nanog mailing list archives

Re: Strange L2 failure


From: Jens Link <lists () quux de>
Date: Thu, 10 Feb 2011 10:32:28 +0100

Jack Bates <jbates () brightok net> writes:

Hi,

a little late, but just catching up the list.

Has anyone seen issues with IOS where certain MACs fail?

54:52:00 (kvm) fails out an old 10mbit port on a 7206 running 12.2
SRE. I've never seen anything like this. DHCP worked, ARP worked, and
arp debugging showed responses for arp to the MAC, however, tcpdump on
the host system 

I had something similar using a Catalyst 3550. Very simple setup:

Host  ----- Cat3550 ----- Router

You could see arp-request from the host to the router and arp-replies
from the router using tcpdump, but the arp-replies didn't make it to the
host. No change in the interface counters on the switch either. 

When using a static arp-entry on the host and then ping the router you
could the echo-request and echo-replies there but still no answers. 

Jens
-- 
-------------------------------------------------------------------------
| Foelderichstr. 40   | 13595 Berlin, Germany    | +49-151-18721264     |
| http://blog.quux.de | jabber: jenslink () guug de | -------------------  | 
-------------------------------------------------------------------------


Current thread: