RPF Check
This section describes the implementation mechanism and process of the RPF check.
The Reverse Path Forwarding (RPF) check rules are as follows: According to the source of a packet, a multicast device searches its unicast routing table and static multicast routing table for an optimal route as an RPF route. A packet passes the RPF check only when the interface that the packet reaches is the same as the RPF interface.
As shown in Figure 1, a multicast packet arrives at GE0/0/0 on Router C. Router C performs the RPF check on the packet and finds that the incoming interface of the packet is not GE0/0/10 in the forwarding entry. The RPF check fails, and Router C discards the packet.
