[c-nsp] Layer-2 Flapping log messages
Djerk Geurts
djerk.cisco at easynet.nl
Wed Jan 12 04:19:38 EST 2005
Afaik, it's a message about a MAC address in the CAM table shifting to
another port before it has timed out and removed from the CAM table.
3 options possible:
- Duplicate MAC address on the network
- L2 loop (great for broadcast storms)
Loop could exist due to:
- STP error (configuration etc)
- Switch attched with 2 ports (also an STP error)
- Someone with a laptop moving his laptop from one desk to another
Djerk
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Robert Walton
> Sent: Wednesday, January 12, 2005 9:55 AM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] Layer-2 Flapping log messages
>
>
> Hi,
>
> Just looking at some logs for flapping and wonder what
> the difference is between these two logs i.e. is there a
> specific meaning behind the specifying of the interfaces
> being the opposite way round on the second log entry.
>
> Jan 10 12:07:35.776 GMT: %C4K_EBM-4-HOSTFLAPPING: Host
> 00:00:5E:00:01:1C in vlan 215 is flapping between port Fa2/48
> and port Fa2/3
> Jan 10 12:07:41.676 GMT: %C4K_EBM-4-HOSTFLAPPING: Host
> 00:00:5E:00:01:1C in vlan 215 is flapping between port Fa2/3
> and port Fa2/48
>
> cheers,
> Rob
>
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