Distance Vector Multicast Routing Protocol

The Distance Vector Multicast Routing Protocol ( DVMRP ) is used in computer networks to distribute multicast packets in a network coupling to interested hosts.

It is based on the unicast routing protocol RIP, which has been extended to effectively route calculation to the Reverse Path Forwarding Mechanism ( RPF). The router creates a table in which it has a so-called distance-vector holds for all other known routers. This is an entry that includes the cost to a destination router; this may be the hops for example, the transmission delay or number. Furthermore, it is noted at which the directly adjacent router the packet should be forwarded to reach the destination. When a router receives a multicast packet now, it forwards it to all output channels further, unless the packet has arrived on an input link that corresponds to one's own path to the source. Thus, the amount of sent packets is reduced, so that network capacity is saved. In addition, this procedure prevented infinite loops when forwarding the packets.

Use IGMP to communicate

DVMRP uses its messages according to the Internet Group Management Protocol (IGMP ) to exchange information with other routers. Basically, as described above, received packets to all neighboring routers forwarded ( Flooding ). A router can also have a non -membership -report, a special IGMP message to inform that he is not interested in the packages for a specific multicast address. The receiving router passes through this receiver then from his Verteilbaum.

Alternatives

The alternatives include MOSPF and the newer methods Protocol Independent Multicast ( PIM).