9
CONFIDENTIAL
26-Jan-04
© 2002 Procket Networks, Inc. All rights reserved.
Multicast Forwarding
•What is RPF?
•A router forwards a multicast datagram only if received on the up stream interface to the source (i.e. it follows the distribution tree).
•The RPF Check
•The source IP address of incoming multicast packets are checked against a unicast routing table.
•If the datagram arrived on the interface specified in the
 routing table for the source address; then the RPF check
  succeeds.
•Otherwise, the RPF Check fails.
Reverse Path Forwarding (RPF)
Reverse Path Forwarding
Routers forward multicast datagrams received from incoming interface on distribution tree leading to source
Routers check the source IP address against their multicast routing tables (RPF check); ensure that the multicast datagram was received on the specified incoming interface