Multicast Border Gateway Protocol (MBGP)
MBGP makes use of the multi-protocol extensions to BGP version 4. Two path attributes, MP_REACH_NLRI and MP_UNREACH_NLRI, are introduced to yield BGP4+ as described in Internet Draft draft-ietf-idr-bgp4-multiprotocol-01.txt.
MBGP is a simple way to carry two sets of routes. One set for unicast routing and one set for multicast routing. The routes associated with multicast routing are used by the multicast routing protocols to build data distribution trees.
Advantages:
o An internet can support non-congruent unicast and multicast topologies.
o An internet, when the unicast and multicast topologies are congruent, can support differing policies.
Disadvantages:
o Multiple sets of routes for the same prefixes are carried in BGP and stored in routers.