BigIron RX Series Configuration Guide 84753-1001986-01Chapter27Configuring MBGPThis chapter provides details on how to configure Multi-protocol Border Gateway Protocol (MBGP).MBGP is an extension to BGP that allows a router to support separate unicast and multicasttopologies. BGP4 cannot support a multicast network topology that differs from the network’sunicast topology. MBGP allows you to support a multicast topology that is distinct from thenetwork’s unicast topology. For example, if you want to dedicate a link on your Internet router tomulticast traffic, use MBGP to handle the routes on that link.MBGP provides the following benefits:• You can support a network whose multicast topology is different from its unicast topology.Even if the unicast and multicast networks have the same topologies, you can supportdifferent sets of routing policies for unicast and multicast.• You can use BGP4's powerful feature set with MBGP.Figure 116 shows an example of a network that contains both a unicast topology and a multicasttopology. The unicast and multicast router in this example receives unicast and multicast routesfrom the Internet. The router advertises the multicast routes to the multicast router and advertisesthe unicast routes to the unicast router. Likewise, the unicast and multicast router can advertiseunicast routes received from the unicast router to the Internet, and can advertise multicast routesreceived from the multicast router to the Internet.FIGURE 116 MBGP used when multicast topology is different from unicast topologyAn MBGP router learns MBGP routes from its neighbors in other ASs. An MBGP router also canadvertise MBGP routes to its neighbors. The Brocade implementation of MBGP enables you toadvertise multicast routes from the following sources:• Explicitly configured network prefixes• Static IP multicast routes• Directly-connected multicast routes redistributed into MBGP.You can configure an aggregate address to aggregate network prefixes into a single, more generalprefix for advertisement.MBGP is described in detail in RFC 2858.InternetAS 10BGP4MBGPMBGPBGP4MulticastRouterUnicastRouterUnicastandMulticastRouter
