Avaya Configuring IP Multicasting and Multimedia Services Instrukcja Użytkownika Pobierz pdf (Strona 188)

Configuring IP Multicasting and Multimedia Services

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117355-D Rev 00

PIM Concepts and Terminology

PIM, which is defined in RFC 2362, is a multicast routing protocol that efficiently

routes packets between members of multicast groups that are sparsely distributed

throughout the internetwork. Dense-mode protocols, such as DVMRP, broadcast

multicast traffic to all routers over an entire internetwork. PIM sends multicast

traffic only to those routers that want to receive traffic for a particular multicast

group. PIM reduces the traffic flow over WAN links and reduces overhead costs

for processing unwanted multicast packets.

PIM is independent of any specific unicast routing protocol, but does require the

presence of a unicast routing protocol somewhere in the internetwork. PIM uses

the information from the unicast routing table to create and maintain the shared

multicast tree that enables routers to communicate in a PIM network.

The Bay Networks implementation of PIM supports only sparse mode. A typical

PIM sparse mode network consists of several multipoint data streams, each

targeted to a small number of LANs in the internetwork. For example, customers

whose networks consist of multiple hosts on different LANs can use PIM to

simultaneously access a video data stream, such as a video teleconference, on a

different subnet.

In sparse mode, PIM uses a shared multicast distribution tree that is rooted at the

central core point of the PIM network, known as the rendezvous point (RP) router.

Sources use RPs routers to identify themselves to other routers on the network;

receivers use RPs routers to learn about new sources.

PIM is scalable, making it ideal for a large network, such as an ISP.

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Avaya Configuring IP Multicasting and Multimedia Services Instrukcja Użytkownika Strona 188