H3C Technologies H3C S7500E Series Switches - Manual (Page 70)

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Analysis
z The ACL rule is incorrectly configured.
z The multicast group policy is not correctly applied.
z The function of dropping unknown multicast data is not enabled, so unknown multicast data
is flooded.
Solution
1) Use the display acl command to check the configured ACL rule. Make sure that the ACL
rule conforms to the multicast group policy to be implemented.
2) Use the display this command in IGMP snooping view or in the corresponding interface
view to check whether the correct multicast group policy has been applied. If not, use the
group-policy or igmp-snooping group-policy command to apply the correct multicast
group policy.
3) Use the display current-configuration command to check whether the function of
dropping unknown multicast data is enabled. If not, use the drop-unknown or
igmp-snooping drop-unknown command to enable the function of dropping unknown
multicast data.
Appendix
Processing of Multicast Protocol Messages
With Layer 3 multicast routing enabled, an IGMP snooping switch processes multicast protocol
messages differently under different conditions, specifically as follows:
1) If only IGMP is enabled, or both IGMP and PIM are enabled on the switch, The switch
z Maintains dynamic member ports or dynamic router ports according to IGMP packets.
z Maintains dynamic router ports according to PIM hello packets.
2) If only PIM is enabled on the switch:
z The switch broadcasts IGMP messages as unknown messages in the VLAN.
z Upon receiving a PIM hello message, the switch will maintain the corresponding dynamic
router port.
3) When IGMP is disabled on the switch:
z If PIM is disabled, the switch deletes all its dynamic member ports and dynamic router
ports.
z If PIM is enabled, the switch deletes only its dynamic member ports without deleting its
dynamic router ports.