49
Incoming interface: Vlan-interface101
List of 1 outgoing interfaces:
1: Vlan-interface104
Matched 19648 packets(20512512 bytes), Wrong If 0 packets
Forwarded 19648 packets(20512512 bytes)
The output shows that Switch A maintains a multicast forwarding entry for multicast packets from Source
1 to 224.1.1.1. No forwarding entry exists for packets from Source 2 to 224.1.1.1, which indicates that
multicast packets from Source 2 are blocked.
Troubleshooting IGMP snooping
Layer 2 multicast forwarding cannot function
Symptom
Layer 2 multicast forwarding cannot function.
Analysis
IGMP snooping is not enabled.
Solution
1.
Use the
display current-configuration
command to check 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 the
igmp-snooping enable
command to enable IGMP snooping in VLAN
view.
3.
If IGMP snooping is disabled only for the corresponding VLAN, 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 interface view to
verify that 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.