Alcatel Carrier Internetworking Solutions 6800 User Manual

Troubleshooting PIM-SM

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OmniSwitch Troubleshooting Guide

page 16-21

When a source starts transmitting to a multicast group, the DR on the segment encapsulates the data and 
sends it as unicast to the RP representing the group. The source IP address will be the DR and the destina-
tion IP address will be the RP. Two behaviors are possible:

1-The RP joins the source tree by sending a PIM join to the DR. Packets will then flow from the source to 
the RP unencapsulated.

2-The RP does not join the source tree. The multicast packets will be encapsulated by the DR and send to 
the unicast address of the RP.

Upon reception of the multicast stream, the RP forwards the packets unencapsulated to receivers if any. If 
there are no receivers the RP issues a REGISTER STOP message to the source.

192.168.13.1

192.168.11.1

192.168.11.2

192.168.12.2

192.168.12.1

192.168.13.101