Troubleshooting Igmp Snooping Configuration; Switch Fails In Layer 2 Multicast Forwarding; Configured Multicast Group Policy Fails To Take Effect - 3Com 4500G Family Configuration Manual

Troubleshooting IGMP Snooping Configuration

Switch Fails in Layer 2 Multicast Forwarding

Symptom
A switch fails to implement Layer 2 multicast forwarding.
Analysis
IGMP Snooping is not enabled.
Solution
1) Enter the display current-configuration command to view the running status of IGMP Snooping.
2) If IGMP Snooping is not enabled, use the igmp-snooping command to enable IGMP Snooping
globally, and then use igmp-snooping enable command to enable IGMP Snooping in VLAN view.
3) If IGMP Snooping is disabled only for the corresponding VLAN, just use the igmp-snooping
enable command in VLAN view to enable IGMP Snooping in the corresponding VLAN.

Configured Multicast Group Policy Fails to Take Effect

Symptom
Although a multicast group policy has been configured to allow hosts to join specific multicast groups,
the hosts can still receive multicast data addressed to other multicast groups.
Analysis
The ACL rule is incorrectly configured.
The multicast group policy is not correctly applied.
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 port 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 igmp-snooping drop-unknown command to
enable the function of dropping unknown multicast data.
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