HP MSR2000/3000/4000 Router Series IP Multicast Configuration Guide

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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
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: Ethernet1/2
Protocol: pim-ssm, UpTime: 00:12:05, Expires: 00:03:25
Troubleshooting PIM
A multicast distribution tree cannot be correctly built
Symptom
A multicast distribution tree cannot be correctly built because no multicast forwarding entries are
established on the routers (including routers directly connected with multicast sources or receivers) in a
PIM network.
Analysis
• On a PIM-DM enabled network, multicast data is flooded from the router that directly connects to
the multicast source to the routers that directly connects to the receivers. When the multicast data is
flooded to a router, the router creates an (S, G) entry only if it has a route to the multicast source. If
the router does not have a route to the multicast source, or if PIM-DM is not enabled on the RPF
interface toward the multicast source, the router cannot create an (S, G) entry.
• On a PIM-SM enabled network, when a router wants to join the SPT, the router creates an (S, G)
entry only if it has a route to the multicast source. If the router does not have a route to the multicast
source, or if PIM-SM is not enabled on the RPF interface toward the multicast source, the router
cannot create an (S, G) entries.
• When a multicast router receives a multicast packet, it looks up the existing unicast routing table for
the optimal route to the packet source. The outgoing interface of this route act as the RPF interface
and the next hop acts the RPF neighbor. The RPF interface completely relies on the existing unicast
route and is independent of PIM. The RPF interface must be enabled with PIM, and the RPF neighbor
must be a PIM neighbor. If PIM is not enabled on the RPF interface or the RPF neighbor, the multicast
distribution tree cannot be built correctly, causing abnormal multicast forwarding.
• Because a hello message does not carry PIM mode information, a PIM router cannot identify what
PIM mode its PIM neighbor is running. If the RPF interface on a router and the connected interface