Re: Router stops routing after changing MAC Address

[Stephen Hemminger <shemminger@osdl.org>]

On Fri, 10 Mar 2006 18:33:15 -0600
"Greg Scott" <GregScott@InfraSupportEtc.com> wrote:

> Hello - This feels like a kernel issue.  I spent hours and hours and
> hours looking for documentation and archives around this but did not
> find anything.  
> 
> I have a Linux router and I need the ability to swap hardware without
> causing downtime.  The problem, of course, is ARPs.  The NICs in the
> replacement system need the same MAC Addresses as the NICs in the
> original system.  I'd like this all to be in the kernel and not depend
> on a daemon process that can die.
> 
> How to change MAC addresses is documented well enough - and it works -
> but when I change MAC addresses, my router stops routing.  From the
> router, I can see the systems on both sides - but the router just
> refuses to forward packets.  Here are my little test scripts to change
> MAC Addresses.

You probably just need to flush the route cache after the address change?