Cisco Nexus 5000 Series NX-OS Quality of Service Configuration Guide
Configuring QoS
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Configuring QoS

Contents

Configuring QoS

This chapter describes how to configure quality of service (QoS) on Cisco Nexus 5000 Series switches. It contains the following sections:

Information About QoS

The configurable Cisco NX-OS QoS features on the Cisco Nexus 5000 Series switch allow you to classify the network traffic, police and prioritize the traffic flow, and provide congestion avoidance.

The default QoS configuration on the switch 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 Nexus 5000 Series QoS features are configured using Cisco Modular QoS CLI (MQC).


Note


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.


MQC

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:


  1. Define traffic classes.
  2. Associate policies and actions with each traffic class.
  3. 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 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 switch 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 5000 Series switch, 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 switch. Up to four additional system classes can be created by the administrator.

Default System Classes

The Cisco Nexus 5000 Series switch provides the following default 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.

  • FCoE system class

    All Fibre Channel and FCoE control and data traffic is automatically classified into the FCoE system class, which provides no-drop service.

    This class is created automatically when the system starts up (the class is named class-fcoe in the CLI). You cannot delete this class, and you can only modify the IEEE 802.1p CoS value to associate with this class. This class is identified by qos-group 1.

    The switch classifies packets into the FCoE system class as follows:


    • FCoE traffic is classified based on EtherType.

    • Native Fibre Channel traffic is classified based on the physical interface type.


      Note


      The optional N5K-M1404 or N5K-M1008 expansion modules provide native 1/2/4-Gigabit Fibre Channel ports.


Policy Types

The Cisco Nexus 5000 Series switch supports a number of policy types. You create class maps in the policy types.

There are three policy types. 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.

      • 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.

      • Set CoS value—This configuration is used to mark 802.1p values for all traffic mapped to this system class. The marking value for a system class needs to be unique and cannot be used as a marking value for any other system class.

  • 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 queueing policy is used to configure output queues on the switch associated with system classes. The input queuing policy is used to configure scheduling for queues in the CNA. The input queuing policy parameters are signalled 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 protocol 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 corresponding 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 5000 Series switch, 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. By default, link-level pause is disabled.

MTU

The Cisco Nexus 5000 Series switch 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 2112 bytes across the switch. As a result, the rxbufsize for Fibre Channel interfaces is fixed at 2112 bytes. If the Cisco Nexus 5000 Series switch receives an rxbufsize from a peer that is different than 2112 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 2240 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 2240 bytes. This value cannot be modified.

  • The default drop system class has a default MTU of 1538 bytes. You can configure this value.

  • 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. A packet tagged with an 802.1p CoS value is classified into a system class using the value in the packet.

  • 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 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 port characteristics (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. When you define a traffic class, you can specify multiple match criteria, you can choose to not match on a particular criterion, or you can determine traffic class by matching any or all 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 six queues, one for each system class. The queues have the following default configuration:


  • In addition to the six 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 50 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 a 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 Multicast Traffic

The system provides six multicast queues per interface and allocates one queue for each system class. 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 six queues to service the multicast traffic (all six queues are given equal priority).

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

Optimized multicasting achieves better throughput and improves performance for multicast frames.

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 switch 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 BPDU frames, is given higher priority to ensure delivery.

QoS Configuration Guidelines and Limitations

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.

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


  • 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.


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 System Classes

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.

SUMMARY STEPS

1.    switch# configure terminal

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

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


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configure terminal
 

Enters configuration mode.

 
Step 2 switch(config)# class-map [type {network-qos | qos | queuing}] class-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)# no class-map [type {network-qos | queuing | 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.

 

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 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.

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 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 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). The standard DSCP values are listed in the following table:

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

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.    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 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 . The standard DSCP values are shown in the preceding table.

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

Removes the match from the traffic class.

 

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 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 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.

 

This 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 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 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

1.    switch# configure terminal

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

Configures the traffic class by matching packets based on precedence-values . Values are shown in the preceding table.

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

Removes the match from the traffic class.

 

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 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 protocol field in the IP header. The following table shows the protocol arguments:

Table 3 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
 

Configuring 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 switch 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

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 switch 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 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 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)# multicast-optimize

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

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

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

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

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

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

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

Resets the MTU value in this class.

 
Step 6 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.

 
Step 7 switch(config-pmap-c-nq)# no multicast-optimize
 
(Optional)

Disables multicast optimization.

 
Step 8 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 9 switch(config-pmap-c-nq)# no pause no-drop
 
(Optional)

Removes the no-drop option from this class.

 
Step 10 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.

 
Step 11 switch(config-pmap-c-nq)# no queue-limit number-bytes bytes
 
(Optional)

Disables the queue limit specification in this class.

 
Step 12 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 13 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)# pause no-drop pfc-cos 1-3,5
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)# bandwidth percent percentage

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

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

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


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configure terminal
 

Enters 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)# 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 5 switch(config-pmap-c-que)# no bandwidth percent percentage
 
(Optional)

Removes the bandwidth specification from this class.

 
Step 6 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 7 switch(config-pmap-c-que)# no priority
 
(Optional)

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

 

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)# bandwidth 20
 

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 input traffic only.

SUMMARY STEPS

1.    switch# configure terminal

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

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

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

5.    (Optional) switch(config-pmap-c-qos)# no set qos-group qos-group-value


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configure terminal
 

Enters 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 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 range of qos-group-value is from 2 to 5. There is no default value.

Note   

The Cisco Nexus 5000 Series switch can only support a maximum of five qos-groups within this range.

 
Step 5 switch(config-pmap-c-qos)# no set qos-group qos-group-value
 
(Optional)

Removes the qos-group values from this class.

 

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
 

Attaching the System Service Policy

You can use the service-policy command to associate 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


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configure terminal
 

Enters 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.

 

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 cos 4
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, you must reapply the default policies to restore the system.

SUMMARY STEPS

1.    switch# configure terminal

2.    switch(config)# system qos

3.    switch(config-sys-qos)# service-policy type qos input default-in-policy

4.    switch(config-sys-qos)# service-policy type network-qos default-nq-policy

5.    switch(config-sys-qos)# service-policy type queuing output default-out-policy

6.    switch(config-sys-qos)# service-policy type queuing input default-in-policy


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configure terminal
 

Enters configuration mode.

 
Step 2 switch(config)# system qos
 

Enters system class configuration mode.

 
Step 3 switch(config-sys-qos)# service-policy type qos input default-in-policy
 

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)# service-policy type network-qos default-nq-policy
 

Resets the network-wide policy map.

 
Step 5 switch(config-sys-qos)# service-policy type queuing output default-out-policy
 

Resets the output queuing mode policy map.

 
Step 6 switch(config-sys-qos)# service-policy type queuing input default-in-policy
 

Resets the input queuing mode policy map.

 

This example shows how to reset the system qos configuration:

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

The default service policies are shown in this example:

switch# show policy-map
 
 
   Type qos policy-maps
   ====================
 
   policy-map type qos default-in-policy
     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 default-in-policy
     class type queuing class-fcoe
       bandwidth percent 50
     class type queuing class-default
       bandwidth percent 50
   policy-map type queuing default-out-policy
     class type queuing class-fcoe
       bandwidth percent 50
     class type queuing class-default
       bandwidth percent 50
 
 
   Type network-qos policy-maps
   ===============================
 
   policy-map type network-qos default-nq-policy
     class type network-qos class-fcoe
       pause no-drop
       mtu 2240
     class type network-qos class-default
       mtu 1538
 

Enabling the Jumbo MTU

You can enable the jumbo 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).

This example shows how to configure the default Ethernet system class to support the jumbo MTU:

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
switch(config-pmap-c-nq)# exit
switch(config-pmap-nq)# exit
switch(config)# system qos
switch(config-sys-qos)# service-policy type network-qos jumbo
 

Note


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


Verifying the Jumbo MTU

To verify that the jumbo MTU is enabled, enter the show interface ethernet slot/port command for an Ethernet interface that carries traffic with jumbo MTU.

This example shows how to display summary jumbo MTU information for Ethernet 1/2 (the relevant part of the output is shown in bold font):

switch# show interface ethernet 1/2
Ethernet1/2 is up
...
    Rx
    1547805598 Input Packets 1547805596 Unicast Packets 0 Multicast Packets
    0 Broadcast Packets 1301767362 Jumbo Packets 33690 Storm Suppression Packets
    7181776513802 Bytes
    Tx
    1186564478 Output Packets 7060 Multicast Packets
    0 Broadcast Packets 997813205 Jumbo Packets
    4813632103603 Bytes
...
 

This example shows how to display detailed jumbo MTU information for Ethernet 1/2 (the relevant part of the output is shown in bold font):

switch# show interface ethernet 1/2 counters detailed
Rx Packets: 1547805598
Rx Unicast Packets: 1547805596
Rx Jumbo Packets: 1301767362
Rx Bytes: 7181776513802
Rx Storm Suppression: 33690
Rx Packets from 0 to 64 bytes: 169219
Rx Packets from 65 to 127 bytes: 10657133
Rx Packets from 128 to 255 bytes: 21644488
Rx Packets from 256 to 511 bytes: 43290596
Rx Packets from 512 to 1023 bytes: 86583071
Rx Packets from 1024 to 1518 bytes: 83693729
Rx Trunk Packets: 1547805596
Tx Packets: 1186564481
Tx Unicast Packets: 1005445334
Tx Multicast Packets: 7063
Tx Jumbo Packets: 997813205
Tx Bytes: 4813632103819
Tx Packets from 0 to 64 bytes: 137912
Tx Packets from 65 to 127 bytes: 8288443
Tx Packets from 128 to 255 bytes: 16596457
Tx Packets from 256 to 511 bytes: 33177999
Tx Packets from 512 to 1023 bytes: 66363944
Tx Packets from 1024 to 1518 bytes: 64186521
Tx Trunk Packets: 1005451729
 

Configuring QoS on Interfaces

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.


Note


Untagged CoS and type qos input policies are mutually exclusive on an Ethernet or EtherChannel interface. If a type qos policy is configured at the interface, untagged frames received over that interface will not match any match cos 0 commands in the policy.


SUMMARY STEPS

1.    switch# configure terminal

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

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


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configure terminal
 

Enters configuration mode.

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

Enters configuration mode for the specified interface or port channel.

 
Step 3 switch(config-if)# untagged cos cos-value
 

Configures the untagged CoS value.

 

Configuring 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 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.


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 configuration mode.

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

Enters 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 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 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

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.

SUMMARY STEPS

1.    switch# configure terminal

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

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

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


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configure terminal
 

Enters configuration mode.

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

Specifies the interface to be changed.

 
Step 3 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 4 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
 

Configuring Link-Level Flow Control

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

SUMMARY STEPS

1.    switch# configure terminal

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

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

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


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configure terminal
 

Enters configuration mode.

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

Specifies the interface to be changed.

 
Step 3 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 4 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
 

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 number]

Displays the queue configuration and statistics.

You can clear the QoS policy statistics.

Command

Purpose

switch# clear qos statistics

Clears the policy statistics.

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 statistics:

switch# show queuing interface ethernet 1/1
 
Interface Ethernet1/1 TX Queuing
qos-group  sched-type  oper-bandwidth
    0       WRR              5
    1       WRR             10
    2       priority         5
    3       WRR             20
    4       WRR             20
    5       WRR             40
 
Interface Ethernet1/1 RX Queuing
qos-group  0:
    q-size: 21120, MTU: 1538
    drop-type: drop, xon: 0, xoff: 132
    Statistics:
        Pkts received over the port             : 1265258330
        Ucast pkts sent to the cross-bar        : 0
        Mcast pkts sent to the cross-bar        : 2883444539
        Ucast pkts received from the cross-bar  : 0
        Pkts sent to the port                   : 367529517
        Pkts discarded on ingress               : 781087 (36419)
        Per-priority-pause status               : Rx (Inactive), Tx (Inactive)
 
qos-group  1:
    q-size: 76800, MTU: 2240
    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 (0)
        Per-priority-pause status               : Rx (Inactive), Tx (Inactive)
 
qos-group  2:
    q-size: 20480, MTU: 5000
    drop-type: drop, xon: 0, xoff: 128
    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 (0)
        Per-priority-pause status               : Rx (Inactive), Tx (Inactive)
 
qos-group  3:
    q-size: 30080, MTU: 9216
    drop-type: drop, xon: 0, xoff: 188
    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 (0)
        Per-priority-pause status               : Rx (Inactive), Tx (Inactive)
 
qos-group  4:
    q-size: 20480, MTU: 8000
    drop-type: drop, xon: 0, xoff: 128
    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(0)
        Per-priority-pause status               : Rx (Inactive), Tx (Inactive)
 
qos-group  5:
    q-size: 76800, MTU: 1538
    drop-type: no-drop, xon: 128, xoff: 242
    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(0)
        Per-priority-pause status               : Rx (Inactive), Tx (Inactive)
 
Total Multicast crossbar statistics:
    Mcast pkts received from the cross-bar      : 557155515
 

Example QoS Configurations

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