avaya 4524GT - oversizePkts

[lemah]

Hi,

We have 2 datacenters. In each datacenter a stack of 2 Avaya 4524GT switches.

Between the 2 datacenters, a trunk with 2 connections is configured (a trunk - lacp on each stack).

This is the config of the stack:
! *** LACP ***
!
interface fastEthernet ALL
lacp key port 1/23,2/23 10
lacp mode port 1/23,2/23 active
lacp aggregation port 1/23,2/23 enable
exit

Problem : I have a lot of Oversized Pkts:
Unit/Port Drop Octets Pkts Bdcast Mtcast CRCErr Undersz Oversz Fragm Coll Jabb
--------- ---- ------ ---- ------ ------ ------ ------- ------ ----- ---- ----
2/23 19548 479245274 1824718948 5844118 20650388 0 0 4220533729 0 0 0

The average of oversized packets is more than 100 / sec

My question:
- what could be the cause of these oversized packets?
- What could be the impact of these oversized packets?
- How could I solve this (or is there a need to solve this) ?

Thanks for your help!

[zakabog]

The packets come from devices on your network, by default the 4500 had jumbo frames enabled so it should allow oversized packets through, are the two stacks connected via a direct connection or is there a router between them? If there is a router and it doesn't have jumbo-frame support enabled then your switches will drop the oversized packets.

[lemah]

Well, I don't know exactly what is in between but it isn't a direct connection. So it's possible that a device (a router or a L3 switch) doesn't accept jumbo frames.

I'll take contact with the 'connection supplier' to find out what's in between.

What could be the easiest way to find out where the jumbo frames come from? Set-up a mirror on the port and capture all packets to see what's the source and destination?

Or do you see another possibility ?

Thanks!

[vultierp]

You could use the following command to display interfaces statistics:

show port-statistics

Find the counters for frames that are bigger than 1'500 bytes (jumbo frames have a size between 1501 and 9600 bytes).