Overview Of Ip Multicasting; Multicast Terms - Foundry Networks Switch and Router Installation And Configuration Manual

This chapter describes how to configure Foundry Layer 3 Switches for Protocol Independent Multicast (PIM) and
Distance Vector Multicast Routing Protocol (DVMRP). Foundry Layer 3 Switches support RFC 1075 for DVMRP
and PIM Dense (PIM-DM). They also support RFC 2362 for PIM Sparse (PIM-SM). PIM-DM version 1 and PIM-
SM version 2 are supported.
NOTE: Each of the multicast protocols uses Internet Group Membership Protocol (IGMP). IGMP is
automatically enabled on an interface when you configure PIM or DVMRP on an interface and is disabled on the
interface if you disable PIM or DVMRP on the interface.
A summary of all CLI commands discussed in this chapter can also be found in the Foundry Switch and Router
Command Line Interface Reference.

Overview of IP Multicasting

Multicast protocols allow a group or channel to be accessed over different networks by multiple stations (clients)
for the receipt and transmit of multicast data.
Distribution of stock quotes, video transmissions such as news services and remote classrooms, and video
conferencing are all examples of applications that use multicast routing.
Foundry Layer 3 Switches support two different multicast routing protocols—Distance Vector Multicast Routing
Protocol (DVMRP) and Protocol-Independent Multicast (PIM) protocol along with the Internet Group Membership
Protocol (IGMP).
PIM and DVMRP are broadcast and pruning multicast protocols that deliver IP multicast datagrams. The
protocols employ reverse path lookup check and pruning to allow source-specific multicast delivery trees to reach
all group members. DVMRP and PIM build a different multicast tree for each source and destination host group.
NOTE: Both DVMRP and PIM can concurrently operate on different ports of a Foundry router.

Multicast Terms

The following are commonly used terms in discussing multicast-capable routers. These terms are used
throughout this chapter:
Node: Refers to a router.
Root Node: The node that initiates the tree building process. It is also the router that sends the multicast packets
down the multicast delivery tree.
December 2000
Configuring IP Multicast Protocols
Chapter 18
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