H3C Technologies H3C WX6000 Series Access Controllers - Manual (Page 327)

29-9
Configuring Simulated Joining
Generally, a host running IGMP responds to IGMP queries from the IGMP querier. If a host fails to
respond due to some reasons, the multicast router may deem that no member of this multicast group
exists on the network segment, and therefore will remove the corresponding forwarding path.
To avoid this situation from happening, you can enable simulated joining on a port of the switch, namely
configure the port as a simulated member host for a multicast group. When an IGMP query is heard, the
simulated host gives a response. Thus, the switch can continue receiving multicast data.
A simulated host acts like a real host, as follows:
z
When a port is configured as a simulated member host, the switch sends an unsolicited IGMP
report through that port.
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 group
message through that port.
Follow these steps to configure simulated joining:
To do... Use the command... Remarks
Enter system view system-view —
Enter Ethernet port
view interface interface-type
interface-number
Enter the
corresponding view Enter port group
view
port-group { manual port-group-name
| aggregation agg-id }
Use either command
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 group messages in a fast
way. With the fast leave processing feature enabled, when receiving an IGMP leave group 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.