Cisco Catalyst 3650 User Manual

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If a PIM router or multilayer device has a source-tree state (that is, an (S, G) entry is present in the
multicast routing table), it performs the RPF check against the IP address of the source of the multicast
packet.
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If a PIM router or multilayer device has a shared-tree state (and no explicit source-tree state), it performs
the RPF check on the RP address (which is known when members join the group).
Sparse-mode PIM uses the RPF lookup function to decide where it needs to send joins and prunes:
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(S, G) joins (which are source-tree states) are sent toward the source.
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(*,G) joins (which are shared-tree states) are sent toward the RP.
DVMRP is not supported on the device.Note
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.
The following figure 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.
Figure 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 devices to a source tree upon receiving the first data packet from a
source.
This process describes the move from a shared tree to a source tree:
IP Multicast Routing Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3650 Switches)
122 OL-29890-01
Configuring PIM
PIM Shared Tree and Source Tree

Cisco Catalyst 3650 Specifications

General

Brand	Cisco
Model	Catalyst 3650
Category	Switch
Language	English