CHAPTER 7. MultiCast Protocols132 © SAMSUNG Electronics Co., Ltd.Distance Vector Multicast Routing Protocol(DVMRP)Distance Vector Multicast Routing Protocol(DVMRP) is a multicast routingprotocol that provides an efficient mechanism for connectionless datagramdelivery to a group of hosts across an internetwork. It is a distributed protocolthat dynamically generates IP multicast delivery trees using a technique calledReverse Path Multicasting.TerminologyFollowing is a brief description of terms and concepts used to describe theDVMRP protocol.DRIBUbigate iBG2016 DVMRP is a separate daemon serviced by the NSM daemon.It maintains the DVMRP Routing Information Base(DRIB).The DRIB contains the table of routes for multicast sources learned throughDVMRP route exchanges. Both the upstream and the downstream parts of aroute-state reside physically in a combined, single DRIB node. A DRIB nodeis called a DVMRP Routing Table(DRT) entry.The DRT entry contains a vector of downstream interfaces; each vector slotposition represents a virtual interface(VIF). It is used to store all requiredinformation for the state to ultimately decide the set of forwarding interfacesfor corresponding multicasting data packets.DVMRP requires a per-source network Designated Forwarder(DF) on eachdownstream interface, i.e., DF(S, I). DF election is based on the metric towardthe source network.If DF(S,I) changes for an interface, Ubigate iBG2016 updates the outgoing VIFlist(Olist) for all prune(S, G) states and their corresponding forwarding caches.VIF TableThe VIF table is a tree of virtualized physical and tunnel interfaces indexed bya virtual interface number.
