Avaya Configuring IP Multicasting and Multimedia Services Uživatelský manuál stáhnout pdf (Strana 193)

Customizing Protocol Independent Multicast

117355-D Rev 00

6-7

Join/Prune, Register, and Assert Messages

PIM routers communicate with each other using the following messages.

Join/Prune Messages

The DR sends join/prune messages from a receiver toward a group’s RP to either

join the shared tree or remove (prune) a branch from it. A single message contains

both a join and a prune list. This list includes a set of source addresses, indicating

the shortest-path trees (SPTs) or the shared trees that the host wants to join.

The DR sends join and prune messages hop by hop to each PIM router on the path

to the source or the RP.

The DR sends register and register-stop messages to the RP on behalf of a directly

connected source. The register message informs the RP of a new source, causing

the RP to send join messages back toward the DR of the source.

The DR stops sending multicast packets after it receives a register-stop message

from the RP. The RP sends a register-stop message if there are no downstream

receivers for a group, or if the RP has successfully joined the shortest-path tree

(SPT).

Assert Messages

PIM uses assert messages to determine which of the routers connected to a LAN

is responsible for forwarding packets onto the LAN. PIM sends assert messages

when two parallel routers have forwarding entries for the same group with

outgoing interfaces toward the same LAN.

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Avaya Configuring IP Multicasting and Multimedia Services Uživatelský manuál Strana 193