Cisco – Jumbo frame on Nexus 5k

ciscocisco-nexus-5kmtuqos

I would like to enable the jumbo frame support on my N5k for specific SCSI trafic.

I've read we can't do it per interface but only on the system itself :

policy-map type network-qos JUMBO_MTU
  class type network-qos class-default
    mtu 9216

!

system qos
  service-policy type network-qos JUMBO_MTU

But this enables jumbo frame on the whole switch. Can I identify the SCSI traffic on the policy-map so that it's applied just for the traffic I want?

And so the jumbo from other type of traffic would be processed normally ?

Thanks,

Best Answer

Yes you can, you just have to classify the traffic. Here is an example where we classify iSCSI into its own class. The class-default class will match any other traffic.

class-map type qos match-all iSCSI
  match protocol iscsi
  match cos 4

policy-map type qos POLICY-QOS
  class iSCSI
    set qos-group 3
  class class-fcoe
    set qos-group 1

class-map type network-qos iSCSI
  match qos-group 3

policy-map type network-qos JUMBO
  class type network-qos iSCSI
    mtu 9216
    pause no-drop
  class type network-qos class-fcoe
    pause no-drop
    mtu 2158
  class type network-qos class-default
    multicast-optimize


system qos
  service-policy type network-qos JUMBO
  service-policy type qos input POLICY-QOS

Just an additional note, you should modify the classification to match your environment and requirements. You can classify based on other criteria as well such as IP address. 

class-map type qos match-all iSCSI
  match access-group name PERMIT-ANY

Edit:

N5K Configuration Guide

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