FEX Queuing

FEX Queuing provides a mechanism to support queuing on host interfaces (HIF) of a FEX device. Queuing of data traffic is based on the COS or DSCP values of an Ethernet packet. Traffic that is not marked with these values are dropped to a default queue.

Finding Feature Information

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Information About FEX Queuing

Queuing Ethernet Frames Using COS

With this feature, data and control Ethernet frames can be prioritized based on the COS value of an Ethernet header and sent to separate queues of a FEX host interface.  This ensures that control frames are not dropped during a traffic burst.

Every FEX interface has a COS2Q map associated with it. And depending on the COS2Q map, the ethernet frame is enqueued.

Queuing Ethernet Frames Using DSCP

With this feature, data and control Ethernet frames can be prioritized based on the DSCP value of an IP header and sent to separate queues of a FEX host interface.  This ensures that control frames are not dropped during a traffic burst.

Queuing is based on the DSCP to Queue mapping configuration on the network-qos template

Queueing FCoE Frames Using COS 3

With this feature, FCoE and Ethernet frames can be prioritized based on the COS 3 of FCoE and COS value of Ethernet header and sent to separate queues of a FEX host interface.  This ensures that control frames are not dropped during a traffic burst.

This is driven by the COS2Q mapping and the network-qos template on the Nexus 7000.

How to Configure FEX Queuing

Changing COS2Q mapping

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. class-map type queuing match-any queue
  4. match cos 4-7
  5. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:

Device> enable
Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal
Enters global configuration mode.

Step 3

class-map type queuing match-any queue

Example:

Device(config)# class-map type queuing match-any 2q4t-8e-in-q1
Configures the global queuing class map.

Step 4

match cos 4-7

Example:

Device(config-cmap-que)# match cos 4-7
Configures COS2Q value

Step 5

end

Example:

Device(config-cmap-que)# end
Exits to previliged EXEC mode.

Changing DSCP2Q Mapping

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. class-map type queuing match-any 2q4t-8e-in-q-default
  4. match dscp value-range
  5. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:

Device> enable
Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal
Enters global configuration mode.

Step 3

class-map type queuing match-any 2q4t-8e-in-q-default

Example:

Device(config)# class-map type queuing match-any 2q4t-8e-in-q-default
Configures the global queuing class map.

Step 4

match dscp value-range

Example:

Device(config-cmap-que)# match dscp 1-10
Configures DSCP2Q value

Step 5

end

Example:

Device(config-cmap-que)# end
Exits to previliged EXEC mode.

Changing network-qos Template

The cos2q map, bandwidth, mtu and priority for the queues are defined for each network-qos templates. The FEX is configured based on the default values for a given network-qos template. To change these default values, you should clone a template and change the values. The policy can then be applied to the system qos.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. system qos
  4. service-policy type network-qos policy
  5. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:

Device> enable
Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal
Enters global configuration mode.

Step 3

system qos

Example:

Device(config)# system qos
Enters system class configuration mode.

Step 4

service-policy type network-qos policy

Example:

Device(config-sys-qos)# service-policy type network-qos default-nq-7e-4q8q-policy
Configures the policy map that is to be used as the network-wide service policy, and enters Network-wide (system qos) mode.

Step 5

end

Example:

Device(config-sys-qos)# end
Exits to previliged EXEC mode.

Configuring FEX Queue Parameters

SUMMARY STEPS

  1. hardware fex-card-type shared-buffer-size size
  2. hardware fex-card-type queue-limit queue-limit

DETAILED STEPS

  Command or Action Purpose

Step 1

hardware fex-card-type shared-buffer-size size

Example:

Device# hardware N2248PQ shared-buffer-size 3072
This command is applicable for N2248PQ only. The range is from 3072 to 10240. The command is hosted on default-vdc and admin-vdc.

Step 2

hardware fex-card-type queue-limit queue-limit

Example:

Device# hardware N2248T queue-limit 327680
The range is from 81920 to 652800 for a Cisco Nexus 2148T Fabric Extender and from 2560 to 652800 for all other supported Fabric Extenders. The command is hosted on default-vdc and admin-vdc.

Verifying FEX Queuing

SUMMARY STEPS

  1. show queuing interface fex-interface value/slot

DETAILED STEPS

show queuing interface fex-interface value/slot

Example:

Device# show queuing interface ethernet 101/1/1
  
    invalid interface
     
    slot  4
    =======
     
    Interface is not in this module.
     
    slot  9
    =======
     
    Ethernet101/1/1 queuing information:
      Input buffer allocation:
      Qos-group: ctrl
      frh: 0
      drop-type: drop
      cos: 7
      xon       xoff     
      buffer-size
     
      ---------+---------+-----------
      2560      7680      10240    
     
      Qos-group: 0  2 
      (shared)
      frh: 8
      drop-type: drop
      cos: 0 1 2 3 4 5 6
      xon       xoff     
      buffer-size
     
      ---------+---------+-----------
      0         142080    151040   
     
      Queueing:
      queue    qos-group    cos            priority  bandwidth mtu 
     
      --------+------------+--------------+---------+---------+----
      ctrl-hi  n/a          7               PRI         0     
      2400
      ctrl-lo  n/a          7               PRI         0     
      2400
      2        0            0 1 2
        3         WRR        80     
      1600
      4        2            4 5
        6           WRR        20     
      1600
     
      Queue limit: 66560 bytes
     
      Queue Statistics:
      queue 
        rx              tx              flags
     
      ------+---------------+---------------+-----
      0      0              
        0               
      ctrl
      1      0              
        0               
      ctrl
      2      0              
        0               
      data
      4      6               0                data
     
      Priority-flow-control enabled:
      no
      Flow-control status: rx 0x0, tx 0x0,
      rx_mask 0x0
      cos     qos-group   rx pause  tx pause  masked
      rx pause
     
      -------+-----------+---------+---------+---------------
      0  
                   0    xon      
        xon       xon 
      1              0    xon       xon      
      xon 
      2              0    xon       xon      
      xon 
      3              0    xon       xon      
      xon 
      4              2    xon       xon      
      xon 
      5              2    xon       xon       xon 
      6              2    xon       xon      
      xon 
      7            n/a    xon       xon      
      xon 
     
      DSCP to Queue mapping on
      FEX
     ----+--+-----+-------+--+---
     
     queue          DSCPs
     -----          -----
     02             0-9,14-25,27-38,40-51,53-63,
     04             10-13,26,39,52,
     03             **EMPTY**
     05             **EMPTY**
     
     
    slot 10
    =======

Feature Information for FEX Queuing

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to https://cfnng.cisco.com/. An account on Cisco.com is not required.
Table 1. Feature Information for FEX Queuing

Feature Name

Releases

Feature Information

FEX Queuing

7.2(0)D1(1)

The FEX Queuing

The following commands were introduced by this feature: hardware shared-buffer-size, hardware queue-limit .