Cisco Systems 78-11741-02 manual IPC-494, Network Topology Using PGM Host and Router Assist

Configuring PGM Host and Router Assist

PGM Overview

Note PGM contains an element that assists routers and switches in handling PGM transport data as it flows through a network. Unlike the Router Assist element, the Host element does not have a current practical application.

PGM is network-layer independent; PGM Host and Router Assist in the Cisco IOS software support PGM over IP. Both PGM Host and Router Assist use a unique transport session identifier (TSI) that identifies each individual PGM session.

Figure 81 shows a simple network topology using the PGM Host and Router Assist feature.

Figure 81 Network Topology Using PGM Host and Router Assist

Router C

Receiver

Source

Multicast

application

PGM Host

IP multicast

Router A

PGM Host

PGM Router

Assist

IP multicast

PGM Host

IP multicast

Router B

PGM Router

Assist

IP multicast

Multicast

application

PGM Host

IP multicast

Receiver
Multicast
application
PGM Host	34212
IP multicast

When the router is functioning as a network element (PGM Router Assist is configured) and PGM Host is configured (Router A in Figure 81), the router can process received PGM packets as a virtual PGM Host, originate PGM packets and serve as its own first hop PGM network element, and forward received PGM packets.

When the router is functioning as a network element and PGM Host is not configured (Router B in Figure 81), the router forwards received PGM packets as specified by PGM Router Assist parameters.

When the router is not functioning as a network element and PGM Host is configured (Router C in Figure 81), the router can receive and forward PGM packets on any router interface simultaneously as specified by PGM Host feature parameters. Although this configuration is supported, it is not recommended in a PGM network because PGM Host works optimally on routers that have PGM Router Assist configured.

Cisco IOS IP Configuration Guide

IPC-494