After the Source DR Sends a Register Message to the RP, the Registration Interface Still Exists in the Corresponding Multicast Forwarding Entry

Fault Description

On a deployed multicast network, the multicast source sends multicast data to the source designated router (DR). The source DR encapsulates the multicast data into a Register message and sends the Register message to the rendezvous point (RP). After the source DR sends the Register message to the RP, the registration interface still exists in the corresponding multicast forwarding entry. No SPT is set up between the source DR and RP.

Fault Analysis

The source DR does not delete the registration interface from the corresponding multicast forwarding entry if the source DR does not receive any Register Stop message from the RP. A common cause of this problem is that unicast routes between the source DR and PR are unreachable.

Procedure

Ensure that the source DR and RP have reachable unicast routes to each other and can ping each other successfully.
- If the source DR has no reachable unicast route to the RP or has a route but cannot ping the RP, the RP cannot receive the Register message from the source DR and therefore does not send a Register Stop message to the source DR.
- If the PR has no reachable unicast route to the source DR or has a route but cannot ping the source DR, the Register Stop message sent from the RP cannot reach the source DR.
Run the display pim routing-table source-address command on the RP to check whether the corresponding (S, G) entry exists.
If the source DR and RP can ping each other successfully, check whether the RP has completed the shortest path tree (SPT) switchover to set up a multicast forwarding path toward the multicast source. If the SPT switchover has not completed, the RP does not send a Register Stop message to the source DR. In such a case, different PIM protocols may be configured on interfaces of devices between the RP and source DR.