Troubleshooting Ipv6 Pim Configuration; Failure Of Building A Multicast Distribution Tree Correctly - HP 4800G Series Configuration Manual

Total number of downstreams: 1
1: Vlan-interface100
Protocol: mld, UpTime: 00:00:11, Expires: 00:03:25
The information on Switch B and Switch C is similar to that on Switch A.
# View the IPv6 PIM multicast routing table information on Switch B.
[SwitchD] display pim ipv6 routing-table
Total 0 (*, G) entry; 1 (S, G) entry
(4001::100, FF3E::101)
Protocol: pim-ssm, Flag: LOC
UpTime: 00:08:02
Upstream interface: Vlan-interface300
Upstream neighbor: NULL
RPF prime neighbor: NULL
Downstream interface(s) information:
Total number of downstreams: 1
1: Vlan-interface105
Protocol: pim-ssm, UpTime: 00:08:02, Expires: 00:03:25

Troubleshooting IPv6 PIM Configuration

Failure of Building a Multicast Distribution Tree Correctly

Symptom
None of the routers in the network (including routers directly connected with IPv6 multicast sources and
receivers) has IPv6 multicast forwarding entries. That is, a multicast distribution tree cannot be built
correctly and clients cannot receive IPv6 multicast data.
Analysis
An IPv6 PIM routing entry is created based on an IPv6 unicast route, whichever IPv6 PIM mode is
running. Multicast works only when unicast does.
IPv6 PIM must be enabled on the RPF interface. An RPF neighbor must be an IPv6 PIM neighbor
as well. If IPv6 PIM is not enabled on the RPF interface or the RPF neighbor, the establishment of
a multicast distribution tree will surely fail, resulting in abnormal multicast forwarding.
IPv6 PIM requires that the same IPv6 PIM mode, namely DM or SM, must run on the entire network.
Otherwise, the establishment of a multicast distribution tree will surely fail, resulting in abnormal
multicast forwarding.
Solution
1) Check IPv6 unicast routes. Use the display ipv6 routing-table command to check whether a
unicast route exists to the IPv6 multicast source or the RP.
2) Check that the RPF interface is IPv6 PIM enabled. Use the display pim ipv6 interface command
to view the IPv6 PIM information on each interface. If IPv6 PIM is not enabled on the interface, use
the pim ipv6 dm or pim ipv6 sm command to enable IPv6 PIM.
3) Check that the RPF neighbor is an IPv6 PIM neighbor. Use the display pim ipv6 neighbor
command to view the PIM neighbor information.
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