H3C Technologies H3C S12500 Series Switches - Manual (Page 444)

428
Assume that Host A needs to receive the information a specific IPv6 multicast source S
4001::100/64 sends to IPv6 multicast group G FF3E::101. Switch A builds an SPT toward the
IPv6 multicast source. Switches on the SPT path (Switch A and Switch D) have generated an (S, G)
entry, but Switch E, which is not on the SPT path, does not have IPv6 multicast routing entries. You
can use the display pim ipv6 routing-table command to view the IPv6 PIM routing table
information on each switch. For example:
# Display the IPv6 PIM multicast routing table information on Switch A.
[SwitchA] display pim ipv6 routing-table
Total 0 (*, G) entry; 1 (S, G) entry
(4001::100, FF3E::101)
Protocol: pim-ssm, Flag:
UpTime: 00:00:11
Upstream interface: Vlan-interface101
Upstream neighbor: 1002::2
RPF prime neighbor: 1002::2
Downstream interface(s) information:
Total number of downstreams: 1
1: Vlan-interface100
Protocol: mld, UpTime: 00:00:11, Expires: 00:03:25
# Display 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
A multicast distribution tree cannot be built correctly
Symptom
None of the routers in the network (including routers directly connected with IPv6 multicast sources and
receivers) has IPv6 multicast forwarding entries. 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.