Grafts To A Multicast Tree; Configuring Dvmrp; Enabling Dvmrp On The Layer 3 Switch And Interface - Foundry Networks FESX Manual

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Pruning leaf nodes from a multicast tree

Prune Message

sent to upstream router (R4)

(No Group Members)

Grafts to a Multicast Tree

A DVMRP router restores pruned branches to a multicast tree by sending graft messages towards the upstream

router. Graft messages start at the leaf node and travel up the tree, first sending the message to its neighbor

upstream router.

In the example above, if a new 229.255.0.1 group member joins on router R6, which had been pruned previously,

a graft will be sent upstream to R4. Since the forwarding state for this entry is in a prune state, R4 sends a graft to

R1. Once R4 has joined the tree, it along with R6 will once again receive multicast packets.

You do not need to perform any configuration to maintain the multicast delivery tree. The prune and graft

messages automatically maintain the tree.

Suppose you want to initiate the use of desktop video for fellow users on a sprawling campus network. All

destination workstations have the appropriate hardware and software but the Layer 3 Switches that connect the

various buildings need to be configured to support DVMRP multicasts from the designated video conference

server as seen in Figure 19.7.

DVMRP is enabled on each of the Foundry Layer 3 Switches shown in Figure 19.7, on which multicasts are

expected. You can enable DVMRP on each Layer 3 Switch independently or remotely from one Layer 3 Switch by

a Telnet connection. Follow the same steps for each router.

December 2005

Interrmediate Node

(No Group Members)

Video Conferencing

(207.95.5.1, 229.225.0.1)

(Source, Group)

Configuring IP Multicast Protocols

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