topic Re: MTU issue on SLX border Leaf in ExtremeSwitching (EXOS/Switch Engine)

MTU issue on SLX border Leaf

Neeraj_Singh — Wed, 05 Mar 2025 08:28:40 GMT

Hello team,

I have configured MTU 1522 on port-channel 1 , eth 0/25:1, eth 0/27:1 is the part of the Port-channel. Now we are getting below error as severity warning:

2025/02/25-11:45:36, [HSL-1039], 381812,, WARNING, ABC-0001, L2MTU: 1522 value will be ignored for the Egress Validation, instead Default MTU value: 9216 will be used for interface 0/25:1.
2025/02/25-11:45:36, [HSL-1039], 381813,, WARNING, ABC-0001, L2MTU: 1522 value will be ignored for the Egress Validation, instead Default MTU value: 9216 will be used for interface 0/27:1.

So, it seems that the SLX works in a way that the configured MTU on the interface is only applicable to the incoming traffic. For the outgoing traffic? the configured MTU is ignored, and the default value is applied (9216).

Please suggest, how we could force the switch not to exceed 1514 bytes of packet size.

thanks! Neeraj singh

Re: MTU issue on SLX border Leaf

Neeraj_Singh — Wed, 12 Mar 2025 12:02:06 GMT

@OscarK @Michael_Morey can you guys please check and reply. thanks in advance

Re: MTU issue on SLX border Leaf

Michael_Morey — Wed, 12 Mar 2025 13:23:48 GMT

Neeraj,

From what I can see this was in an older release, 20.2.x or 20.3.x. This happens when you have an L2 MTU is changed from the default in the global level. Assuming you have configured a non default global MTU value, you can try removing that and only use interface level. I tried this in 20.7.1 and I am not seeing the same thing, so possibly upgrade to a newer release as well if you are running older code.

Thanks,