H3C Technologies H3C S12500 Series Switches - Manual (Page 60)

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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 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-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.
{
If PIM is enabled, the switch deletes only its dynamic member ports but not its dynamic router
ports.
NOTE:
On a switch with Layer-3 multicast routing enabled, use the display igmp group port-info command
to view Layer-2 port information.
• If PIM is disabled on the switch, one of the following occurs:
{
If IGMP is disabled, the switch deletes all its dynamic router ports.
{
If IGMP is enabled, the switch maintains all its dynamic member ports and dynamic router
ports.