Cisco Systems 78-11741-02 Wireless Office Headset User Manual


 
Configuring PGM Host and Router Assist
PGM Overview
IPC-494
Cisco IOS IP Configuration Guide
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
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.
34212
Source
Multicast
application
PGM Host
IP multicast
Receiver
Multicast
application
PGM Host
IP multicast
Router C
PGM Host
IP multicast
Router A
PGM Router
Assist
PGM Host
IP multicast
Receiver
Multicast
application
PGM Host
IP multicast
Router B
PGM Router
Assist
IP multicast