In message <Pine.NEB.4.53.0308111101210.688@rivendell.starwolf.com>, Greywolf w
rites:
>Thus spake Thor Lancelot Simon ("TLS> ") sometime Yesterday...
>
>TLS> The correct way to do this sort of thing is with network-layer routing
>TLS> updates, not with disgusting link-layer hackery.
>
>You might want to tell this to the people who make failover boxes which
>do just this in hardware.  They do exist.  Or, at least, this used to be
>quite a common practice a few years ago.  I never got to manage one, but
>I saw the setup for it.  I believe Cisco's failover HW takes the
>"I-Will-Assume-The-Other's-IP-Address-AND-its-MAC-address" approach.
>
>Someone will, no doubt, tell me {if,that} I am mistaken.

It's called "Virtual Router Redundancy Protocol", RFC 2338.

		--Steve Bellovin, http://www.research.att.com/~smb