[c-nsp] standby use-bia?

[Oliver Boehmer (oboehmer)]

> We ran into an issue recently where an HSRP switchover happened and a
> bunch of our L3 switches either didn't get or didn't act on the
> gratuitous arp the active router is supposed to send when it's
> configured with use-bia and goes active.  This got me thinking about
> ways around having the HSRP group members having different MAC
> addresses. 
> 
> The limitation we have is that the VIP2s in our 7500s only have a 32
> addr AF.  What's the limit on VIP4?  I haven't been able to find that
> anywhere? 

Ack, this limit also applies to the VIP4.
 
> While looking into this, I noticed that there is "standby [group #]
> mac-addr xxxx.xxxx.xxxx" command.  Assuming an FE or Portchannel has
> lots of subinterfaces, each of which is doing HSRP with one or more
> other routers, but there's only one HSRP group per VLAN, is there any
> reason I can't use "standby [group #] mac-addr" to make all the HSRP
> virtual MAC addresses the same?...using either a made up MAC address
> or perhaps an actual MAC address from one of the routers, and use
> that same MAC as the configured virtual MAC address on all the HSRP
> member routers? 

Bruce has already responded to this, and I can confirm that it works (a
customer used this) and is a feasible workaround to get around the
limitation on the VIP. I'd use a made-up address (or use an address from
one of your lab routes which you'll never use "in the wild")..

	oli