H3C Technologies H3C WX6000 Series Access Controllers - Manual (Page 177)

24-5
If no IGMP report in response to the group-specific query is heard on a member port before its
aging timer expires, this means that no hosts attached to the port are still listening to that group
address. The switch removes the port from the outgoing port list of the forwarding table entry for
that multicast group when the aging timer expires.
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 handles
multicast protocol messages in the normal way.
2) If only PIM is enabled on the switch:
The switch broadcasts IGMP messages as unknown messages in the VLAN.
Upon receiving a PIM hello message, the switch will maintain the corresponding router port.
3) When IGMP is disabled on the switch:
If PIM is disabled, the switch clears all dynamic member ports and dynamic router ports.
If PIM is disabled, the switch clears all dynamic member ports but still maintains dynamic router
ports.
4) When PIM is disabled on the switch:
If IGMP is disabled, the switch clears all its dynamic router ports.
If IGMP is enabled, the switch keeps maintaining all dynamic member ports and dynamic router
ports.
Protocols and Standards
IGMP snooping is documented in:
RFC 4541: Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener
Discovery (MLD) Snooping Switches
Configuring IGMP Snooping
Configuration Task List
Perform the tasks in Table 24-1 to configure IGMP snooping.