Grafts To A Multicast Tree - Dell PowerConnect B-RX Configuration Manual

23
DVMRP overview
FIGURE 97

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.
650
Pruning leaf nodes from a multicast tree
229.225.0.1
Group Group
Member Member
R2
Prune Message
sent to upstream router (R4)
R5
Leaf Node
(No Group Members)
(No Group Members)
Video Conferencing
Server
(207.95.5.1, 229.225.0.1)
(Source, Group)
R1
R4
...
Intermediate Node
229.225.0.1
Group Group Group
Member Member
Member
...
R3
R6
...
Group
Group Group
Member Member Member
229.225.0.1
BigIron RX Series Configuration Guide
53-1002253-01