51
Solution
1.
Use the
display current-configuration
command to display the running status of IGMP
snooping.
2.
If IGMP snooping is not enabled, use the
igmp-snooping
command in system view to enable
IGMP snooping globally. Then, use the
igmp-snooping enable
command in VLAN view to
enable IGMP snooping for the VLAN.
3.
If IGMP snooping is enabled globally but not enabled for the VLAN, use the
igmp-snooping
enable
command in VLAN view to enable IGMP snooping for the 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 verify 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.
3.
Use the
display current-configuration
command to verify that 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
This section describes details about processing multicast protocol messages.
Processing of multicast protocol messages
With Layer 3 multicast routing enabled, an IGMP snooping-enabled switch processes multicast
protocol messages differently under different conditions, as follows:
•
If only IGMP is enabled on the switch, or if both IGMP and PIM are enabled on the switch, the
switch does the following:
{
Maintains dynamic member ports or dynamic router ports according to IGMP packets
{
Maintains dynamic router ports according to PIM hello packets
•
If only PIM is enabled on the switch, the following occur:
{
The switch broadcasts IGMP messages as unknown messages in the VLAN.
{
After receiving a PIM hello message, the switch maintains the corresponding dynamic
router port.
•
If IGMP is disabled on the switch, one of the following occurs:
{
If PIM is disabled, the switch deletes all its dynamic member ports and dynamic router ports.
