DVMRP
Distance Vector Multicast Acquisition Agreement (DVMRP) is authentic in RFC 1075, and was the aboriginal broadly implemented multicast acquisition protocol. This agreement is agnate to RIP in abounding ways. There are a few important differences, though. The best bore of a RIP arrangement is 16 hops, as we mentioned in Chapter 6. DVMRP has a best metric of 32, which acutely improves its flexibility. It's not adamantine to acquisition a arrangement with a bore greater than 16 hops, but a 32-hop bore is acceptable for best real-world accumulated networks. It is not acceptable for the accessible Internet, but that is why multiprotocol extensions to the Border Gateway Protocol, sometimes additionally alleged Multicast Border Gateway Agreement ( MBGP) was invented.
DVMRP is about a acceptable best for acceptance routers from altered manufacturers to barter multicast acquisition information. It is a close approach protocol, however, so it is about beneath able with arrangement resources. We acclaim application DVMRP primarily as a apparatus for exchanging multicast acquisition advice with earlier nonCisco devices. In contempo years, PIM has become the accepted best for multicast acquisition amid best ample router vendors, though, so DVMRP's alcove is now mostly in abutting with absolute nonCisco multicast networks.
In abounding ways, DVMRP functions in a agnate way to PIM-DM. It uses a dense-mode action that armament all routers to clip themselves from any multicast copse that they don't require. And it additionally uses the unicast acquisition table to actuate the beeline aisle aback to the antecedent device. The capital difference, however, is that DVMRP includes its own centralized unicast acquisition agreement that it uses to advice accomplish decisions about the best SPT.
DVMRP uses an algorithm alleged Truncated Reverse Aisle Broadcasting (TRPB) to acquiesce every router in the arrangement to actuate area it is about to the multicast source, and to account the optimal SPT aback to the source. Because DVMRP uses its own centralized unicast acquisition protocol, it is not advised protocol-independent.
You charge booty appropriate measures to force DVMRP to chase the accepted unicast acquisition table and accomplish it agreement independent. Of course, this would breach one of the capital affidavit for application DVMRP in the aboriginal place. Because it maintains its own acquisition tables, DVMRP is able to assignment in networks area the multicast and unicast topologies are different. This is not aberrant in cases area genitalia of the unicast arrangement don't abutment multicast routing, or area cartage engineering leads you to put multicast cartage through altered arrangement links.
In fact, Cisco routers do not accommodate a abounding DVMRP implementation. They can booty allotment in advertent and exchanging acquisition advice with DVMRP neighbors. But the absolute multicast acquisition is done application PIM while apropos to the DVMRP acquisition tables.