Nexus 9000 Jumbo

[j.a.m.e.s]

Could anyone shed some light on how jumbo frames should be activated on the N9K in NX-OS 7.x please?

There appears to be two ways of doing it:

1. Interface Level
! Layer 2 or Layer 3:
interface Ethx/x
mtu 9216
exit

2. Network QoS Policy
policy-map type network-qos PM-MY-NETQOS
class type network-qos class-default
mtu 9216
exit
exit

system qos
service-policy type network-qos PM-MY-NETQOS
exit

Do I need to apply both, or does say interface-level override the network-qos policy?

Thank you in advance for any assistance.

Regards

James.

[Vinit Jain]

You can apply just the first method but applying both methods is recommended.

[j.a.m.e.s]

Thank you Vinit, but why is applying both methods recommended (operationally, it's quite difficult to get people to remember the "mtu XXXX" command)? If we only apply at the policy level, will it work?

[Reza Sharifi · Accepted solution]

The second method is a global policy and will change the MTU for all interfaces but the layer-3 SVIs and the first method will enable it for layer-3 SVIs.  So, if you need it for layer-2, layer-3, than you need to apply both methods.

HTH 

[Darian O'Dirling - TCE]

Hi Terry,

There is a couple different senarios that allow for Jumbo frames. This process is done with adjusting MTU size. The following commands are for configuring MRU on a Layer 3 port

Nexus(config)#interface ethernet 1/1
Nexus(config-if)#no switchport
Nexus(config-if)#mtu 9216

This document contains all of the other senarios : https://www.cisco.com/c/en/us/support/docs/switches/nexus-9000-series-switches/118994-config-nexus-00.html

And this video provides steps for configuring MTU on a Nexus 9000 switch. The video outlines the need for proper MTU in the network and explains how to remedy MTU related interface errors, via interface MTU configuration.

https://www.youtube.com/watch?v=GbBeB6h9MKk