Quick Reference Guide

PowerConnect B-Series TI24X Configuration Guide 471
53-1002269-02
PIM Dense
19
In Figure 86, switch S5 is a leaf node with no group members in its IGMP database. Therefore, the
switch must be pruned from the multicast tree. S5 sends a prune message upstream to its
neighbor switch S4 to remove itself from the multicast delivery tree and install a prune state, as
seen in Figure 86. Switch S5 will not receive any further multicast traffic until the prune age
interval expires.
When a node on the multicast delivery tree has all of its downstream branches (downstream
interfaces) in the prune state, a prune message is sent upstream. In the case of S4, if both S5 and
S6 are in a prune state at the same time, S4 becomes a leaf node with no downstream interfaces
and sends a prune message to S1. With S4 in a prune state, the resulting multicast delivery tree
would consist only of leaf nodes S2 and S3.
FIGURE 85 Transmission of multicast packets from the source to host group members
FIGURE 86 Pruning leaf nodes from a multicast tree
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229.225.0.1
Group
Member
Group
Member
Video Conferencing
Server
(207.95.5.1, 229.225.0.1)
(Source, Group)
229.225.0.1
Group
Member
Group
Member
Group
Member
Group
Member
Group
Member
Group
Member
229.225.0.1
Leaf Node
Leaf Node
Leaf Node
(No Group Members)
Intermediate Node
(No Group Members)
R2
R1
R3
R4
R5
R6