Configuring Classification

About Classification

Classification is the separation of packets into traffic classes. You configure the device to take a specific action on the specified classified traffic, such as policing or marking down, or other actions.

You can create class maps to represent each traffic class by matching packet characteristics with the classification criteria in the following table:

Table 1 Classification Criteria

Classification Criteria

Description

CoS

Class of service (CoS) field in the IEEE 802.1Q header.

IP precedence

Precedence value within the type of service (ToS) byte of the IP header.

Differentiated Services Code Point (DSCP)

DSCP value within the DiffServ field of the IP header.

ACL

IP, IPv6, or MAC ACL name.

Packet length

Size range of Layer 3 packet lengths.

IP RTP

Identify applications using Real-time Transport Protocol (RTP) by UDP port number range.

You can specify multiple match criteria, you can choose to not match on a particular criterion, or you can determine the traffic class by matching any or all criteria.


Note

However, if you match on an ACL, no other match criteria, except the packet length, can be specified in a match-all class. In a match-any class, you can match on ACLs and any other match criteria.

Traffic that fails to match any class in a QoS policy map is assigned to a default class of traffic called class-default. The class-default can be referenced in a QoS policy map to select this unmatched traffic.

You can reuse class maps when defining the QoS policies for different interfaces that process the same types of traffic.

Licensing Requirements for Classification

The following table shows the licensing requirements for this feature:

Product

License Requirement

Cisco NX-OS

The QoS feature does not a require license. Any feature not included in a license package is bundled with the NX-OS image and is provided at no extra charge to you. For a complete explanation of the Cisco NX-OS licensing scheme, see the Cisco NX-OS Licensing Guide.

Prerequisites for Classification

Classification has the following prerequisites:

  • You must be familiar with using modular QoS CLI.

  • You are logged on to the device.

Guidelines and Limitations

Classification has the following configuration guidelines and limitations:

  • You can specify a maximum of 1024 match criteria in a class map.

  • You can configure a maximum of 128 classes for use in a single policy map.

  • When you match on an ACL, the only other match you can specify is the Layer 3 packet length in a match-all class.

  • The match-all option in the class-map type qos match-all command is not supported. The match criteria of this command becomes the same as in the class-map type qos match-any command. The class-map type qos match-all command yields the same results as the class-map type qos match-any command.

  • You can classify traffic on Layer 2 ports based on either the port policy or VLAN policy of the incoming packet but not both. If both are present, the device acts on the port policy and ignores the VLAN policy.

  • When a Cisco Nexus Fabric Extender (FEX) is connected and in use, data traffic should not be marked with a CoS value of 7. CoS 7 is reserved for control traffic transiting the Fabric Extender.

  • FEX host interfaces (HIF) are supported by the FEX QoS policy.

    • QoS TCAM carving is supported on ALE (Application Leaf Engine) enabled switches.

    • Only system level policies are supported.

    • Match on CoS is supported.

    • Match on QoS-group is supported.

Configuring Traffic Classes

Configuring ACL Classification

You can classify traffic by matching packets based on existing ACLs. The permit and deny ACL keywords are ignored in the matching. QoS does not use the permit-deny functions of ACLs. You can classify by either IPv4, IPv6, or MAC address.

SUMMARY STEPS

    1.    configure terminal

    2.    class-map [type qos] [match-any | match-all] class-name

    3.    match access-group name acl-name


DETAILED STEPS
     Command or ActionPurpose
    Step 1configure terminal


    Example: 
    switch# configure terminal
switch(config)#
     

    Enters global configuration mode.

     
    Step 2class-map [type qos] [match-any | match-all] class-name


    Example: 
    switch(config)# class-map class_acl
     

    Creates or accesses the class map named class-name and enters class-map mode. The class map name can contain alphabetic, hyphen, or underscore characters, and can be up to 40 characters. (match-any is the default when no option is selected and multiple match statements are entered.)

     
    Step 3match access-group name acl-name


    Example: 
    switch(config-cmap-qos)# match
access-group name my_acl
     

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

     

    This example shows how to display the ACL class-map configuration: 

    switch# show class-map class_acl

    Configuring DSCP Classification

    You can classify traffic based on the DSCP value in the DiffServ field of the IP header. The standard DSCP values are listed in the following table:

    Table 2 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.    configure terminal

      2.    class-map [type qos] [match-any | match-all] class-name

      3.    match [not] dscp dscp-values

      4.    exit

      5.    copy running-config startup-config


    DETAILED STEPS
       Command or ActionPurpose
      Step 1configure terminal


      Example: 
      switch# configure terminal
switch(config)#
       

      Enters global configuration mode.

       
      Step 2class-map [type qos] [match-any | match-all] class-name


      Example: 
      switch(config)# class-map class_dscp
       

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

       
      Step 3match [not] dscp dscp-values


      Example: 
      switch(config-cmap-qos)# match dscp af21, af32
       

      Configures the traffic class by matching packets based on dscp-values. The standard DSCP values are shown in the following table.

      Use the not keyword to match on values that do not match the specified range.

       

      Step 4exit


      Example: 
      switch(config-cmap-qos)# exit
switch(config)#
       

      Exits global class-map queuing mode and enters global configuration mode.

       
      Step 5copy running-config startup-config


      Example: 
      switch(config)# copy running-config
startup-config
       

      (Optional) Saves the running configuration to the startup configuration.

       

      This example shows how to display the DSCP class-map configuration: 

      switch# show class-map class_dscp

      Configuring IP Precedence Classification

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

      Table 3 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.    configure terminal

        2.    class-map [type qos] [match-any | match-all] class-name

        3.    match [not] precedence precedence-values

        4.    exit

        5.    copy running-config startup-config


      DETAILED STEPS
         Command or ActionPurpose
        Step 1configure terminal


        Example: 
        switch# configure terminal
switch(config)#
         

        Enters global configuration mode.

         
        Step 2class-map [type qos] [match-any | match-all] class-name


        Example: 
        switch(config)# class-map class_ip_precedence
         

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

         
        Step 3 match [not] precedence precedence-values


        Example: 
        switch(config-cmap-qos)# match precedence 1-2, 5-7
         

        Configures the traffic class by matching packets based on precedence-values. Values are shown in the following table. Use the not keyword to match on values that do not match the specified range.

         
        Step 4exit


        Example: 
        switch(config-cmap-qos)# exit
switch(config)#
         

        Exits global class-map queuing mode and enters global configuration mode.

         
        Step 5copy running-config startup-config


        Example: 
        switch(config)# copy running-config
startup-config
         

        (Optional) Saves the running configuration to the startup configuration.

         

        This example shows how to display the IP precedence class-map configuration: 

        switch# show class-map class_ip_precedence

        Configuring Protocol Classification

        For Layer 3 protocol traffic, you can use the ACL classification match.

        Table 4 match Command Protocol Arguments

        Argument

        Description

        arp

        Address Resolution Protocol (ARP)

        bridging

        Bridging

        cdp

        Cisco Discovery Protocol (CDP)

        dhcp

        Dynamic Host Configuration (DHCP)

        isis

        Intermediate system to intermediate system (IS-IS)

        SUMMARY STEPS

          1.    configure terminal

          2.    class-map [type qos] [match-any | match-all] class-name

          3.    match [not] protocol {arp | bridging | cdp | dhcp | isis}

          4.    exit

          5.    copy running-config startup-config


        DETAILED STEPS
           Command or ActionPurpose
          Step 1configure terminal


          Example: 
          switch# configure terminal
switch(config)#
           

          Enters global configuration mode.

           
          Step 2class-map [type qos] [match-any | match-all] class-name


          Example: 
          switch(config)# class-map class_protocol
           

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

           
          Step 3match [not] protocol {arp | bridging | cdp | dhcp | isis}


          Example: 
          switch(config-cmap-qos)# match protocol isis
           

          Configures the traffic class by matching packets based on the specified protocol. Use the not keyword to match on protocols that do not match the protocol specified.

           
          Step 4exit


          Example: 
          switch(config-cmap-qos)# exit
switch(config)#
           

          Exits global class-map queuing mode and enters global configuration mode.

           
          Step 5copy running-config startup-config


          Example: 
          switch(config)# copy running-config
startup-config
           

          (Optional) Saves the running configuration to the startup configuration.

           

          This example shows how to display the protocol class-map configuration: 

          switch# show class-map class_protocol

          Configuring Layer 3 Packet Length Classification

          You can classify Layer 3 traffic based on various packet lengths.


          Note

          This feature is designed for IP packets only.

          SUMMARY STEPS

            1.    configure terminal

            2.    class-map [type qos] [match-any | match-all] class-name

            3.    match [not] packet length packet-length-list

            4.    exit

            5.    copy running-config startup-config


          DETAILED STEPS
             Command or ActionPurpose
            Step 1configure terminal


            Example: 
            switch# configure terminal
switch(config)#
             

            Enters global configuration mode.

             
            Step 2class-map [type qos] [match-any | match-all] class-name


            Example: 
            switch(config)# class-map class_packet_length
             

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

             
            Step 3 match [not] packet length packet-length-list


            Example: 
            switch(config-cmap-qos)# match packet length min 2000
             

            Configures the traffic class by matching packets based on various packet lengths (bytes). Values can range from 1 to 9198. Use the not keyword to match on values that do not match the specified range.

             
            Step 4exit


            Example: 
            switch(config-cmap-qos)# exit
switch(config)#
             

            Exits global class-map queuing mode and enters global configuration mode.

             
            Step 5copy running-config startup-config


            Example: 
            switch(config)# copy running-config
startup-config
             

            (Optional) Saves the running configuration to the startup configuration.

             

            This example shows how to display the packet length class-map configuration: 

            switch# show class-map class_packet_length

            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

              1.    configure terminal

              2.    class-map [type qos] [match-any | match-all] class-name

              3.    match [not] cos cos-list

              4.    exit

              5.    copy running-config startup-config


            DETAILED STEPS
               Command or ActionPurpose
              Step 1configure terminal


              Example: 
              switch# configure terminal
switch(config)#
               

              Enters global configuration mode.

               
              Step 2class-map [type qos] [match-any | match-all] class-name


              Example: 
              switch(config)# class-map class_cos
               

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

               
              Step 3 match [not] cos cos-list


              Example: 
              switch(config-cmap-qos)# match cos 4,5-6
               

              Configures the traffic class by matching packets based on the list of CoS values. Values can range from 0 to 7. Use the not keyword to match on values that do not match the specified range.

              Note   

              When a Cisco Nexus Fabric Extender (FEX) is connected and in use, data traffic should not be marked with a CoS value of 7. CoS 7 is reserved for control traffic transiting the Fabric Extender.

               
              Step 4exit


              Example: 
              switch(config-cmap-qos)# exit
switch(config)#
               

              Exits global class-map queuing mode and enters global configuration mode.

               
              Step 5copy running-config startup-config


              Example: 
              switch(config)# copy running-config
startup-config
               

              (Optional) Saves the running configuration to the startup configuration.

               

              This example shows how to display the CoS class-map configuration: 

              switch# show class-map class_cos

              Configuring CoS Classification for FEX

              You can classify traffic based on the class of service (CoS) for a FEX.

              Before You Begin

              Before configuring the FEX, enable feature-set fex.

              SUMMARY STEPS

                1.    configure terminal

                2.    class-map [type qos] [match-any | match-all] class-name

                3.    match [not] cos cos-list

                4.    exit

                5.    copy running-config startup-config


              DETAILED STEPS
                 Command or ActionPurpose
                Step 1configure terminal


                Example: 
                switch# configure terminal
switch(config)#
                 

                Enters global configuration mode.

                 
                Step 2class-map [type qos] [match-any | match-all] class-name


                Example: 
                switch(config)# class-map class_cos
                 

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

                 
                Step 3 match [not] cos cos-list


                Example: 
                switch(config-cmap-qos)# match cos 4,5-6
                 

                Configures the traffic class by matching packets based on the list of CoS values. Values can range from 0 to 7. Use the not keyword to match on values that do not match the specified range.

                Note   

                When a Cisco Nexus Fabric Extender (FEX) is connected and in use, data traffic should not be marked with a CoS value of 7. CoS 7 is reserved for control traffic transiting the Fabric Extender.

                 
                Step 4exit


                Example: 
                switch(config-cmap-qos)# exit
switch(config)#
                 

                Exits global class-map queuing mode and enters global configuration mode.

                 
                Step 5copy running-config startup-config


                Example: 
                switch(config)# copy running-config
startup-config
                 

                (Optional) Saves the running configuration to the startup configuration.

                 

                This example shows how to configure the CoS class-map configuration: 

                switch# conf t
switch(config)# class-map type qos match-all cos6
switch(config-cmap-qos)# match cos 6
switch(config)# class-map type qos match-all cos1
switch(config-cmap-qos)# match cos 1
switch(config)# class-map type qos match-all cos2
switch(config-cmap-qos)# match cos 2
switch(config)# class-map type qos match-all cos3
switch(config-cmap-qos)# match cos 3
switch(config)# class-map type qos match-all cos0
switch(config-cmap-qos)# match cos 0

                Configuring IP RTP Classification

                The IP Real-time Transport Protocol (RTP) is a transport protocol for real-time applications that transmit 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 uses an even-numbered port and the next higher odd-numbered port is used for RTP Control Protocol (RTCP) communications.

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

                SUMMARY STEPS

                  1.    configure terminal

                  2.    class-map [type qos] [match-any | match-all] class-name

                  3.    match [not] ip rtp udp-port-value

                  4.    exit

                  5.    copy running-config startup-config


                DETAILED STEPS
                   Command or ActionPurpose
                  Step 1configure terminal


                  Example: 
                  switch# configure terminal
switch(config)#
                   

                  Enters global configuration mode.

                   
                  Step 2class-map [type qos] [match-any | match-all] class-name


                  Example: 
                  switch(config)# class-map class_rtp
                   

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

                   
                  Step 3 match [not] ip rtp udp-port-value


                  Example: 
                  switch(config-cmap-qos)# match ip rtp 2000-2100, 4000-4100
                   

                  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. Use the not keyword to match on values that do not match the specified range.

                   
                  Step 4exit


                  Example: 
                  switch(config-cmap-qos)# exit
switch(config)#
                   

                  Exits global class-map queuing mode and enters global configuration mode.

                   
                  Step 5copy running-config startup-config


                  Example: 
                  switch(config)# copy running-config
startup-config
                   

                  (Optional) Saves the running configuration to the startup configuration.

                   

                  This example shows how to display the RTP class-map configuration: 

                  switch# show class-map class_rtp

                  Verifying the Classification Configuration

                  Use the show class-map command to verify the class-map configuration. This command displays all class maps.

                  Configuration Examples for Classification

                  The following example shows how to configure classification for two classes of traffic: 

                  class-map class_dscp
match dscp af21, af32
exit
class-map class_cos
match cos 4, 5-6
exit