H3C Technologies H3C S12500 Series Switches - Manual (Page 66)

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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 determine 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.
Solution
1. Use the pim hello-option neighbor-tracking command to enable the neighbor tracking function on
the interfaces of PIM routers that connect to the PIM snooping-capable switch.
2. If a PIM-capable router cannot be enabled with the neighbor tracking function, you have to disable
PIM snooping on the switch.