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New Member

Why IP checksum errors ?

I am getting following error messages on a cat6513 switch running IOS 12.1(13)E :

Nov 8 18:53:43: %MLS_STAT-SP-4-IP_CSUM_ERR: IP checksum errors

The question are :

1. Could it be a Physical link problem

2. Could it be a Duplex issue ? My only Fast ethernet port is forced half duplex and forced speed 10 MNov 8 18:53:43: %MLS_STAT-SP-4-IP_CSUM_ERR: IP checksum errorss. Rest are GigE

3. Could it be because of a GigE link ?

4. Is there any way to trace this error to an interface ?

5. Cisco TAC tool "Error Message Decoder" could not decode this ereror message.

6. Any other reasons for this error message ?



Cisco Employee

Re: Why IP checksum errors ?

These are informational messages only. They mean there was data traffic received by the system where the IP length doesn't match the MAC length of the frame (ie. L3 length is greater than L2 length). The problem is with the source of the frames and not with the switch system. If you use traffic generator, make sure that you don't select 'Length override' as that will cause the packet to be dropped by the system and this msg to be generated. Also the end users like PC, workstation, traffic tools causes these bad packets. The switch itself shouldn't create them.

I have found that the messages you are seeing are part of an enhancement defect, meaning that the reporting was added as an enhancement, but it should not be reporting the way it is. The reporting of the error is going to be changed to the "show mls statistics" counter instead of being reported to the syslog.

New Member

Re: Why IP checksum errors ?

Thanks for the detailed reply.

I do see the IP header length error counter incrementing under "show mls statistics". Is there any way to see this counter on a per interface basis ? This will help me to track the port on which I am getting such errored packets.

This is a production switch and I can not shut down any port.