111
Assume that Host A needs to receive the information a specific multicast source S 10.110.5.100/24 sends
to multicast group G 232.1.1.1. Router A builds an SPT toward the multicast source. Routers on the SPT path
(Router A and Router D) have generated (S, G) entry, but Router E, which is not on the SPT path, does not
have multicast routing entries. You can use the
display pim routing-table
command to display the PIM
routing table information on each router. For example:
# Display PIM routing table information on Router A.
[RouterA] display pim routing-table
VPN-Instance: public net
Total 0 (*, G) entry; 1 (S, G) entry
(10.110.5.100, 232.1.1.1)
Protocol: pim-ssm, Flag:
UpTime: 00:13:25
Upstream interface: Serial2/0
Upstream neighbor: 192.168.1.2
RPF prime neighbor: 192.168.1.2
Downstream interface(s) information:
Total number of downstreams: 1
1: Ethernet1/1
Protocol: igmp, UpTime: 00:13:25, Expires: 00:03:25
# Display PIM routing table information on Router D.
[RouterD] display pim routing-table
VPN-Instance: public net
Total 0 (*, G) entry; 1 (S, G) entry
(10.110.5.100, 232.1.1.1)
Protocol: pim-ssm, Flag: LOC
UpTime: 00:12:05
Upstream interface: Ethernet1/1
Upstream neighbor: NULL
RPF prime neighbor: NULL
Downstream interface(s) information:
Total number of downstreams: 1
1: Serial2/0
Protocol: pim-ssm, UpTime: 00:12:05, Expires: 00:03:25
Troubleshooting PIM
This section describes common PIM problems and how to troubleshoot them.
A multicast distribution tree cannot be built correctly
Symptom
None of the routers in the network (including routers directly connected with multicast sources and
receivers) have multicast forwarding entries. In other words, a multicast distribution tree cannot be
correctly built and the receivers cannot receive multicast data.