Cisco Nexus 5000 Series NX-OS Quality of Service Configuration Guide, Rel 5.0(3)N1(1)

Information About Quality of Service

The configurable Cisco NX-OS quality of service (QoS) features allow you to classify the network traffic, prioritize the traffic flow, and provide congestion avoidance.

The default QoS configuration on the device provides lossless service for Fibre Channel and Fibre Channel over Ethernet (FCoE) traffic and best-effort service for Ethernet traffic. QoS can be configured to provide additional classes of service for Ethernet traffic. Cisco NX-OS QoS features are configured using Cisco Modular QoS CLI (MQC).

Standard Ethernet is a best-effort medium which means that it lacks any form of flow control. In the event of congestion or collisions, Ethernet will drop packets. The higher level protocols detect the missing data and retransmit the dropped packets.

Fibre Channel requires a reliable transport system that guarantees the delivery of every packet. To properly support FCoE, Ethernet has been enhanced with a priority flow control (PFC) mechanism to prevent congestion.

The FCoE QoS must be configured either if native FC or FCoE or FC and FCoE are in use. The FCoE QoS must be added even if Ethernet is not configured on the switch.

The following commands will enable the default QoS configuration:

switch(config)# system qos
switch(config-sys-qos)# service-policy type queuing input fcoe-default-in-policy
switch(config-sys-qos)# service-policy type queuing output fcoe-default-out-policy
switch(config-sys-qos)# service-policy type qos input fcoe-default-in-policy
switch(config-sys-qos)# service-policy type network-qos fcoe-default-nq-policy

Modular QoS CLI
System Classes
Default System Classes
Information About Policy Types
Link-Level Flow Control
Priority Flow Control
MTU
Trust Boundaries
Ingress Queuing Policies
Ingress Classification Policies
Egress Queuing Policies
Buffering and Queue Limits on the Cisco Nexus Device
Buffering and Queue Limits on the Cisco Nexus 5000 Platform
QoS for Multicast Traffic
Policy for Fibre Channel Interfaces
QoS for Traffic Directed to the CPU

Modular QoS CLI

The Cisco Modular QoS CLI (MQC) provides a standard set of commands for configuring QoS.

You can use MQC to define additional traffic classes and to configure QoS policies for the whole system and for individual interfaces. Configuring a QoS policy with MQC consists of the following steps:

Define traffic classes.
Associate policies and actions with each traffic class.
Attach policies to logical or physical interfaces as well as at the global system level.

MQC provides two command types to define traffic classes and policies:

class-map

Defines a class map that represents a class of traffic based on packet-matching criteria. Class maps are referenced in policy maps.

The class map classifies incoming packets based on matching criteria, such as the IEEE 802.1p class of service (CoS) value. Unicast and multicast packets are classified.

policy-map

Defines a policy map that represents a set of policies to be applied on a class-by-class basis to class maps.

The policy map defines a set of actions to take on the associated traffic class, such as limiting the bandwidth or dropping packets.

You define the following class-map and policy-map object types when you create them:

network-qos: Defines MQC objects that you can use for system level related actions.
qos: Defines MQC objects that you can use for classification.
queuing: Defines MQC objects that you can use for queuing and scheduling.

Note

The qos type is the default for the class-map and policy-map commands, but not for the service-policy which requires that you specify an explicit type.

You can attach policies to interfaces or EtherChannels as well as at the global system level by using the service-policy command.

You can view all or individual values for MQC objects by using the show class-map and show policy-map commands.

An MQC target is an entity (such as an Ethernet interface) that represents a flow of packets. A service policy associates a policy map with an MQC target and specifies whether to apply the policy on incoming or outgoing packets. This mapping enables the configuration of QoS policies such as marking, bandwidth allocation, buffer allocation, and so on.

System Classes

The system qos is a type of MQC target. You use a service policy to associate a policy map with the system qos target. A system qos policy applies to all interfaces on the switch unless a specific interface has an overriding service-policy configuration. The system qos policies are used to define system classes, the classes of traffic across the entire switch, and their attributes. To ensure QoS consistency (and for ease of configuration), the device distributes the system class parameter values to all its attached network adapters using the Data Center Bridging Exchange (DCBX) protocol.

If service policies are configured at the interface level, the interface-level policy always takes precedence over system class configuration or defaults.

On the Cisco Nexus device, a system class is uniquely identified by a qos-group value. A total of six system classes are supported. Two of the six system classes are defaults and are always present on the device. Up to four additional system classes can be created by the administrator.

Default System Classes

The device provides the following system classes:

Drop system class

By default, the software classifies all unicast and multicast Ethernet traffic into the default drop system class. This class is identified by qos-group 0.

This class is created automatically when the system starts up (the class is named class-default in the CLI). You cannot delete this class and you cannot change the match criteria associated with the default class.

Note

If congestion occurs when data traffic (class-default) and FCoE traffic (class-fcoe) is flowing at the same time, then the queuing percentage configuration starts up.

The FCoE traffic is a no-drop class and does not get policed to the bandwidth assigned as per the queuing class. FCoE traffic cannot be dropped as it expects a lossless medium. When congestion occurs PFC frames are generated at FCoE ingress interfaces and dropping only occurs on the data traffic, even if data traffic is below the assigned bandwidth.

For optimizing the throughput you can spread the data traffic load for a longer duration.

FCoE system class (For the Cisco Nexus 5500 Series device)

For the Cisco Nexus 5500 Series device, the class-fcoe is not automatically created. Before you enable FCoE on the Cisco Nexus 5500 Series device running Cisco NX-OS Release 5.0(2)N1(1), you must enable class-fcoe in the three types of qos policies:
- type qos policy maps
- type network-qos policy map (attached to system qos)
- type queuing policy map (class-fcoe must be configured with a non-zero bandwidth percentage for input queuing policy maps.
  
  When class-fcoe is not included in the qos policies, vFC interfaces do not come up and increased drops occur.
Note

The Cisco Nexus 5500 Series device supports five user-defined classes and one default drop system class.

Information About Policy Types

The device supports a number of policy types. You create class maps in the policy types.

There are three policy types

Network-qos
Queuing
QoS

Before you enable FCoE on the Cisco Nexus device, you must enable class-fcoe in the three types of qos policies (network QoS, queuing, and QoS) by entering the type qos policy maps command and applying at least one FCoE QoS policy under system QoS.

The following QoS parameters can be specified for each type of class:

Type network-qos—A network-qos policy is used to instantiate system classes and associate parameters with those classes that are of system-wide scope.
- Classification—The traffic that matches this class are as follows:
  - QoS Group—A class map of type network-qos identifies a system class and is matched by its associated qos-group.
- Policy—The actions that are performed on the matching traffic are as follows:
  
  Note
  
  A network-qos policy can only be attached to the system QoS target.
  - MTU—The MTU that needs to be enforced for the traffic that is mapped to a system class. Each system class has a default MTU and the system class MTU is configurable.
  - Multicast optimization—This configuration specifies if the performance of multicast traffic mapped to this class will be optimized.
  - Pause no-drop—No drop specifies lossless service for the system class. Drop specifies that tail drop is used (arriving packets are dropped when the queue reaches its allocated size) when a queue for this system class is full.
    
    An additional parameter pfc-cos can be configured. This parameter identifies the class of service (CoS) values to assert priority flow control (PFC) when traffic for a no-drop system class is not mapped based purely on CoS experiences congestion.
  - You can change the buffer for the no-drop class.
  - Queue Limit—This configuration specifies the number of buffers that need to be reserved to the queues of this system class. This option is not configurable for no-drop system classes.

Type queuing—A type queuing policy is used to define the scheduling characteristics of the queues associated with system classes.

Note

Some configuration parameters when applied to an EtherChannel are not reflected on the configuration of the member ports.

Classification—The traffic that matches this class are as follows:
- QoS Group—A class map of type queuing identifies a system class and is matched by its associated QoS group.

Policy—The actions that are performed on the matching traffic are as follows:

Note

These policies can be attached to the system qos target or to any interface. The output queuing policy is used to configure output queues on the device associated with system classes. The input queuing policy is used to configure scheduling for queues in the CNA. The input queuing policy parameters are signaled to the CNA over the DCBX protocol.

Bandwidth—Sets the guaranteed scheduling deficit weighted round robin (DWRR) percentage for the system class.
Priority—Sets a system class for strict-priority scheduling. Only one system class can be configured for priority in a given queuing policy.

Type qos—A type QoS policy is used to classify traffic that is based on various Layer 2, Layer 3, and Layer 4 fields in the frame and to map it to system classes.

Note

Some configuration parameters when applied to an EtherChannel are not reflected on the configuration of the member ports.
- Classification—The traffic that matches this class are as follows:
  - Access Control Lists—Classifies traffic based on the criteria in existing ACLs.
  - Class of Service—Matches traffic based on the CoS field in the frame header.
  - DSCP—Classifies traffic based on the Differentiated Services Code Point (DSCP) value in the DiffServ field of the IP header.
  - IP Real Time Protocol—Classifies traffic on the port numbers used by real-time applications.
  - Precedence—Classifies traffic based on the precedence value in the type of service (ToS) field of the IP header.
  - Protocol—Classifies traffic based on the IPv4 Protocol field or the IPv6 Next Header field of the IP header.
- Policy—The actions that are performed on the matching traffic are as follows:
  
  Note
  
  This policy can be attached to the system or to any interface. It applies to input traffic only.
  - QoS Group—Sets the QoS group that corresponds to the system class this traffic flow is mapped to.

Link-Level Flow Control

IEEE 802.3x link-level flow control allows a congested receiver to communicate a transmitter at the other end of the link to pause its data transmission for a short period of time. The link-level flow control feature applies to all the traffic on the link.

The transmit and receive directions are separately configurable. By default, link-level flow control is disabled for both directions.

On the Cisco Nexus device, Ethernet interfaces do not automatically detect the link-level flow control capability. You must configure the capability explicitly on the Ethernet interfaces.

On each Ethernet interface, the switch can enable either priority flow control or link-level flow control (but not both).

Priority Flow Control

Priority flow control (PFC) allows you to apply pause functionality to specific classes of traffic on a link instead of all the traffic on the link. PFC applies pause functionality based on the IEEE 802.1p CoS value. When the switch enables PFC, it communicates to the adapter which CoS values to apply the pause.

Ethernet interfaces use PFC to provide lossless service to no-drop system classes. PFC implements pause frames on a per-class basis and uses the IEEE 802.1p CoS value to identify the classes that require lossless service.

In the switch, each system class has an associated IEEE 802.1p CoS value that is assigned by default or configured on the system class. If you enable PFC, the switch sends the no-drop CoS values to the adapter, which then applies PFC to these CoS values.

The default CoS value for the FCoE system class is 3. This value is configurable.

By default, the switch negotiates to enable the PFC capability. If the negotiation succeeds, PFC is enabled and link-level flow control remains disabled regardless of its configuration settings. If the PFC negotiation fails, you can either force PFC to be enabled on the interface or you can enable IEEE 802.x link-level flow control.

If you do not enable PFC on an interface, you can enable IEEE 802.3X link-level pause.

Note

Ensure that pause no-drop is configured on a class map for link-level pause.

By default, link-level pause is disabled.

MTU

The Cisco Nexus device is a Layer 2 switch, and it does not support packet fragmentation. A maximum transmission unit (MTU) configuration mismatch between ingress and egress interfaces may result in packets being truncated.

When configuring MTU, follow these guidelines:

MTU is specified per system class. The system class allows a different MTU for each class of traffic but they must be consistent on all ports across the entire switch. You cannot configure MTU on the interfaces.
Fibre Channel and FCoE payload MTU is 2158 bytes across the switch. As a result, the rxbufsize for Fibre Channel interfaces is fixed at 2158 bytes. If the Cisco Nexus device receives an rxbufsize from a peer that is different than 2158 bytes, it will fail the exchange of link parameters (ELP) negotiation and not bring the link up.
Enter the system jumbomtu command to define the upper bound of any MTU in the system. The system jumbo MTU has a default value of 9216 bytes. The minimum MTU is 2158 bytes and the maximum MTU is 9216 bytes.
The system class MTU sets the MTU for all packets in the class. The system class MTU cannot be configured larger than the global jumbo MTU.
The FCoE system class (for Fibre Channel and FCoE traffic) has a default MTU of 2158 bytes. This value cannot be modified.
The switch sends the MTU configuration to network adapters that support DCBX.

Note

MTU is not supported in Converged Enhanced Ethernet (CEE) mode for DCBX.

Trust Boundaries

The trust boundary is enforced by the incoming interface as follows:

All Fibre Channel and virtual Fibre Channel interfaces are automatically classified into the FCoE system class.
By default, all Ethernet interfaces are trusted interfaces.The 802.1p CoS and DSCP are preserved unless the marking is configured. There is no default CoS to queue and DSCP to queue mapping. You can define and apply a policy to create these mappings. By default, without a user defined policy, all traffic is assigned to the default queue.
Any packet that is not tagged with an 802.1p CoS value is classified into the default drop system class. If the untagged packet is sent over a trunk, it is tagged with the default untagged CoS value, which is zero.
You can override the default untagged CoS value for an Ethernet interface or port channel.
You can override the default untagged CoS value for an Ethernet interface or a port channel interface using the untagged cos cos-value command.
You can override the default untagged Cos value for an Ethernet or a Layer 3 interface or a port channel interface using the untagged cos cos-value command.

After the system applies the untagged CoS value, QoS functions the same as for a packet that entered the system tagged with the CoS value.

Ingress Queuing Policies

You can associate an ingress policy map with an Ethernet interface to guarantee bandwidth for the specified traffic class or to specify a priority queue.

The ingress policy is applied in the adapter to all outgoing traffic that matches the specified CoS value.

When you configure an ingress policy for an interface, the switch sends the configuration data to the adapter. If the adapter does not support the DCBX protocol or the ingress policy type-length-value (TLV), the ingress policy configuration is ignored.

Ingress Classification Policies

You use classification to partition traffic into classes. You classify the traffic based on the packet property (CoS field) or the packet header fields that include IP precedence, Differentiated Services Code Point (DSCP), and Layer 2 to Layer 4 parameters. The values used to classify traffic are called match criteria.

Traffic that fails to match any class is assigned to a default class of traffic called class-default.

Egress Queuing Policies

You can associate an egress policy map with an Ethernet interface to guarantee the bandwidth for the specified traffic class or to configure the egress queues.

The bandwidth allocation limit applies to all traffic on the interface including any FCoE traffic.

Each Ethernet interface supports up to eight queues, one for each system class. The queues have the following default configuration:

In addition to these queues, control traffic that is destined for the CPU uses strict priority queues. These queues are not accessible for user configuration.
FCoE traffic (traffic that maps to the FCoE system class) is assigned a queue. This queue uses weighted round-robin (WRR) scheduling with 50 percent of the bandwidth.
Standard Ethernet traffic in the default drop system class is assigned a queue. This queue uses WRR scheduling with 100 percent of the bandwidth.

If you add a system class, a queue is assigned to the class. You must reconfigure the bandwidth allocation on all affected interfaces. Bandwidth is not dedicated automatically to user-defined system classes.

You can configure one strict priority queue. This queue is serviced before all other queues except the control traffic queue (which carries control rather than data traffic).

Buffering and Queue Limits on the Cisco Nexus Device

On the Cisco Nexus device, the packet buffer per port is 640KB.

On the Nexus 5500 platform, the packet buffer per port is 640KB. The Nexus 5548P, Nexus 5548UP, and the Nexus 5596UP switch share the same buffer architecture. The Nexus 5500 platform implements Virtual Output Queueing (VOQ) and ingress buffer architecture with the majority of the buffer allocated at ingress. The architecture allows the switch to store packets at multiple ingress ports when there are multiple ports sending traffic to one egress port which causes congestion.

The following default buffer allocations per port exist for the Cisco Nexus 5500 Platform:

Table 1 Cisco Nexus 5500 Platform Default Buffer Allocations Per Port
Traffic Class	Ingress Buffer (KB)
Class-fcoe	79.360
User-defined no-drop with an MTU less than 2240	79.360
User-defined no-drop class with an MTU greater than 2240	90.204
Tail drop traffic class	22.720
Class-default	All of the remaining buffer (470 with default QoS configuration)

The default buffer allocation varies depending on the type of class. For example, if you create a regular tail drop traffic class the default allocation is 22.7KB, unless you specify a larger size using the queue-limit command.

To increase the ingress buffer space available to a user-created qos-group, from a network-qos policy-map, use the queue-limit command.

In addition to ingress buffer allocated for each user-created qos-group there is an additional 29.76KB buffer required at egress for each qos-group.

With the default QoS configuration, all of the available buffer (470KB) is allocated to the class-default. When you create a new qos-group, the buffer required for the new qos-group will be taken away from class-default. The amount of buffer that is left for class-default equals 470 minus the ingress buffer used by other qos-groups minus 29.76KB and times the number of qos-groups.

Note

Each new class requires an additional 29.76KB, so the exact amount of buffer that is left in the class default equals 478 minus the buffer used by other qos-groups minus 18.880KB times the number of qos-groups.

The default QoS policy for the Cisco Nexus device does not create class-fcoe and does not reserve buffer and qos-group for FCoE traffic.

The show queuing interface command can display the amount of ingress buffer allocated for each qos-group

Buffering and Queue Limits on the Cisco Nexus 5000 Platform

The following buffering limits exist for the Cisco Nexus 5000 Platform:

Maximum ingress port buffering: 320KB per port.
Maximum egress port buffering: 160KB per port.

The following default buffer allocations per port exist for the Cisco Nexus 5000 Platform:

Table 2 Cisco Nexus 5000 Platform Default Buffer Allocations Per Port
Traffic Class	Ingress Buffer (KB)
Class-fcoe	76.8
User-defined no-drop class of service with an MTU less than 2240	76.8
User-defined no-drop class of service with an MTU greater than 2240	81.9
Tail drop class of service	20.48
Class-default	All of the remaining buffer (243.2KB with the default QoS configuration)

The default buffer allocation varies depending on the type of class. For example, if you create a regular tail drop traffic class the default allocation is 20.48KB, unless you specify a larger size using the queue-limit command.

To increase the buffer space available to a user-created qos-group, from a network-qos policy-map, use the queue-limit command.

All of the available buffer is allocated to the class-default. When you define a new qos-group, the required buffer for the new qos-group is taken from the class-default buffer.

Note

Each new class requires an additional 18.880KB, so the exact amount of buffer that is left in the class default is 243.2KB minus the buffer used by other qos-groups minus 18.880KB times the number of qos-groups.

The default QoS configuration for the Nexus 5000 platform creates the class-fcoe and class-default.

The show queuing interface command displays the configured qos-group and the ingress buffer allocated for each qos-group.

QoS for Multicast Traffic

By default, all multicast Ethernet traffic is classified into the default drop system class. This traffic is serviced by one multicast queue.

Optimized multicasting allows use of the unused multicast queues to achieve better throughput for multicast frames. If optimized multicast is enabled for the default drop system class, the system will use all 128 queues to service the multicast traffic. When optimized multicast is enabled for the default drop system class, all 128 queues are given equal priority.

If you define a new system class, a dedicated multicast queue is assigned to that class. This queue is removed from the set of queues available for the optimized multicast class.

The system provides two predefined class maps for matching broadcast or multicast traffic. These class maps are convenient for creating separate policy maps for unicast and multicast traffic.

The predefined class maps are as follows:

class-all-flood: The class-all-flood class map matches all broadcast, multicast, and unknown unicast traffic (across all CoS values). If you configure a policy map with the class-all-flood class map, the system automatically uses all available multicast queues for this traffic.
class-ip-multicast: The class-ip-multicast class map matches all IP multicast traffic. Policy options configured in this class map apply to traffic across all Ethernet CoS values. For example, if you enable optimized multicast for this class, the IP multicast traffic for all CoS values is optimized.

Note

If you configure either of these predefined class maps as a no-drop class, the priority flow control capability is applied across all Ethernet CoS values. In this configuration, pause will be applied to unicast and multicast traffic.

Policy for Fibre Channel Interfaces

The egress queues are not configurable for native Fibre Channel interfaces. Two queues are available as follows:

A strict priority queue to serve high-priority control traffic.
A queue to serve all data traffic and low-priority control traffic.

QoS for Traffic Directed to the CPU

The device automatically applies QoS policies to traffic that is directed to the CPU to ensure that the CPU is not flooded with packets. Control traffic, such as bridge protocol data units (BPDU) frames, is given higher priority to ensure delivery.

QoS Configuration Guidelines and Limitations

To maintain optimal switch performance, follow these guidelines when configuring system classes and policies:

Switch resources (such as buffers, virtual output queues, and egress queues) are partitioned based on the default and user-defined system classes. Cisco NX-OS automatically adjusts the resource allocation to accommodate the configured system classes.

If less than four Ethernet classes are defined, up to two of these classes can be configured as no-drop classes. If more than three Ethernet classes are defined, only one of these classes can be configured as a no-drop class. The default drop class is counted as an Ethernet class.
If priority flow control is enabled on an Ethernet interface, pause will never be applied to traffic with a drop system class. PFC does not apply pause to drop classes and the link-level pause feature is never enabled on an interface with PFC.
All FCoE traffic on an Ethernet interface is mapped to one no-drop system class. By default, this class is associated with CoS value 3, although you can configure a different value. If you configure standard Ethernet traffic to use the same CoS value as FCoE, this traffic is still mapped to the FCoE system class and the switch will apply priority flow control on the FCoE CoS value.
When a Cisco Nexus 2148T Fabric Extender is connected and in use, data traffic should never be marked with a CoS value of 7. CoS 7 is reserved for control traffic transiting the Fabric Extender.
On the Cisco Nexus 5548 Switch, the FCoE class-fcoe system class is not enabled by default in the QoS configuration. Before enabling FCoE, you must include class-fcoe in each of the three policy types (network-qos, queuing, and qos).

Note

Type qos policies can be activated only on Cisco Nexus 5000 Series interfaces and Cisco Nexus 2000 Series Fabric Extender interfaces. Type qos policies on Fabric Extender fabric interfaces or Fabric Extender fabric EtherChannel interfaces are ineffective, though the Cisco NX-OS CLI does not reject the configuration.

We recommend that you do not configure type qos policy-maps on Fabric Extender fabric interfaces or Fabric Extender fabric EtherChannel interfaces to avoid wasting hardware resources.

When configuring EtherChannels, note the following guidelines:

The service policy configured on an EtherChannel applies to all member interfaces.
The priority flow control configured on an EtherChannel applies to all member interfaces.

Configuring Class Maps

You can create or modify a class map with the class-map command. The class map is a named object that represents a class of traffic. In the class map, you specify a set of match criteria for classifying the packets. You can then reference class maps in policy maps.

Note

The class map type default is type qos and its match criteria default is match-all.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# class-map [type {network-qos | qos | queuing}] class-map name

3. (Optional) switch(config)# class-map [type qos] [match-all | match-any] class-map name

4. (Optional) switch(config)# no class-map [type {network-qos | qos | queuing}] class-name

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# class-map [type {network-qos | qos | queuing}] class-map name

Creates or accesses a named object that represents the specified class of traffic.

Class-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

The three class-map configuration modes are as follows:

network-qos—Network-wide (global) mode. CLI prompt: switch(config-cmap-nq)#
qos—Classification mode; this is the default mode. CLI prompt: switch(config-cmap-qos)#
queuing—Queuing mode. CLI prompt: switch(config-cmap-que)#

Step 3

switch(config)# class-map [type qos] [match-all | match-any] class-map name

(Optional)

Specifies that packets must match any or all criteria that is defined for a class map.

match-all—Classifies traffic if packets match all criteria that is defined for a specified class map (for example, if both the defined CoS and the ACL criteria match).
match-any—Classifies traffic if packets match any criteria that is defined for a specified class map (for example, if either the CoS or the ACL criteria matches).

Class-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 4

switch(config)# no class-map [type {network-qos | qos | queuing}] class-name

(Optional)

Deletes the specified class map.

Note

You cannot delete the two system-defined class maps: class-fcoe and class-default.

Class-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Configuring ACL Classification

You can classify traffic by matching packets based on an existing access control list (ACL). Traffic is classified by the criteria defined in the ACL. The permit and deny ACL keywords are ignored in the matching; even if a match criteria in the access-list has a deny action, it is still used for matching for this class.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# class-map type qos class-name

3. switch(config-cmap-qos)# match access-group name acl-name

4. (Optional) switch(config-cmap-qos)# no match access-group name acl-name

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# class-map type qos class-name

Creates a named object that represents a class of traffic. Class-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3

switch(config-cmap-qos)# match access-group name acl-name

Configures a traffic class by matching packets based on the acl-name. The permit and deny ACL keywords are ignored in the matching.

Note

You can only define a single ACL in a class map.

You cannot add any other match criteria to a class with a match access-group defined.

Step 4

switch(config-cmap-qos)# no match access-group name acl-name

(Optional)

Removes the match from the traffic class.

This example shows how to classify traffic by matching packets based on existing ACLs:

switch# configure terminal

switch(config)# class-map type qos class_acl

switch(config-cmap-qos)# match access-group name acl-01

Use the show class-map command to display the ACL class-map configuration:

switch# show class-map class_acl

Configuring CoS Classification

You can classify traffic based on the class of service (CoS) in the IEEE 802.1Q header. This 3-bit field is defined in IEEE 802.1p to support QoS traffic classes. CoS is encoded in the high order 3 bits of the VLAN ID Tag field and is referred to as user_priority.

Note

The Cisco Nexus 2148 Fabric Extender does not support frames with the dot1p vlan 0 tag.

If a system class is configured with a no-drop function, the match cos command serves an additional purpose. The switch sends the CoS value to the adapter so that the adapter will apply a PFC pause for this CoS value.

The FCoE system class has a default CoS value of 3. You can add a match cos configuration to the FCoE system class to set a different CoS value. A PFC pause will be applied to traffic that matches the new value.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# class-map type qos class-name

3. switch(config-cmap-qos)# match cos cos-value

4. (Optional) switch(config-cmap-qos)# no match cos cos-value

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# class-map type qos class-name

Creates a named object that represents a class of traffic. Class-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3

switch(config-cmap-qos)# match cos cos-value

Specifies the CoS value to match for classifying packets into this class. You can configure a CoS value in the range of 0 to 7.

Note

When a Cisco Nexus 2148T Fabric Extender is connected and in use, data traffic should never be marked with a CoS value of 7. CoS 7 is reserved for control traffic transiting the Fabric Extender.

Step 4

switch(config-cmap-qos)# no match cos cos-value

(Optional)

Removes the match from the traffic class.

This example shows how to classify traffic by matching packets based on a defined CoS value:

switch# configure terminal
switch(config)# class-map type qos match-any class_cos
switch(config-cmap-qos)# match cos 4, 5-6

Use the show class-map command to display the CoS value class-map configuration:

switch# show class-map class_cos

Configuring DSCP Classification

You can classify traffic based on the Differentiated Services Code Point (DSCP) value in the DiffServ field of the IP header (either IPv4 or IPv6).

Table 3 Standard DSCP Values
Value	List of DSCP Values
af11	AF11 dscp (001010)—decimal value 10
af12	AF12 dscp (001100)—decimal value 12
af13	AF13 dscp (001110)—decimal value 14
af21	AF21 dscp (010010)—decimal value 18
af22	AF22 dscp (010100)—decimal value 20
af23	AF23 dscp (010110)—decimal value 22
af31	AF31 dscp (011010)—decimal value 26
af32	AF32 dscp (011100)—decimal value 28
af33	AF33 dscp (011110)—decimal value 30
af41	AF41 dscp (100010)—decimal value 34
af42	AF42 dscp (100100)—decimal value 36
af43	AF43 dscp (100110)—decimal value 38
cs1	CS1 (precedence 1) dscp (001000)—decimal value 8
cs2	CS2 (precedence 2) dscp (010000)—decimal value 16
cs3	CS3 (precedence 3) dscp (011000)—decimal value 24
cs4	CS4 (precedence 4) dscp (100000)—decimal value 32
cs5	CS5 (precedence 5) dscp (101000)—decimal value 40
cs6	CS6 (precedence 6) dscp (110000)—decimal value 48
cs7	CS7 (precedence 7) dscp (111000)—decimal value 56
default	Default dscp (000000)—decimal value 0
ef	EF dscp (101110)—decimal value 46

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# class-map type qos class-name

3. switch(config-cmap-qos)# match dscp dscp-list

4. (Optional) switch(config-cmap-qos)# no match dscp dscp-list

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch(config)# class-map type qos class-name	Creates a named object that represents a class of traffic. Class-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.
Step 3	switch(config-cmap-qos)# match dscp dscp-list	Configures the traffic class by matching packets based on the values in the dscp-list variable. For a list of DSCP values, see the Standard DSCP Values table.
Step 4	switch(config-cmap-qos)# no match dscp dscp-list	(Optional) Removes the match from the traffic class. For a list of DSCP values, see the Standard DSCP Values table.

This example shows how to classify traffic by matching packets based on the DSCP value in the DiffServ field of the IP header:

switch# configure terminal
switch(config)# class-map type qos match-any class_dscp
switch(config-cmap-qos)# match  dscp af21, af32

Use the show class-map command to display the DSCP class-map configuration:

switch# show class-map class_dscp

Configuring IP RTP Classification

The IP Real-time Transport Protocol (RTP) is a transport protocol for real-time applications that transmits data such as audio or video and is defined by RFC 3550. Although RTP does not use a common TCP or UDP port, you typically configure RTP to use ports 16384 to 32767. UDP communications use an even port and the next higher odd port is used for RTP Control Protocol (RTCP) communications.

You can classify based on UDP port ranges, which are likely to target applications using RTP.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# class-map type qos class-name

3. switch(config-cmap-qos)# match ip rtp port-number

4. (Optional) switch(config-cmap-qos)# no match ip rtp port-number

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch(config)# class-map type qos class-name	Creates a named object that represents a class of traffic. Class-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.
Step 3	switch(config-cmap-qos)# match ip rtp port-number	Configures the traffic class by matching packets based on a range of lower and upper UDP port numbers, which is likely to target applications using RTP. Values can range from 2000 to 65535.
Step 4	switch(config-cmap-qos)# no match ip rtp port-number	(Optional) Removes the match from the traffic class.

The following example shows how to classify traffic by matching packets based on UDP port ranges that are typically used by RTP applications:

switch# configure terminal
switch(config)# class-map type qos match-any class_rtp
switch(config-cmap-qos)# match  ip rtp 2000-2100, 4000-4100

Use the show class-map command to display the RTP class-map configuration:

switch# show class-map class_rtp

Configuring Precedence Classification

You can classify traffic based on the precedence value in the type of service (ToS) byte field of the IP header (either IPv4 or IPv6). The following table shows the precedence values:

Table 4 Precedence Values
Value	List of Precedence Values
<0-7>	IP precedence value
critical	Critical precedence (5)
flash	Flash precedence (3)
flash-override	Flash override precedence (4)
immediate	Immediate precedence (2)
internet	Internetwork control precedence (6)
network	Network control precedence (7)
priority	Priority precedence (1)
routine	Routine precedence (0)

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# class-map type qos match-any class-name

3. switch(config-cmap-qos)#match precedence precedence-values

4. (Optional) switch((config-cmap-qos)# no match precedence precedence-values

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch(config)# class-map type qos match-any class-name	Creates a named object that represents a class of traffic. Class-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.
Step 3	switch(config-cmap-qos)#match precedence precedence-values	Configures the traffic class by matching packets based on precedence values. For a list of precedence values, see the Precedence Values table.
Step 4	switch((config-cmap-qos)# no match precedence precedence-values	(Optional) Removes the match from the traffic class. For a list of precedence values, see the Precedence Values table.

This example shows how to classify traffic by matching packets based on the precedence value in the ToS byte field of the IP header:

switch# configure terminal
switch(config)# class-map type qos match-any class_precedence
switch(config-cmap-qos)# match precedence 1-2, critical

Use the show class-map command to display the IP precedence value class-map configuration:

switch# show class-map class_precedence

Configuring Protocol Classification

You can classify traffic based on the IPv4 Protocol field or the IPv6 Next Header field in the IP header. The following table shows the protocol arguments:

Table 5 Protocol Arguments
Argument	Description
arp	Address Resolution Protocol (ARP)
clns_es	CLNS End Systems
clns_is	CLNS Intermediate System
dhcp	Dynamic Host Configuration (DHCP)
ldp	Label Distribution Protocol (LDP)
netbios	NetBIOS Extended User Interface (NetBEUI)

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# class-map type qos class-name

3. switch(config-cmap-qos)# match protocol {arp | clns_es | clns_is | dhcp | ldp | netbios}

4. (Optional) switch(config-cmap-qos)# no match protocol {arp | clns_es | clns_is | dhcp | ldp | netbios}

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters configuration mode.
Step 2	switch(config)# class-map type qos class-name	Creates a named object that represents a class of traffic. Class-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.
Step 3	switch(config-cmap-qos)# match protocol {arp \| clns_es \| clns_is \| dhcp \| ldp \| netbios}	Configures the traffic class by matching packets based on the specified protocol.
Step 4	switch(config-cmap-qos)# no match protocol {arp \| clns_es \| clns_is \| dhcp \| ldp \| netbios}	(Optional) Removes the match from the traffic class.

This example shows how to classify traffic by matching packets based on the protocol field:

switch# configure terminal

switch(config)# class-map type qos class_protocol

switch(config-cmap-qos)# match protocol arp

Use the show class-map command to display the protocol class-map configuration:

switch# show class-map class_protocol

Configuring QoS Group Classification

You can classify traffic based on the value of the QoS group internal label, that represents a system class. You can set the value of the QoS group within a policy map using the set qos-group command.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# class-map type {network-qos | queuing} class-name

3. switch(config-cmap-que)# match qos-group qos-group-value

4. (Optional) switch(config-cmap-que)# no match qos-group qos-group-value

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters configuration mode.

Step 2

switch(config)# class-map type {network-qos | queuing} class-name

Creates a named object that represents a class of traffic. Class-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3

switch(config-cmap-que)# match qos-group qos-group-value

Configures the traffic class by matching packets based on a list of QoS group values. Values can range from 0 to 5. QoS group 0 is equivalent to class-default and QoS group 1 is equivalent to class-fcoe.

Note

qos-groups 0 and 1 are reserved for default classes and cannot be configured.

Step 4

switch(config-cmap-que)# no match qos-group qos-group-value

(Optional)

Removes the match from the traffic class.

This example shows how to classify traffic based on the value of the QoS group:

switch# configure terminal

switch(config)# class-map type queuing class_qos_group

switch(config-cmap-que)# match qos-group 4

Use the show class-map command to display the QoS group class-map configuration:

switch# show class-map class_qos_group

Creating Policy Maps

The policy-map command is used to create a named object that represents a set of policies that are to be applied to a set of traffic classes.

The device provides two default system classes: a no-drop class for lossless service (class-fcoe) and a drop class for best-effort service (class-default). You can define up to four additional system classes for Ethernet traffic.

The following predefined policy maps are used as default service policies:

network-qos: default-nq-policy
Input qos: default-in-policy
Input queuing: default-in-policy
Output queuing: default-out-policy

service-policy type qos input fcoe-default-in-policy
service-policy type queuing input fcoe-default-in-policy
service-policy type queuing output fcoe-default-out-policy
service-policy type network-qos fcoe-default-nq-policy

When class-fcoe is not included in the qos policies, vFC interfaces do not come up and increased drops occur.

You need to create a policy map to specify the policies for any user-defined class. In the policy map, you can configure the QoS parameters for each class. You can use the same policy map to modify the configuration of the default classes.

The device distributes all the policy-map configuration values to the attached network adapters.

Before You Begin

Before creating the policy map, define a class map for each new system class.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# policy-map [type {network-qos | qos | queuing}] policy-name

3. (Optional) switch(config)# no policy-map [type {network-qos | qos | queuing}] policy-name

4. switch(config-pmap)# class [type {network-qos | qos | queuing}] class-name

5. (Optional) switch(config-pmap)# no class [type {network-qos | qos | queuing}] class-name

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# policy-map [type {network-qos | qos | queuing}] policy-name

Creates a named object representing a set of policies that are to be applied to a set of traffic classes. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

The three policy-map configuration modes are as follows:

network-qos—Network-wide (global) mode. CLI prompt: switch(config-pmap-nq)#
qos—Classification mode; this is the default mode. CLI prompt: switch(config-pmap-qos)#
queuing—Queuing mode. CLI prompt: switch(config-pmap-que)#

Step 3

switch(config)# no policy-map [type {network-qos | qos | queuing}] policy-name

(Optional)

Deletes the specified policy map.

Step 4

switch(config-pmap)# class [type {network-qos | qos | queuing}] class-name

Associates a class map with the policy map, and enters configuration mode for the specified system class. The three class-map configuration modes are as follows:

network-qos—Network-wide (global) mode. CLI prompt: switch(config-pmap-c-nq)#
qos—Classification mode; this is the default mode. CLI prompt: switch(config-pmap-c-qos)#
queuing—Queuing mode. CLI prompt: switch(config-pmap-c-que)#

Note

The associated class map must be the same type as the policy-map type.

Step 5

switch(config-pmap)# no class [type {network-qos | qos | queuing}] class-name

(Optional)

Deletes the class map association.

Configuring Type QoS Policies

Type qos policies are used for classifying the traffic of a specific system class identified by a unique qos-group value. A type qos policy can be attached to the system or to individual interfaces (including Fabric Extender host interfaces) for ingress traffic only.

You can set a maximum of five QoS groups for ingress traffic.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# policy-map type qos policy-name

3. switch(config-pmap-qos)# [class | class-default] type qos class-name

4. switch(config-pmap-c-qos)# set qos-group qos-group-value

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# policy-map type qos policy-name

Creates a named object that represents a set of policies that are to be applied to a set of traffic classes. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3

switch(config-pmap-qos)# [class | class-default] type qos class-name

Associates a class map with the policy map, and enters configuration mode for the specified system class.

Note

The associated class map must be the same type as the policy map type.

Step 4

switch(config-pmap-c-qos)# set qos-group qos-group-value

Configures one or more qos-group values to match on for classification of traffic into this class map. The list below identifies the ranges of the qos-group-value . There is no default value.

This example shows how to define a type qos policy map:

switch# configure terminal
switch(config)# policy-map type qos policy-s1
switch(config-pmap-qos)# class type qos class-s1
switch(config-pmap-c-qos)# set qos-group 2

Configuring Type Network QoS Policies

Type network qos policies can only be configured on the system qos attachment point. They are applied to the entire switch for a particular class.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# policy-map type network-qos policy-name

3. switch(config-pmap-nq)# class type network-qos class-name

4. switch(config-pmap-c-nq)# mtu mtu-value

5. (Optional) switch(config-pmap-c-nq)# no mtu

6. switch(config-pmap-c-nq)# pause no-drop

7. switch(config-pmap-c-nq)# multicast-optimize

8. (Optional) switch(config-pmap-c-nq)# no multicast-optimize

9. switch(config-pmap-c)# pause no-drop [pfc-cos pfc-cos-value]

10. (Optional) switch(config-pmap-c-nq)# no pause no-drop

11. switch(config-pmap-c-nq)# queue-limit number-bytes bytes

12. (Optional) switch(config-pmap-c-nq)# no queue-limit number-bytes bytes

13. switch(config-pmap-c-nq)# set cos cos-value

14. (Optional) switch(config-pmap-c-nq)# no set cos cos-value

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# policy-map type network-qos policy-name

Creates a named object that represents a set of policies that are to be applied to a set of traffic classes. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3

switch(config-pmap-nq)# class type network-qos class-name

Associates a class map with the policy map, and enters configuration mode for the specified system class.

Note

The associated class map must be the same type as the policy map type.

Step 4

switch(config-pmap-c-nq)# mtu mtu-value

Specifies the MTU value in bytes.

Note

The mtu-value that you configure must be less than the value set by the system jumbomtu command.

Step 5

switch(config-pmap-c-nq)# no mtu

(Optional)

Resets the MTU value in this class.

Step 6

switch(config-pmap-c-nq)# pause no-drop

Configures a no-drop class.

Step 7

switch(config-pmap-c-nq)# multicast-optimize

Enables multicast optimization. Multicast traffic in this class will be served by all available multicast queues.

Note

Only one class in a policy map can be configured for multicast optimization.

Note

For the Cisco Nexus device, multicast optimization is enabled by default on class-default. You must remove it from class-default before enabling it on a user-defined class.

Step 8

switch(config-pmap-c-nq)# no multicast-optimize

(Optional)

Disables multicast optimization.

Step 9

switch(config-pmap-c)# pause no-drop [pfc-cos pfc-cos-value]

Configures a no-drop class. If you do not specify this command, the default policy is drop.

Note

The operation for the drop policy is a simple tail drop, where arriving packets will be dropped if the queue increases to its allocated size.

The pfc-cos-value range is from 0 to 7. This option is supported only for for a ACL-based system class (which filters traffic using criteria other than cos-based matches).

Caution

The list of CoS values can potentially include the CoS value that is used for FCoE traffic in class-fcoe. You must determine if this is desired behavior for your topology.

Step 10

switch(config-pmap-c-nq)# no pause no-drop

(Optional)

Removes the no-drop option from this class.

Step 11

switch(config-pmap-c-nq)# queue-limit number-bytes bytes

Specifies the tail drop threshold on this interface. The threshold range is from 20480 to 204800 bytes.

Note

The queue limit can only be configured on drop classes. If you try to configure a queue limit on a no-drop class, or try to configure no-drop on a class where a queue limit is already defined, the CLI will return an error.

Use the pause no-drop buffer size option to change the buffer size and pause threshold for the no-drop class.

Step 12

switch(config-pmap-c-nq)# no queue-limit number-bytes bytes

(Optional)

Disables the queue limit specification in this class.

Step 13

switch(config-pmap-c-nq)# set cos cos-value

Specifies a 802.1Q CoS value which is used to mark packets on this interface. The value range is from 0 to 7.

Step 14

switch(config-pmap-c-nq)# no set cos cos-value

(Optional)

Disables the marking operation in this class.

This example shows how to define a type network-qos policy map:

switch# configure terminal
switch(config)# policy-map type network-qos policy-que1
switch(config-pmap-nq)# class type network-qos class-que1
switch(config-pmap-c-nq)# mtu 5000
switch(config-pmap-c-nq)# set cos 4

Configuring Type Queuing Policies

Type queuing policies are used for scheduling and buffering the traffic of a specific system class. A type queuing policy is identified by its QoS group and can be attached to the system or to individual interfaces (except for Fabric Extender host interfaces) for input or output traffic.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# policy-map type queuing policy-name

3. switch(config-pmap-que)# class type queuing class-name

4. switch(config-pmap-c-que)# priority

5. (Optional) switch(config-pmap-c-que)# no priority

6. switch(config-pmap-c-que)# bandwidth percent percentage

7. (Optional) switch(config-pmap-c-que)# no bandwidth percent percentage

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# policy-map type queuing policy-name

Creates a named object that represents a set of policies that are to be applied to a set of traffic classes. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3

switch(config-pmap-que)# class type queuing class-name

Associates a class map with the policy map, and enters configuration mode for the specified system class.

Step 4

switch(config-pmap-c-que)# priority

Specifies that traffic in this class is mapped to a strict priority queue.

Note

Only one class in each policy map can have strict priority set on it.

Step 5

switch(config-pmap-c-que)# no priority

(Optional)

Removes the strict priority queuing from the traffic in this class.

Step 6

switch(config-pmap-c-que)# bandwidth percent percentage

Specifies the guaranteed percentage of interface bandwidth allocated to this class. By default, no bandwidth is specified for a class.

Note

Before you can successfully allocate bandwidth to the class, you must first reduce the default bandwidth configuration on class-default and class-fcoe.

Step 7

switch(config-pmap-c-que)# no bandwidth percent percentage

(Optional)

Removes the bandwidth specification from this class.

Information About Marking

Marking is a method that you use to modify the QoS fields of the incoming and outgoing packets.

You can use marking commands in traffic classes that are referenced in a policy map. The marking features that you can configure are listed below:

DSCP
IP precedence
CoS

Configuring CoS Marking

The value of the CoS field is recorded in the high-order three bits of the VLAN ID Tag field in the IEEE 802.1Q header.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config) # policy-map [type network-qos] policy-map name

3. switch(config-pmap-nq) # class [type network-qos] {class-map name |class-default}

4. switch(config-pmap-c-nq) # set cos cos-value

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config) # policy-map [type network-qos] policy-map name

Creates or accesses the policy map named policy-map-name and enters policy-map mode.

The policy-map name can contain alphabetic, hyphen, or underscore characters, is case sensitive, and can be up to 40 characters.

Step 3

switch(config-pmap-nq) # class [type network-qos] {class-map name |class-default}

Creates a reference to the class-map-name and enters policy-map class configuration mode.

Use the class-default keyword to select all traffic that is not currently matched by classes in the policy map.

Step 4

switch(config-pmap-c-nq) # set cos cos-value

Specifies the CoS value to cos-value.

The cos-value can range from 0 to 7.

Note

This command is supported only for egress policies.

Configuring DSCP Marking

For Cisco Nexus devices, you can set the DSCP value in the six most significant bits of the DiffServ field of the IP header to a specified value. You can enter numeric values from 0 to 63, in addition to the standard DSCP values shown in the table below:

Note

You can set DSCP or IP Precedence but you can not set both values because they modify the same field in the IP packet.

Table 6 Standard DSCP Values
Value	List of DSCP Values
af11	AF11 dscp (001010)—decimal value 10
af12	AF12 dscp (001100)—decimal value 12
af13	AF13 dscp (001110)—decimal value 14
af21	AF21 dscp (010010)—decimal value 18
af22	AF22 dscp (010100)—decimal value 20
af23	AF23 dscp (010110)—decimal value 22
af31	AF31 dscp (011010)—decimal value 26
af32	AF40 dscp (011100)—decimal value 28
af33	AF33 dscp (011110)—decimal value 30
af41	AF41 dscp (100010)—decimal value 34
af42	AF42 dscp (100100)—decimal value 36
af43	AF43 dscp (100110)—decimal value 38
cs1	CS1 (precedence 1) dscp (001000)—decimal value 8
cs2	CS2 (precedence 2) dscp (010000)—decimal value 16
cs3	CS3 (precedence 3) dscp (011000)—decimal value 24
cs4	CS4 (precedence 4) dscp (100000)—decimal value 32
cs5	CS5 (precedence 5) dscp (101000)—decimal value 40
cs6	CS6 (precedence 6) dscp (110000)—decimal value 48
cs7	CS7 (precedence 7) dscp (111000)—decimal value 56
default	Default dscp (000000)—decimal value 0
ef	EF dscp (101110)—decimal value 46

SUMMARY STEPS

1. config t

2. policy-map type qos qos-policy-map-name

3. class [type qos] {class-map-name | class-default}

4. set dscp dscp-value

5. set qos-group y

DETAILED STEPS

Command or Action

Purpose

Step 1

config t

Enters configuration mode.

Step 2

policy-map type qos qos-policy-map-name

Creates or accesses the policy map named policy-map-name, and then enters policy-map mode. The policy-map name can contain alphabetic, hyphen, or underscore characters, is case sensitive, and can be up to 40 characters.

Step 3

class [type qos] {class-map-name | class-default}

Creates a reference to class-map-name, and enters policy-map class configuration mode. Use the class-default keyword to select all traffic that is not currently matched by classes in the policy map.

Step 4

set dscp dscp-value

Sets the DSCP value to dscp-value. See the Standards DSCP Values table.

Step 5

set qos-group y

Specifies the qos-group. The group value can be from 1 to 5.

Note

Traffic in the class-default system class (qos-group 0), cannot be marked with DSCP.

This example shows how to set the DSCP value to 10 and specify the qos-group to 2.

 policy-map type qos test-bulkdata
    class type qos bulkdata
      set dscp 10
      set qos-group 2

Configuring IP Precedence Marking

You can set the value of the IP precedence field in bits 0 to 2 of the IPv4 type of service (ToS) field or the equivalent Traffic Class field for IPv6 of the IP header. The following table shows the precedence values:

Note

You can set IP Precedence or DSCP but you can not set both values because they modify the same field in the IP packet.

Table 7 Precedence Values
Value	List of Precedence Values
<0-7>	IP precedence value
critical	Critical precedence (5)
flash	Flash precedence (3)
flash-override	Flash override precedence (4)
immediate	Immediate precedence (2)
internet	Internetwork control precedence (6)
network	Network control precedence (7)
priority	Priority precedence (1)
routine	Routine precedence (0)

SUMMARY STEPS

1. config t

2. policy-map [type qos] qos-policy-map-name

3. class [type qos] {class-map-name | class-default}

4. set precedence precedence-value

DETAILED STEPS

	Command or Action	Purpose
Step 1	config t	Enters configuration mode.
Step 2	policy-map [type qos] qos-policy-map-name	Creates or accesses the policy map named policy-map-name, and then enters policy-map mode. The policy-map name can contain alphabetic, hyphen, or underscore characters, is case sensitive, and can be up to 40 characters.
Step 3	class [type qos] {class-map-name \| class-default}	Creates a reference to class-map-name, and enters policy-map class configuration mode. Use the class-default keyword to select all traffic that is not currently matched by classes in the policy map.
Step 4	set precedence precedence-value	Sets the IP precedence value to precedence-value. You can enter one of the values shown in the Precedence Values table.

switch(config)# policy-map type qos my_policy
switch(config-pmap-qos)# class type qos my_class
switch(config-pmap-c-qos)# set precedence 5
switch(config-pmap-c-qos)#

Required CoS Marking Configuration in a Layer 3 Topology

In Layer 3 topologies, you must configure each QoS group in the network-qos policy with a unique cos value.

SUMMARY STEPS

1. switch# show policy-map system

2. switch# configure terminal

3. switch(config) # policy-map [type network-qos] policy-map name

4. switch(config-pmap-nq) # class [type network-qos] {class-map name |class-default}

5. switch(config-pmap-nq-c) # set cos cos-value

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# show policy-map system

Displays the already configured policy maps and CoS values.

In Layer 3 topologies, each qosgroup must have a unique CoS value. Use the show policy-map system command to view CoS values that have been used and that are unavailable for QoS groups.

Step 2

switch# configure terminal

Enters global configuration mode.

Step 3

switch(config) # policy-map [type network-qos] policy-map name

Creates or accesses the policy map named policy-map-name and enters policy-map mode.

The policy-map name can contain alphabetic, hyphen, or underscore characters, is case sensitive, and can be up to 40 characters.

Step 4

switch(config-pmap-nq) # class [type network-qos] {class-map name |class-default}

Creates a reference to the class-map-name and enters policy-map class configuration mode.

Use the class-default keyword to select all traffic that is not currently matched by classes in the policy map.

Step 5

switch(config-pmap-nq-c) # set cos cos-value

Specifies the CoS value.

The value can range from 0 to 7.

Note

You can use this command only in egress policies.

In Layer 3 topologies, each qos-group must have a unique cos configuration.

This example shows how to set the CoS value to 4 in a Layer 3 topology:

switch# show policy-map system
  Type network-qos policy-maps
  ===============================
 
  policy-map type network-qos pn-01
    class type network-qos cn-01      match qos-group 1
      mtu 8500
      pause no-drop 
      set cos 2
    class type network-qos cn-02      match qos-group 2
      set cos 4
      mtu 9216
    class type network-qos cn-03      match qos-group 3 
      mtu 8000
      set cos 6
    class type network-qos cn-04      match qos-group 4 
      mtu 8750
      set cos 7
    class type network-qos cn-ip-multicast      match qos-group 5
      set cos 5
      mtu 7500
    class type network-qos class-default      match qos-group 0 
      mtu 1500
      multicast-optimize
      set cos 1
...
switch# configure terminal 
switch(config)# policy-map type network-qos pn-01 
switch(config-pmap-nq)# class type network-qos cn-05 
switch(config-pmap-c-nq)# set cos 3

Configuring Layer 3 Multicast Queuing

Beginning with NX-OS Release 5.0(3)N1(1), on Cisco Nexus 5000 Platform switches, you can map CoS values to an egress queue. You can have a maximum of 4 multicast queues for Layer 3 multicast traffic.

You can use this procedure to distribute traffic into different queues, where each queue is configured with different weighted round robin (WRR) parameters.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# wrr-queue cos-map queue-id cos1 ...cos8

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# wrr-queue cos-map queue-id cos1 ...cos8

Maps the assigned CoS values to an egress queue.

The egress queue range is from 1 to 4, where 4 can be configured as the expedite queue.

You can enter up to eight CoS values. Separate each value with a space. The range is from 0 to 7.

The defaults are as follows:

Receive queue 0 and transmit queue 0: CoS 0 and 1.
Receive queue 1 and transmit queue 1: CoS 2 and 3.
Receive queue 2 and transmit queue 2: CoS 4 and 5.
Receive queue 3 and transmit queue 3: CoS 6 and 7.

This example shows how to configure a Layer 3 interface:

switch# configure terminal
switch(config)# wrr-queue cos-map 1 0 1
switch(config)#

Configuring a Service Policy for a Layer 3 Interface

You can configure a service policy for a Layer 3 interface.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# interface ethernet slot/port

3. switch(config-if)# no switchport

4. switch(config-if)# service-policy [type {qos | queuing} [input | output]policy-name

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface ethernet slot/port

Enters the configuration mode for the specified interface.

Step 3

switch(config-if)# no switchport

Selects the Layer 3 interface.

Step 4

switch(config-if)# service-policy [type {qos | queuing} [input | output]policy-name

Specifies the policy map to use as the service policy for the Layer 3 interface. There are two policy-map configuration modes:

qos—Classification mode (this is the default mode).
queuing—Queuing mode.

Note

The input keyword specifies that this policy map should be applied to traffic received on an interface. The output keyword specifies that this policy map should be applied to traffic transmitted from an interface. You can only apply input to a qos policy; you can apply both input and output to a queuing policy.

The following example shows how to attach a queuing policy map to a Layer 3 interface:

switch# configure terminal
switch(config)# interface ethernet 1/5
switch(config-if)# no switchport
switch(config-if)# service-policy type queuing output my_output_q_policy
switch(config-if)#

The following example shows how to attach an input qos policy map to a Layer 3 interface:

switch# configure terminal
switch(config)# interface ethernet 1/5
switch(config-if)# no switchport
switch(config-if)# service-policy type qos input my_input_qos_policy
switch(config-if)#

Attaching the System Service Policy

The service-policy command specifies the system class policy map as the service policy for the system.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# system qos

3. switch(config-sys-qos)# service-policy type {network-qos | qos | queuing} [input | output] policy-name

4. (Optional) switch(config-sys-qos)# service-policy type {network-qos | qos | queuing} [input | output] fcoe default policy-name

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# system qos

Enters system class configuration mode.

Step 3

switch(config-sys-qos)# service-policy type {network-qos | qos | queuing} [input | output] policy-name

Specifies the policy map to use as the service policy for the system. There are three policy-map configuration modes:

network-qos—Network-wide (system qos) mode.
qos—Classification mode (system qos input or interface input only).
queuing—Queuing mode (input and output at system qos and interface).

Note

There is no default policy-map configuration mode; you must specify the type. The input keyword specifies that this policy map should be applied to traffic received on an interface. The output keyword specifies that this policy-map should be applied to traffic transmitted from an interface. You can only apply input to a qos policy; you can apply both input and output to a queuing policy.

Step 4

switch(config-sys-qos)# service-policy type {network-qos | qos | queuing} [input | output] fcoe default policy-name

(Optional)

Specifies the default FCoE policy map to use as the service policy for the system. There are four pre-defined policy-maps for FCoE:

service-policy type qos input fcoe-default-in-policy
service-policy type queuing input fcoe-default-in-policy
service-policy type queuing output fcoe-default-out-policy
service-policy type network-qos fcoe-default-nq-policy

Note

Before enabling FCoE on a Cisco Nexus device, you must attach the pre-defined FCoE policy maps to the type qos, type network-qos, and type queuing policy maps.

This example shows how to set a no-drop Ethernet policy map as the system class:

switch(config)# class-map type network-qos ethCoS4
switch(config-cmap-nq)# match qos-group
switch(config-cmap-nq)# exit
switch(config)# policy-map type network-qos ethNoDrop
switch(config-pmap-nq)# class type network-qos ethCoS4
switch(config-pmap-c-nq)# pause no-drop
switch(config-pmap-c-nq)# exit
switch(config-pmap-nq)# exit
switch(config)# system qos
switch(config-sys-qos)# service-policy type network-qos ethNoDrop

Restoring the Default System Service Policies

If you have created and attached new policies to the system QoS configuration, enter the no form of the command to reapply the default policies.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# system qos

3. switch(config-sys-qos)# no service-policy type qos input policy-map name

4. switch(config-sys-qos)# no service-policy type network-qos policy-map name

5. switch(config-sys-qos)# no service-policy type queuing output policy-map name

6. switch(config-sys-qos)# no service-policy type queuing input policy-map name

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch(config)# system qos	Enters system class configuration mode.
Step 3	switch(config-sys-qos)# no service-policy type qos input policy-map name	Resets the classification mode policy map. This policy-map configuration is for system QoS input or interface input only:
Step 4	switch(config-sys-qos)# no service-policy type network-qos policy-map name	Resets the network-wide policy map.
Step 5	switch(config-sys-qos)# no service-policy type queuing output policy-map name	Resets the output queuing mode policy map.
Step 6	switch(config-sys-qos)# no service-policy type queuing input policy-map name	Resets the input queuing mode policy map.

The following example shows how to reset the system QoS configuration:

switch# configure terminal
switch(config)# system qos
switch(config-sys-qos)# no service-policy type qos input my-in-policy
switch(config-sys-qos)# no service-policy type network-qos my-nq-policy
switch(config-sys-qos)# no service-policy type queuing output my-out-policy
switch(config-sys-qos)# no service-policy type queuing input my-in-policy

Configuring the Queue Limit for Fabric Extenders

At the system level, you can enable or disable tail drop for Fabric Extenders for egress direction (from the network to the host).

By default, the tail drop threshold applies to each Fabric Extender port to limit the amount of buffer allocated to each port. To restore the default queue limit, use the fex queue-limit command. To disable the tail drop threshold and to allow Fabric Extender ports to use all available buffer space, use the no form of this command.

Note

You can also set the queue limit for a specified Fabric Extender by using the hardware fex-card-type queue-limit command. Configuring specific Fabric Extenders overrides the queue limit configuration set at the global system level for that Fabric Extender.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# system qos

3. switch(config-sys-qos)# fex queue-limit

4. switch(config-sys-qos)# no fex queue-limit

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch(config)# system qos	Enters system class configuration mode.
Step 3	switch(config-sys-qos)# fex queue-limit	Limits the amount of input buffer space allocated to each Fabric Extender port.
Step 4	switch(config-sys-qos)# no fex queue-limit	Allows a Fabric Extender port to use all available buffer space.

This example shows how to set the queue limit for the input buffer for each Fabric Extender port:

switch# configure terminal
switch(config)# system qos
switch(config-sys-qos)# fex queue-limit

This example shows how to remove the queue limit that is enabled by default:

switch# configure terminal
switch(config)# system qos
switch(config-sys-qos)# no fex queue-limit

Enabling the Jumbo MTU

You can enable the jumbo Maximum Transmission Unit (MTU) for the whole switch by setting the MTU to its maximum size (9216 bytes) in the policy map for the default Ethernet system class (class-default).

When you configure jumbo MTU on a port-channel subinterface you must first enable MTU 9216 on the base interface and then configure it again on the subinterface. If you enable the jumbo MTU on the subinterface before you enable it on the base interface then the following error will be displayed on the console:

switch(config)# int po 502.4
switch(config-subif)# mtu 9216
ERROR: Incompatible MTU values

For Layer 3 routing on Cisco Nexus devices, you need to configure the MTU on the Layer 3 interfaces (SVIs and physical interfaces with IP addresses) in addition to the global QoS configuration below.

To use FCoE on switch, add class-fcoe in the custom network-qos policy. If already using FCoE, make sure to add the below lines in the config so that the FCoE does not go down on the switch after enabling the jumbo qos policy.

switch# conf t
switch(config)# policy-map type network-qos jumbo
switch(config-pmap-nq)# class type network-qos class-fcoe
switch(config-pmap-nq-c)# end

This example shows how to change qos to enable the jumbo MTU:

switch# conf t
switch(config)# policy-map type network-qos jumbo
switch(config-pmap-nq)# class type network-qos class-default
switch(config-pmap-c-nq)# mtu 9216

Note

The system jumbomtu command defines the maximum MTU size for the switch. However, jumbo MTU is supported only for system classes that have MTU configured.

Verifying the Jumbo MTU

On the Cisco Nexus device, traffic is classified into one of eight QoS groups. The MTU is configured at the QoS group level. By default, all Ethernet traffic is in QoS group 0. To verify the jumbo MTU for Ethernet traffic, use the show queueing interface ethernet slot/chassis_number command and find "HW MTU" in the command output to check the MTU for QoS group 0. The value should be 9216.

The show interface command always displays 1500 as the MTU. Because the Cisco Nexus device supports different MTUs for different QoS groups, it is not possible to represent the MTU as one value on a per interface level.

Note

For Layer 3 routing on the Cisco Nexus device, you must verify the MTU on the Layer 3 interfaces (SVIs and physical interfaces with IP addresses) in addition to the global QoS MTU. You can verify the Layer 3 MTU by using the show interface vlan vlan_number or show interface slot/chassis_number.

This example shows how to display jumbo MTU information for Ethernet 1/19:

switch# show queuing interface ethernet1/19
Ethernet1/19 queuing information:
  TX Queuing
    qos-group  sched-type  oper-bandwidth
        0       WRR             50
        1       WRR             50

  RX Queuing
    qos-group 0
    q-size: 243200, HW MTU: 9280 (9216 configured)
    drop-type: drop, xon: 0, xoff: 1520
    Statistics:
        Pkts received over the port             : 2119963420
        Ucast pkts sent to the cross-bar        : 2115648336
        Mcast pkts sent to the cross-bar        : 4315084
        Ucast pkts received from the cross-bar  : 2592447431
        Pkts sent to the port                   : 2672878113
        Pkts discarded on ingress               : 0
        Per-priority-pause status               : Rx (Inactive), Tx (Inactive)

    qos-group 1
    q-size: 76800, HW MTU: 2240 (2158 configured)
    drop-type: no-drop, xon: 128, xoff: 240
    Statistics:
        Pkts received over the port             : 0
        Ucast pkts sent to the cross-bar        : 0
        Mcast pkts sent to the cross-bar        : 0
        Ucast pkts received from the cross-bar  : 0
        Pkts sent to the port                   : 0
        Pkts discarded on ingress               : 0
        Per-priority-pause status               : Rx (Inactive), Tx (Inactive)

  Total Multicast crossbar statistics:
    Mcast pkts received from the cross-bar      : 80430744

Configuring Untagged CoS

Any incoming packet not tagged with an 802.1p CoS value is assigned the default untagged CoS value of zero (which maps to the default Ethernet drop system class). You can override the default untagged CoS value for an Ethernet or EtherChannel interface.

You can configure flow control on a Layer 2 or Layer 3 interface. Use the no switchport command to configure a Layer 3 interface

On a Cisco Nexus device, you can configure a type qos policy map and untagged CoS on the same interface.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# interface {ethernet [chassis/]slot/port | port-channel channel-number}

3. (Optional) switch(config-if)# no switchport

4. switch(config-if)# untagged cos cos-value

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch(config)# interface {ethernet [chassis/]slot/port \| port-channel channel-number}	Enters the configuration mode for the specified interface or port channel.
Step 3	switch(config-if)# no switchport	(Optional) Selects a Layer 3 interface.
Step 4	switch(config-if)# untagged cos cos-value	Configures the untagged CoS value. Values can be from 1 to 7.

The following example shows how to set the CoS value to 4 for untagged frames received on an interface:

switch# configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# untagged cos 4

The following example shows how to set the CoS value to 3 for untagged frames received on a Layer 3 interface:

switch# configure terminal
switch(config)# interface ethernet 1/5
switch(config-if) no switchport
switch(config-if)# untagged cos 3
switch(config-if)#

Configuring an Interface Service Policy

An input qos policy is a service policy applied to incoming traffic on an Ethernet interface for classification. For type queuing, the output policy is applied to all outgoing traffic that matches the specified class. When you configure an input queuing policy on an interface or EtherChannel, the switch sends the configuration data to the adapter using the DCBX protocol.

Note

Type qos policies can be activated only on Cisco Nexus device interfaces and Cisco Nexus Fabric Extender interfaces. Type qos policies on Fabric Extender fabric interfaces or Fabric Extender fabric EtherChannel interfaces are ineffective, though the Cisco NX-OS CLI does not reject the configuration.

We recommend that you do not configure type qos policy-maps on Fabric Extender fabric interfaces or Fabric Extender fabric EtherChannel interfaces to avoid wasting hardware resources.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# interface {ethernet [chassis/]slot/port | port-channel channel-number}

3. switch(config-if)# service-policy [type {qos | queuing}] [input | output]policy-name

4. switch(config-if)# service-policy input policy-name

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface {ethernet [chassis/]slot/port | port-channel channel-number}

Enters the configuration mode for the specified interface.

Note

The service policy on a port channel applies to all member interfaces.

Step 3

switch(config-if)# service-policy [type {qos | queuing}] [input | output]policy-name

Specifies the policy map to use as the service policy for the system. There are two policy-map configuration modes:

qos—Classification mode; this is the default mode.
queuing—Queuing mode.

Note

The input keyword specifies that this policy map should be applied to traffic received on an interface. The output keyword specifies that this policy map should be applied to traffic transmitted from an interface. You can only apply input to a qos policy; you can only apply both input and output to a queuing policy.

Step 4

switch(config-if)# service-policy input policy-name

Applies the policy map to the interface.

Note

There is a restriction that system type qos policy cannot be the same as any the type qos policy applied to an interface or EtherChannel.

This example shows how to apply a policy to an Ethernet interface:

switch# configure terminal

switch(config)# interface ethernet 1/1

switch(config-if)# service-policy type qos input policy1

Configuring the Queue Limit for a Specified Fabric Extender

At the Fabric Extender configuration level, you can control the queue limit for a specified Fabric Extender for egress direction (from the network to the host). You can use a lower queue limit value on the Fabric Extender to prevent one blocked receiver from affecting traffic that is sent to other noncongested receivers ("head-of-line blocking"). A higher queue limit provides better burst absorption and less head-of-line blocking protection. You can use the no form of this command to allow the Fabric Extender to use all available hardware space.

Note

At the system level, you can set the queue limit for Fabric Extenders by using the fex queue-limit command. However, configuring the queue limit for a specific Fabric Extender will override the queue limit configuration set at the system level for that Fabric Extender.

You can specify the queue limit for the following Fabric Extenders:

Cisco Nexus 2148T Fabric Extender (48x1G 4x10G SFP+ Module)
Cisco Nexus 2224TP Fabric Extender (24x1G 2x10G SFP+ Module)
Cisco Nexus 2232P Fabric Extender (32x10G SFP+ 8x10G SFP+ Module)
Cisco Nexus 2248T Fabric Extender (48x1G 4x10G SFP+ Module)
Cisco Nexus N2248TP-E Fabric Extender (48x1G 4x10G Module)
Cisco Nexus N2348UPQ Fabric Extender (48x10G SFP+ 6x40G QSFP Module)

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# fex fex-id

3. switch(config-fex)# hardware fex_card_type queue-limit queue-limit

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch(config)# fex fex-id	Specifies the Fabric Extender and enters the Fabric Extender mode.
Step 3	switch(config-fex)# hardware fex_card_type queue-limit queue-limit	Configures the queue limit for the specified Fabric Extender. The queue limit is specified in bytes. The range is from 81920 to 652800 for a Cisco Nexus 2148T Fabric Extender and from 2560 to 652800 for all other supported Fabric Extenders.

This example shows how to restore the default queue limit on a Cisco Nexus 2248T Fabric Extender:

switch# configure terminal
switch(config-if)# fex 101
switch(config-fex)# hardware N2248T queue-limit 327680

This example shows how to remove the queue limit that is set by default on a Cisco Nexus 2248T Fabric Extender:

switch# configure terminal
switch(config)# fex 101
switch(config-fex)# no hardware N2248T queue-limit 327680

Configuring No-Drop Buffer Thresholds

You can configure the no-drop buffer threshold settings for 3000m lossless Ethernet.

Note

To achieve lossless Ethernet for both directions, the devices connected to the Cisco Nexus device must have the similar capability. The default buffer and threshold value for the no-drop can ensure lossless Ethernet for up to 300 meters.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# policy-map type network-qos policy-map name

3. switch(config-pmap-nq)# class type network-qos class-map name

4. switch(config-pmap-nq-c)# pause no-drop buffer-size buffer-size pause-threshold xoff-size resume-threshold xon-size

5. (Optional) switch(config-pmap-nq-c)# no pause no-drop buffer-size buffer-size pause-threshold xoff-size resume-threshold xon-size

6. switch(config-pmap-nq-c)# exit

7. switch(config-pmap-nq)# exit

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# policy-map type network-qos policy-map name

Enters policy-map network-qos class mode and identifies the policy map assigned to the type network-qos policy map.

Step 3

switch(config-pmap-nq)# class type network-qos class-map name

References an existing network QoS class map in a policy map and enters class mode.

Step 4

switch(config-pmap-nq-c)# pause no-drop buffer-size buffer-size pause-threshold xoff-size resume-threshold xon-size

Specifies the buffer threshold settings for pause and resume for 3000m lossless Ethernet:

buffer-size—Buffer size for ingress traffic, in bytes. Valid values are from 10240 to 490880.

Note

On a Cisco Nexus 5020 switch, you can configure a maximum buffer size of 143680 bytes.

On a Cisco Nexus 5500 Series device, you can configure a maximum buffer size of 152000 bytes.

pause-threshold—Specifies the buffer limit at which the port pauses the peer.

xoff-size—Buffer limit for pausing, in bytes. Valid values are 0 to 490880.

Note

On a Cisco Nexus 5020 switch, you can configure a maximum pause-threshold value of 58860 bytes.

On a Cisco Nexus 5500 Series device, you can configure a maximum pause-threshold value of 103360 bytes.

resume-threshold—Specifies the buffer limit at which the port resumes the peer.

xon-size—Buffer limit at which to resume, in bytes. Valid values are 0 to 490880.

Note

On a Cisco Nexus 5020 switch, you can configure a maximum resume-threshold value of 38400 bytes.

On a Cisco Nexus 5500 Series device, you can configure a maximum resume-threshold value of 83520 bytes.

Step 5

switch(config-pmap-nq-c)# no pause no-drop buffer-size buffer-size pause-threshold xoff-size resume-threshold xon-size

(Optional)

Removes the buffer threshold settings for pause and resume for 3000m lossless Ethernet.

Step 6

switch(config-pmap-nq-c)# exit

Exits class mode.

Step 7

switch(config-pmap-nq)# exit

Exits policy-map network-qos mode.

This example shows how to configure the no-drop buffer threshold for the Cisco Nexus device for 3000 meters.

switch(config-pmap-nq)# policy-map type network-qos nqos_policy
switch(config-pmap-nq)# class type network-qos nqos_class
switch(config-pmap-nq-c)# pause no-drop buffer-size 152000 pause-threshold 103360 resume-threshold 83520 
switch(config-pmap-nq-c)# exit
switch(config-pmap-nq)# exit
switch(config)# exit
switch#

Configuring the Buffer Threshold for the Cisco Nexus 2148T Fabric Extender

In the Fabric Extender configuration mode, you can configure the buffer threshold for the Cisco Nexus 2148T Fabric Extender. The buffer threshold sets the consumption level of input buffers before an indication is sent to the egress queue to start observing the tail drop threshold. If the buffer usage is lower than the configured buffer threshold, the tail drop threshold is ignored.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# fex fex-id

3. switch(config-fex)# hardware N2148T buffer-threshold buffer limit

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch(config)# fex fex-id	Specifies the Fabric Extender and enters the Fabric Extender mode.
Step 3	switch(config-fex)# hardware N2148T buffer-threshold buffer limit	Configures the buffer threshold for the Cisco Nexus 2148T Fabric Extender. The buffer threshold is specified in bytes. The range is from 81920 to 316160 for the Cisco Nexus 2148T Fabric Extender.

This example shows how to restore the default buffer threshold on the Cisco Nexus 2148T Fabric Extender:

switch# configure terminal
switch(config)# fex 101
switch(config-fex)# hardware N2148T buffer-threshold 163840

This example shows how to remove the default buffer threshold on the Cisco Nexus 2148T Fabric Extender:

switch# configure terminal
switch(config)# fex 101
switch(config-fex)# no hardware N2148T buffer-threshold

Priority Flow Control and Link-Level Flow Control

Cisco Nexus 5000 Series switches support priority flow control (PFC) and Link-Level Flow Control (LLC) on Ethernet interfaces. The Ethernet interface can operate in two different modes: FCoE mode or standard Ethernet mode.

If the interface is operating in FCoE mode, the Ethernet link is connected at the server port using a converged network adapter (CNA).

If the interface is operating in a standard Ethernet mode, the Ethernet link is connected at the server port with a standard Ethernet network adapter (NIC). The network adapter must support the Data Center Bridging Exchange protocol (DCBX) for PFC or ingress policing to be supported on the interface.

Note

You must configure a system class with the pause no-drop parameter for PFC to operate on Ethernet traffic (PFC will be applied to traffic that matches the CoS value configured for this class).

Configuring Priority Flow Control
Configuring Link-Level Flow Control

Configuring Priority Flow Control

By default, Ethernet interfaces negotiate PFC with the network adapter using the DCBX protocol. When PFC is enabled, PFC is applied to traffic that matches the CoS value configured for the no-drop class.

You can override the negotiation result by forcing the interface to enable PFC.

Beginning in Cisco NX-OS Release 5.0(3)N1(1), you can configure priority flow control on a Layer 2 or Layer 3 interface.

Note

Use the no switchport command to configure an interface as a Layer 3 interface

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# interface type slot/port

3. (Optional) switch(config-if)# no switchport

4. switch(config-if)# priority-flow-control mode {auto | on}

5. (Optional) switch(config-if)# no priority-flow-control mode on

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch(config)# interface type slot/port	Specifies the interface to be changed.
Step 3	switch(config-if)# no switchport	(Optional) Selects a Layer 3 interface.
Step 4	switch(config-if)# priority-flow-control mode {auto \| on}	Sets PFC mode for the selected interface. Specifies auto to negotiate PFC capability. This is the default. Specifies on to force-enable PFC.
Step 5	switch(config-if)# no priority-flow-control mode on	(Optional) Disables the PFC setting for the selected interface.

This example shows how to force-enable PFC on an interface:

switch# configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# priority-flow-control mode on

This example shows how to force-enable PFC on a Layer 3 interface:

switch# configure terminal
switch(config)# interface ethernet 1/5
switch(config-if)# no switchport
switch(config-if)# priority-flow-control mode on

Configuring Link-Level Flow Control

By default, LLC on Ethernet interfaces is disabled. You can enable LLC for the transmit and receive directions.

You can configure flow control on a Layer 2 or Layer 3 interface.

Note

Use the no switchport command to configure an interface as a Layer 3 interface.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# interface type slot/port

3. (Optional) switch(config-if)# no switchport

4. switch(config-if)# flowcontrol [receive {on | off}] [transmit {on | off}]

5. (Optional) switch(config-if)# no flowcontrol [receive {on | off}] [transmit {on | off}]

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch(config)# interface type slot/port	Specifies the interface to be changed.
Step 3	switch(config-if)# no switchport	(Optional) Selects a Layer 3 interface.
Step 4	switch(config-if)# flowcontrol [receive {on \| off}] [transmit {on \| off}]	Enables LLC for the selected interface. Set receive and/or transmit on or off.
Step 5	switch(config-if)# no flowcontrol [receive {on \| off}] [transmit {on \| off}]	(Optional) Disables LLC for the selected interface.

This example shows how to enable LLC on an interface:

switch# configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# flowcontrol receive on transmit on

This example shows how to enable LLC on a Layer 3 interface:

switch# configure terminal
switch(config)# interface ethernet 1/4
switch(config-if)# no switchport
switch(config-if)# flowcontrol receive on transmit on

Disabling Slow Port Pruning on Multicast Traffic on the Cisco Nexus 5500 Series Device

You can disable slow port pruning on multicast packets.

An interface on the Cisco Nexus 5500 Series device can become congested when it receives excessive multicast traffic or when the mixed unicast and multicast traffic rate exceeds the port bandwidth. When multiple interfaces receive the same multicast flow and one or more ports experience congestion, the slow port prunning feature allows the switch to drop only the multicast packets for the congested port. This feature is turned on by default. To turn the slow port pruning feature off, enter the hardware multicast disable-slow-port-pruning command.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# hardware multicast disable-slow-port-pruning

3. switch(config)# no hardware multicast disable-slow-port-pruning

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters configuration mode.
Step 2	switch(config)# hardware multicast disable-slow-port-pruning	Disables slow port pruning on multicast packets. The default is enabled.
Step 3	switch(config)# no hardware multicast disable-slow-port-pruning	Enables the slow port pruning feature.

This example shows how to disable slow port pruning on a Cisco Nexus 5548 switch:

switch(config)# hardware multicast disable-slow-port-pruning
switch(config)#

Enabling Virtual Output Queuing Limits for Unicast Traffic on the Cisco Nexus Device

You can enable the Virtual Output Queuing (VOQ) limit for unicast traffic. To alleviate congestion and blocking, use VOQ to prevent one blocked receiver from affecting traffic that is sent to other noncongested blocking receivers.

SUMMARY STEPS

1. switch# configure terminal

2. switch(config)# hardware unicast voq-limit

3. switch(config)# no hardware unicast voq-limit

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters configuration mode.
Step 2	switch(config)# hardware unicast voq-limit	Enables the VOQ limit for unicast traffic. The default is disabled.
Step 3	switch(config)# no hardware unicast voq-limit	Disables the VOQ limit for unicast traffic.

This example shows how to enable the VOQ limits for unicast packets on a switch:

switch(config)# hardware unicast voq-limit
switch(config)#

Verifying QoS Configuration

To verify QoS configuration information, perform one of these tasks:

Command	Purpose
switch# show class-map	Displays the class maps defined on the switch.
switch# show policy-map [name]	Displays the policy maps defined on the switch. Optionally, you can display the named policy only.
switch# show policy-map interface [interface number]	Displays the policy map settings for an interface or all interfaces.
switch# show policy-map system	Displays the policy map settings attached to the system qos.
switch# show policy-map type {network-qos \| qos \| queuing} [name]	Displays the policy map settings for a specific policy type. Optionally, you can display the named policy only.
switch# show queuing interface [interface slot/port]	Displays the queue configuration and statistics.
switch# show interface flowcontrol [ module number]	Displays the detailed listing of the flow control settings on all interfaces.
switch# show interface [interface slot/port] priority-flow-control [ module number]	Displays the priority flowcontrol details for a specified interface.
switch# show interface untagged-cos [ module number]	Displays the untagged CoS values for all interfaces.
switch# show wrr-queue cos-map [var]	Displays the mapped CoS values to egress queues.
switch# running-config ipqos	Displays information about the running configuration for QoS.
switch# startup-config ipqos	Displays information about the startup configuration for QoS.

Examples

This example shows how to display all type queuing class maps:

switch# show class-map type queuing
Type queuing class-maps
=======================
class-map type queuing class-fcoe
match qos-group 1
class-map type queuing class-default
match qos-group 0
class-map type queuing class-all-flood
match qos-group 2
class-map type queuing class-ip-multicast
match qos-group 2
switch#

This example shows how to display the flow control settings on Layer 3 interfaces where Ethernet 1/5 is configured as a routed interface:

switch# show interface flowcontrol
Port    Send    FlowControl Receive FlowControl RxPause TxPause
        admin      oper     admin     oper
--------------------------------------------------------------------------------
Eth1/1   off       off       off      off          0        0
Eth1/2   off       off       off      off          0        0
Eth1/3   off       off       off      off          0        0
Eth1/4   off       off       off      off          0        0
Eth1/5   off       off       on       on           0        0
Eth1/6   off       off       off      off          0        0
Eth1/7   off       off       off      off          0        0
Eth1/8   off       off       off      off          0        0
Eth1/9   off       off       off      off          0        0
Eth1/10  off       off       off      off          0        0
Eth1/11  off       off       off      off          0        0
Eth1/12  off       off       off      off          0        0
Eth1/13  off       off       off      off          0        0
Eth1/14  off       off       off      off          0        0
<--Output truncated-->
switch#
--------------------------------------------------------------------------------

This example shows how to display the priority flow control information for a specified Layer 3 interface:

switch# show interface ethernet 1/5 priority-flow-control
============================================================
Port           Mode Oper(VL bmap) RxPPP TxPPP
============================================================
Ethernet1/5    On   On   (0) 0 0
switch#

This example shows how to display the untagged CoS values for all interfaces (Layer 2, Layer 3):

switch# show interface untagged-cos
S3(config-if)# show int untagged-cos
=================================
Interface Untagged-CoS
=================================
port-channel100
port-channel127
port-channel128
Ethernet1/1
Ethernet1/2
Ethernet1/3
Ethernet1/4
Ethernet1/5 3
Ethernet1/6
Ethernet1/7
Ethernet1/8
Ethernet1/9
Ethernet1/10
Ethernet1/11
Ethernet1/12
:
<--snip-->
Ethernet3/31
Ethernet3/32
Ethernet100/1/1
Ethernet100/1/2
<--Output truncated-->
switch#

This example shows how to display QoS information:

switch# show running-config ipqos
!Command: show running-config ipqos
!Time: Sun Apr 20 07:22:36 2008

version 5.0(3)N1(1)
class-map type qos class-fcoe
class-map type qos match-all c1
  match cos 3-5
class-map type queuing class-fcoe
  match qos-group 1
class-map type queuing class-all-flood
  match qos-group 2
class-map type queuing class-ip-multicast
  match qos-group 2
policy-map type qos p1
  class c1
   set qos-group 3
class-map type network-qos n1
 match qos-group 1
class-map type network-qos class-fcoe
  match qos-group 1
class-map type network-qos class-all-flood
  match qos-group 2
class-map type network-qos class-ip-multicast
  match qos-group 2
policy-map type network-qos n2
  class type network-qos n1
  class type network-qos class-default
   multicast-optimize

interface Ethernet1/5
  priority-flow-control mode on
  untagged cos 3
switch#

The above display shows the QoS information for Layer 3 interfaces (Ethernet 1/5 configured as a Layer
3 interface).

This example shows how to display the CoS values that are mapped to the egress queue:

switch# show wrr-queue cos-map
MCAST Queue ID     Cos Map
0                    0 1
1                    2
2                    3 4 5
3                    6 7
switch#

This example shows how to display the class maps defined on the switch:

switch# show class-map

 Type qos class-maps
 ===================
    class-map type qos c1
      match cos 0,7
    class-map type qos c2
      match protocol ldp
      match ip rtp 2000-65535
      match dscp 10,12
      match precedence 6-7
      match protocol dhcp
      match protocol arp
    class-map type qos c3
      match cos 2,4-6
    class-map type qos c4
      match access-group name ipv4
    class-map type qos class-fcoe
      match cos 3
    class-map type qos class-default
      match any
    class-map type qos class-ip-multicast
      match ip multicast
  Type queuing class-maps
  =======================
    class-map type queuing c1
      match qos-group 2
    class-map type queuing c2
     match qos-group 3
    class-map type queuing c3
      match qos-group 4
    class-map type queuing class-fcoe
      match qos-group 1
    class-map type queuing class-default

      match qos-group 0

  Type network-qos class-maps

  ==============================

    class-map type network-qos c1

      match qos-group 2

    class-map type network-qos c2

      match qos-group 3

    class-map type network-qos c3

      match qos-group 4

    class-map type network-qos c4

      match qos-group 5

    class-map type network-qos class-fcoe

      match qos-group 1

    class-map type network-qos class-default

      match qos-group 0

This example shows how to display the policy maps defined on the switch:

switch# show policy-map

  Type qos policy-maps

  ====================

  policy-map type qos p1

    class type qos c1

      set qos-group 2

    class type qos c3

      set qos-group 4

    class type qos c4

      set qos-group 5

    class type qos c2

      set qos-group 3

    class type qos c22

      set qos-group 3

    class type qos class-fcoe

      set qos-group 1

    class type qos class-default

      set qos-group 0

  Type queuing policy-maps

  ========================

  policy-map type queuing p1

    class type queuing c2

      bandwidth percent 10

    class type queuing c4

      bandwidth percent 25

    class type queuing c1

      bandwidth percent 20

    class type queuing c3

      bandwidth percent 5

    class type queuing class-fcoe

      bandwidth percent 30

    class type queuing class-default

      bandwidth percent 10

  Type network-qos policy-maps

  ===============================

  policy-map type network-qos p1

    class type network-qos c1

      mtu 5000

    class type network-qos c2

      mtu 9216

      queue-limit 30000 bytes

    class type network-qos c3

      mtu 8000

    class type network-qos c4

      pause no-drop

    class type network-qos class-fcoe

      pause no-drop

      mtu 2240

    class type network-qos class-default

      mtu 1538

This example shows how to display the policy maps attached on the system qos:

switch# show policy-map system

  Type network-qos policy-maps

  ===============================

  policy-map type network-qos p1

    class type network-qos c1      match qos-group 2

      mtu 5000

    class type network-qos c2      match qos-group 3

      mtu 9216

      queue-limit 30000 bytes

    class type network-qos c3      match qos-group 4

      mtu 8000

    class type network-qos c4      match qos-group 5

      pause no-drop

    class type network-qos class-fcoe      match qos-group 1

      pause no-drop

      mtu 2240

    class type network-qos class-default      match qos-group 0

      mtu 1538

  Service-policy (queuing) input:   p1

    policy statistics status:   disabled

    Class-map (queuing):   c2 (match-any)

      Match: qos-group 3

      bandwidth percent 10

    Class-map (queuing):   c4 (match-any)

      Match: qos-group 5

      bandwidth percent 25

    Class-map (queuing):   c1 (match-any)

      Match: qos-group 2

      bandwidth percent 20

    Class-map (queuing):   c3 (match-any)

      Match: qos-group 4

      bandwidth percent 5

    Class-map (queuing):   class-fcoe (match-any)

      Match: qos-group 1

      bandwidth percent 30

    Class-map (queuing):   class-default (match-any)

      Match: qos-group 0

      bandwidth percent 10

  Service-policy (queuing) output:   default-out-policy

    policy statistics status:   disabled

    Class-map (queuing):   class-fcoe (match-any)

      Match: qos-group 1

      bandwidth percent 50

    Class-map (queuing):   class-default (match-any)

      Match: qos-group 0

      bandwidth percent 50

This example shows how to display the policy maps attached to an interface:

switch# show policy-map interface ethernet 1/1

Global statistics status :   disabled

Ethernet1/1

  Service-policy (qos) input:   p2

    policy statistics status:   disabled

    Class-map (qos):   c1 (match-any)

      Match: cos 0,7

      set qos-group 2

    Class-map (qos):   c2 (match-any)

      Match: protocol ldp

      Match: ip rtp 2000-65535

      Match: dscp 10,12

      Match: precedence 6-7

      Match: protocol dhcp

      Match: protocol arp

      set qos-group 3

    Class-map (qos):   c3 (match-any)

      Match: cos 2,4-6

      set qos-group 4

    Class-map (qos):   class-ip-multicast (match-any)

      Match: ip multicast

      set qos-group 5

    Class-map (qos):   class-fcoe (match-any)

      Match: cos 3

      set qos-group 1

    Class-map (qos):   class-default (match-any)

      Match: any

      set qos-group 0

  Service-policy (queuing) input:   p1

    policy statistics status:   disabled

    Class-map (queuing):   c2 (match-any)

      Match: qos-group 3

      bandwidth percent 10

    Class-map (queuing):   c4 (match-any)

      Match: qos-group 5

      bandwidth percent 25

    Class-map (queuing):   c1 (match-any)

      Match: qos-group 2

      bandwidth percent 20

    Class-map (queuing):   c3 (match-any)

      Match: qos-group 4

      bandwidth percent 5

    Class-map (queuing):   class-fcoe (match-any)

      Match: qos-group 1

      bandwidth percent 30

    Class-map (queuing):   class-default (match-any)

      Match: qos-group 0

      bandwidth percent 10

  Service-policy (queuing) output:   p2

    policy statistics status:   disabled

    Class-map (queuing):   c1 (match-any)

      Match: qos-group 2

      bandwidth percent 5

      priority

    Class-map (queuing):   c2 (match-any)

      Match: qos-group 3

      bandwidth percent 20

    Class-map (queuing):   c3 (match-any)

      Match: qos-group 4

      bandwidth percent 20

    Class-map (queuing):   c4 (match-any)

      Match: qos-group 5

      bandwidth percent 40

    Class-map (queuing):   class-fcoe (match-any)

      Match: qos-group 1

      bandwidth percent 10

    Class-map (queuing):   class-default (match-any)

      Match: qos-group 0

      bandwidth percent 5

This example shows how to display the queue configuration and counter information:

switch# show interface ethernet101/1/1

Ethernet101/1/1 is up
Hardware: 100/1000 Ethernet, address: e8b7.4855.6e02 (bia
e8b7.4855.6e02)
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA
Port mode is trunk
full-duplex, 1000 Mb/s
Beacon is turned off
Input flow-control is off, output flow-control is on
Switchport monitor is off
EtherType is 0x8100
Last link flapped 23:45:12
Last clearing of "show interface" counters never
30 seconds input rate 0 bits/sec, 0 packets/sec
30 seconds output rate 144 bits/sec, 0 packets/sec
Load-Interval #2: 5 minute (300 seconds)
input rate 0 bps, 0 pps; output rate 112 bps, 0 pps
RX
0 unicast packets 0 multicast packets 0 broadcast packets
0 input packets 0 bytes
0 jumbo packets 0 storm suppression bytes
0 runts 0 giants 0 CRC 0 no buffer
0 input error 0 short frame 0 overrun 0 underrun 0
ignored
0 watchdog 0 bad etype drop 0 bad proto drop 0 if down drop
0 input with dribble 0 input discard
0 Rx pause
TX
0 unicast packets 9452 multicast packets 0 broadcast packets
9452 output packets 1591946 bytes
0 jumbo packets
0 output errors 0 collision 0 deferred 0 late collision
0 lost carrier 0 no carrier 0 babble 0 output discard
0 Tx pause
1 interface resets

This example shows how to display the queue configuration and statistics:

switch# show queuing interface ethernet101/1/1

Ethernet101/1/1 queuing information:
  Input buffer allocation:
  Qos-group: 0  2  3  4  5  (shared)
  frh: 2
  drop-type: no-drop
  cos: 0 1 2 3 4 5 6
  xon       xoff      buffer-size
  ---------+---------+-----------
  81920     114688    286720   

  Queueing:
  queue    qos-group    cos            priority  bandwidth mtu 
  --------+------------+--------------+---------+---------+----
  2        0            0 2 3           WRR        73      2048
  4        2            1               WRR         1      5120
  5        3            6               WRR         6      8192
  6        4            4               WRR        20      6144
  7        5            5               PRI         0      9728

  Queue Limit Tx: 30015488 bytes
  Queue Limit Rx: 30007296 bytes

  Queue Statistics:
  ---+----------------+-----------+------------+----------+-----------+
  Que|Received /      |Tail Drop  |No Buffer   |MAC Error |Multicast  |
  No |Transmitted     |           |            |          |Tail Drop  |
  ---+----------------+-----------+------------+----------+-----------+
  2rx|               0|                       0|         0|     -     |
  2tx|               0|          0|           0|         0|          0|
  ---+----------------+-----------+------------+----------+-----------+
  4rx|               0|                       0|         0|     -     |
  4tx|               0|          0|           0|         0|          0|
  ---+----------------+-----------+------------+----------+-----------+
  5rx|               0|                       0|         0|     -     |
  5tx|               0|          0|           0|         0|          0|
  ---+----------------+-----------+------------+----------+-----------+
  6rx|               0|                       0|         0|     -     |
  6tx|               0|          0|           0|         0|          0|
  ---+----------------+-----------+------------+----------+-----------+
  7rx|               0|                       0|         0|     -     |
  7tx|               0|          0|           0|         0|          0|
  ---+----------------+-----------+------------+----------+-----------+

  Priority-flow-control enabled: no
  Flow-control status: 
  cos     qos-group   rx pause  tx pause  masked rx pause
  -------+-----------+---------+---------+---------------
  0              0    xon       xon       xon 
  1              2    xon       xon       xon 
  2              0    xon       xon       xon 
  3              0    xon       xon       xon 
  4              4    xon       xon       xon 
  5              5    xon       xon       xon 
  6              3    xon       xon       xon 
  7            n/a    xon       xon       xon

QoS Example 1

This example shows how to configure traffic in the entire system matching an access control list to have the frame CoS fields rewritten to the value 5.

SUMMARY STEPS

1. Set up the ingress classification policy (the access control list was defined previously).

2. Attach the classification policy to the system.

3. Set up the system class allocation and rewrite policy. Allocate the system class for qos-group 4 and define the rewrite action.

4. Attach the allocation and rewrite policy to the system.

DETAILED STEPS

	Command or Action	Purpose
Step 1	Set up the ingress classification policy (the access control list was defined previously).	(config)# `class-map type qos cmap-qos-acl` (config-cmap-qos)# `match access-group ACL-CoS` (config-cmap-qos)# `exit` (config)# `policy-map type qos pmap-qos-acl` (config-pmap-qos)# `class cmap-qos-acl` (config-pmap-c-qos)# `set qos-group 4` (config-pmap-c-qos)# `exit` (config-pmap-qos)# `exit`
Step 2	Attach the classification policy to the system.	(config)# `system qos` (config-sys-qos)# `service-policy type qos input pmap-qos-acl` (config-sys-qos)# `exit`
Step 3	Set up the system class allocation and rewrite policy. Allocate the system class for qos-group 4 and define the rewrite action.	(config)# `class-map type network-qos cmap-nq-acl` (config-cmap-nq)# `match qos-group 4` (config-cmap-nq)# `exit` (config)# `policy-map type network-qos pmap-nq-acl` (config-pmap-nq)# `class type network-qos cmap-nq-acl` (config-pmap-c-nq)# `set cos 5` (config-pmap-c-nq)# `exit` (config-pmap-nq)# `exit`
Step 4	Attach the allocation and rewrite policy to the system.	(config)# `system qos` (config-sys-qos)# `service-policy type network-qos pmap-nq-acl` (config-sys-qos)# `exit`

QoS Example 2

This example shows how to use an access control list to apply 50% bandwidth to traffic on Ethernet interface 1/3 that matches traffic on Ethernet interface 1/1.

SUMMARY STEPS

1. Set up the ingress classification policy.

2. Attach the classification policy to the interface Ethernet 1/1.

3. Set up the system-wide definition of the qos-group first.

4. Set up the egress bandwidth policy.

5. Attach the bandwidth policy to the egress interface.

6. Allocate the system class for qos-group 2.

7. Set up the network-qos policy.

8. Attach the network-qos policy to the system.

DETAILED STEPS

Command or Action

Purpose

Step 1

Set up the ingress classification policy.

(config)# class-map type qos cmap-qos-bandwidth

(config-cmap-qos)# match access-group ACL-bandwidth

(config-cmap-qos)# exit

(config)# policy-map type qos pmap-qos-eth1-1

(config-pmap-qos)# class cmap-qos-bandwidth

(config-pmap-c-qos)# set qos-group 2

(config-pmap-c-qos)# exit

(config-pmap-qos)# exit

Step 2

Attach the classification policy to the interface Ethernet 1/1.

(config)# interface ethernet 1/1

(config-if)# service-policy type qos input pmap-qos-eth1-1

(config-if)# exit

Step 3

Set up the system-wide definition of the qos-group first.

(config)# class-map type queuing cmap-que-bandwidth

(config-cmap-que)# match qos-group 2

(config-cmap-que)# exit

Step 4

Set up the egress bandwidth policy.

Note

Before you can successfully allocate bandwidth to the user-defined class cmap-que-bandwidth, you must first reduce the default bandwidth configuration on class-default and class-fcoe.

(config)# policy-map type queuing pmap-que-eth1-2

(config-pmap-que)# class type queuing class-default

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

(config-pmap-c-que)# exit

(config-pmap-que)# class type queuing class-fcoe

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

(config-pmap-c-que)# exit

(config-pmap-que)# class type queuing cmap-que-bandwidth

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

(config-pmap-c-que)# exit

(config-pmap-que)# exit

Step 5

Attach the bandwidth policy to the egress interface.

(config)# interface ethernet 1/3

(config-if)# service-policy type queuing output pmap-que-eth1-2

(config-if)# exit

Step 6

Allocate the system class for qos-group 2.

(config)# class-map type network-qos cmap-nq-bandwidth

(config-cmap-nq)# match qos-group 2

(config-cmap-nq)# exit

Step 7

Set up the network-qos policy.

(config)# policy-map type network-qos pmap-nq-bandwidth

(config-pmap-nq)# class type network-qos cmap-nq-bandwidth

(config-pmap-c-nq)# exit

(config-pmap-nq)# exit

Step 8

Attach the network-qos policy to the system.

(config)# system qos

(config-sys-qos)# service-policy type network-qos pmap-nq-bandwidth

(config-sys-qos)# exit

QoS Example 3

This example shows how to attach a 802.1p tag with a CoS value of 3 to incoming untagged packets, and force priority-flow-control negotiation on Ethernet interface 1/15.

SUMMARY STEPS

1. Set up the ingress classification policy (the access control list was defined previously).

DETAILED STEPS

Command or Action

Purpose

Step 1

Set up the ingress classification policy (the access control list was defined previously).

(config)# interface Ethernet 1/15

(config-if)# untagged cos 3

(config-if)# priority-flow-control mode on

(config-if)# exit

Bias-Free Language

Results

Chapter: Configuring QoS

Configuring QoS

Information About Quality of Service

Modular QoS CLI

System Classes

Default System Classes

Information About Policy Types

Link-Level Flow Control

Priority Flow Control

MTU

Trust Boundaries

Ingress Queuing Policies

Ingress Classification Policies

Egress Queuing Policies

Buffering and Queue Limits on the Cisco Nexus Device

Buffering and Queue Limits on the Cisco Nexus 5000 Platform

QoS for Multicast Traffic

Policy for Fibre Channel Interfaces

QoS for Traffic Directed to the CPU

QoS Configuration Guidelines and Limitations

Configuring Class Maps

Configuring ACL Classification

Configuring CoS Classification

Configuring DSCP Classification

Configuring IP RTP Classification

Configuring Precedence Classification

Configuring Protocol Classification

Configuring QoS Group Classification

Creating Policy Maps

Configuring Type QoS Policies

Configuring Type Network QoS Policies

Configuring Type Queuing Policies

Information About Marking

Configuring CoS Marking

Configuring DSCP Marking

Configuring IP Precedence Marking

Required CoS Marking Configuration in a Layer 3 Topology

Configuring Layer 3 Multicast Queuing

Configuring a Service Policy for a Layer 3 Interface

Attaching the System Service Policy

Restoring the Default System Service Policies

Configuring the Queue Limit for Fabric Extenders

Enabling the Jumbo MTU

Verifying the Jumbo MTU

Configuring Untagged CoS

Configuring an Interface Service Policy

Configuring the Queue Limit for a Specified Fabric Extender

Configuring No-Drop Buffer Thresholds

Configuring the Buffer Threshold for the Cisco Nexus 2148T Fabric Extender

Priority Flow Control and Link-Level Flow Control

Configuring Priority Flow Control

Configuring Link-Level Flow Control

Disabling Slow Port Pruning on Multicast Traffic on the Cisco Nexus 5500 Series Device

Enabling Virtual Output Queuing Limits for Unicast Traffic on the Cisco Nexus Device

Verifying QoS Configuration

Examples

QoS Example 1

QoS Example 2

QoS Example 3

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