NETGEAR M7100, M4100 manual Dvmrp, Distance Vector Multicast Routing Protocol

31. DVMRP	31
Distance Vector Multicast Routing Protocol

The DVMRP is used for multicasting over IP networks without routing protocols to support multicast. The DVMRP is based on the RIP protocol but more complicated than RIP. DVRMP maintains a link-state database to keep track of the return paths to the source of multicast packages.

The DVMRP operates as follows:

•The first message for any source-group pair is forwarded to the entire multicast network, with respect to the time-to-live (TTL) of the packet.

•TTL restricts the area to be flooded by the message.

•All the leaf routers that do not have members on directly attached subnetworks send back prune messages to the upstream router.

•The branch that transmitted a prune message is deleted from the delivery tree.

•The delivery tree, which is spanning to all the members in the multicast group, is constructed.

In this example, DVMRP is running on switches A, B, and C. IGMP is also running on Switch C, which is connected to the host directly. After the host sends an IGMP report to switch C,

Chapter 31. DVMRP 524