Cisco Nexus 3548 Switch NX-OS Quality of Service Configuration Guide, Release 10.5(x)

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 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).

In the event of congestion or collisions, Ethernet will drop packets. The higher level protocols detect the missing data and retransmit the dropped packets.

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.

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

Default System Classes

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

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.

Note

The Cisco Nexus device supports one MTU for all classes for all ports.

Set CoS value—This configuration is used to mark 802.1p values for all traffic mapped to this system class.

Congestion Control ECN—Data Center TCP (DCTCP) is an enhancement to the TCP congestion control algorithm for data center networks. It leverages Explicit Congestion Notification (ECN) feature, to mark all the packets when the queue length exceeds a configured ECN threshold value. The routers and end hosts use this marking as a signal that the network is congested to slow down sending packets. To enable an ECN, use the congestion-control dctcp ecn command in the network-qos policy map mode.

Note

Enabling ECN on a class on a network-qos policy implies that ECN is enabled for all ports in the system.

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

The Cisco Nexus device supports type queuing in the egress direction.

Note

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

Note

On Cisco Nexus 3500 Series switches, QoS remarking will never work until a qos-group is defined under the qos policy. This is an expected behaviour that if there no qos-group is applied, it must get classified under the default queue.

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.

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.

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.


The Cisco Nexus 3500 Series switches support:	Five QoS groups Five queues for unicast Five queues for multicast

Network QoS Policy Type

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.

Note

All user defined classes have to be defined under network-qos policy and the network-qos policy has to be applied under "system qos".

MTU—The MTU that needs to be enforced for the traffic that is mapped to a system class.

Note

The Cisco Nexus device supports one MTU for all classes for all ports.

Set CoS value—This configuration is used to mark 802.1p values for all traffic mapped to this system class.

Congestion Control DCTCP and ECN—Data Center TCP (DCTCP) is an enhancement to the TCP congestion control algorithm for data center networks. It leverages Explicit Congestion Notification (ECN) feature, to mark all the packets when the queue length exceeds a configured DCTCP threshold value. The routers and end hosts use this marking as a signal that the network is congested to slow down sending packets.

To enable an DCTCP/ECN, use either the congestion-control dctcp ecn-threshold threshold-bytes command or the congestion-control random-detect ecn command in the network-qos policy-map mode.

Note

Enabling DCTCP and ECN on a class on a network-qos policy implies that DCTCP and ECN is enabled for all ports in the system.

Beginning with Cisco NX-OS Release 9.3(3), the congestion-control random-detect ecn command is not supported.

The following example shows how to enable DCTCP and ECN and verify the configuration on the network QoS policy maps:


switch# configuration terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# policy-map type network-qos system_network_policy
switch(config-pmap-nq)# class type network-qos nc1
switch(config-pmap-nq-c)# set cos 2
switch(config-pmap-nq-c)# class type network-qos nc2
switch(config-pmap-nq-c)# congestion-control dctcp ecn-threshold 30000 bytes
switch(config-pmap-nq-c)#
switch(config-pmap-nq-c)# class type network-qos nc3
switch(config-pmap-nq-c)# congestion-control random-detect ecn

switch(config-pmap-nq-c)# system qos
switch(config-sys-qos)# service-policy type network-qos system_network_policy
switch(config-sys-qos)# end
switch#
switch# show policy-map system


Type network-qos policy-maps
===============================

policy-map type network-qos system_network_policy
class type network-qos nc1
match qos-group 1

mtu 1500
set cos 2
class type network-qos nc2
match qos-group 2

mtu 1500
congestion-control dctcp ecn-threshold 30000 bytes

class type network-qos nc3
match qos-group 3

mtu 1500
congestion-control random-detect ecn

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

mtu 1500

Note

When configuring LLFC/PFC, use the pause no-drop/pfc-cos command. For more information, see "Configuring Link Level Flow Control" and "Configuring Priority Flow Control".

Queuing Policy Type

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

The Cisco Nexus device supports type queuing in the egress direction.

Note

Some configuration parameters when applied to a Port Channel are not reflected on the configuration of the member ports.

Note

Queuing shaping functionality is not supported for the Nexus 3500.

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.

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.

QoS Policy Type

A QoS policy type 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 a Port Channel 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.

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.

Note

Ingress/Egress policers are not supported in Nexus 3500.

QoS Group—Sets the QoS group that corresponds to the system class this traffic flow is mapped to.
- Cisco Nexus device supports the following:
  - Five QoS groups
  - Five queues for unicast
  - Five queues for multicast

MTU

The Cisco Nexus device supports one MTU for all classes for all ports.

When configuring MTU, follow these guidelines:

For the Cisco Nexus device, the MTU is controlled by the value configured on the class default. No MTU configuration is required under non-default network-qos classes. MTU configuration CLI under non-default classes is blocked. MTU configuration under default class is implicitly applied to all user defined classes.
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 1500 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 default system class has a default MTU of 1500 bytes. You can configure this value.
You can specify the MTU value for either a single Layer 3 interface or a range of Layer 3 interfaces. When you change the Layer 3 interface MTU value to the jumbo MTU value (1500 bytes or greater), you must also change the network QoS MTU value to 1500 bytes or greater. The device generates a syslog message to inform you of this requirement.

Trust Boundaries

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

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.

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 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.

Each Ethernet interface supports up to five 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.
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).

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.
For QoS policy maps, DSCP/Prec marking will not occur unless the set qos-group command is configured.
When configuring Port Channels, the service policy configured on an Port Channel applies to all member interfaces.
By default, queues 6 and 7 are reserved for control plane traffic and queue 5 for SPAN traffic. So you can configure four classes along with the default class.
On Cisco Nexus 3548 Series switches, the bandwidth percentage that is configured under the queuing policy is not honored under the following conditions:
- When there is an egress port that is experiencing congestion due to an input/output rate mismatch.
- When there are multiple traffic classes using different UC/MC queues.
- If all streams are competing for the buffers because the input rate of all streams is more than the output rate.
Some streams experience buffer crunch as the competing streams use up all the system buffers. There is no fair distribution of the shared buffers on Cisco Nexus N3548 Series switches, due to which the streams that can not be buffered are dropped aggressively. This results in the output rates that are less than the configured bandwidth for that stream and the other streams that exceed the configured bandwidth.

To work around this issue, you have to configure the CLI command hardware profile buffer qos-group X threshold Y where X is the qos-group number of the traffic that is exceeding the configured bandwidth and Y is the percentage of the shared buffers that can be used by the stream. The threshold value Y should be a small value, for example, 10 or 20. It can be fine tuned based on the burst absorption rate that is required at the same time honoring the bandwidth. The default threshold is 95%.
For Weighted Round-Robin (wrr), the wrr unicast-bandwidth bandwidth_in_percent command is used to specify the total bandwidth allocated for unicast traffic. The default is 50%.
Enabling QoS statistics using the 'qos statistics' command is not supported on the Cisco Nexus 3548 Series switches.

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

switch# configure terminal
switch(config)# class-map [type {network-qos | qos | queuing}] class-map name
(Optional) switch(config)# class-map [type qos] [match-all | match-any] class-map name
(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	(Optional) 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	(Optional) switch(config)# no class-map [type {network-qos \| qos \| queuing}] `class-name`	(Optional) Deletes the specified class map. 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

switch# configure terminal
switch(config)# class-map type qos class-name
switch(config-cmap-qos)# match access-group name acl-name
(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

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

(Optional)

Removes the match from the traffic class.

Example

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.

SUMMARY STEPS

switch# configure terminal
switch(config)# class-map type qos class-name
switch(config-cmap-qos)# match cos cos-value
(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.
Step 4	(Optional) switch(config-cmap-qos)# no match cos `cos-value`	(Optional) Removes the match from the traffic class.

Example

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.

Table 1. 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

switch# configure terminal
switch(config)# class-map type qos class-name
switch(config-cmap-qos)# match dscp dscp-list
(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	(Optional) 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.

Example

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

switch# configure terminal
switch(config)# class-map type qos class-name
switch(config-cmap-qos)# match ip rtp port-number
(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	(Optional) switch(config-cmap-qos)# no match ip rtp `port-number`	(Optional) Removes the match from the traffic class.

Example

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 RDMA over Converged Ethernet (RoCE) Classification

The following is how to configure for the ROCE protocol,

Note

When configuring RoCE, the port list ranges from 2000 to 65535. The recommended port to use is 3804.

SUMMARY STEPS

switch# configure terminal
switch(config)# class-map type qos class-name
switch(config-cmap-qos)# match ip roce port-number
(Optional) switch(config-cmap-qos)# no match ip roce 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 roce `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. The recommended port is 3804.
Step 4	(Optional) switch(config-cmap-qos)# no match ip roce `port-number`	(Optional) Removes the match from the traffic class.

Configuring Precedence Classification

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

Table 2. 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

switch# configure terminal
switch(config)# class-map type qos match-any class-name
switch(config-cmap-qos)#match precedence precedence-values
(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	(Optional) 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.

Example

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

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 one default system class: 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
Output queuing: default-out-policy

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

switch# configure terminal
switch(config)# policy-map [type {network-qos | qos | queuing}] policy-name
(Optional) switch(config)# no policy-map [type {network-qos | qos | queuing}] policy-name
switch(config-pmap)# class [type {network-qos | qos | queuing}] class-name
(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

(Optional) 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

(Optional) 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 for ingress traffic only.

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

SUMMARY STEPS

switch# configure terminal
switch(config)# policy-map type qos policy-name
switch(config-pmap-qos)# [class | class-default] type qos class-name
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.

Example

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

switch# configure terminal
switch(config)# policy-map type network-qos policy-name
switch(config-pmap-nq)# class type network-qos class-name
switch(config-pmap-c-nq)# mtu mtu-value
(Optional) switch(config-pmap-c-nq)# no mtu
switch(config-pmap-c-nq)# set cos cos-value
(Optional) switch(config-pmap-c-nq)# no set cos cos-value

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters 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

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

(Optional)

Resets the MTU value in this class.

Step 6

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 7

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

(Optional)

Disables the marking operation in this class.

Example

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

switch# configure terminal
switch(config)# policy-map type queuing policy-name
switch(config-pmap-que)# class type queuing class-name
switch(config-pmap-c-que)# priority
(Optional) switch(config-pmap-c-que)# no priority
switch(config-pmap-c-que)# bandwidth percent percentage
(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

(Optional) 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

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

(Optional)

Removes the bandwidth specification from this class.

Example

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

switch# configure terminal
switch(config)# policy-map type queuing policy-queue1
switch(config-pmap-que)# class type queuing class-queue1
switch(config-pmap-c-que)# priority
switch(config-pmap-c-que)# bandwidth 20

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

Configuring DSCP Marking

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 60, in addition to the standard DSCP values shown in the table below:

Note

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

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	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

configure terminal
policy-map type qos qos-policy-map-name
class [type qos] {class-map-name | class-default}
set dscp dscp-value
set qos-group qos-group-value

DETAILED STEPS

Command or Action

Purpose

Step 1

configure terminal

Enters global configuration mode.

Step 2

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

Creates or accesses the policy map named qos-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 qos-group-value

Configures one or more qos-group values to match on for DSCP remarking of traffic into this class map. There is no default value.

Note

For QoS policy maps, DSCP marking does not occur unless the set qos-group command is configured.

Example

This example shows how to display the policy-map configuration:

switch# show policy-map policy1

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. The following table shows the precedence values:

Note

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

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

config terminal
policy-map [type qos] qos-policy-map-name
class [type qos] {class-map-name | class-default}
set precedence precedence-value
set qos-group qos-group-value

DETAILED STEPS

Command or Action

Purpose

Step 1

config terminal

Enters global 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.

Step 5

set qos-group qos-group-value

Configures one or more qos-group values to match for IP precedence remarking of traffic into this class map. There is no default value.

Note

For QoS policy maps, IP precedence marking does not occur unless the set qos-group command is configured.

Example

This example shows how to set the precedence marking to 5:

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

Attaching the System Service Policy

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

SUMMARY STEPS

switch# configure terminal
switch(config)# system qos
switch(config-sys-qos)# service-policy type {network-qos | qos input |queuing [input | output]} 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 input |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 (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 only apply output to a queuing policy.

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

switch# configure terminal
switch(config)# system qos
switch(config-sys-qos)# no service-policy type qos input policy-map name
switch(config-sys-qos)# no service-policy type network-qos policy-map name
switch(config-sys-qos)# no service-policy type queuing output 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.

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

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.

This example shows how to display jumbo MTU information:


switch# sh queuing interface ethernet 1/1

slot  1
=======


HW MTU of Ethernet1/1 : 1500 bytes

Egress Queuing for Ethernet1/1 [System]
------------------------------------------------------------------------------
QoS-Group# Bandwidth% PrioLevel                Shape                   QLimit
                                   Min          Max        Units   
------------------------------------------------------------------------------
      4            20         -           -            -     -      4969339(S)
      3            30         -           -            -     -      4969339(S)
      2            20         -           -            -     -      4969339(S)
      1            10         -           -            -     -      4969339(S)
      0            20         -           -            -     -      4969339(S)

Mcast pkts dropped      : 0

+-------------------------------------------------------------------+
|                              QOS GROUP 0                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 1                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 2                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 3                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 4                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 5                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 6                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 7                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+


Ingress Queuing for Ethernet1/1
------------------------------------------------------------------
QoS-Group#                 Pause                        QLimit
           Buff Size       Pause Th      Resume Th      
------------------------------------------------------------------
      7              -            -            -            0(S)
      6              -            -            -            0(S)
      5              -            -            -            0(S)
      4              -            -            -            0(S)
      3              -            -            -            0(S)
      2              -            -            -            0(S)
      1              -            -            -            0(S)
      0              -            -            -            0(S)

PFC Statistics
----------------------------------------------------------------------------
TxPPP:                    0, RxPPP:                    0
----------------------------------------------------------------------------
 COS QOS Group   TxCount         RxCount
   0         -         0               0
   1         -         0               0
   2         2         0               0
   3         3         0               0
   4         -         0               0
   5         -         0               0
   6         -         0               0
   7         -         0               0
----------------------------------------------------------------------------
switch#

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.

SUMMARY STEPS

switch# configure terminal
switch(config)# interface {ethernet [chassis/]slot/port | port-channel channel-number}
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)# untagged cos `cos-value`	Configures the untagged CoS value. Values can be from 1 to 7.

Example

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

Configuring a Multicast Slow Receiver Port

When you have a combination of 10-gigabyte and 1-gigabyte ports, you can use this command on the 1-gigabyte port to reduce the effects of the 1-gigabyte port blocking the 10-gigabyte port. Use this command on the 1-gigabyte port only when there is Head-of-Line Blocking (HOLB) on the 10-gigabyte port due to a slow receiver on the 1-gigabyte port.

SUMMARY STEPS

switch# configure terminal
switch(config)# hardware profile multicast slow-receiver port port port-number}
(Optional) switch(config)# copy running-config startup-config

DETAILED STEPS

Command or Action

Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# hardware profile multicast slow-receiver port port port-number}

Configures a specific 1-Gigabyte port as a slow-receiver port so that it does not block the 10-Gigabyte port.

Note

You can use this configuration on only one of the four ports of a port-group.

Step 3

(Optional) switch(config)# copy running-config startup-config

(Optional)

Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration.

Example

The following example shows how to configure port 46 as the multicast slow-receiver port:


switch# configure terminal
switch(config)# hardware profile multicast slow-receiver port 46
switch(config)# copy running-config startup-config

Configuring the Percentage of Buffer Used for a Specific QoS Group or Virtual Lane

You can configure the percentage of shared buffer used for a specific QoS group or virtual lane (VL)

SUMMARY STEPS

switch# configure terminal
switch# hardware profile buffer qosgroup number threshold percentage
(Optional) switch(config)# copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch# hardware profile buffer qosgroup `number` threshold `percentage`	Configures the buffer for the specified QoS group. The `number` argument specifies the QoS group number. The range is from 0 to 4. The `percentage` argument specified the percentage of maximum usages. The range is from 1 to 100.
Step 3	(Optional) switch(config)# copy running-config startup-config	(Optional) Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration.

Example

The following example shows how to configure the shared buffer for QoS group 1 to a maximum of 40 percent usage:


switch# configure terminal
switch(config)# hardware profile buffer qosgroup 1 threshold 40
switch(config)# copy running-config startup-config

Configuring the Percentage of Buffer Used for SPAN Traffic

You can configure the percentage of shared buffer used for SPAN traffic.

SUMMARY STEPS

switch# configure terminal
switch# hardware profile buffer span-threshold percentage
(Optional) switch(config)# copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	switch# configure terminal	Enters global configuration mode.
Step 2	switch# hardware profile buffer span-threshold `percentage`	Configures the percentage of maximum usage of the hardware buffer for SPAN traffic. The `percentage` range is from 2 to 100.
Step 3	(Optional) switch(config)# copy running-config startup-config	(Optional) Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration.

Example

The following example shows how to configure 30 percent of the hardware buffer for SPAN traffic:


switch# configure terminal
switch(config)# hardware profile buffer span-threshold 30
switch(config)# copy running-config startup-config

Verifying the QoS Configuration

To verify the QoS configurations, perform one of these tasks:


Command	Purpose
switch# show class-map	Displays the class maps defined on the device.
switch# show policy-map [`name`]	Displays the policy maps defined on the device. 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 interface [`interface` `slot/port`] priority-flow-control [ module `number`] [detail]	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 running-config ipqos	Displays information about the running configuration for QoS.
switch# show startup-config ipqos	Displays information about the startup configuration for QoS.
switch# show queuing interface ethernet `slot-no/port-no`	Displays the queuing information on interfaces.

Note

Monitoring of QoS statistics using the 'qos statistics' command is not supported on the Cisco Nexus 3548 Series switches.

Note

In the following examples, beginning with Cisco NX-OS Release 9.3(3), the congestion-control random-detect ecn command is not supported.

This example shows how to configure a network QoS policy:

switch(config)# class-map type network-qos cnq1
switch(config-cmap-nq)# match qos-group 1
switch(config-cmap-nq)# exit
switch(config)# class-map type network-qos cnq2
switch(config-cmap-nq)# match qos-group 2
switch(config-cmap-nq)# 
switch(config-cmap-nq)# exit
switch(config)# policy-map type network-qos pnqos
switch(config-pmap-nq)# class type network-qos cnq1
switch(config-pmap-nq-c)# set cos 4
switch(config-pmap-nq-c)# exit
switch(config-pmap-nq)# class type network-qos cnq2
switch(config-pmap-nq-c)# set cos 5
switch(config-pmap-nq-c)# congestion-control random-detect ecn
switch(config-pmap-nq-c)# exit
switch(config-pmap-nq)# class type network-qos class-default
switch(config-pmap-nq-c)# mtu 9216
switch(config-pmap-nq-c)# exit
switch(config-pmap-nq)# exit
switch(config)# system qos
switch(config-sys-qos)# service-policy type network-qos pnqos
switch(config-sys-qos)#

This example shows how to configure a queuing policy:

switch(config)# class-map type queuing cqu1
switch(config-cmap-que)# match qos-group 1
switch(config-cmap-que)# exit
switch(config)# class-map type queuing cqu6
switch(config-cmap-que)# match qos-group 2
switch(config-cmap-que)# exit
switch(config)# policy-map type queuing pqu
switch(config-pmap-que)# class type queuing class-default
switch(config-pmap-c-que)# bandwidth percent 70
switch(config-pmap-c-que)# exit
switch(config-pmap-que)# class type queuing cqu1
switch(config-pmap-c-que)# bandwidth percent 10
switch(config-pmap-c-que)# exit
switch(config-pmap-que)# class type queuing cqu6
switch(config-pmap-c-que)# bandwidth percent 20
switch(config-pmap-c-que)# exit
switch(config-pmap-que)# exit
switch(config)# system qos
switch(config-sys-qos)# service-policy type queuing output pqu
switch(config-sys-qos)#

This example shows how to configure a QoS policy:

switch(config)# class-map type qos cqos1
switch(config-cmap-qos)# match cos 1
switch(config-cmap-qos)# exit
switch(config)# class-map type qos cqos6
switch(config-cmap-qos)# match cos 6
switch(config-cmap-qos)# exit
switch(config)# policy-map type qos pqos
switch(config-pmap-qos)# class type qos cqos1
switch(config-pmap-c-qos)# set qos-group 1
switch(config-pmap-c-qos)# exit
switch(config-pmap-qos)# class type qos cqos6
switch(config-pmap-c-qos)# set qos-group 2
switch(config-pmap-c-qos)# exit
switch(config-pmap-qos)# exit
switch(config)# system qos
switch(config-sys-qos)# service-policy type qos input pqos
switch(config-sys-qos)#

This example shows how to verify the untagged-cos configuration on interfaces:


switch# show interface untagged-cos 
Legend: * - On conversion to L2 interface
===========================
Interface Untagged-CoS
===========================
Eth1/10   3 
Eth1/11   4 
switch#

This example shows how to display the QoS running configuration:

switch(config)# show running-config ipqos

!Command: show running-config ipqos!Running configuration last done at: Tue Oct 16 06:59:37 2018
!Time: Tue Oct 16 07:00:15 2018

version 9.2(2) Bios:version 5.1.0 
class-map type qos match-all cqos1
  match cos 1
class-map type qos match-all cqos6
  match cos 6
class-map type queuing cqu1
  match qos-group 1
class-map type queuing cqu6
  match qos-group 2
policy-map type qos pqos
  class cqos1
    set qos-group 1
  class cqos6
    set qos-group 2
policy-map type queuing pqu
  class type queuing cqu1
    bandwidth percent 10
  class type queuing cqu6
    bandwidth percent 20
  class type queuing class-default
    bandwidth percent 70
class-map type network-qos cnq1
  match qos-group 1
class-map type network-qos cnq2
  match qos-group 2
policy-map type network-qos pnqos
  class type network-qos cnq1
    set cos 4
  class type network-qos cnq2
    set cos 5
    congestion-control random-detect ecn
  class type network-qos class-default
    mtu 9216
system qos
  service-policy type qos input pqos
  service-policy type network-qos pnqos
  service-policy type queuing output pqu


interface Ethernet1/1
  untagged cos 4

interface Ethernet1/3
  untagged cos 5

switch(config)#

This example shows how to display the class map configuration:

switch(config)# show class-map


  Type qos class-maps
  ===================

    class-map type qos match-all cqos1
      match cos 1

    class-map type qos match-all cqos2
      match cos 2

    class-map type qos match-any class-default
      match any


  Type queuing class-maps
  =======================

    class-map type queuing cqu1
      match qos-group 1

    class-map type queuing cqu2
      match qos-group 2

    class-map type queuing class-default
      match qos-group 0



  Type network-qos class-maps
  ==============================

    class-map type network-qos cnq1
      match qos-group 1

    class-map type network-qos cnq2
      match qos-group 2

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

switch(config)#

This example shows how to display the policy map configuration:

switch(config)# show policy-map


  Type qos policy-maps
  ====================

  policy-map type qos pqos
    class type qos cqos1
      set qos-group 1
    class type qos cqos2
      set qos-group 2
    class type qos class-default
      set qos-group 0
  policy-map type qos default-in-policy
    class type qos class-default
      set qos-group 0

  Type queuing policy-maps
  ========================

  policy-map type queuing pqu
    class type queuing cqu1
      bandwidth percent 10
    class type queuing cqu2
      bandwidth percent 20
    class type queuing class-default
      bandwidth percent 70
  policy-map type queuing default-out-policy
    class type queuing class-default
      bandwidth percent 100


  Type network-qos policy-maps
  ===============================

  policy-map type network-qos pnqos
    class type network-qos cnq1
      mtu 1500
      set cos 4
    class type network-qos cnq2
      mtu 1500
      set cos 5
      congestion-control random-detect ecn
    class type network-qos class-default
      mtu 9216
  policy-map type network-qos default-nq-policy
    class type network-qos class-default
      mtu 1500
switch(config)#

This example shows how to display all active policy maps in the system:

switch(config)# show policy-map system


  Type network-qos policy-maps
  ===============================

  policy-map type network-qos pnqos
    class type network-qos cnq1      match qos-group 1

      mtu 1500
      set cos 4
    class type network-qos cnq2      match qos-group 2

      mtu 1500
      set cos 5
      congestion-control random-detect ecn
    class type network-qos class-default      match qos-group 0

      mtu 9216

  Service-policy (qos) input:   pqos
    policy statistics status:   disabled

    Class-map (qos):   cqos1 (match-all)
      Match: cos 1
      set qos-group 1

    Class-map (qos):   cqos2 (match-all)
      Match: cos 2
      set qos-group 2

    Class-map (qos):   class-default (match-any)
      Match: any
      set qos-group 0

  Service-policy (queuing) output:   pqu
    policy statistics status:   disabled

    Class-map (queuing):   cqu1 (match-any)
      Match: qos-group 1
      bandwidth percent 10

    Class-map (queuing):   cqu6 (match-any)
      Match: qos-group 2
      bandwidth percent 20

    Class-map (queuing):   class-default (match-any)
      Match: qos-group 0
      bandwidth percent 70

switch(config)#

This example shows how to display the service policy maps configured on the interfaces:

switch(config)# show policy-map interface ethernet 1/1


Global statistics status :   disabled

Ethernet1/1

  Service-policy (qos) input:   pqos
    policy statistics status:   disabled

    Class-map (qos):   cqos1 (match-all)
      Match: cos 1
      set qos-group 1

    Class-map (qos):   cqos2 (match-all)
      Match: cos 2
      set qos-group 2

    Class-map (qos):   class-default (match-any)
      Match: any
      set qos-group 0

  Service-policy (queuing) output:   pqu
    policy statistics status:   disabled

    Class-map (queuing):   cqu1 (match-any)
      Match: qos-group 1
      bandwidth percent 10

    Class-map (queuing):   cqu2 (match-any)
      Match: qos-group 2
      bandwidth percent 20

    Class-map (queuing):   class-default (match-any)
      Match: qos-group 0
      bandwidth percent 70

switch(config)#

This example shows how to display the queuing information for a specific interface:


switch# sh queuing interface ethernet 1/1

slot  1
=======


HW MTU of Ethernet1/1 : 1500 bytes

Egress Queuing for Ethernet1/1 [System]
------------------------------------------------------------------------------
QoS-Group# Bandwidth% PrioLevel                Shape                   QLimit
                                   Min          Max        Units   
------------------------------------------------------------------------------
      4            20         -           -            -     -      4969339(S)
      3            30         -           -            -     -      4969339(S)
      2            20         -           -            -     -      4969339(S)
      1            10         -           -            -     -      4969339(S)
      0            20         -           -            -     -      4969339(S)

Mcast pkts dropped      : 0

+-------------------------------------------------------------------+
|                              QOS GROUP 0                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 1                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 2                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 3                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 4                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 5                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 6                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+
|                              QOS GROUP 7                          |
+-------------------------------------------------------------------+
|                |  Unicast       | OOBFC Unicast  |  Multicast     |
+-------------------------------------------------------------------+
|   Dropped Pkts |               0|               0|               0|
+-------------------------------------------------------------------+


Ingress Queuing for Ethernet1/1
------------------------------------------------------------------
QoS-Group#                 Pause                        QLimit
           Buff Size       Pause Th      Resume Th      
------------------------------------------------------------------
      7              -            -            -            0(S)
      6              -            -            -            0(S)
      5              -            -            -            0(S)
      4              -            -            -            0(S)
      3              -            -            -            0(S)
      2              -            -            -            0(S)
      1              -            -            -            0(S)
      0              -            -            -            0(S)

PFC Statistics
----------------------------------------------------------------------------
TxPPP:                    0, RxPPP:                    0
----------------------------------------------------------------------------
 COS QOS Group   TxCount         RxCount
   0         -         0               0
   1         -         0               0
   2         2         0               0
   3         3         0               0
   4         -         0               0
   5         -         0               0
   6         -         0               0
   7         -         0               0
----------------------------------------------------------------------------
switch#

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

Network QoS Policy Type

Queuing Policy Type

QoS Policy Type

MTU

Trust Boundaries

Ingress Classification Policies

Egress Queuing Policies

QoS for Traffic Directed to the CPU

QoS Configuration Guidelines and Limitations

Configuring Class Maps

SUMMARY STEPS

DETAILED STEPS

Configuring ACL Classification

SUMMARY STEPS

DETAILED STEPS

Example

Configuring CoS Classification

SUMMARY STEPS

DETAILED STEPS

Example

Configuring DSCP Classification

SUMMARY STEPS

DETAILED STEPS

Example

Configuring IP RTP Classification

SUMMARY STEPS

DETAILED STEPS

Example

Configuring RDMA over Converged Ethernet (RoCE) Classification

SUMMARY STEPS

DETAILED STEPS

Configuring Precedence Classification

SUMMARY STEPS

DETAILED STEPS

Example

Creating Policy Maps

Before you begin

SUMMARY STEPS

DETAILED STEPS

Configuring Type QoS Policies

SUMMARY STEPS

DETAILED STEPS

Example

Configuring Type Network QoS Policies

SUMMARY STEPS

DETAILED STEPS

Example

Configuring Type Queuing Policies

SUMMARY STEPS

DETAILED STEPS

Example

Information About Marking

Configuring DSCP Marking

SUMMARY STEPS

DETAILED STEPS

Example

Configuring IP Precedence Marking

SUMMARY STEPS

DETAILED STEPS

Example

Attaching the System Service Policy

SUMMARY STEPS

DETAILED STEPS

Restoring the Default System Service Policies

SUMMARY STEPS

DETAILED STEPS

Enabling the Jumbo MTU

Verifying the Jumbo MTU

Configuring Untagged CoS

SUMMARY STEPS