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%MLS_STAT-DFC6-4-IP_CSUM_ERR: IP checksum errors

I hav a cat6509 reporting the errors below and can pinpoint a problem. Could it be a bogus error ?

OS (tm) c6sup2_rp Software (c6sup2_rp-JS-M), Version 12.1(13)E

Apr 28 20:15:02: %MLS_STAT-DFC6-4-IP_CSUM_ERR: IP checksum errors

Apr 28 20:46:02: %MLS_STAT-DFC6-4-IP_CSUM_ERR: IP checksum errors

Apr 28 21:38:32: %MLS_STAT-DFC6-4-IPX_LEN_ERR: MAC/IPX length inconsistencies

Apr 28 23:19:33: %MLS_STAT-DFC6-4-IP_LEN_ERR: MAC/IP length inconsistencies

Apr 29 00:00:33: %MLS_STAT-DFC6-4-IP_CSUM_ERR: IP checksum errors

Apr 29 01:45:34: %MLS_STAT-DFC6-4-IP_LEN_ERR: MAC/IP length inconsistencies

Apr 29 03:19:04: %MLS_STAT-DFC6-4-IP_CSUM_ERR: IP checksum errors

Apr 29 04:24:04: %MLS_STAT-DFC6-4-IP_CSUM_ERR: IP checksum errors

Apr 29 04:54:35: %MLS_STAT-DFC6-4-IP_CSUM_ERR: IP checksum errors

1 REPLY
Cisco Employee

Re: %MLS_STAT-DFC6-4-IP_CSUM_ERR: IP checksum errors

These messages are not error messages for the switch, they are generated by the switch to inform that there is a bad input packet detected from one of

the sources and that packet was dropped.

The error messages that you see in logs indicate that the switch forwarding engine is getting an IP-packet which is less than the minimum length of allowed IP- packet and hence dropped it. In older code we just used to silently drop the packet and count it in the forwarding engine stats and in newer code we are syslogging it . There is nothing to worry about from the switch side, as it is dropping the bad packet, which would have been dropped anyway by the receiving device. The only thing you have to be concerned about is that there is a device which is sending these bad packets (possibly due to bad nic driver, nic driver bug (or) bad application etc..). Unfortunately, our forwarding engine doesn't keep track of the source-ip of the device which is sending these bad packets. Hence, the only way to detect these devices is to use a sniffer and trackit down to a source. So the origin of the problem is external to the switch. The switch is just reporting that it received those "bad" packets and it will drop them.

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