SPT on a PIM-DM Network Fails to Be Established

Procedure

1. Check whether a reachable unicast route to the multicast source is available.

   Run the display ip routing-table command to check whether the router has a unicast route to the multicast source.

   Multicast routing depends on unicast routing. If the router does not have a unicast route to the multicast source, configure a unicast routing protocol to dynamically generate a route or configure a unicast static route to the multicast source.

2. Check whether PIM-DM is enabled on interfaces, especially the reverse path forwarding (RPF) interface towards the multicast source.

   Run the display pim interface command to check PIM information on each interface.

   If no PIM information is displayed on an interface or the PIM mode on the interface is sparse, PIM-DM is not enabled on the interface. Run the pim dm command in the interface view to enable PIM-DM.

3. Check whether IGMP is enabled on the interface directly connected to the network segment of the user hosts.

   Run the display igmp interface command to check the IGMP configuration on the interface directly connected to the network segment of the user hosts.

   If no information is displayed, IGMP is not enabled on the interface. Run the igmp enable command in the interface view to enable IGMP.

4. Check whether a source-based filtering policy is used on the router.

   Run the display current-configuration configuration pim command to check the current configuration in the PIM view.

   If the command output contains "source-policy acl-number" or "source-policy acl-name", a source-based filtering policy is configured. If the received multicast data is not in the range permitted by the ACL, the router drops the multicast data. Run the undo source-policy command to delete the source-based filtering policy or configure new ACL rules to permit the multicast data requested by the user hosts.