The Distance Vector Multicast Routing Protocol (DVMRP), defined in RFC 1075, is a routing protocol used to share information between routers to facilitate the transportation of IP multicast packets among networks.
It formed the basis of the Internet's historic multicast backbone, Mbone.
DVMRP operates via a reverse path flooding technique, sending a copy of a received packet (specifically IGMP messages for exchanging routing information with other routers) out through each interface except the one at which the packet arrived.
Being a naïve distance-vector protocol, DVMRP has difficulties with network scaling in some topologies,[2] primarily due to the periodic reflooding necessary to detect new hosts.
[3] DVMRP's flat unicast routing mechanism, which is used to determine the source interface of a data stream, also affects its ability to scale.