Avaya Configuring IP Multicasting and Multimedia Services Instrukcja Użytkownika Pobierz pdf (Strona 97)

Customizing DVMRP

117355-D Rev 00

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Router E considers the network connecting it to router D to be on the shortest path

to the source network connected to router A. Router D has an interface (d3) that is

part of the shortest path from router E to the network connected to router A.

If neighboring routers have the same metric to a given source network, the router

with the lower IP address is responsible for propagating multicast traffic

originating from that source network onto the network or tunnel that is common to

these neighboring routers.

A network is considered a leaf network if it has no dependent downstream

neighbors for a source. In Figure 4-1

, the network connected to router E (net 5) is

a leaf network.

Tree Pruning

If no members are detected on a branch of the shortest-path tree for a given group,

DVMRP prunes the branch.

The following conditions cause DVMRP to prune the shortest-path tree for a given

group:

• The router determines that the attached network on which the host is located

(or any other locally attached network) has no active member of the group.

• The router determines that all neighbors on all attached networks other than

the next-hop network to the source have pruned the source and group.

• The router determines that it is not located on the shortest network path to any

remote network that includes a member of the group.

If any of these conditions are true, the router sends a DVMRP prune message to its

DVMRP neighbor. The neighbor removes the router from its forwarding table.

If the host later rejoins the group, the router sends the neighbor a DVMRP graft

message. The neighbor restores the router to its forwarding table.

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Avaya Configuring IP Multicasting and Multimedia Services Instrukcja Użytkownika Strona 97