[j-nsp] VRRP between mixed M7i and M10i

[Chuck Anderson]

On Mon, Sep 03, 2012 at 03:48:09PM +0200, sthaug at nethelp.no wrote:
> > > > 1) Did someone have a chance to configure a subnet with 4 Mixed routers M7i
> > > > and M10i and VRRP enabled between all of them ?
> > > 
> > > VRRP runs between *two* routers. Aside from that, no specific problems
> > > with M7i vs M10i (and why should there be? M7i and M10i are hardware
> > > and software wise very much alike).
> > 
> > VRRP can run on more than two routers just fine.  All but one router
> > on any LAN will become a backup.
> 
> Thanks for the correction. A followup question: Under what circumstances
> would you want to configure VRRP on more than two routers on the same
> LAN segment? We've always used just two...

If you have routers in different geographical locations (say in
different datacenters), but you want to provide streatched subnets
across multiple datacenters (for VM migration), you might want to
provide capability for local routing off that subnet in case the data
center's connection to the outside world is lost.  If each datacenter
has two routers, you might have 4 or more routers running VRRP for the
same subnet.