Excessive undersized/giant packets

[keshavboodhun]

Hello,

Actually I have an Aruba controller 7005 and the access points are connected to a Aruba 2530 PoE J9773A.

From Aruba 2530 logs, i can error "Excessive undersized/giant packets" on ports where the access points are connected to.

I another switch 2530 8P PoE, I got the same errors and they use the same controller.

What are those errors ?

The reason why I'm checking these logs is because, users when they browse a local web server, frequently it takes a lot of time to load pages and sometimes handheld devices loses WIFI signals. 

Thanks if someone can help.

[Ivan_B]

Hi @keshavboodhun !

Check this article - https://community.arubanetworks.com/browse/articles/blogviewer?blogkey=21de830d-f853-49fd-8b64-85a8285d7614

[keshavboodhun]

This seems to be something related to MTU. Maybe this seems to be affecting performance. Can this be disabled or modified on Aruba switch ?

[Ivan_B]

If my assumption is correct, your APs use MTU 1500 inside GRE tunnel, so the resulting frames can be bigger than 1500 bytes (GRE header + new IP header add 24 bytes on top of the original frame) and such frames are larger than standard MTU set in the switch which is 1500 bytes. I am not familiar with all the options in Aruba controller, but in general you can resolve such situations in two ways:

1. Adjust MTU size in the controller and force APs to use, for example 1400 bytes MTU. Thus even after all encapsulations their frames won't be larger than 1500 bytes
2. Allow jumbo frames in the switch for the respective VLAN/-s.

First or second solution may be more appropriate depending on your enviornment, requirements etc, but the idea is more or less the same - equalize MTU size on all infrastructure devices.

Aruba 2530 Management and Configuration Guide - https://www.intesiscon.com/ficheros/manuales-tecnicos/206-Switch-hp-aruba-j97773a.pdf , Page 133 (Jumbo Frames)
How to change the MTU of a GRE tunnel - https://community.arubanetworks.com/browse/articles/blogviewer?blogkey=c7c2fc6e-445e-4b4b-a94d-8818f0e2ae31

[keshavboodhun]

I tried adding jumbo command on the specified vlan, and indeed I stopped getting these errors.

But now the issue i'm having, all the access points lost connection frquently to the controller for 2-5mins and then it's restored back. 

The weird thing I noticed is that, when it's up again and shows as green, the uptime shows 3 weeks ago. It should have been minutes or secs ago.

Thanks if you have any idea.

[Ivan_B]

Unfortunately it's not the right place to find assistance for Aruba 7xxx controllers. These were Aruba "native" products (before acquisition by HPE) and are very different from ProCurve or Comware product lines.

https://community.arubanetworks.com/community-home?CommunityKey=867d34a4-1e6a-4b9a-9349-df7b4c84b3cb seems to be a better place to find assistance on the disconnection cause. First, you need to understand what is the reason for disconnections. Since APs are commanded by the controller, its logs should reveal the reason.

[keshavboodhun]

Ok thanks Ivan. Really apreciate your help on that.