Brocade TurboIron 24X Series Configuration Guide - Manual (Page 835)

Brocade TurboIron 24X Series Configuration Guide 801
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PIM Dense
FIGURE 105 Pruning leaf nodes from a multicast tree
Grafts to a multicast Tree
A PIM switch restores pruned branches to a multicast tree by sending graft messages towards the
upstream switch. Graft messages start at the leaf node and travel up the tree, first sending the
message to its neighbor upstream switch.
In the example above, if a new 229.255.0.1 group member joins on switch S6, which was
previously pruned, a graft is sent upstream to S4. Since the forwarding state for this entry is in a
prune state, S4 sends a graft to S1. Once S4 has joined the tree, S4 and S6 once again receive
multicast packets.
Prune and graft messages are continuously used to maintain the multicast delivery tree. No
configuration is required on your part.