Troubleshooting Pim Configuration; Failure To Build A Multicast Distribution Tree Correctly - HP A6600 Configuration Manual

Upstream neighbor: 192.168.1.2
RPF prime neighbor: 192.168.1.2
Downstream interface(s) information:
Total number of downstreams: 1
1: GigabitEthernet0/0/0
The information on Router B and Router C is similar to that on Router A.
# View the 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: GigabitEthernet0/0/0
Upstream neighbor: NULL
RPF prime neighbor: NULL
Downstream interface(s) information:
Total number of downstreams: 1
1: GigabitEthernet0/0/3

Troubleshooting PIM configuration

Failure to build a multicast distribution tree correctly

Symptom
None of the routers in the network (including routers directly connected with multicast sources and
receivers) has multicast forwarding entries. That is, a multicast distribution tree cannot be built correctly
and clients cannot receive multicast data.
Analysis
When PIM-DM runs on the entire network, multicast data is flooded from the first hop router
•
connected with the multicast source to the last hop router connected with the clients. When the
multicast data is flooded to a router, no matter which router is, it creates (S, G) entries 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 router's RPF interface to the multicast source, the router cannot create (S, G)
entries.
When PIM-SM runs on the entire network, and when a router will join the SPT, the router creates (S,
•
G) entries only if it has a route to the multicast source. If the router does not have a router to the
multicast source, or if PIM-DM is not enabled on the router's RPF interface to the multicast source, the
router cannot create (S, G) entries.
When a multicast router receives a multicast packet, it searches the existing unicast routing table for
•
the optimal route to the RPF check object. The outgoing interface of this route will act as the RPF
interface and the next hop will be taken as the RPF neighbor. The RPF interface completely relies on
Protocol: igmp, UpTime: 00:13:25, Expires: 00:03:25
Protocol: pim-ssm, UpTime: 00:12:05, Expires: 00:03:25
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