H3C Technologies H3C S5120 Series Switches - Manual (Page 316)

2-11
z After a port is configured as a simulated member host, the switch responds to IGMP general
queries by sending IGMP reports through that port.
z When the simulated joining function is disabled on a port, the switch sends an IGMP leave
message through that port.
Follow these steps to configure simulated joining:
To do... Use the command... Remarks
Enter system view system-view —
interface interface-type
interface-number
Enter Ethernet interface/Layer
2 aggregate interface view or
port group view
port-group manual port-group-name
Required
Use either approach
Configure simulated (*, G) or
(S, G) joining
igmp-snooping host-join
group-address [ source-ip
source-address ] vlan vlan-id
Required
Disabled by default
z Each simulated host is equivalent to an independent host. For example, when receiving an IGMP
query, the simulated host corresponding to each configuration responds respectively.
z Unlike a static member port, a port configured as a simulated member host will age out like a
dynamic member port.
Configuring Fast Leave Processing
The fast leave processing feature allows the switch to process IGMP leave messages in a fast way.
With the fast leave processing feature enabled, when receiving an IGMP leave message on a port, the
switch immediately removes that port from the outgoing port list of the forwarding table entry for the
indicated group. Then, when receiving IGMP group-specific queries for that multicast group, the switch
will not forward them to that port.
In VLANs where only one host is attached to each port, fast leave processing helps improve bandwidth
and resource usage. However, if fast leave processing is enabled on a port to which more than one host
is attached, when one host leaves a multicast group, the other hosts attached to the port and interested
in the same multicast group will fail to receive multicast data for that group. Therefore, if the function of
dropping unknown multicast traffic is already enabled on the switch or in the VLANs, the fast leave
processing function should not be enabled.
Configuring fast leave processing globally
Follow these steps to configure fast leave processing globally:
To do... Use the command... Remarks
Enter system view system-view —
Enter IGMP snooping view igmp-snooping —
Enable fast leave processing fast-leave [ vlan vlan-list ]
Required
Disabled by default