36 IntroductionMulticast FeaturesIPv4 Multicast FeaturesUpdated IPv4 Multicast Routing SupportThe Multicast package code has been extensively re-engineered and furnished with the following:• PIM-DM advanced to RFC 3973• PIM-SM advanced to RFC 4601, pim-sm-bsr-05, draft-ietf-pim-mib-v2-03• DVMRP advanced to draft-ietf-idmr-dvmrp-v3-10.txt, draft-ietf-idmr-dvmrp-mib-11.txtDistance Vector Multicast Routing ProtocolDistance Vector Multicast Routing Protocol (DVMRP) exchanges probe packets with all DVMRP-enabled routers, establishing two way neighboring relationships and building a neighbor table. Itexchanges report packets and creates a unicast topology table, which is used to build the multicastrouting table. This multicast route table is then used to route the multicast packets.Internet Group Management ProtocolThe Internet Group Management Protocol (IGMP) is used by IPv4 systems (hosts and routers) to reporttheir IP multicast group memberships to any neighboring multicast routers. The PowerConnect 6200Series performs the "multicast router part" of the IGMP protocol, which means it collects themembership information needed by the active multicast routing.Protocol Independent Multicast-Dense ModeProtocol Independent Multicast (PIM) is a standard multicast routing protocol that provides scalableinter-domain multicast routing across the Internet, independent of the mechanisms provided by anyparticular unicast routing protocol. The Protocol Independent Multicast-Dense Mode (PIM-DM)protocol uses an existing Unicast routing table and a Join/Prune/Graft mechanism to build a tree. PIM-DM creates source-based shortest-path distribution trees, making use of reverse path forwarding (RPF).Protocol Independent Multicast-Sparse ModeProtocol Independent Multicast-Sparse Mode (PIM-SM) is used to efficiently route multicast traffic tomulticast groups that may span wide area networks, and where bandwidth is a constraint. PIM-SM usesshared trees by default and implements source-based trees for efficiency. This data threshold rate is usedto toggle between trees.IPv6 Multicast FeaturesProtocol Independent Multicast IPv6 SupportPIM-DM and PIM-SM support IPv6 routes.
