VRRP is the virtual router redundancy protocol. VRRP is an IETF WG product described at http://www.ietf.org/html.charters/vrrp-charter.html. Excerpt:

A virtual router redundancy protocol is a protocol which allows several
routers on a multiaccess link to utilize the same virtual IP address.
One router will be elected as a master with the other routers acting as
backups in case of the failure of the master router. The primary
motivation to using a virtual router redundancy protocol is that host
systems may be configured (manually or via DHCP) with a single default
gateway, rather than running an active routing protocol. The protocol
should also support the ability to load share traffic when both routers
are up.