Some Downstream Pim-Capable Routers Cannot Receive Multicast Data - HP A8800 Configuration Manual

Analysis
IGMP snooping or PIM snooping is not enabled on the router.
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.
If PIM snooping is not enabled, enter VLAN view and use the pim-snooping enable command to
3.
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 addressed to 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 router 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 router.
2. If a PIM-capable router cannot be enabled with the neighbor tracking function, you have to disable
PIM snooping on the PIM snooping-capable router.
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