H3C Technologies H3C S10500 Series Switches - Manual (Page 76)

61
Expires: 00:03:01, FSM: J
(*, 225.1.1.1)
Upstream neighbor: 10.1.1.1
Upstream port: GE1/0/2
Total number of downstream ports: 1
1: GE1/0/4
Expires: 00:01:05, FSM: J
The output shows that Switch A will forward the multicast data intended for multicast group 224.1.1.1 to
only Router C, and forward the multicast data intended for multicast group 225.1.1.1 to only Router D.
Troubleshooting PIM snooping
PIM snooping does not work
Symptom
PIM snooping does not work on the switch.
Analysis
IGMP snooping or PIM snooping is not enabled on the switch.
Solution
1. Use the display current-configuration command to check the status of IGMP snooping and PIM
snooping.
2. If IGMP snooping is not enabled, enter system view and use the igmp-snooping command to
enable IGMP snooping globally. Then, enter VLAN view and use the igmp-snooping enable and
pim-snooping enable commands to enable IGMP snooping and PIM snooping in the VLAN.
3. If PIM snooping is not enabled, enter VLAN view and use the pim-snooping enable command to
enable PIM snooping in the VLAN.
Some downstream PIM-capable routers cannot receive
multicast data
Symptom
In a network with fragmented join/prune messages, some downstream PIM-capable routers cannot
receive multicast data.
Analysis
PIM snooping cannot reassemble messages, and it cannot maintain the status of downstream routers that
the join/prune message fragments carry. To ensure the normal operation of the system, PIM snooping
must broadcast join/prune message fragments in the VLAN. However, if the VLAN has a PIM-capable
router that has the join suppression function enabled, the broadcast join/prune message fragments might
suppress the join messages of other PIM-capable routers in the VLAN. As a result, some PIM-capable
routers cannot receive the multicast data destined for a specific multicast group because their join
messages are suppressed. To solve this problem, disable the join suppression function on all PIM-capable
routers that connect to the PIM snooping-capable switch in the VLAN.