H3C Technologies H3C S10500 Series Switches - Manual (Page 445)

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1: Vlan-interface100
Protocol: mld, UpTime: 00:00:11, Expires: 00:03:25
# 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 to build a multicast distribution tree correctly
Symptom
None of the routers in the network (including routers directly connected with IPv6 multicast sources and
receivers) have 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 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 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.
4. Check that IPv6 PIM and MLD are enabled on the interfaces that are directly connected to the IPv6
multicast source and to the receiver.