Distance Vector Multicast Routing Protocol
The Distance Vector Multicast Routing Protocol (DVMRP) is in computer networks used to multicast packets in a network coupling to interested hosts to distribute.
It is based on the unicast routing protocol RIP , which has been expanded to include the reverse path forwarding mechanism (RPF) for effective route calculation . The router creates a table in which it has a so-called distance vector for all other known routers . This is an entry that contains the cost of a destination router; this can be, for example, the transmission delay or the number of hops . It is also noted to which of the directly neighboring routers the packet must be forwarded in order to reach the destination. If a router now receives a multicast packet, it forwards it on all output channels, provided the packet has arrived on an inbound link that corresponds to its own path to the source. This reduces the number of packets sent, so that network capacity is saved. This procedure also prevented infinite loops when forwarding the packets.
Use of IGMP for communication
DVMRP uses messages in accordance with the Internet Group Management Protocol (IGMP) to exchange information with other routers. Basically, as described above, received packets are forwarded to all neighboring routers ( flooding ). However, a router can use a non-membership report, a special IGMP message, to report that it is not interested in the packets for a specific multicast address. The receiving router then deletes this recipient from its distribution tree.
Alternatives
- The alternatives include MOSPF and the newer Protocol Independent Multicast (PIM) method .
- IEEE 802.1aq - Shortest Path Bridging (SPB)