Intra-Domain Routing protocols are used to exchange reachability information
within an autonomous system (AS). They are referred to as a class by the
acronym igp. There are two intra-domain routing protocols currently
supported by this version of GateD:
PIM Dense Mode provides multicast routing for a densely populated group.
PIM Sparse Mode (PIM-SM) provides efficient routing for a group distributed sparsely across a wide area. PIM Sparse Mode is specified in RFC 2117.
Core Based Trees (CBT) like PIM-SM provides a mechanism for creating shared delivery trees for multicast groups. Shared trees allow for a single tree per multicast group (*,G) instead of trees based in each source-group pair (S,G). CBT depends on existing multicast routing to provide a route to do the Reverse Path Forwarding. In contrast, DVMRP passes this set of routes within the protocol.
BGP for Multicast - protocol not ready yet
Internet Group Management Protocol (IGMP) was primarily designed for
hosts on multi-access networks to inform locally attached routers of their
group membership information. This is performed by hosts multicasting IGMP
Host Membership Reports. Multicast routers listen for these messages and
can then exchange group membership information with other multicast routers.
This allows distribution trees to be formed to deliver multicast datagrams.
Last updated November 22, 1997
gated@gated.merit.edu