As is known, because it is a distance vector protocol, DVMRP works with source trees (SPT).
Basically, the difference between DVMRP and PIM-DM is that DVMRP, before sending packets through a certain connection, makes sure the connection leads to a node that recognizes the local node as a node that is on the shortest path between it and the source (this ensures that with DVRMP sending packets takes place across the shortest road from source to destination).
DVMRP. [On line], accessed 10 April 2014, available:http://www.juniper.net/techpubs/en_US/junos11.4/topics/topic-map/mcast-pim-dvmrp.html
DM PIM is similar to DVMRP. Our discussion will focus on SP PIM, which is suitable for wide area networks.
Therefore this makes PIM "unicast routing protocol independent," compared to other multicast routing protocols derived from either link-state (MOSPF) or distance-vector (DVMRP) routing .
Toward this goal, the Proteon MOSPF implementation also includes a DVMRP implementation and the "glue logic" allowing routing information to be passed between the two multicast routing protocols.
Using MOSPF instead of DVMRP in parts of the Internet has the following advantages:
MOSPF's link state technology converges faster and is less prone to looping during the convergence time than DVMRP, which suffers some of the same problems that the Internet's RIP protocol does when faced with topological changes in a redundant topology.