Cisco Systems 78-11741-02 manual IP Multicast

IP Overview

IP Multicast

For example, RIP uses a hop-count metric and IGRP uses a five-element vector of metric information. If routing information is being exchanged between different networks that use different routing protocols, you can use many configuration options to filter the exchange of routing information.

The Cisco IOS software can handle simultaneous operation of up to 30 dynamic IP routing processes. The combination of routing processes on a router consists of the following protocols (with the limits noted):

•Up to 30 IGRP routing processes

•Up to 30 EIGRP routing processes

•Up to 30 OSPF routing processes

•One RIP routing process

•One IS-IS process

•One BGP routing process

IP Multicast

IP multicast routing provides an alternative to unicast and broadcast transmission. It allows a host to send packets to a subset of all hosts, known as group transmission. IP multicast runs on top of the other IP routing protocols.

In addition to IP multicast routing itself, other multicast features are available, each discussed in a separate chapter, as follows:

•Source Specific Multicast (SSM) is an extension of IP multicast where datagram traffic is forwarded to receivers from only those multicast sources to which the receivers have explicitly joined.

•Bidirectional PIM is a variant of the PIM suite of routing protocols for IP multicast. In bidirectional mode, datagram traffic is routed only along a bidirectional shared tree that is rooted at the rendezvous point (RP) for the multicast group.

•Multicast Source Discovery Protocol (MSDP) is a mechanism for the router to discover multicast sources in other PIM domains.

•Pragmatic General Multicast (PGM) is a reliable multicast transport protocol for applications that require ordered, duplicate-free, multicast data delivery from multiple sources to multiple receivers. The PGM Host feature is the Cisco implementation of the transport layer of the PGM protocol, and the PGM Router Assist feature is the Cisco implementation of the network layer of the PGM protocol.

•Unidirectional link routing (UDLR) provides a way to forward multicast packets over a physical unidirectional interface, such as a satellite link.

•The Multicast Routing Monitor (MRM) feature is a management diagnostic tool that provides network fault detection and isolation in a large multicast routing infrastructure. This feature is described in the “Using IP Multicast Tools” chapter.

•Router-Port Group Management Protocol (RGMP) is a Layer 2 protocol that enables a router to communicate to a switch (or a networking device that is functioning as a Layer 2 switch) the multicast group for which the router would like to receive or forward traffic.

Cisco IOS IP Configuration Guide

IPC-4