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3.
If PIM snooping is not enabled, enter VLAN view and use the
pim-snooping enable
command
to enable PIM snooping for 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 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.
