Unable to set MTU on interface on Nexus 7K

[BrunoDe]

Hi guys, come across an annoying issue in my organisation and I can't find anything solid online regarding this. As per the title, I have a Nexus 7K and I'm trying to set the MTU size for a specific interface but get the following error:

MTU on L2 interfaces can only be set to default or system-jumboMTU

I can see with a sh run int x there are other interfaces on my 7K that have a specific MTU set, so why am I unable to do it on another? I don't want to configure the default or system-jumboMTU because it's going to mess with my other interfaces that I have on the 7K, and in addition to that I shouldn't have to as I can see it is able to be applied on others.

Appreciate any help

[Orlando Barboza · Accepted solution]

Hi BrunoDe,

Looks like this error has to do with the system MTU value. Something that you have to take into account is that for L2 interfaces the only value you can provide is the value of the " global system jumboMTU", this value by default is 9216 as you can see below:

7k(config)# sh run all | i i jumbo system jumbomtu 9216

If I try to put a value different than this it will display an error:

7k(config)# int po 1

7k(config-if)# mtu 9000 ERROR: port-channel1: MTU on L2 interfaces can only be set to default or system-jumboMTU

If I change that value I can put a different MTU:

7k(config)# system jumbomtu 9000

7k(config)# int po 40

7k(config-if)# mtu 9000

The L2-interface takes either the default (or) the configured system jumbomtu value. If you try to cofigure any other value, you will get that error.

HTH,

- Orlando -

[BrunoDe]

Hi Orlando, thank you for replying. I was getting confused as I saw other interfaces having an MTU set so was wondering why it wouldn't set it on another, but then I realized the MTU set on those interfaces was actually the same as the jumbomtu so that clears that up.

Thank you again