What Multicast Routing Protocols are in Use Today ?
The protocols for multicast data transport have evolved over the years. The original multicast proposal was for dense mode, where all possible receivers are assumed to want multicast traffic initially and so multicast traffic is flooded throughout the network until receivers specifically request to leave the multicast group and stop receiving the traffic (i.e., are “pruned”). This “flood and prune” technique is relatively straightforward to implement, but is not very efficient as the size of the network increases (it “does not scale,” in the jargon). The first multicast routing protocol in common use, DVMRP (for Distance Vector Multicast Routing Protocol), used this technique, and was the protocol of the MBONE for years. More recently, a sparse mode protocol has come into common use. In sparse mode, no receiver is assumed to want multicast traffic until it explicitly asks for it. There is thus no unwanted flooding of traffic throughout the network, and so the protocol scales much bette
