[137234] in North American Network Operators' Group
Re: Strange L2 failure
daemon@ATHENA.MIT.EDU (Jens Link)
Thu Feb 10 04:32:39 2011
From: Jens Link <lists@quux.de>
Cc: NANOG list <nanog@nanog.org>
Date: Thu, 10 Feb 2011 10:32:28 +0100
In-Reply-To: <4D4485A6.3040203@brightok.net> (Jack Bates's message of "Sat, 29
Jan 2011 15:24:54 -0600")
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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
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