a match.

Step 4

end

Return to privileged EXEC mode.

Step 5

show access-lists [ access-list-number | access-list-name ]

Verify your entries.

Step 6

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To delete an access list, use the no mac access-list extended access-list-name global configuration command.

EXAMPLE

This example shows how to create a Layer 2 MAC ACL with two permit statements. The first statement allows traffic from the host with MAC address 0001.0000.0001 to the host with MAC address 0002.0000.0001. The second statement allows only Ethertype XNS-IDP traffic from the host with MAC address 0001.0000.0002 to the host with MAC address 0002.0000.0002.

Switch(config)# mac access-list extended maclist1

Switch(config-ext-macl)# permit 0001.0000.0001 0.0.0 0002.0000.0001 0.0.0

Switch(config-ext-macl)# permit 0001.0000.0002 0.0.0 0002.0000.0002 0.0.0 xns-idp

Switch(config-ext-macl)# exit

Using Class Maps to Define a Traffic Class

You use the class-map global configuration command to name and to isolate a specific traffic flow (or class) from all other traffic. A class map defines the criteria to use to match against a specific traffic flow to further classify it. Match statements can include criteria such as an ACL, CoS value, DSCP value, IP precedence values, QoS group values, or VLAN IDs. You define match criterion with one or more match statements entered in the class-map configuration mode.

BEFORE YOU BEGIN

Follow these guidelines when configuring class maps:

- A match-all class map cannot have more than one classification criterion (one match statement), but a match-any class map can contain multiple match statements.

- The match cos and match vlan commands are supported only on Layer 2 802.1Q trunk ports.

- You use a class map with the match vlan command in the parent policy in input hierarchical policy maps for per-port, per-VLAN QoS on trunk ports. A policy is considered a parent policy map when it has one or more of its classes associated with a child policy map. Each class within a parent policy map is called a parent class. You can configure only the match vlan command in parent classes. You cannot configure the match vlan command in classes within the child policy map.

- For an input policy map, you cannot configure an IP classification ( match ip dscp , match ip precedence , match access-group for an IP ACL) and a non-IP classification ( match cos or match access-group for a MAC ACL) in the same policy map or class map. For a per-port, per-VLAN hierarchical policy map, this applies to the child policy map.

- You cannot configure match qos-group for an input policy map.

- In an output policy map, no two class maps can have the same classification criteria; that is, the same match qualifiers and values.

- The maximum number of class maps on the switch is 1024.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

class-map [ match-all | match-any ] class-map-name

Create a class map and enter class-map configuration mode. By default, no class maps are defined.

- (Optional) Use the match-all keyword to perform a logical AND of all matching statements under this class map. All match criteria in the class map must be matched.

- (Optional) Use the match-any keyword to perform a logical OR of all matching statements under this class map. One or more match criteria must be matched.

- For class-map-name , specify the name of the class map.

If no matching statements are specified, the default is match-all .
class map cannot have more than one classification criterion (match statement).

Step 3

match { access-group acl-index-or-name | cos cos-list | ip dscp dscp-list | ip precedence ip-precedence-list | qos-group value | vlan vlan-list }

Define the match criterion to classify traffic. By default, no match criterion is defined.

Only one match type per class map is supported, and only one ACL per class map is supported.

- For access-group acl-index-or-name, specify the number or name of an ACL. Matching access groups is supported only in input policy maps.

- For cos cos-list , enter a list of up to four CoS values in a single line to match against incoming packets. Separate each value with a space. You can enter multiple cos-list lines to match more than four CoS values. The range is 0 to 7.

- For ip dscp dscp-list , enter a list of up to eight IPv4 DSCP values to match against incoming packets. Separate each value with a space. You can enter multiple dscp-list lines to match more than eight DSCP values. The numerical range is 0 to 63. You can also configure DSCP values in other forms. See the “Classification Based on IP DSCP” section.

- For ip precedence ip-precedence-list , enter a list of up to four IPv4 precedence values to match against incoming packets. Separate each value with a space. You can enter multiple ip-precedence-list lines to match more than four precedence values. The range is 0 to 7.

- For vlan vlan-list, specify a VLAN ID or a range of VLANs to be used in a parent policy map for per-port, per-VLAN QoS on a trunk port. The VLAN ID range is 1 to 4094.

- For qos-group value, specify the QoS group number. The range is 0 to 99. Matching of QoS groups is supported only in output policy maps.

Step 4

end

Return to privileged EXEC mode.

Step 5

show class-map

Verify your entries.

Step 6

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Use the no form of the appropriate command to delete an existing class map or remove a match criterion.

EXAMPLE

This example shows how to create access list 103 and configure the class map called class1 . The class1 has one match criterion, which is access list 103. It permits traffic from any host to any destination that matches a DSCP value of 10.

Switch(config)# access-list 103 permit any any dscp 10

Switch(config)# class-map class1

Switch(config-cmap)# match access-group 103

Switch(config-cmap)# exit

This example shows how to create a class map called class2 , which matches incoming traffic with DSCP values of 10, 11, and 12:

Switch(config)# class-map match-any class2

Switch(config-cmap)# match ip dscp 10 11 12

Switch(config-cmap)# exit

This example shows how to create a class map called class3 , which matches incoming traffic with IP-precedence values of 5, 6, and 7:

Switch(config)# class-map match-any class3

Switch(config-cmap)# match ip precedence 5 6 7

Switch(config-cmap)# exit

This example shows how to create a parent class-map called parent-class , which matches incoming traffic with VLAN IDs in the range from 30 to 40:

Switch(config)# class-map match-any parent-class

Switch(config-cmap)# match vlan 30-40

Switch(config-cmap)# exit

Configuring Table Maps

You can configure table maps to manage a large number of traffic flows with a single command. You use table maps to correlate specific DSCP, IP precedence, and CoS values to each other, to mark down a DSCP, IP precedence, or CoS value, or to assign default values. You can specify table maps in set commands and use them as mark-down mapping for the policers.

These table maps are supported on the switch:

- DSCP to CoS, precedence, or DSCP

- CoS to DSCP, precedence, or CoS

- Precedence to CoS, DSCP, or precedence

BEFORE YOU BEGIN

Note these guidelines when configuring table maps:

- The switch supports a maximum of 256 unique table maps.

- The maximum number of map statements within a table map is 64.

- Table maps cannot be used in output policy maps.

- Table maps are not supported for violate-action for aggregate policing unless you configure a table map for exceed-action and no explicit action is configured for violate-action .

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

table-map table-map-name

Create a table map by entering a table map name and entering table-map configuration mode.

Step 3

map from from-value to to-value

Enter the mapping values to be included in the table. For example, if the table map is a DSCP-to-CoS table map, the from-value would be the DSCP value and the to_value would be the CoS value. Both ranges are from 0 to 63.

Enter this command multiple times to include all the values that you want to map.

Step 4

default { default-value | copy | ignore }

Set the default behavior for a value not found in the table map.

- Enter a default-value to specify a certain value. For example, in a DSCP-to-CoS table map, this would be a specific CoS value to apply to all unmapped DSCP values. The range is from 0 to 63.

- Enter copy to map unmapped values to an equivalent value. In a DSCP-to-CoS table map, this command maps all unmapped DSCP values to the equivalent CoS value.

- Enter ignore to leave unmapped values unchanged. In a DSCP-to-CoS table map, the switch does not change the CoS value of unmapped DSCP values.

Step 5

end

Return to privileged EXEC mode.

Step 6

show table-map [ table-map-name ]

Verify your entries.

Step 7

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To delete a table map, use the no table-map table-map-name global configuration command.

EXAMPLE

This example shows how to create a DSCP-to-CoS table map. A complete table would typically include additional map statements for the higher DSCP values. The default of 4 in this table means that unmapped DSCP values will be assigned a CoS value of 4.

Switch(config)# table-map dscp-to-cos

Switch(config-tablemap)# map from 1 to 1

Switch(config-tablemap)# map from 2 to 1

Switch(config-tablemap)# map from 3 to 1

Switch(config-tablemap)# map from 4 to 2

Switch(config-tablemap)# map from 5 to 2

Switch(config-tablemap)# map from 6 to 3

Switch(config-tablemap)# default 4

Switch(config-tablemap)# end

Switch# show table-map dscp-to-cos

Attaching a Traffic Policy to an Interface

You use the service-policy interface configuration command to attach a traffic policy to an interface and to specify the direction in which the policy should be applied: either an input policy map for incoming traffic or an output policy map for outgoing traffic. Input and output policy maps support different QoS features.

Note If you enter the no policy-map configuration command or the no policy-map policy-map-name global configuration command to delete a policy map that is attached to an interface, a warning message appears that lists any interfaces from which the policy map is being detached. The policy map is then detached and deleted. For example:

Warning: Detaching Policy test1 from Interface GigabitEthernet0/1

BEFORE YOU BEGIN

- See the “Configuring Input Policy Maps” section and the “Configuring Output Policy Maps” section for restrictions on input and output policy maps.

- You can attach a service policy only to a physical port. You can attach only one input policy map and one output policy map per port.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

interface interface-id

Specify the port to attach to the policy map, and enter interface configuration mode. Valid interfaces are physical ports.

Step 3

service-policy { input | output } policy-map-name

Specify the policy map name and whether it is an input policy map or an output policy map.

Step 4

end

Return to privileged EXEC mode.

Step 5

show policy-map interface [ interface-id ]

Verify your entries.

Step 6

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To remove the policy map and port association, use the no service-policy { input | output } policy-map-name interface configuration command.

Configuring Input Policy Maps

Policy maps specify which traffic class to act on and what actions to take. All traffic that fails to meet matching criteria of a traffic class belongs to the default class. Input policy maps regulate traffic entering the switch. In an input policy, you can match CoS, DSCP, IP precedence, ACLs, or VLAN IDs and configure individual policing, aggregate policing, or marking to a CoS, DSCP, IP precedence, or QoS group value.

Follow these guidelines when configuring input policy maps:

- You can attach only one input policy map per port.

- The maximum number of policy maps configured on the switch is 256.

- The total number of configurable policer profiles on the switch is 256; the total number of supported policer instances on the switch is 1024 minus one more than the total number of interfaces on the switch. On a 24-port switch, the number of available policer instances is 999. You can use a policer profile in multiple instances.

- The maximum number of classes in each input policy map is 64 plus class-default .

- The number of input policy maps that can be attached in a switch is limited by the availability of hardware resources. If you attempt to attach an input policy map that causes any hardware resource limitation to be exceeded, the configuration fails.

- After you have attached a single-level policy map to an interface by using the service-policy input interface configuration command, you can modify the policy without detaching it from the interface. You can add or delete classification criteria, add or delete classes, add or delete actions, or change the parameters of the configured actions (policers, rates, mapping, marking, and so on). This also applies to changing criteria for the child policy of a hierarchical policy map, as in a per-port per-VLAN hierarchical policy map.

For the parent policy of a hierarchical policy map, you cannot add or delete a class at the parent level if the policy map is attached to an interface. You must detach the policy from the interface, modify the policy, and then re-attach it to the interface.

- You can configure a maximum 2-level hierarchical policy map as an input policy map only with VLAN-based classification at the parent level and no VLAN-based classification at the child level.

- When an input policy map with only Layer 2 classification is attached to a routed port or a switch port containing a routed SVI, the service policy acts only on switching eligible traffic and not on routing eligible traffic.

- On an 802.1Q tunnel port, you can use only an input policy map with Layer 2 classification based on MAC ACLs to classify traffic. Input policy maps with Layer 3 classification or with Layer 2 classification based on CoS or VLAN ID are not supported on tunnel ports.

- Input policy maps support policing and marking, not scheduling or queuing. You cannot configure bandwidth , priority , queue-limit , or shape average in input policy maps.

These sections describe how to configure different types of input policy maps:

- Configuring Input Policy Maps with Individual Policing

- Configuring Input Policy Maps with Aggregate Policing

- Configuring Input Policy Maps with Marking

- Configuring Per-Port Per-VLAN QoS with Hierarchical Input Policy Maps

Configuring Input Policy Maps with Individual Policing

You use the police policy-map class configuration command to configure individual policers to define the committed rate limitations, committed burst size limitations of the traffic, and the action to take for a class of traffic. Follow this procedure to create an input policy map with individual 2-rate, 3-color policing.

BEFORE YOU BEGIN

Follow these guidelines when configuring individual policers:

- Policing is supported only on input policy maps.

- The switch supports a maximum of 229 policers. (228 user-configurable policers and 1 policer reserved for internal use).

- When CPU protection is enabled (the default), you can configure 45 ingress policers per port. If you disable CPU protection by entering the no policer cpu uni all global configuration command and reloading the switch, you can configure a maximum of 63 policers per port for user-defined classes and one for class-default. You can enter the show policer cpu uni-eni {drop | rate} privileged EXEC command to see if CPU protection is enabled.

- When you use a table map for police exceed-action in an input policy map, the protocol type of the map from type of action must be the same as the protocol type of the associated classification. For example, if the associated class map represents an IP classification, the map from type of action that references the table map must be dscp or precedence . If the associated class map represents a non-IP classification, the map from type of action that references the table map must be cos .

- 2-rate, 3-color policing is supported only on input policy maps; 1-rate, 2-color policing is supported on both input and output policy maps.

- The number of policer instances on the switch can be 1024 minus 1 more than the number interfaces. The switch supports a maximum of 256 policer profiles.

- If you do not configure a violate action, by default the violate class is assigned the same action as the exceed action.

If you enter the no policy-map configuration command or the no policy-map policy-map-name global configuration command to delete a policy map that is attached to an interface, a warning message appears that lists any interfaces from which the policy map is being detached. The policy map is then detached and deleted. For example:

Warning: Detaching Policy test1 from Interface GigabitEthernet0/1

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode. By default, no class maps are defined.

Step 3

class { class-map-name | class-default }

Enter a class-map name or class-default to match all unclassified packets, and enter policy-map class configuration mode.

If you enter a class-map name, you must have already created the class map by using the class-map global configuration command.

Step 4

police { rate-bps | cir { cir-bps } [ burst-bytes ] [ bc [ conform-burst ] [ pir pir-bps [ be peak-burst ]]

Define a policer using one or two rates—committed information rate (CIR) and peak information rate (PIR) for the class of traffic.

By default, no policer is defined.

- For rate-bps, specify average traffic rate in bits per second (bps). The range is 8000 to 1000000000.

- For cir cir-bps, specify a committed information rate at which the bc token bucket is updated in bits per second (b/s). The range is 8000 to 1000000000.

- For burst-bytes (optional) , specify the normal burst size in bytes. The range is 8000 to 1000000.

- (Optional) For bc conform-burst, specify the conformed burst used by the bc token bucket for policing.The range is 8000 to 1000000 bytes.

- (Optional) For pir pir-bps, specify the peak information rate at which the be token bucket for policing is updated. The range is 8000 to 1000000000 b/s. If you do not enter a pir pir-bps , the policer is configured as a 1-rate, 2-color policer.

- For be peak-burst , specify the peak burst size used by the be token bucket. The range is 8000 to 1000000 bytes. The default is internally calculated based on the user configuration.

Step 5

conform-action [drop | set-cos-transmit { cos_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-dscp-transmit { dscp_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-prec-transmit { precedence_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-qos-transmit qos-group_value | transmit ]

| exceed-action [ drop | set-cos-transmit { cos_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-dscp-transmit { dscp_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-prec-transmit { precedence_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-qos-transmit qos-group_value | transmit ]

| violate- action [ drop | set-cos-transmit { cos_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-dscp-transmit { dscp_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-prec-transmit { precedence_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-qos-transmit qos-group_value | transmit ]

(Optional) Enter the action to be taken on packets, depending on whether or not they conform to the CIR and PIR.

- (Optional) For conform-action , specify the action to perform on packets that conform to the CIR and PIR. The default is transmit .

- (Optional) For exceed-action , specify the action to perform on packets that conform to the PIR but not the CIR. The default is drop .

- (Optional) For violate-action , specify the action to perform on packets that exceed the PIR. The default is drop .

- (Optional) For action , specify one of these actions to perform on the packets:

– drop —Drop the packet.
.
– set-cos-transmit cos-value —Enter a new CoS value to be assigned to the packet, and send the packet. The range is from 0 to 7.

– set-dscp-transmit dscp-value —Enter a new IP DSCP value to be assigned to the packet, and send the packet. The range is from 0 to 63. You can also enter a mnemonic name for a commonly used value.

– set-prec-transmit cos-value —Enter a new IP precedence value to be assigned to the packet, and send the packet. The range is from 0 to 7.

– set-qos-transmit qos-group-value —Identify a qos-group to be used at egress to specify packets. The range is from 0 to 99.

– transmit —Send the packet without altering it.
command to enter policy-map class police configuration mode, where you can enter multiple actions. In policy-map class police configuration mode, you must enter an action to take.

Step 6

exit

Return to policy-map configuration mode.

Step 7

exit

Return to global configuration mode.

Step 8

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 9

service-policy input policy-map-name

Attach the policy map (created in Step 2) to the ingress interface.

Step 10

end

Return to privileged EXEC mode.

Step 11

show policy-map [ policy-map-name| interface ]

Verify your entries.

Step 12

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an input policy map, you attach it to an interface in the input direction. See the “Attaching a Traffic Policy to an Interface” section.

Use the no form of the appropriate command to delete an existing policy map, class map, or policer.

EXAMPLE

This example shows how to configure 2-rate, 3-color policing using policy-map configuration mode:

Switch(config)# class-map cos-4

Switch(config-cmap)# match cos 4

Switch(config-cmap)# exit

Switch(config)# policy-map in-policy

Switch(config-pmap)# class cos-4

Switch(config-pmap-c)# police cir 5000000 pir 8000000 conform-action transmit exceed-action set-dscp-transmit 24 violate-action drop

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy input in-policy

Switch(config-if)# exit

This example shows how to create the same configuration using policy-map class police configuration mode:

Switch(config)# class-map cos-4

Switch(config-cmap)# match cos 4

Switch(config-cmap)# exit

Switch(config)# policy-map in-policy

Switch(config-pmap)# class cos-4

Switch(config-pmap-c)# police cir 5000000 pir 8000000

Switch(config-pmap-c-police)# conform-action transmit

Switch(config-pmap-c-police)# exceed-action set-dscp-transmit 24

Switch(config-pmap-c-police)# violate-action drop

Switch(config-pmap-c-police)# end

This example shows how to create a traffic classification with a CoS value of 4, create a policy map, and attach it to an ingress port. The average traffic rate is limited to 10000000 b/s with a burst size of 10000 bytes:

Switch(config)# class-map video-class

Switch(config-cmap)# match cos 4

Switch(config-cmap)# exit

Switch(config)# policy-map video-policy

Switch(config-pmap)# class video-class

Switch(config-pmap-c)# police 10000000 10000

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy input video-policy

Switch(config-if)# exit

This example shows how to create policy map with a conform action of set dscp and a default exceed action:

Switch(config)# class-map in-class-1

Switch(config-cmap)# match dscp 14

Switch(config-cmap)# exit

Switch(config)# policy-map in-policy

Switch(config-pmap)# class in-class-1

Switch(config-pmap-c)# police 230000 8000 conform-action set-dscp-transmit 33 exceed-action drop

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy input in-policy

Switch(config-if)# exit

This example shows how to use policy-map class police configuration mode to set multiple conform actions and an exceed action. The policy map sets a committed information rate of 23000 bits per second (b/s) and a conform burst size of 10000 bytes. The policy map includes multiple conform actions (for DSCP and for Layer 2 CoS) and an exceed action.

Switch(config)# class-map cos-set-1

Switch(config-cmap)# match cos 3

Switch(config-cmap)# exit

Switch(config)# policy-map map1

Switch(config-pmap)# class cos-set-1

Switch(config-pmap-c)# police cir 23000 bc 10000

Switch(config-pmap-c-police)# conform-action set-dscp-transmit 48

Switch(config-pmap-c-police)# conform-action set-cos-transmit 5

Switch(config-pmap-c-police)# exceed-action drop

Switch(config-pmap-c-police)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy input map1

Switch(config-if)# exit

This example shows how to use policy-map class police configuration mode to set exceed action mark-down using table maps. The policy map sets a committed information rate of 23000 b/s and a conform burst-size of 10000 bytes. The policy map includes the default conform action ( transmit ) and the exceed action to mark the Layer 2 CoS value based on the table map and to mark IP DSCP to af41.

Switch(config)# policy-map in-policy

Switch(config-pmap)# class in-class-1

Switch(config-pmap-c)# police cir 23000 bc 10000

Switch(config-pmap-c-police)# exceed-action set-cos-transmit cos table police-cos-markdn-tablemap

Switch(config-pmap-c-police)# exceed-action set-dscp-transmit af41

Switch(config-pmap-c-police)# exit

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy input in-policy

Switch(config-if)# exit

Configuring Input Policy Maps with Aggregate Policing

You use the policer aggregate global configuration command to configure an aggregate policer. An aggregate policer is shared by multiple traffic classes within the same policy map. You define the aggregate policer, create a policy map, associate a class map with the policy map, associate the policy map with the aggregate policer, and apply the service policy to a port. Follow this procedure to create a 2-rate, 3-color aggregate policer.

BEFORE YOU BEGIN

Follow these guidelines when configuring aggregate policers:

- Aggregate policing is supported only on input policy maps.

- The switch supports a maximum of 229 policers associated with ports (228 user-configurable policers and 1 policer reserved for internal use). You can configure up to 45 policers on a port.

- When CPU protection is enabled (the default), you can configure 45 ingress policers per port. If you disable CPU protection by entering the no policer cpu uni all global configuration command and reloading the switch, you can configure a maximum of 63 policers per port for user-defined classes and one for class-default. You can enter the show policer cpu uni-eni { drop | rate } privileged EXEC command to see if CPU protection is enabled.

- The maximum number of configured aggregate policers is 256.

- The number of policer instances on the switch can be 1024 minus 1 more than the total number interfaces on the switch. The switch supports a maximum of 256 policer profiles.

- If you do not configure a violate action, by default the violate class is assigned the same action as the exceed action.

- Only one policy map can use any specific aggregate policer. Aggregate policing cannot be used to aggregate streams across multiple interfaces. You can use aggregate policing only to aggregate streams across multiple classes in a policy map attached to an interface and to aggregate traffic streams across VLANs on a port in a per-port, per-VLAN policy map.

- When you use a table map for police exceed-action in an input policy map, the protocol type of the map from type of action must be the same as the protocol type of the associated classification. For example, if the associated class map represents an IP classification, the map from type of action that references the table map must be either dscp or precedence . If the associated class map represents a non-IP classification, the map from type of action that references the table map must be cos .

- Table maps are not supported for violate-action for aggregate policing unless a table map is configured for exceed-action and no explicit action is configured for violate-action .

You can configure multiple conform, exceed, and violate actions simultaneously for an aggregate policer as parameters in the policer aggregate global configuration command, but you must enter the actions in this order:

- conform-action must be followed by drop or transmit or by set actions in this order:

set-qos-transmit

set-dscp-transmit or set-prec-transmit

set-cos-transmit

- exceed-action must be followed by drop or transmit or by set actions in this order:

set-qos-transmit

set-dscp-transmit or set-prec-transmit

set-cos-transmit

- violate-action must be followed by drop or transmit or by set actions in this order:

set-qos-transmit

set-dscp-transmit or set-prec-transmit

set-cos-transmit

Note You do not configure aggregate policer conform-action, exceed-action, and violate-action in policy-map class police configuration mode; you must enter all actions in a string. Consequently, if you enter multiple conform, exceed, and violate actions, the command can become quite long, in which case it might be truncated and difficult to read.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

policer aggregate aggregate-policer-name { rate-bps | cir cir-bps } [ burst-bytes ] [ bc [ conform-burst ] [ pir pir-bps [ be peak-burst ]]

[ conform - action [ drop | set-cos-transmit { cos_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-dscp-transmit { dscp_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-prec-transmit { precedence_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-qos-transmit qos-group_value | transmit ]

[ exceed-action [ drop | set-cos-transmit { cos_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-dscp-transmit { dscp_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-prec-transmit { precedence_value | [ cos | dscp | precedence ] [ table table-map name ]} | set-qos-transmit qos-group_value | transmit ]]

[ violate- action [ drop | set-cos-transmit { cos_value | [ cos | dscp | precedence ]} | set-dscp-transmit { dscp_value | [ cos | dscp | precedence ]} | set-prec-transmit { precedence_value | [ cos | dscp | precedence ]} | set-qos-transmit qos-group_value | transmit ]]

Define the policer parameters that can be applied to multiple traffic classes within the same policy map.

- For aggregate-policer-name , specify the name of the aggregate policer.

- For rate-bps, specify average traffic rate in bits per second (b/s). The range is 8000 to 1000000000.

- For cir cir-bps, specify a committed information rate (CIR) at which the first token bucket is updated in b/s. The range is 8000 to 1000000000.

- For burst-bytes (optional) , specify the normal burst size in bytes. The range is 8000 to 1000000.

- (Optional) For bc conform-burst, specify the conformed burst used by the first token bucket for policing. The range is 8000 to 1000000 bytes.

- (Optional) For pir pir-bps, specify the peak information rate at which the second token bucket for policing is updated. The range is 8000 to 1000000000 bits per second. If you do not enter a pir pir-bps , the policer is configured as a 1-rate, 2-color policer.

- For be peak-burst , specify the peak burst size used by the second token bucket. The range is 8000 to 1000000 bytes. The default is internally calculated based on the user configuration.

- (Optional) For conform-action , specify the action to take on packets that conform to the CIR. The default is to send the packet.

.

- (Optional) For exceed-action , specify the action to take on packets that exceed the CIR. The default is to drop the packet.

- (Optional) For violate-action , specify the action to take on packets that exceed the CIR. The default is to drop the packet.

See the command reference for this release or the “Configuring Input Policy Maps with Individual Policing” section for definitions of the action keywords.
.

Step 3

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 4

class { class-map-name | class-default }

Enter a class-map name or class-default to match all unclassified packets, and enter policy-map class configuration mode.

If you enter a class-map name, you must have already created the class map by using the class-map global configuration command.

Step 5

police aggregate aggregate-policer-name

Apply an aggregate policer to multiple classes in the same policy map. For aggregate-policer-name , enter the name specified in Step 2.

Step 6

exit

Return to policy-map configuration mode.

Step 7

exit

Return to global configuration mode.

Step 8

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 9

service-policy input policy-map-name

Attach the policy map (created in Step 3) to the ingress interface.

Step 10

end

Return to privileged EXEC mode.

Step 11

show policer aggregate [ aggregate-policer-name ]

Verify your entries.

Step 12

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an aggregate policer, you attach it to an ingress port. See the “Attaching a Traffic Policy to an Interface” section.

To remove the specified aggregate policer from a policy map, use the no police aggregate aggregate-policer-name policy map configuration mode. To delete an aggregate policer and its parameters, use the no policer aggregate aggregate-policer-name global configuration command.

EXAMPLE

This example shows how to create an aggregate policer and attach it to multiple classes within a policy map. The policy map is attached to an ingress port.

Switch(config)# policer aggregate example 10900000 80000 conform-action transmit exceed-action drop

Switch(config)# class-map testclass1

Switch(config-cmap)# match access-group 1

Switch(config-cmap)# exit

Switch(config)# class-map testclass2

Switch(config-cmap)# match access-group 2

Switch(config-cmap)# exit

Switch(config)# policy-map testexample

Switch(config-pmap)# class testclass

Switch(config-pmap-c)# police aggregate example

Switch(config-pmap-c)# exit

Switch(config-pmap)# class testclass2

Switch(config-pmap-c)# police aggregate example

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy input testexample

Switch(config-if)# exit

This example shows how to create a 2-rate, 3-color aggregate policer and attach it to multiple classes within a policy map. The policy map is attached to an ingress port.

Switch(config)# policer aggregate example cir 10900000 pir 80000000 conform-action transmit exceed-action drop violate-action drop

Switch(config)# class-map testclass1

Switch(config-cmap)# match access-group 1

Switch(config-cmap)# exit

Switch(config)# class-map testclass2

Switch(config-cmap)# match access-group 2

Switch(config-cmap)# exit

Switch(config)# policy-map testexample

Switch(config-pmap)# class testclass

Switch(config-pmap-c)# police aggregate example

Switch(config-pmap-c)# exit

Switch(config-pmap)# class testclass2

Switch(config-pmap-c)# police aggregate example

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy input testexample

Switch(config-if)# exit

Configuring Input Policy Maps with Marking

You use the set policy-map class configuration command to set or modify the attributes for traffic belonging to a specific class.

BEFORE YOU BEGIN

Follow these guidelines when configuring marking in policy maps:

- You can configure a maximum of 100 QoS groups on the switch.

- When you use a table map for marking in an input policy map, the protocol type of the map from type of action must be the same as the protocol type of the associated classification. For example, if the associated class map represents an IP classification, the map from type of action that references the table map must be either dscp or precedence . If the associated class map represents a non-IP classification, the map from type of action that references the table map must be cos .

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3

class { class-map-name | class-default }

Enter a class-map name, or class-default to match all unclassified packets, and enter policy-map class configuration mode.

If you enter a class-map name, you must have already created the class map by using the class-map global configuration command.

Step 4

set qos-group value

and/or

set cos { cos_value | cos [ table table-map-name ] | dscp [ table table-map-name ] | precedence [ table table-map-name ]}

and/or

set [ ip ] dscp { dscp_value | cos [ table table-map-name ] | dscp [ table table-map-name ] | precedence [ table table-map-name ]}

and/or

set [ ip ] precedence { precedence_value | cos [ table table-map-name ] | dscp [ table table-map-name ] | precedence [ table table-map-name ]}

Mark traffic by setting a new value in the packet, specifying a table map, or specifying a QoS group.

- For qos-group value, identify a QoS group to be used at egress to identify specific packets. The range is from 0 to 99.

- For cos cos_value, enter a new CoS value to be assigned to the classified traffic. The range is 0 to 7.

- For [ip] dscp new-dscp , enter a new DSCP value to be assigned to the classified traffic. The range is 0 to 63.

- For [ip] precedence new-precedence, enter a new IP-precedence value to be assigned to the classified traffic. The range is 0 to 7.

- You can also configure a CoS, DSCP, or IP precedence table and optionally enter the table name. If you do not enter table table-map name , the table map default behavior is copy . See the “Configuring Table Maps” section.

Step 5

exit

Return to policy-map configuration mode.

Step 6

exit

Return to global configuration mode.

Step 7

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 8

service-policy input policy-map-name

Attach the policy map (created in Step 2) to the ingress interface.

Step 9

end

Return to privileged EXEC mode.

Step 10

show policy-map [ policy-map-name [ class class-map-name ]]

Verify your entries.

Step 11

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Use the no form of the appropriate command to delete a policy map or table map or remove an assigned CoS, DSCP, precedence, or QoS-group value.

EXAMPLE

This example uses a policy map to remark a packet. The first marking (the set command) applies to the QoS default class map that matches all traffic not matched by class AF31-AF33 and sets all traffic to an IP DSCP value of 1. The second marking sets the traffic in classes AF31 to AF33 to an IP DSCP of 3.

Switch(config)# policy-map Example

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# set ip dscp 1

Switch(config-pmap-c)# exit

Switch(config-pmap)# class AF31-AF33

Switch(config-pmap-c)# set ip dscp 3

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy input Example

Switch(config-if)# exit

Configuring Per-Port Per-VLAN QoS with Hierarchical Input Policy Maps

Per-port, per-VLAN QoS allows classification based on VLAN IDs for applying QoS for frames received on a given interface and VLAN. This is achieved by using a hierarchical policy map, with a parent policy and a child policy.

Configuring per-port, per-VLAN QoS includes these tasks:

- Creating Child-Policy Class Maps

- Creating Parent-Policy Class Maps

- Creating Child Policy Maps

- Creating a Parent Policy Map

- Attaching a Parent Policy Map to an Interface

BEFORE YOU BEGIN

Note these guidelines and limitations when configuring per-port, per-VLAN QoS:

- The feature is supported only by using a two-level hierarchical input policy map, where the parent level defines the VLAN-based classification, and the child level defines the QoS policy to be applied to the corresponding VLAN or VLANs.

- You can configure multiple service classes at the parent level to match different combinations of VLANs, and you can apply independent QoS policies to each parent-service class using any child policy map

- A policy is considered a parent policy map when it has one or more of its classes associated with a child policy map. Each class within a parent policy-map is called a parent-class. In parent classes, you can configure only the match vlan class-map configuration command. You cannot configure the match vlan command in classes within the child policy map.

- A per-port, per-VLAN parent level class map supports only a child-policy association; it does not allow any actions to be configured. For a parent-level class map, you cannot configure an action or a child-policy association for the class class-default .

- You cannot configure a mixture of Layer 2 and Layer 3 class maps in a child policy map. When you attempt to associate such a child policy map with a parent policy, the configuration is rejected. However, you can associate Layer 2 child policies and Layer 3 child policies with different parent-level class maps.

- Per-port, per-VLAN QoS is supported only on 802.1Q trunk ports.

- When the child policy-map attached to a VLAN or set of VLANs contains only Layer 3 classification ( match ip dscp , match ip precedence , match IP ACLs ), take care to ensure that these VLANs are not carried on any other port besides the one on which the per-port, per-vlan policy is attached. Not following this rule could result in improper QoS behavior for traffic ingressing the switch on these VLANs.

- We also recommend that you restrict VLAN membership on the trunk ports to which the per-port, per-VLAN is applied by using the switchport trunk allowed vlan interface configuration command. Overlapping VLAN membership between trunk ports that have per-port, per-VLAN policies with Layer 3 classification could also result in unexpected QoS behavior.

Creating Child-Policy Class Maps

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

class-map [ match-all | match-any ] child-class-map-name

Create a class map, and enter class-map configuration mode. By default, no class maps are defined.

- (Optional) Use the match-all keyword to perform a logical AND of all matching statements under this class map. All match criteria in the class map must be matched.

- (Optional) Use the match-any keyword to perform a logical OR of all matching statements under this class map. One or more match criteria must be matched.

- For class-map-name , specify the name of the class map.

If no matching statements are specified, the default is match-all .
class map cannot have more than one classification criterion (match statement).

Step 3

match { access-group acl-index-or-name | cos cos-list | ip dscp dscp-list | ip precedence ip-precedence-list | qos-group value | vlan vlan-list }

Define the match criterion to classify traffic. By default, no match criterion is defined.

Only one match type per class map is supported, and only one ACL per class map is supported.

- For access-group acl-index-or-name, specify the number or name of an ACL. Matching access groups is supported only in input policy maps.

- For cos cos-list , enter a list of up to four CoS values in a single line to match against incoming packets. Separate each value with a space. You can enter multiple cos-list lines to match more than four CoS values. The range is 0 to 7.

- For ip dscp dscp-list , enter a list of up to eight IPv4 DSCP values to match against incoming packets. Separate each value with a space. You can enter multiple dscp-list lines to match more than eight DSCP values. The numerical range is 0 to 63. You can also configure DSCP values in other forms. See the “Classification Based on IP DSCP” section.

- For ip precedence ip-precedence-list , enter a list of up to four IPv4 precedence values to match against incoming packets. Separate each value with a space. You can enter multiple ip-precedence-list lines to match more than four precedence values. The range is 0 to 7.

- For qos-group value, specify the QoS group number. The range is 0 to99. Matching of QoS groups is supported only in output policy maps.

- For vlan vlan-list, specify a VLAN ID or a range of VLANs to be used in a parent policy map for per-port, per-VLAN QoS on a trunk port. The VLAN ID range is 1 to 4094.

Step 4

end

Return to privileged EXEC mode.

Step 5

show class-map

Verify your entries.

Step 6

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Creating Parent-Policy Class Maps

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

class-map match-any parent-class-map-name

Create a match-any class map for the parent policy, and enter class-map configuration mode.
) if you are going to match only one VLAN ID.

Step 3

match vlan vlan-id

Define the VLAN or VLANs on which to classify traffic.

For vlan-id, specify a VLAN ID, a series of VLAN IDs separated by a space, or a range of VLANs separated by a hyphen to be used in a parent policy map for per-port, per-VLAN QoS on a trunk port. The VLAN ID range is 1 to 4094.

You can also enter the match vlan command multiple times to match multiple VLANs.

Step 4

end

Return to privileged EXEC mode.

Step 5

show class-map

Verify your entries.

Step 6

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Creating Child Policy Maps

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

policy-map child-polic y-map-name

Create a child policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3

class { child-class-map-name | class-default }

Enter a child class-map name or class-default to match all unclassified packets, and enter policy-map class configuration mode.

Step 4

Use the police policy-map class configuration command to configure policers and the action to take for a class of traffic, or use the set policy-map class configuration command to mark traffic belonging to the class.

Step 5

end

Return to privileged EXEC mode.

Step 6

show policy-map [ child- policy-map-name [ class class-map-name ]]

Verify your entries.

Step 7

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Creating a Parent Policy Map

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

policy-map parent-polic y-map-name

Create a parent policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3

class parent-class-map-name

Enter the parent class-map name, and enter policy-map class configuration mode.

Step 4

service policy child-polic y-map-name

Associate the child policy map with the parent policy map

Step 5

end

Return to privileged EXEC mode.

Step 6

show policy-map [ parent-policy-map-name [ class class-map-name ]]

Verify your entries.

Step 7

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Attaching a Parent Policy Map to an Interface

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 3

switchport mode trunk

Configure the port as a trunk port.

Step 4

switchport trunk allowed vlan vlan-list

(Recommended) Restrict VLAN membership for trunk ports to avoid overlapping VLAN membership if the per-port, per-VLAN policy includes Layer 3 classification.

Step 5

service-policy input parent- policy-map-name

Attach the parent policy map (created in the previous section) to the ingress interface.

Step 6

end

Return to privileged EXEC mode.

Step 7

show policy-map interface [ interface-id ]

Verify your entries.

Step 8

copy running-config startup-config

(Optional) Save your entries in the configuration file.

EXAMPLE

This is an example of using multiple parent classes to classify matching criteria for voice and video on customer VLANs:

Switch(config)# class-map match-any video

Switch(config-cmap)# match ip dscp af41

Switch(config-cmap)# exit

Switch(config)# class-map match-any voice

Switch(config-cmap)# match ip dscp ef

Switch(config-cmap)# exit

Switch(config)# class-map match-any customer1-vlan

Switch(config-cmap)# match vlan 100-105

Switch(config-cmap)# exit

Switch(config)# class-map match-any customer2-vlan

Switch(config-cmap)# match vlan 110-120

Switch(config-cmap)# exit

Switch(config)# policy-map child-policy-1

Switch(config-pmap)# class voice

Switch(config-pmap-c)# police cir 10000000 bc 50000

Switch(config-pmap-c-police)# conform-action set-cos-transmit 5

Switch(config-pmap-c-police)# exceed-action drop

Switch(config-pmap-c-police)# exit

Switch(config-pmap-c)# exit

Switch(config-pmap)# class video

Switch(config-pmap-c)# set cos 4

Switch(config-pmap-c)# exit

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# set cos 0

Switch(config-pmap-c)# exit

Switch(config)# policy-map child-policy-2

Switch(config-pmap)# class voice

Switch(config-pmap-c)# police cir 5000000

Switch(config-pmap-c-police)# conform-action set-cos-transmit 5

Switch(config-pmap-c-police)# exceed-action drop

Switch(config-pmap-c-police)# exit

Switch(config-pmap-c)# exit

Switch(config-pmap)# class video

Switch(config-pmap-c)# police cir 40000000

Switch(config-pmap-c-police)# conform-action set-cos-transmit 4

Switch(config-pmap-c-police)# exceed-action set-cos-transmit 1

Switch(config-pmap-c-police)# exit

Switch(config-pmap-c)# exit

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# set cos 0

Switch(config-pmap-c)# exit

Switch(config)# policy-map uni-parent

Switch(config-pmap)# class customer1-vlan

Switch(config-pmap-c)# service-policy child-policy-1

Switch(config-pmap-c)# exit

Switch(config-pmap)# class customer2-vlan

Switch(config-pmap-c)# service-policy child-policy-2

Switch(config-pmap-c)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# switchport mode trunk

Switch(config-if)# switchport trunk allowed vlan 100-105, 110-120

Switch(config-if)# service-policy input uni-parent

Switch(config-pmap-c)# exit

Configuring Output Policy Maps

You use output policy maps to manage congestion avoidance, queuing, and scheduling of packets leaving the switch. The switch has four egress queues, and you use output policy maps to control the queue traffic. You configure shaping, queue limit, and bandwidth on these queues. You can use high priority (class-based priority queuing). Policing is not supported on output policy maps, except when configuring priority with police for class-based priority queuing. Output policy map classification criteria are matching a CoS, DSCP, or IP precedence value or a QoS group.

Follow these guidelines when configuring output policy maps on physical ports:

- You can configure and attach as many output policy maps as there are ports on the switch. Multiple output policy maps can use the same queue-limit configuration. However, these policy maps can have only three unique queue-limit configurations.

- Output policy maps can have a maximum of four classes, including the class class-default .

- All output policy maps must have the same number of defined class-maps defined, either 1, 2, or 3.

- All output policy maps must use the same set of classes, although the actions for each class can differ for each output policy map.

- In a child policy map, the class-default supports all output policy map actions except priority and police . Action restrictions for class-default are the same as for other classes except that a queue limit configuration for class-default does not require a scheduling action.

- To classify based on criteria at the output, the criteria must be established at the input. You can establish criteria at the input through classification only when you configure only policing and not marking, or through explicit marking when you configure any marking (policing with conform or exceed marking or unconditional set marking).

- You cannot configure class-based priority queuing under the class class-default in an output policy map.

- In an output policy map, unless priority queuing is configured, the class default receives a minimum bandwidth guarantee equal to the unconfigured bandwidth on the port.

- After you have attached an output policy map to an interface by using the service-policy interface configuration command, you can change only the parameters of the configured actions (rates, percentages, and so on) or add or delete classification criteria of the class map while the policy map is attached to the interface. To add or delete a class or action, you must detach the policy map from all interfaces, modify it, and then reattach it to interfaces.

Note If you anticipate that you might need three classes in a policy map, you should define three classes when you create the policy map, even if you are not ready to use all three at that time. You cannot add a class to a policy map after it has been attached to an interface.

- When at least one output policy map is attached to a active port, other active ports without output policy maps attached might incorrectly schedule and incorrectly order traffic that uses the same classes as the attached output policy maps. We recommend attaching output policy maps to all ports that are in use. We also recommend putting any unused ports in the shutdown state by entering the shutdown interface configuration command. For example, if you attach an output policy map that shapes DSCP 23 traffic to a port, DSCP traffic that is sent out of any other port without a policy map attached could be incorrectly scheduled or ordered incorrectly with respect to other traffic sent out of the same port.

- We strongly recommended that you disable port-speed autonegotiation when you attach an output policy map to a port to prevent the port from autonegotiating to a rate that would make the output policy map invalid. You can configure a static port speed by using the speed interface configuration command. If an output policy map is configured on a port that is set for autonegotiation and the speed autonegotiates to a value that invalidates the policy, the port is put in the error-disabled state.

- You can attach only one output policy map per port.

- The maximum number of policy maps configured on the switch is 256.

These sections describe how to configure different types of output policy maps:

- Configuring Output Policy Maps with Class-Based-Weighted-Queuing

- Configuring Output Policy Maps with Class-Based Shaping

- Configuring Output Policy Maps with Port Shaping

- Configuring Output Policy Maps with Class-Based Priority Queuing

- Configuring Output Policy Maps with Weighted Tail Drop

Configuring Output Policy Maps with Class-Based-Weighted-Queuing

You use the bandwidth policy-map class configuration command to configure Class-Based Weighted Fair Queuing (CBWFQ). CBWFQ sets the relative precedence of a queue by allocating a portion of the total bandwidth that is available for the port. Follow this procedure to use CBWFQ to control bandwidth allocated to a traffic class by specifying a minimum bandwidth as a bit rate or a percentage.

BEFORE YOU BEGIN

Follow these guidelines when configuring CBWFQ:

- When configuring bandwidth in a policy map, all rate configurations must be in the same format: either a configured rate or a percentage.

- The total rate of the minimum bandwidth guarantees for each queue of the policy cannot exceed the total speed for the interface.

- You cannot configure CBWFQ ( bandwidth ) and traffic ( shape average ) or priority queuing ( priority ) for the same class in an output policy map.

- You cannot configure bandwidth as an absolute rate or a percentage of total bandwidth when strict priority (priority without police) is configured for another class map.

- You can configure bandwidth as a percentage of remaining bandwidth only when strict priority (priority without police) is configured for another class in the output policy map.

- When you configure CIR bandwidth for a class as an absolute rate or a percentage of total bandwidth, any excess bandwidth that remains after servicing the CIR of all classes in the policy map is divided among the classes the same proportion as the CIR rates. If you configure the CIR rate of a class to be 0, that class is not eligible for any excess bandwidth and will receive no bandwidth.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3

class { class-map-name | class-default }

Enter a child class-map name or class-default to match all unclassified packets, and enter policy-map class configuration mode.

Step 4

bandwidth { rate | percent value | remaining percent value }

Set output bandwidth limits for the policy map class.

- Enter a rate to set bandwidth in kilobits per second. The range is from 64 to 1000000.

- Enter percent value to set bandwidth as a percentage of the total bandwidth. The range is 1 to 100 percent.

- Enter remaining percent value to set bandwidth as a percentage of the remaining bandwidth. The range is 1 to 100 percent. This keyword is valid only when strict priority (priority without police) is configured for another class in the output policy map.

You must specify the same units in each bandwidth configuration in an output policy (absolute rates or percentages). The total guaranteed bandwidth cannot exceed the total available rate.

Step 5

exit

Return to policy-map configuration mode.

Step 6

exit

Return to global configuration mode.

Step 7

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 8

service-policy output policy-map-name

Attach the policy map (created in Step 2) to the egress interface.

Step 9

end

Return to privileged EXEC mode.

Step 10

show policy-map [ policy-map-name [ class class-map-name ]]

Verify your entries.

Step 11

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an output policy map, you attach it to an egress port. See the “Attaching a Traffic Policy to an Interface” section.

Use the no form of the appropriate command to delete an existing policy map, class map, or bandwidth configuration.

Note If you enter the no policy-map configuration command or the no policy-map policy-map-name global configuration command to delete a policy map that is attached to an interface, a warning message appears that lists any interfaces from which the policy map is being detached. The policy map is then detached and deleted. For example:

Warning: Detaching Policy test1 from Interface GigabitEthernet0/1

EXAMPLE

This example shows how to set the precedence of a queue by allocating 25 percent of the total available bandwidth to the traffic class defined by the class map:

Switch(config)# policy-map gold_policy

Switch(config-pmap)# class out_class-1

Switch(config-pmap-c)# bandwidth percent 25

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface gigabitethernet0/1

Switch(config-if)# service-policy output gold_policy

Switch(config-if)# exit

Configuring Output Policy Maps with Class-Based Shaping

You use the shape average policy-map class configuration command to configure traffic shaping. Class-based shaping is a control mechanism that is applied to classes of traffic leaving an interface and uses the shape average command to limit the rate of data transmission used for the committed information rate (CIR) for the class. Follow this procedure to use class-based shaping to configure the maximum permitted average rate for a class of traffic.

BEFORE YOU BEGIN

Follow these guidelines when configuring class-based shaping:

- Configuring a queue for traffic shaping sets the maximum bandwidth or peak information rate (PIR) of the queue. In the switch, configuring traffic shaping automatically also sets the minimum bandwidth guarantee or CIR of the queue to the same value as the PIR.

- You cannot configure CBWFQ ( bandwidth ) or priority queuing ( priority ) and traffic ( shape average ) for the same class in an output policy map.

- You cannot configure traffic shaping for a traffic class when strict priority (priority without police) is configured for another class within the output policy map.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3

class { class-map-name | class-default }

Enter a child class-map name or class-default to match all unclassified packets, and enter policy-map class configuration mode.

Step 4

shape average target bps

Specify the average class-based shaping rate.

For target bps , specify the average bit rate in bits per second (b/s). The range is from 64000 to 1000000000.

Step 5

exit

Return to policy-map configuration mode.

Step 6

exit

Return to global configuration mode.

Step 7

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 8

service-policy output policy-map-name

Attach the policy map (created in Step 2) to the egress interface.

Step 9

end

Return to privileged EXEC mode.

Step 10

show policy-map [ policy-map-name [ class class-map-name ]]

Verify your entries.

Step 11

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an output policy map, you attach it to an egress port. See the “Attaching a Traffic Policy to an Interface” section.

Use the no form of the appropriate command to delete an existing policy map or class map or to delete a class-based shaping configuration.

EXAMPLE

This example shows how to configure traffic shaping for outgoing traffic on a Fast Ethernet port so that outclass1 , outclass2 , and outclass3 get a maximum of 50, 20, and 10 Mb/s of the available port bandwidth. The class class-default gets the remaining bandwidth.

Switch(config)# policy-map out-policy

Switch(config-pmap)# class classout1

Switch(config-pmap-c)# shape average 50000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class classout2

Switch(config-pmap-c)# shape average 20000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class classout3

Switch(config-pmap-c)# shape average 10000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy output out-policy

Switch(config-if)# exit

Configuring Output Policy Maps with Port Shaping

Port shaping is applied to all traffic leaving an interface. It uses a policy map with only class default when the maximum bandwidth for the port is specified by using the shape average command. A child policy can be attached to the class-default in a hierarchical policy map format to specify class-based actions for the queues on the shaped port.

Follow this procedure to use port shaping to configure the maximum permitted average rate for a class of traffic.

BEFORE YOU BEGIN

The total of the minimum bandwidth guarantees (CIR) for each queue of the child policy cannot exceed the total port shape rate.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

policy-map policy-map-name

Create a hierarchical policy map by entering the hierarchical policy map name, and enter policy-map configuration mode for the parent policy.

Step 3

class class-default

Enter a policy-map class configuration mode for the default class.

Step 4

shape average target bps

Specify the average class-based shaping rate.

For target bps , specify the average bit rate in bits per second. The range is from 4000000 to 1000000000.

Step 5

service-policy policy-map-name

Specify the child policy map to be used in the hierarchical policy map if required.

Step 6

exit

Return to policy-map configuration mode.

Step 7

exit

Return to global configuration mode.

Step 8

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 9

service-policy output policy-map-name

Attach the parent policy map (created in Step 2) to the egress interface.

Step 10

end

Return to privileged EXEC mode.

Step 11

show policy-map [ policy-map-name [ class class-map-name ]]

Verify your entries.

Step 12

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created the hierarchical output policy map, you attach it to an egress port. See the “Attaching a Traffic Policy to an Interface” section.

Use the no form of the appropriate command to delete an existing hierarchical policy map, to delete a port shaping configuration, or to remove the policy map from the hierarchical policy map.

EXAMPLE

This example shows how to configure port shaping by configuring a hierarchical policy map that shapes a port to 90 Mb/s, allocated according to the out-policy policy map configured in the previous example:

Switch(config)# policy-map out-policy-parent

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# shape average 90000000

Switch(config-pmap-c)# service-policy out-policy

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy output out-policy-parent

Switch(config-if)# exit

Configuring Output Policy Maps with Class-Based Priority Queuing

You can use the priority policy-map class configuration command to ensure that a particular class of traffic is given preferential treatment. With strict priority queuing, the priority queue is constantly serviced; all packets in the queue are scheduled and sent until the queue is empty. Excessive use of the priority queues can delay packets in other queues and create unnecessary congestion.

You can configure strict priority queuing (priority without police), or you can configure an unconditional priority policer (priority with police). Follow these guidelines when configuring priority queuing:

- You can associate the priority command with a single unique class for all attached output policies on the switch.

- When you configure a traffic class as a priority queue, you can configure only police and queue-limit as other queuing actions for the same class. You cannot configure bandwidth or shape average with priority queues in the same class.

- You cannot associate the priority command with the class-default of the output policy map.

Configuring Priority Without Police

BEFORE YOU BEGIN

Follow these guidelines when configuring strict priority queuing (priority without police):

- You cannot configure priority queuing without policing for a traffic class when class-based shaping ( shape average ) or CBWFQ ( bandwidth ) is configured for another class within the output policy map.

- When you configure priority queuing without policing for a traffic class, you can only configure the other queues for sharing by using the bandwidth remaining percent policy-map class configuration command to allocate excess bandwidth. This command does not guarantee the allocated bandwidth, but does ensure the rate of distribution.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

class-map class-map-name

Create classes for three egress queues. Enter match conditions classification for each class.

Step 3

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 4

class class-map-name

Enter the name of the priority class (created by using the class-map global configuration command), and enter policy-map class configuration mode for the priority class.

Step 5

priority

Set the strict scheduling priority for this class.
).

Step 6

exit

Exit policy-map class configuration mode for the priority class.

Step 7

class class-map-name

Enter the name of a nonpriority class, and enter policy-map class configuration mode for that class.

Step 8

bandwidth remaining percent value

Set output bandwidth limits for the policy-map class as a percentage of the remaining bandwidth. The range is 1 to 100 percent.

Step 9

exit

Exit policy-map class configuration mode for the class

Step 10

exit

Return to global configuration mode.

Step 11

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 12

service-policy output policy-map-name

Attach the policy map (created in Step 3) to the egress interface.

Step 13

end

Return to privileged EXEC mode.

Step 14

show policy-map

Verify your entries.

Step 15

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an output policy map, you attach it to an egress port. See the “Attaching a Traffic Policy to an Interface” section.

Use the no form of the appropriate command to delete an existing policy map or class map or to cancel strict priority queuing for the priority class or the bandwidth setting for the other classes.

EXAMPLE

This example shows how to configure the class out-class1 as a strict priority queue so that all packets in that class are sent before any other class of traffic. Other traffic queues are configured so that out-class-2 gets 50 percent of the remaining bandwidth and out-class3 gets 20 percent of the remaining bandwidth. The class class-default receives the remaining 30 percent with no guarantees.

Switch(config)# policy-map policy1

Switch(config-pmap)# class out-class1

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# exit

Switch(config-pmap)# class out-class2

Switch(config-pmap-c)# bandwidth remaining percent 50

Switch(config-pmap-c)# exit

Switch(config-pmap)# class out-class3

Switch(config-pmap-c)# bandwidth remaining percent 20

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface gigabitethernet0/1

Switch(config-if)# service-policy output policy1

Switch(config-if)# exit

Configuring Priority With Police

You can use the priority with police feature and configure an unconditional priority policer to limit the bandwidth used by the priority queue and allocate bandwidth or shape other queues.

BEFORE YOU BEGIN

Follow these guidelines when configuring priority with police:

- You cannot configure a policer committed burst size for an unconditional priority policer even though the keyword is visible in the CLI help. Any configured burst size is ignored when you try to attach the output service policy.

- The allowed police rate range is 64000 to 1000000000 b/s, even though the range that appears in the CLI help is 8000 to 1000000000. You cannot attach an output service policy with an out-of-range rate.

- You cannot configure priority with policing for a traffic class when bandwidth remaining percent is configured for another class in the same output policy map.

- You can configure 1-rate, 2-color policers for output policies with priority. You cannot configure 2-rate, 3-color policers for output policies.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

class-map class-map-name

Create classes for three egress queues. Enter match conditions classification for each class.

Step 3

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 4

class class-map-name

Enter the name of the priority class (created by using the class-map global configuration command), and enter policy-map class configuration mode for the priority class.

Step 5

priority

Configure this class as the priority class.
command.

Step 6

police { rate-bps | cir cir-bps }

Define a policer for the priority class of traffic.

- For rate-bps, specify average traffic rate in bits per second (b/s). The range is 64000 to 1000000000.

command in an output policy, the police rate range and the CIR range is 64000 to 1000000000 b/s, even though the range that appears in the CLI help is 8000 to 1000000000. You cannot attach an output service policy with an out-of-range rate.

- For cir cir-bps, specify a committed information rate (CIR) in bits per second (b/s). The range is 64000 to 1000000000.

Note Although visible in the command-line help string, the burst-size option is not supported in output policy maps. You cannot attach an output service policy map that has a configured burst size.

Step 7

conform-action [ transmit ]

(Optional) Enter the action to be taken on packets that conform to the CIR. If no action is entered, the default action is to send the packet.
is supported. Although visible in the command-line help string, the other police conform actions are not supported in output policy maps.

Step 8

exceed-action [ drop ]

(Optional) Enter the action to be taken for packets that do not conform to the CIR. If no action is entered, the default action is to drop the packet.
is supported. Although visible in the command-line help string, the other police exceed actions are not supported in output policy maps.

Step 9

exit

Exit policy-map class configuration mode for the priority class.

Step 10

class class-map-name

Enter the name of the first nonpriority class, and enter policy-map class configuration mode for that class.

Step 11

bandwidth { rate | percent value }

or

shape average target bps

Set output bandwidth limits for the policy map class in kilobits per second (the range is 64 to 1000000) or a percentage of the total bandwidth (the range is 1 to 100 percent) or specify the average class-based shaping rate in bits per second (the range is 64000 to 1000000000).

Step 12

exit

Return to policy-map configuration mode.

Step 13

exit

Return to global configuration mode.

Step 14

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 15

service-policy output policy-map-name

Attach the policy map (created in Step 3) to the egress interface.

Step 16

end

Return to privileged EXEC mode.

Step 17

show policy-map

Verify your entries.

Step 18

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an output policy map, you attach it to an egress port. See the “Attaching a Traffic Policy to an Interface” section.

Use the no form of the appropriate command to delete an existing policy map or class map or to cancel the priority queuing or policing for the priority class or the bandwidth setting for the other classes.

EXAMPLE

This example shows how to use the priority with police commands to configure out-class1 as the priority queue, with traffic going to the queue limited to 20000000 b/s so that the priority queue never uses more than that. Traffic above that rate is dropped. The other traffic queues are configured as in the previous example.

Switch(config)# policy-map policy1

Switch(config-pmap)# class out-class1

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# police 200000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class out-class2

Switch(config-pmap-c)# bandwidth percent 50

Switch(config-pmap-c)# exit

Switch(config-pmap)# class out-class3

Switch(config-pmap-c)# bandwidth percent 20

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface gigabitethernet0/1

Switch(config-if)# service-policy output policy1

Switch(config-if)# exit

Configuring Output Policy Maps with Weighted Tail Drop

Weighted tail drop (WTD) adjusts the queue size (buffer size) associated with a traffic class. You configure WTD by using the queue-limit policy-map class configuration command.

BEFORE YOU BEGIN

Follow these guidelines when configuring WTD:

- Configuring WTD with the queue-limit command is supported only when you first configure a scheduling action, such as bandwidth , shape average , or priority . The exception to this is when you are configuring queue-limit in the class-default .

- You can configure and attach as many output policy maps as there are ports. Multiple output policy maps can use the same queue-limit configuration. However, these policy maps can have only three unique queue-limit configurations.

- You can use the queue-limit command to configure the queue limit for CPU-generated traffic.

- When you use the queue-limit command to configure queue thresholds for a class, the WTD thresholds must be less than or equal to the queue maximum threshold. A queue size configured with no qualifier must be larger than any queue sizes configured with qualifiers.

- You cannot configure more than two unique threshold values for the WTD qualifiers ( cos , dscp , precedence , or qos-group ) in the queue-limit command. However, there is no limit to the number of qualifiers that you can map to those thresholds. You can configure a third unique threshold value to set the maximum queue, using the queue-limit command with no qualifiers.

- A WTD qualifier in the queue-limit command must be the same as at least one match qualifier in the associated class map.

- In an output policy map, when you configure a queue limit for a unique class, all other output policy maps must use the same format of qualifier type and qualifier value. Only queue-limit threshold values can be different. For example, when you configure class A queue-limit thresholds for dscp 30 and dscp 50 in policy-map1 , and you configure class A queue limits in policy map 2, you must use dscp 30 and dscp 50 as qualifiers. You cannot use dscp 20 and dscp 40 . The threshold values can be different, but different threshold values would create a new unique queue-limit configuration.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3

class { class-map-name | class-default }

Enter a child class-map name, or class-default to match all unclassified packets, and enter policy-map class configuration mode.

- If you enter a class-map name, you must perform Step 4 to configure a scheduling action ( bandwidth , shape average , or priority) before you go to Step 5 to configure queue-limit.

- If you enter class-default, you can skip Step 4.

Step 4

bandwidth { rate | percent value | remaining percent value }

or

shape average target bps

or

priority

Configure a scheduling action for the traffic class. For more information, see the “Configuring Output Policy Maps with Class-Based-Weighted-Queuing” section, the “Configuring Output Policy Maps with Class-Based Shaping” section, the “Configuring Output Policy Maps with Port Shaping” section, or the “Configuring Output Policy Maps with Class-Based Priority Queuing” section.

Step 5

queue-limit [ cos value | dscp value | precedence value | qos-group value ] number-of-packets [ packets ]}

Specify the queue size for the traffic class.

- (Optional) For cos value , specify a CoS value. The range is from 0 to 7.

- (Optional) For dscp value , specify a DSCP value. The range is from 0 to 63.

- (Optional) For precedence value , specify an IP precedence value. The range is from 0 to 7.

- (Optional) For qos-group value , enter a QoS group value. The range is from 0 to 99.

- For number-of-packets , s et the minimum threshold for WTD. The range is from 16 to 544, in multiples of 16, where each packet is a fixed unit of 256 bytes.

Note For optimal performance, we strongly recommend that you configure the queue-limit to 272 or less.
The value is specified in packets by default, but the packets keyword is optional.

Note Multiple output policy maps can use the same queue-limit configuration. However these policy maps can have only three unique queue-limit configurations.

Step 6

exit

Return to policy-map configuration mode.

Step 7

exit

Return to global configuration mode.

Step 8

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 9

service-policy output policy-map-name

Attach the policy map (created in Step 2) to the egress interface.

Note If you try to attach an output policy map that contains a fourth queue-limit configuration, you see an error message, and the attachment is not allowed.

Step 10

end

Return to privileged EXEC mode.

Step 11

show policy-map [ policy-map-name [ class class-map-name ]]

Verify your entries.

Step 12

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an output policy map, you attach it to an egress port. See the “Configuring Output Policy Maps” section.

Use the no form of the appropriate command to delete an existing policy map or class map or to delete a WTD configuration.

EXAMPLE

This example shows a policy map with a specified bandwidth and queue size. Traffic that is not DSCP 30 or 10 is assigned a queue limit of 112 packets. Traffic with a DSCP value of 30 is assigned a queue-limit of 48 packets, and traffic with a DSCP value of 10 is assigned a queue limit of 32 packets. All traffic not belonging to the class traffic is classified into class-default, which is configured with 10 percent of the total available bandwidth and a large queue size of 256 packets.

Switch(config)# policy-map gold-policy

Switch(config-pmap)# class traffic

Switch(config-pmap-c)# bandwidth percent 50

Switch(config-pmap-c)# queue-limit 112

Switch(config-pmap-c)# queue-limit dscp 30 48

Switch(config-pmap-c)# queue-limit dscp 10 32

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# bandwidth percent 10

Switch(config-pmap-c)# queue-limit 256

Switch(config-pmap-c)# exit

Switch(config-pmap)# exit

Switch(config)# interface gigabitethernet0/1

Switch(config-if)# service-policy output gold-policy

Switch(config-if)# exit

Configuring QoS Marking and Queuing for CPU-Generated Traffic

Follow this procedure to configure marking and queuing of CPU-generated traffic. This procedure is optional.

BEFORE YOU BEGIN

Follow these guidelines when configuring QoS marking and queuing for CPU-generated traffic:

- This feature must be configured globally for a switch; it cannot be configured per-port or per-protocol.

- Enter each cpu traffic qos marking action on a separate line.

- The cpu traffic qos cos global configuration command configures CoS marking for CPU-generated traffic by using either a specific CoS value or a table map, but not both. A new configuration overwrites the existing configuration.

- The cpu traffic qos dscp global configuration command configures IP-DSCP marking for CPU-generated IP traffic by using either a specific DSCP value or a table map, but not both. A new configuration overwrites the existing configuration.

- The cpu traffic qos precedence global configuration command configures IP-precedence marking for CPU-generated IP traffic by using either a specific precedence value or a table map, but not both. A new configuration overwrites the existing configuration.

- The cpu traffic qos dscp and cpu traffic qos precedence global configuration commands are mutually exclusive. A new configuration overwrites the existing configuration.

- When the cpu traffic qos dscp global configuration command is configured with table maps, you can configure only one map from value at a time: DSCP, precedence, or CoS. A new configuration overwrites the existing configuration. Packets marked by this command can be classified and queued by an output policy map based on the marked DSCP or precedence value.

- When the cpu traffic qos precedence global configuration command is configured with table maps, you can configure only one map from value at a time—DSCP, precedence, or CoS. A new configuration overwrites the existing configuration. Packets marked by this command can be classified and queued by an output policy map based on the marked precedence or DSCP value.

- You cannot configure a map from value of both DSCP and precedence. A new configuration overwrites the existing configuration.

- When the cpu traffic qos cos global configuration command is configured with table maps, you can configure two map from values at a time—CoS and either DSCP or precedence.

- If the cpu traffic qos cos global configuration command is configured with only a map from value of DSCP or precedence:

– The CoS value of IP packets is mapped by using the DSCP (or precedence) value in the packet and the configured table map. Packets can be classified and queued by an output policy map based on the marked CoS value.

– The CoS value of non-IP packets remains unchanged.

- If the cpu traffic qos cos global configuration command is configured with a map from value of CoS:

– The CoS value of IP packets is mapped by using the CoS value in the packet and the configured table map. Packets can be classified and queued by an output policy map based on the marked CoS value.

– The CoS value of non-IP packets is mapped by using the CoS value in the packet and the configured table map. Packets can be classified and queued by an output policy map based on the marked CoS value.

- If the cpu traffic qos cos global configuration command is configured with a map from value of DSCP or precedence and CoS:

– The CoS value of IP packets is mapped by using the DSCP or precedence value in the packet and the configured table map. Packets can be classified and queued by an output policy map based on the marked CoS value.

– The CoS value of non-IP packets is mapped by using the CoS value in the packet and the configured table map. Packets can be classified and queued by an output policy map based on the marked CoS value.

- The cpu traffic qos qos-group global configuration command can be used to configure QoS group marking for CPU-generated traffic only for a specific QoS group. The table-map option is not available.

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

Configure global table maps

Refer to the “Configuring Table Maps” section.

Step 3

cpu traffic qos cos { cos-value | cos [table-map table-map-name ] | dscp [table-map table-map-name ] | prec [table-map table-map-name ]}

Mark traffic by setting a new CoS value or by specifying a table map.

- For cos-value , enter a new CoS value. The range is from 0 to 7.

- You can also mark CoS based on the CoS, DSCP, or IP-precedence value. You can optionally use a table map to configure CoS. If you do not enter table-map table-map-name , the table map default behavior is copy . See the “Table Maps” section.

When you complete this step, go to Step 7 .

Step 4

cpu traffic qos dscp { dscp_value | cos [table-map table-map-name ] | dscp [table-map table-map-name ] | prec [table-map table-map-name ]}

Mark traffic by setting a new DSCP value or by specifying a table map.

- For dscp new-dscp , enter a new DSCP value for the classified traffic. The range is 0 to 63.

- You can also configure a table map to mark DSCP based on the CoS, DSCP, or IP-precedence value. You can optionally enter the table name. If you do not enter table-map table-map-map name, the table map default behavior is copy . See the “Table Maps” section.

- For additional DSCP classification options, see the “Classification Based on IP DSCP” section .

When you complete this step, go to Step 7 .

Step 5

cpu traffic qos precedence { precedence_value | cos [table-map table-map-name ] | dscp [table-map table-map-name ] | prec [ table-map table-map-name ]}

Mark traffic by setting a new precedence value or by specifying a table map.

- For precedence new-precedence , enter a new IP-precedence value as a number from 0 to 7 or by name: routine ( 0 ), priority ( 1 ), immediate ( 2 ), flash ( 3 ), flash-override ( 4 ), critical ( 5 ), internet ( 6 ), network ( 7 ).

- You can also configure a table map to mark precedence based on the CoS, DSCP, or IP-precedence value. You can optionally enter the table name. If you do not enter table-map table-map-map name , the table map default behavior is copy . See the “Table Maps” section.

When you complete this step, go to Step 7 .

Step 6

cpu traffic qos qos-group qos-group-value

Mark traffic by using a QoS group.

For qos-group - value , identify a QoS group to use at egress. The range is 0 to 99.

When you complete this step, go to Step 7 .

Step 7

end

Return to privileged EXEC mode.

Step 8

Configure output policy maps to map QoS markings like COS, IP DSCP, IP precedence and QoS group to class queues, configure queuing and scheduling

Refer to the “Configuring Output Policy Maps” section.

Step 9

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Step 10

show running-config

Display the configured class maps, policy maps, table maps, and CPU traffic QoS settings.

Step 11

show cpu traffic qos

Display the QoS marking values for CPU-generated traffic.

Step 12

show table-map [ table-map-name]

Display information for all table maps or the specified table map.

Step 13

show policy-map [ policy-map-name | interface [ interface-id ] [ output ] [ class class-name ]]

Display QoS policy map information for the specified policy map name, interface, input or output policy maps, or policy-map class.

To disable any command, use the no form of the command.

EXAMPLE

Example 1

This example shows how to configure egress queuing based on the DSCP value of CPU-generated IP packets.

- All CPU-generated IP traffic queues on the egress port, based on its IP DSCP value, and the configured output policy map output-policy .

- All IP SLA or TWAMP probes with the DSCP value ef to simulate voice traffic are assigned to the voice class.

- All IP SLA or TWAMP probes with the DSCP values af41 , af42 and af43 to simulate video traffic are assigned to the video class.

- All IP control protocol traffic with the DSCP values 48 and 56 are assigned to the network-internetwork-control class.

- The rest of the IP traffic is assigned to the default class.

- All CPU-generated non-IP traffic is statically mapped to a fixed queue on the egress port.

- All CFM traffic is queued to the default class because there is no class based on CoS.

Switch(config)# cpu traffic qos dscp dscp

Class:

Switch(config)# class-map match-any video

Switch(config-cmap)# match ip dscp af41 af42 af43

Switch(config-cmap)# exit

Switch(config)# class-map match-any voice

Switch(config-cmap)# match ip dscp ef

Switch(config-cmap)# exit

Switch(config)# class-map match-any network-internetwork-control

Switch(config-cmap)# match ip dscp 48 56

Switch(config-cmap)# exit

Policy:

Switch(config)# policy-map output-policy

Switch(config-pmap)# class voice

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# police cir 10000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class video

Switch(config-pmap-c)# bandwidth percent 40

Switch(config-pmap-c)# exit

Switch(config-pmap)# class network-internetwork-control

Switch(config-pmap-c)# bandwidth percent 10

Switch(config-pmap-c)# exit

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# bandwidth percent 30

Switch(config-pmap-c)# exit

Interface:

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy output output-policy

Switch(config-pmap-c)# exit

Example 2

This example shows how to mark the CoS of CPU-generated IP traffic (including IP-SLA and TWAMP) based on the DSCP value in the packet and to configure egress queuing based on the CoS value.

- All CPU-generated IP traffic queues on the egress port, based on the IP DSCP value and the configured output policy map called output-policy .

- All IP SLA or TWAMP probes with the DSCP value ef to simulate voice traffic are assigned to the voice class.

- All IP SLA or TWAMP probes with the DSCP values af41 , af42 and af43 to simulate video traffic are assigned to the video class.

- All IP control protocol traffic with the DSCP values 48 and 56 are assigned to the network-internetwork-control class.

- The rest of the IP traffic is assigned to the default class.

- All CPU-generated non-IP traffic with CoS 5 is assigned to the voice class.

- All CPU-generated non-IP traffic with CoS 3 is assigned to the video class.

- All CPU-generated non-IP traffic with CoS 6 and 7 is assigned to the network-internetwork-control class.

- All CFM traffic with CoS 5 is assigned to the voice class.

- All CFM traffic with CoS 3 is assigned to the video class.

- All CFM traffic with CoS 6 and 7 is assigned to the network-internetwork-control class.

Table Map:

Switch(config)# table-map dscp-to-cos

Switch(config-tablemap)# map from 46 to 5

Switch(config-tablemap)# map from 48 to 6

Switch(config-tablemap)# map from 56 to 7

Switch(config-tablemap)# map from af41 to 3

Switch(config-tablemap)# map from af42 to 3

Switch(config-tablemap)# map from af43 to 3

Switch(config-tablemap)# default 0

Switch(config-tablemap)# end

CPU QoS:

Switch(config)# cpu traffic qos cos dscp table-map dscp-to-cos

Switch(config)# cpu traffic qos cos cos

Class:

Switch(config)# class-map match-any video

Switch(config-cmap)# match cos 3

Switch(config-cmap)# exit

Switch(config)# class-map match-any voice

Switch(config-cmap)# match cos 5

Switch(config-cmap)# exit

Switch(config)# class-map match-any network-internetwork-control

Switch(config-cmap)# match cos 6 7

Switch(config-cmap)# exit

Policy:

Switch(config)# policy-map output-policy

Switch(config-pmap)# class voice

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# police cir 10000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class video

Switch(config-pmap-c)# bandwidth percent 40

Switch(config-pmap-c)# exit

Switch(config-pmap)# class network-internetwork-control

Switch(config-pmap-c)# bandwidth percent 10

Switch(config-pmap-c)# exit

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# bandwidth percent 30

Switch(config-pmap-c)# exit

Interface:

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy output output-policy

Switch(config-pmap-c)# exit

Example 3

This example shows how to:

- Mark the DSCP value of CPU-generated IP traffic (including IP-SLA and TWAMP) based on the DSCP value in the packet.

- Mark the CoS of CPU-generated IP traffic (including IP-SLA and TWAMP) based on the DSCP value in the packet.

- Mark the CoS of CPU-generated non-IP traffic based on the CoS value in the packet.

- Mark all CPU-generated traffic with the QoS group.

- Configure egress queuing based on the QoS group.

The example has these results:

- All CPU-generated IP traffic with DSCP values 46, 48, and 56 retains the existing markings.

- For all other CPU-generated IP packets, the DSCP value is reset to 0.

- All CPU-generated IP traffic with DSCP values 46, 48, and 56 is mapped to the corresponding CoS values of 5, 6, and 7, respectively.

- For all other CPU-generated IP packets, the CoS value resets to 0.

- All CPU-generated non-IP traffic with the CoS values of 5, 6, and 7 retain the existing markings.

- For all other CPU-generated non-IP packets, the CoS value resets to 0.

- All CPU-generated traffic goes through a single class called cpu-traffic . The user-voice classes user-voice and user-video are reserved for user traffic. As a result, CPU traffic and user traffic are separated into different queues on the egress port.

Table Map:

Switch(config)# table-map dscp-to-cos

Switch(config-tablemap)# map from 46 to 5

Switch(config-tablemap)# map from 48 to 6

Switch(config-tablemap)# map from 56 to 7

Switch(config-tablemap)# default 0

Switch(config-tablemap)# end

Switch(config)# table-map dscp-to-dscp

Switch(config-tablemap)# map from 46 to 46

Switch(config-tablemap)# map from 48 to 48

Switch(config-tablemap)# map from 56 to 56

Switch(config-tablemap)# default 0

Switch(config-tablemap)# end

Switch(config)# table-map cos-to-cos

Switch(config-tablemap)# map from 5 to 5

Switch(config-tablemap)# map from 6 to 6

Switch(config-tablemap)# map from 7 to 7

Switch(config-tablemap)# default 0

Switch(config-tablemap)# end

CPU QoS:

Switch(config)# cpu traffic qos dscp dscp table-map dscp-to-dscp

Switch(config)# cpu traffic qos cos dscp table dscp-to-cos

Switch(config)# cpu traffic qos cos cos table cos-to-cos

Switch(config)# cpu traffic qos qos-group 50

Class:

Switch(config)# class-map match-any cpu-traffic

Switch(config-cmap)# match qos-group 50

Switch(config-cmap)# exit

Switch(config)# class-map match-any user-video

Switch(config-cmap)# match cos 3

Switch(config-cmap)# exit

Switch(config)# class-map match-any user-voice

Switch(config-cmap)# match cos 5

Switch(config-cmap)# exit

Policy:

Switch(config)# policy-map output-policy

Switch(config-pmap)# class user-voice

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# police cir 10000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class user-video

Switch(config-pmap-c)# bandwidth percent 40

Switch(config-pmap-c)# exit

Switch(config-pmap)# class cpu-traffic

Switch(config-pmap-c)# bandwidth percent 10

Switch(config-pmap-c)# exit

Switch(config-pmap)# class class-default

Switch(config-pmap-c)# bandwidth percent 30

Switch(config-pmap-c)# exit

Interface:

Switch(config)# interface fastethernet0/1

Switch(config-if)# service-policy output output-policy

Switch(config-pmap-c)# exit

Implementing High-Priority Traffic to the Host Router

This section describes QoS features for implementing high-priority (low-latency) traffic via the internal data path between the CGR 2010 Ethernet Switch Module (ESM) and the host CGR 2010 router. The internal data path is called PortChannel48 . For details, see Interfaces Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches , the section “Configuring the Backplane Interface Between the ESM and Host Router.”

Note The information in this section applies only to the CGR 2010 ESM.

Note In this section, ingress refers to the direction of the data flow from the CGR 2010 ESM to the host router and egress refers to the direction of the data flow from the host router to the switch module.

Tip QoS configuration for the switch module is concerned only with the ingress traffic from the switch module to the host router.

You can configure QoS on the switch module and the CGR 2010 router using Modular QoS CLI (MQC), with some limitations on the switch module. The following subsections describe the major components in this internal data path and their QoS functions.

Ingress CoS to GDF Queue Mapping

In a substation network, some data frames (for example, GOOSE (Generic Object Oriented Substation Events) messages) require low-latency in the data path. The switch module provides high priority queuing to support low-latency data. This section describes how low-latency data frames from the switch module are mapped to the Generic Data Frame (GDF) queues.

Unlike the switch module, which uses a hardware ASIC to perform Layer 2 to Layer 3 switching, the CGR 2010 router’s data path is implemented in software and can potentially have greater jitter and delay in its data path. If all data packets from the switch module are sent to a single GDF queue in the CGR 2010 router, low-latency data could be blocked by the other low priority data frames in the same queue.

To prevent low-latency data frames from being blocked by other lower priority data frames on the ingress data path to the host CGR 2010 router, the switch module sends high priority data frames and the other lower priority data frames to two separate GDF queues:

- The GDF queue for low-latency (high-priority) data is called the priority queue (GDF queue 0).

- The GDF queue for other data is called the low-priority queue (GDF queue 1).

Network administrators can use MQC to classify and/or mark a data frame based on the information on the Layer 2 and Layer 3 headers. The mapping of data frames to GDF queues is solely based on the CoS field in the 802.1Q tag. Data frames that require low latency in the internal data path from the switch module to the host router should contain an 802.1Q tag and be marked with CoS values that are configured with priority queuing (with or without policing).

All other data frames, which either do not contain an 802.1Q tag or their CoS values are not configured with priority queuing, are mapped to the low-priority queue. For details and example configurations, see “Mapping CoS to the High-Priority GDF Queue” section.

Adjusting for Differences in Ingress Traffic Bandwidth

The CGR 2010 router processes incoming and outgoing packets in software. Depending on the performance of the router’s CPU, the effective bandwidth of the internal data path on the CGR 2010 router’s side could be less than the bandwidth provided by the internal EtherChannel on the switch module.

If the effective bandwidth on the CGR 2010 router is less than the bandwidth of the internal EtherChannel, you should use the MQC command to configure port shaping on the internal EtherChannel on the switch module so that the effective bandwidth on the two sides are roughly equivalent. For more information, see the “Congestion Management and Scheduling” section.

Configuring CPU-Generated Data

The switch module can send control data to the CGR 2010 host router through the backplane PortChannel48. You can configure QoS for the CPU-generated data frames with MQC. If you would like to send the CPU-generated data frames to the GDF priority queue, you have to configure the CPU so that all CPU-generated data would be marked with a non-zero CoS value.

To do so, use the cpu traffic qos cos command in global configuration mode to configure quality of service (QoS) marking based on class of service (CoS) for control plane traffic. To return to the default value, use the no form of this command.

cpu traffic qos cos {cos_value }

For example:

Switch(config)# cpu traffic qos cos 5

Syntax

Description

cos-value

Specify a CoS value. The range is from 0 to 7. If no CoS value is configured, the protocol-specific default value for each packet is applied.

cos

Configure the CoS value based on the CoS value in the packet, using a table-map.

Usage Guidelines

Configure any desired table-maps before configuring marking or queuing of CPU traffic.

This feature must be configured globally for a switch module; it cannot be configured per-port or per-protocol.

Enter each cpu traffic qos marking action on a separate line.

The cpu traffic qos cos global configuration command configures CoS marking for CPU-generated traffic by using either a specific CoS value or a table map, but not both. A new configuration overwrites the existing configuration.

When the cpu traffic qos cos global configuration command is configured with table maps, you can configure two map from values at a time— CoS and either DSCP or precedence .

Mapping CoS to the High-Priority GDF Queue

As mentioned earlier in this section, GDF queue mapping is solely based on the CoS value in the 802.1Q tag. Untagged data frames are mapped to the GDF low-priority queue. This imposes some limitations on how users configure QoS on the internal PortChannel interface in the CGR 2010 ESM.

A native VLAN is the untagged VLAN on an 802.1Q trunked switch module port. The native VLAN and management VLAN could be the same, but it is better security practice that they are not. If a switch module receives untagged frames on a trunk port, they are assumed to be part of the VLAN that is designated on the switch module port as the native VLAN. Frames egressing a switch module port on the native VLAN are not tagged.

By default, the data frames belonging to a native VLAN are untagged. If users would like to configure priority queuing for native VLAN, they should use the vlan dot1q tag native CLI command to enable 802.1Q tagging for native VLAN.

Note vlan dot1q tag native is a global configuration command and applies to all trunk ports in the switch module.

Please note the following:

- Users should not configure priority queuing for data frames marked with CoS 0 because it is the default CoS value for data frames whose CoS value are not marked.

- Low-latency traffic destined to the GDF priority queue should be marked with a non-zero CoS value and configured with priority queuing using MQC (see the “Modular QoS CLI” section).

- Chosen CoS values for priority queuing applies to the data frame for all VLANs

Example Configuration for CoS to GDF Queue Mapping

This section provides an example configuration to map CoS 5 to GDF queue 0 (the high-priority queue) for the internal PortChannel 48 on the CGR 2010 ESM copper model (GRWIC-D-2S-8PC).

Command

Purpose

Step 1

configure terminal

Enters global configuration mode.

Step 2

class-map match-all class0

Creates a class map, and enters class-map configuration mode. For details on using the class-map command, see the “Using Class Maps to Define a Traffic Class” section.

- In this example, we use the match-all keyword to perform a logical-AND of all matching statements under this class map. All match criteria in the class map must be matched.

- In this example, class0 specifies the name of the class map.

Step 3

match cos 5

Defines the match criterion to classify traffic.

Only one match type per class map is supported, and only one ACL per class map is supported.

- The cos 5 parameter specifies a value of 5 for the CoS field to match against incoming packets.

Step 4

policy-map policy0

Creates a policy map by entering the policy map name (for example, policy0 ), and enters policy-map configuration mode.

Step 5

class class0

Enters the name of the priority class (created by using the class-map global configuration command shown in Step 2), and enters policy-map class configuration mode for the priority class.

Step 6

priority

Sets the strict scheduling priority for this class.

Step 7

interface FastEthernet0/9

Specifies the interface to configure, and enters interface configuration mode.

Step 8

switchport mode trunk

Configures the switch’s PortChannel as a Layer 2 VLAN trunk, so that the specified port can transport the frames for multiple VLANs.

Step 9

service-policy output policy0

The service-policy output policy0 interface configuration command attaches all the characteristics of the traffic policy named policy0 to the specified interface. All packets leaving the specified interface are evaluated according to the criteria specified in the traffic policy named policy0 .

Step 10

Repeat Steps 7 through 9 for each interface in the PortChannel48 (a total of eight interfaces).

Step 11

end

Return to privileged EXEC mode.

Step 12

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Verifying Configuration

Command

Purpose

show class-map [ class-map-name ]

Display QoS class-map information for all class maps or the specified class map.

show policer aggregate [ aggregate-policer-name ]

Display information about all aggregate policers or the specified aggregate policer.

show policy-map [ policy-map-name | interface [ interface-id ] [ input | output ] [ class class-name ]]

Display QoS policy map information for the specified policy map name, interface, input or output policy maps, or policy-map class.

show cpu traffic qos

Display the QoS marking values for CPU-generated traffic.

show running-config

Display the configured class maps, policy maps, table maps, and aggregate policers.

show table-map [ table-map-name ]

Display information for all configured table maps or the specified table map.

To test full-path QoS in both directions on an interface, you can configure Ethernet terminal loopback by entering the ethernet loopback facility interface configuration command. In terminal loopback mode, the port appears to be up but the link is actually down and no packets are sent out. Configuration changes on the port immediately affect the traffic being looped back. For information about Ethernet terminal loopback, see the chapter “Enabling Ethernet Loopback” in the System Management Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches .

QoS Statistics

There are several ways to display QoS input and output policy map statistics.

For input policy maps, you can use the show policy-map interface [ interface-id ] privileged EXEC command to display per-class per-policer conform and exceed statistics. Policer conform statistics are the number of packets that conform to the configured policer profile; policer exceed statistics are the number of packets that exceed the configured policer profile. The switch does not support per-class classification statistics, but you can determine these statistics by configuring policing at line rate for the class. In this case, no packets exceed the configured policer profile, and the policer conform statistics would equal the class classification statistics.

This output also includes byte-level statistics for conform, exceed, and violate classes.

Another way to view input QoS statistics is in the output of the show platform qos statistics interface [ interface-id ] privileged EXEC command. The per-port frame statistics are sorted by the DSCP and CoS values of the incoming frames on the port. These statistics do not provide any information about the MQC input policy map configured on the interface.

For output policy maps, you can use the show policy-map interface [ interface-id ] command to display per-class classification statistics that show the total number of packets that match the specified class. This count includes the total number of packets that are sent and dropped for that class. You can use the same command to view the per-class tail drop statistics.

Configuration Examples for Policy Maps

This section includes configuration examples for configuring QoS policies on the switch, including configuration limitations and restrictions. The sections are broken into different configurations actions that a customer might do. Each section provides the exact sequence of steps that you must follow for successful configuration or modification.

- QoS Configuration for Customer A

- QoS Configuration for Customer B

- Modifying Output Policies and Adding or Deleting Classification Criteria

- Modifying Output Policies and Changing Queuing or Scheduling Parameters

- Modifying Output Policies and Adding or Deleting Configured Actions

- Modifying Output Policies and Adding or Deleting a Class

QoS Configuration for Customer A

This section provides examples of the initial configuration and activation of QoS policies for a customer switch. Input and output QoS service policies are configured based on the requirements and attached to relevant ports.

In the initial configuration for Customer A, Fast Ethernet ports 1 through 24 are user network interfaces (UNIs) and are disabled by default. Gigabit Ethernet ports 1 and 2 are network node interfaces (NNIs) and are enabled by default.

This is the overall sequence for initial configuration:

1. Configure classes and policies.

2. Shut down all active ports.

3. Attach policies to ports to be activated.

4. Take the ports out of the shut-down state.

5. Leave unused ports shut down.

Note these restrictions for configuring output policies:

- You can define up to three classes in the output policy map.

- The defined classes must be the same as other output policy maps.

- The number of defined classes in each output policy map must be same.

- You must assign an action to each class; that is, there can be no empty class.

- Each class configuration must be based on the classification/marking done in the input policy map.

This example configures classes for input service policies and defines three classes of service: gold, silver, and bronze. Because a match-all classification (the default) can have only single classification criterion, the match-any classification is used so that you can add classification criteria in the future.

Switch# config terminal

Switch(config)# class-map match-any gold-in

Switch(config-cmap)# match ip dscp af11

Switch(config-cmap)# exit

Switch(config)# class-map match-any silver-in

Switch(config-cmap)# match ip dscp af21

Switch(config-cmap)# exit

Switch(config)# class-map match-any bronze-in

Switch(config-cmap)# match ip dscp af31

Switch(config-cmap)# exit

This example shows how to configure an input policy map that marks the gold class and polices the silver class to 50 Mb/s and the bronze class to 20 Mb/s.

Switch(config)# policy-map input-all

Switch(config-pmap)# class gold-in

Switch(config-pmap-c)# set ip dscp af43

Switch(config-pmap-c)# exit

Switch(config-pmap)# class silver-in

Switch(config-pmap-c)# police 50000000

Switch(config-pmap)# class bronze-in

Switch(config-pmap-c)# police 20000000

Switch(config-pmap-c)# exit

This example configures classes for output service policies with three classes of service: gold, silver, and bronze. The gold class is configured to match the marked value in the input service policy. Because a match-all classification (the default) can have only single classification criterion, the match-any classification is used so that you can add classification criteria in the future.

Switch# config terminal

Switch(config)# class-map match-any gold-out

Switch(config-cmap)# match ip dscp af43

Switch(config-cmap)# exit

Switch(config)# class-map match-any silver-out

Switch(config-cmap)# match ip dscp af21

Switch(config-cmap)# exit

Switch(config)# class-map match-any bronze-out

Switch(config-cmap)# match ip dscp af31

Switch(config-cmap)# exit

This example configures one output service policy to be applied to both Gigabit Ethernet NNIs, providing priority with rate-limiting to the gold class, class-based shaping for the silver class, and a minimum bandwidth guarantee of 10 percent to the bronze class:

Switch(config)# policy-map output-g1-2

Switch(config-pmap)# class gold-out

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# police 50000000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class silver-out

Switch(config-pmap-c)# shape average 200000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class bronze-out

Switch(config-pmap-c)# bandwidth percent 10

Switch(config-pmap-c)# exit

This example configures a second output service policy to be applied to Fast Ethernet UNIs 1 to 8, providing strict priority to the gold class and distributing the remaining bandwidth in the desired proportions over the remaining classes:

Switch(config)# policy-map output1-8

Switch(config-pmap)# class gold-out

Switch(config-pmap-c)# priority

Switch(config-pmap-c)# exit

Switch(config-pmap)# class silver-out

Switch(config-pmap-c)# bandwidth remaining percent 50

Switch(config-pmap-c)# exit

Switch(config-pmap)# class bronze-out

Switch(config-pmap-c)# bandwidth remaining percent 20

Switch(config-pmap-c)# exit

This example attaches the input and output service policies to the Gigabit Ethernet ports and activates them:

Switch(config)# interface range gigabitethernet0/1-2

Switch(config-if-range)# service-policy input input-all

Switch(config-if-range)# service-policy output output-g1-2

Switch(config-if-range)# no shutdown

Switch(config-if-range)# exit

This example attaches the input and output service policies to Fast Ethernet ports 1 to 8 and activates them:

Switch(config)# interface range fastethernet0/1 – 8

Switch(config-if-range)# service-policy input input-all

Switch(config-if-range)# service-policy output output1-8

Switch(config-if-range)# no shutdown

Switch(config-if-range)# exit

QoS Configuration for Customer B

This section provides examples for configuring and activating QoS policies on the switch for a new set of customers without affecting the current customers. Input and output QoS service policies are configured based on the requirements and attached to relevant ports. The example uses an existing input policy map and configures a new output policy map for the new customers.

In the initial configuration for Customer B, Fast Ethernet ports 1 through 8 are UNIs and are active. Fast Ethernet ports 9 through 24 are UNIs and are shut down. Gigabit Ethernet ports 1 and 2 are NNIs and are enabled by default.

This is the overall sequence of initial configuration:

1. Define any new required output policies.

2. Attach input and output policies to ports to be activated.

3. Take the ports out of the shut-down state.

Note these restrictions when configuring output policies:

- You can define up to three classes in the output policy map.

- The defined classes must be the same as other output policy maps.

- The number of defined classes in each output policy map must be same.

- You must assign an action to each class; that is, there can be no empty class.

- Each class configuration must be based on the classification/marking done in the input policy map.

This example configures a third output service policy to be attached to Fast Ethernet UNIs 9 through 12, providing a minimum guaranteed bandwidth of 50 Mb/s to the gold class, 20 Mb/s to the silver class, and 10 Mb/s to the bronze class:

Switch(config)# policy-map output9-12

Switch(config-pmap)# class gold-out

Switch(config-pmap-c)# bandwidth 50000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class silver-out

Switch(config-pmap-c)# bandwidth 20000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class bronze-out

Switch(config-pmap-c)# bandwidth 10000

Switch(config-pmap-c)# exit

This example attaches the output policy for Fast Ethernet ports 9 through 12 and activates the ports:

Switch# config terminal

Switch(config)# interface range fastethernet0/9-12

Switch(config-if-range)# service-policy input input-all

Switch(config-if-range)# service-policy output output9-12

Switch(config-if-range)# no shutdown

Switch(config-if-range)# exit

Modifying Output Policies and Adding or Deleting Classification Criteria

This section provides examples of updating an existing set of output policy maps to add or delete classification criteria. The modification might be required due to a change in the service provisioning requirements or a change in the input service policy map. You can make the change without shutting down any port.

In the initial configuration, Fast Ethernet ports 1 through 12 are UNIs and are active. Fast Ethernet ports 13 through 24 are UNIs and are shut down. Gigabit Ethernet ports 1 and 2 are NNIs and are enabled by default.

This is the overall sequence of initial configuration:

1. Change the configured class map for an input service policy.

2. Change the configured class map for an output service policy.

This example modifies classes for an input service policy by adding classification criteria to the silver-in class to also match dscp cs5. This is required for the output policy map to match to dscp cs5.

Switch(config)# class-map match-any silver-in

Switch(config-cmap)# match ip dscp af21

Switch(config-cmap)# match ip dscp cs5

Switch(config-cmap)# exit

This example modifies classes for an output service policy, adding classification criteria to the silver-out class to also match dscp cs5. This adds dscp cs5 to the silver-out class on all configured and attached output service policies. The dscp cs5 flow now receives the same queuing and scheduling treatment as the silver-out class.

Switch# config terminal

Switch(config)# class-map match-any silver-out

Switch(config-cmap)# match ip dscp af21

Switch(config-cmap)# match ip dscp cs5

Switch(config-cmap)# exit

You should use the same procedure when deleting a match statement associated with a configured class.

Modifying Output Policies and Changing Queuing or Scheduling Parameters

This section provides examples of updating an existing set of output policy maps to modify the parameters of the configured queuing and scheduling actions. The modification in the output policy map might be required due to a change in the service provisioning requirements. You can make the change without shutting down any port.

In the initial configuration, Fast Ethernet ports 1 through 12 are UNIs and are active. Fast Ethernet ports 13 through 24 are UNIs and are shut down. Gigabit Ethernet ports 1 and 2 are NNIs and are enabled by default.

The requirement is to change the action parameters.

Note these restrictions when configuring output policies:

- You can define up to three classes in the output policy map.

- The defined classes must be the same as other output policy maps.

- The number of defined classes in each output policy map must be same.

- You must assign an action to each class; that is, there can be no empty class.

- Each class configuration must be based on the classification or marking done in the input policy map.

This example modifies the third output service policy servicing Fast Ethernet UNIs 8 through 12 by providing minimum guaranteed bandwidth of 40 Mb/s to the gold class (changed from 50 Mb/s), 30 Mb/s to the silver class (changed from 20 Mb/s), and 20 Mb/s to the bronze class (changed from 10 Mb/s).

Switch(config)# policy-map output9-12

Switch(config-pmap)# class gold-out

Switch(config-pmap-c)# bandwidth 40000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class silver-out

Switch(config-pmap-c)# bandwidth 30000

Switch(config-pmap-c)# exit

Switch(config-pmap)# class bronze-out

Switch(config-pmap-c)# bandwidth 20000

Switch(config-pmap-c)# exit

Modifying Output Policies and Adding or Deleting Configured Actions

This section provides examples of updating an existing set of output policy maps to add or delete queuing and scheduling actions. The modification in the output policy map might be required due to a change in the service provisioning requirements. You can make the change without shutting down ports that are not configured with the output policy map to be modified. But you must shut down the ports that are configured with that output policy map. Customers not using this output policy map are not affected.

In the initial configuration, Fast Ethernet ports 1 through 12 are UNIs and are active. Fast Ethernet ports 13 through 24 are UNIs and are shut down. Gigabit Ethernet ports 1 and 2 are NNIs and are enabled by default.

This is the overall sequence of configuration:

- Shut down all active ports carrying the policy to be modified.

- Detach the output policy from all ports to which it is attached.

- Make modifications to the output policy.

- Reattach the output policy to the appropriate ports.

- Take the ports out of the shutdown state.

Note these restrictions for configuring output policies:

- You can define up to three classes in the output policy map.

- The defined classes must be the same as other output policy maps.

- The number of defined classes in each output policy map must be same.

- You must assign an action to each class; that is, there can be no empty class.

- Each class configuration must be based on the classification/marking done in the input policy map.

This example shuts down all ports carrying the output policy, in this case only the Gigabit Ethernet ports.

Switch(config)# interface range gigabitEthernet0/1-2

Switch(config-if-range)# shutdown

Switch(config-if-range)# exit

This example detaches the output policy to be modified, in this case the one configured on the Gigabit Ethernet ports:

Switch(config)# interface range gigabitEthernet0/1-2

Switch(config-if-range)# no service-policy output output-g1-2

Switch(config-if-range)# exit

This example modifies the output service policy servicing the Gigabit Ethernet NNIs. Instead of providing a minimum bandwidth guarantee of 10 percent to the bronze class, the policy is modified to provide class-based shaping to 100000 b/s.

Switch(config)# policy-map output-g1-2

Switch(config-pmap)# class bronze-out

Switch(config-pmap-c)# no bandwidth percent 10

Switch(config-pmap-c)# shape average 100000

Switch(config-pmap-c)# exit

This example reattaches the output policy to the Gigabit Ethernet ports:

Switch(config)# interface range gigabitethernet0/1-2

Switch(config-if-range)# service-policy output output9-12

Switch(config-if-range)# exit

This example activates all Gigabit Ethernet ports:

Switch(config)# interface range gigabitethernet0/1-2

Switch(config-if-range)# no shutdown

Switch(config-if-range)# exit

Modifying Output Policies and Adding or Deleting a Class

This section provides examples of updating an existing set of output policy maps to add or delete entire classes. The modification in the output policy map might be required due to a change in the service provisioning requirements or a change in the input service policy. To make this change, you must shut down all active ports on the switch. For this kind of update to any output policy map, all customers could potentially be affected. To avoid this, we recommend that you consider possible future upgrades when you configure classes in output service policies.

In the initial configuration, Fast Ethernet ports 1 through 12 are UNIs and are active. Fast Ethernet ports 13 through 24 are UNIs and are shut down. Gigabit Ethernet ports 1 and 2 are NNIs and are enabled by default.

This is the overall sequence of configuration:

1. Shut down all active ports.

2. Detach the output policies from all Fast Ethernet and Gigabit Ethernet ports.

3. Delete the class.

4. Reattach the output policies to the Fast Ethernet and Gigabit Ethernet ports.

5. Take the Fast Ethernet and Gigabit Ethernet ports out of the shutdown state.

This example shuts down all active and applicable Fast Ethernet and Gigabit Ethernet ports:

Switch(config)# interface range gigabitethernet0/1-2, fastethernet0/1-12

Switch(config-if-range)# shutdown

Switch(config-if-range)# exit

This example detaches all output policies from the affected Fast Ethernet and Gigabit Ethernet ports:

Switch(config)# interface range fastethernet0/1-8

Switch(config-if-range)# no service-policy output output1-8

Switch(config-if-range)# exit

Switch(config)# interface range fastethernet0/9-12

Switch(config-if-range)# no service-policy output output9-12

Switch(config-if-range)# exit

Switch(config)# interface range gigabitethernet0/1-2

Switch(config-if-range)# no service-policy output output-g1-2

Switch(config-if-range)# exit

This example deletes a class from all output policy maps and input policy maps; the input policy can be left attached or can be detached:

Switch(config)# policy-map output1-8

Switch(config-pmap)# no class bronze-out

Switch(config-pmap-c)# exit

Switch(config)# policy-map output9-12

Switch(config-pmap)# no class bronze-out

Switch(config-pmap-c)# exit

Switch(config)# policy-map output-g1-2

Switch(config-pmap)# no class bronze-out

Switch(config-pmap-c)# exit

Switch(config)# policy-map input-all

Switch(config-pmap)# no class bronze-in

Switch(config-pmap-c)# exit

This example reattaches all policies to the Fast Ethernet and Gigabit Ethernet ports:

Switch(config)# interface range fastethernet0/1-8

Switch(config-if-range)# service-policy output output1-8

Switch(config-if-range)# exit

Switch(config)# interface range fastethernet0/9-12

Switch(config-if-range)# service-policy output output9-12

Switch(config-if-range)# exit

Switch(config)# interface range gigabitethernet0/1-2

Switch(config-if-range)# service-policy output output9-12

Switch(config-if-range)# exit

This example activates all applicable Fast Ethernet and Gigabit Ethernet ports:

Switch(config)# interface range gigabitethernet0/1-2, fastethernet0/1-12

Switch(config-if-range)# no shutdown

Switch(config-if-range)# exit

You should use the same procedure when adding a class to an attached output service policy.

Note Problems can occur if you do not follow the previous sequence.

When a policy map is attached to an interface, all traffic that does not explicitly match the configured class maps within the policy map should go through the default queue (class class-default ). However, in some cases, traffic that does not explicitly match the output policy map classes could go through more than one queue. This queuing problem can occur when you do not follow the previous procedure and do not attach an output policy to all active ports.

For example, consider this case where only two ports are configured with an output policy and we want to delete a class in the output policy.

Shut down two ports:

Switch(config)# interface range fastethernet0/1-2

Switch(config-if-range)# shutdown

Switch(config-if-range)# exit

Detach the output policy from both ports:

Switch(config)# interface range fastEthernet0/1-2

Switch(config-if)# no service-policy output output1-2

Switch(config-if)# exit

Delete a class in the output policy:

Switch(config)# policy-map output1-2

Switch(config-pmap)# no class bronze-out

Switch(config-pmap-c)# exit

Attach the output policy to only one port and not to the other:

Switch(config)# interface FastEthernet0/1

Switch(config-if)# service-policy output output1-2

Switch(config-if)# exit

Enable both ports:

Switch(config)# interface range fastethernet0/1-2

Switch(config-if-range)# no shutdown

Switch(config-if-range)# exit

At this point, when traffic leaves Fast Ethernet port 2, instead of going through a single default queue, it goes through the same number of queues as there are classes defined in the output policy map attached to Fast Ethernet port 1. In this case, it would be three. In some cases, packets for a flow out of Fast Ethernet port 2 might be reordered if a flow splits across more than one queue. You can avoid this problem by leaving ports in a shut-down state until you attach an output policy.

Related Documents

- Quality of Service Solutions Configuration Guide Library, Cisco IOS Release 15M&T

- Cisco IOS Quality of Service Solutions Command Reference

- Cisco IOS Master Command List, All Releases

- System Management Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches

- Layer 2 Switching Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches

- Security Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches

- Interfaces Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches

Feature History

Platform

First Supported Release

IE 2000U

Cisco IOS Release 15.0(2)EH

CGS 2520

Cisco IOS Release 12.2(53)EX

Ethernet Switch Module (ESM) for CGR 2010

Cisco IOS Release 12.2(53)EX