D-Link DES-3326 User Manual - Multicast Routing Protocols
DES-3326 Layer 3 Fast Ethernet Switch User’s Guide
Switch Management and Operating Concepts
105
between a given multicast source and the corresponding multicast
group.
Since the membership of any given multicast group can change and
the network topology can also change, RPM periodically removes
all of the prune information it has gathered from it’s memory, and
the entire process repeats. This gives all subsequent routers on the
network a chance to receive multicast packets from all multicast
sources on the network. It also gives all user’s a chance to join a
given multicast group.
Multicast Routing Protocols
This section contains an overview of two multicast routing
protocols – Distance Vector Multicast Routing Protocol (DVMRP),
and Protocol Independent Multicast-Dense Mode (PIM-DM). The
most commonly used routing protocol (not a multicast routing
protocol), the Routing Information Protocol, is discussed in a later
section.
Distance Vector Multicast Routing
Protocol (DVMRP)
The Distance Vector Multicast Routing Protocol (DVMRP) was
derived from the Routing Information Protocol (RIP) with the
introduction of multicast delivery trees constructed from
information about the ‘distance’ from the local router back toward
the multicast source. DVMRP uses an RPM algorithm to construct
its multicast delivery trees.
The first multicast packet received by a multicast router using
DVMRP is flooded to all interfaces except the one on which the
packet was received. Subsequent prune messages are used to