46-35
Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter46 Configuring IP Multicast Routing
Configuring Advanced PIM Features

Troubleshooting PIMv1 and PIMv2 Interoperability Problems

When debugging interoperability problems between PIMv1 and PIMv2, check these in the order shown:
1. Verify RP mapping with the show ip pim rp-hash privileged EXEC command, making sure that all
systems agree on the same RP for the same group.
2. Verify interoperability between different versions of DRs and RPs. Make sure the RPs are
interacting with the DRs properly (by responding with register-stops and forwarding decapsulated
data packets from registers).
Configuring Advanced PIM Features
These sections describe the optional advanced PIM features:
Understanding PIM Shared Tree and Source Tree, page46-35
Delaying the Use of PIM Shortest-Path Tree, page46-36 (optional)
Modifying the PIM Router-Query Message Interval, page46-37 (optional)

Understanding PIM Shared Tree and Source Tree

By default, members of a group receive data from senders to the group across a single data-distribution
tree rooted at the RP. Figure46-6 shows this type of shared-distribution tree. Data from senders is
delivered to the RP for distribution to group members joined to the shared tree.
Figure46-6 Shared Tree and Source Tree (Shortest-Path Tree)
If the data rate warrants, leaf routers (routers without any downstream connections) on the shared tree
can use the data distribution tree rooted at the source. This type of distribution tree is called a
shortest-path tree or source tree. By default, the software switches to a source tree upon receiving the
first data packet from a source.
Router A
Source
Receiver
Router C RP
Router B
Shared tree
from RP
Source tree
(shortest
path tree)
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