3Com 4200G 24-Port - Configuring a Port as a Simulated Group Member

2-12
Configuring a Port as a Simulated Group Member
Generally, hosts running IGMP respond to the IGMP query messages of the multicast switch. If hosts
fail to respond for some reason, the multicast switch may consider that there is no member of the
multicast group on the local subnet and remove the corresponding path.
To avoid this from happening, you can configure a port of the VLAN of the switch as a multicast group
member. When the port receives IGMP query messages, the multicast switch will respond. As a result,
the port of the VLAN can continue to receive multicast traffic.
Through this configuration, the following functions can be implemented:
z When an Ethernet port is configured as a simulated member host, the switch sends an IGMP report
through this port. Meanwhile, the switch sends the same IGMP report to itself and establishes a
corresponding IGMP entry based on this report.
z When receiving an IGMP general query, the simulated host responds with an IGMP report.
Meanwhile, the switch sends the same IGMP report to itself to ensure that the IGMP entry does not
age out.
z When the simulated joining function is disabled on an Ethernet port, the simulated host sends an
IGMP leave message.
Therefore, to ensure that IGMP entries will not age out, the port must receive IGMP general queries
periodically.
Table 2-17 Configure a port as a simulated group member
Operation Command Remarks
Enter system view system-view —
Enter Ethernet port view
interface interface-type
interface-number
—
Configure the current port as a
simulated multicast group
member
igmp host-join group-address
[source-ip source-address ]
vlan vlan-id
Optional
Simulated joining is disabled by
default.
z Before configuring a simulated host, enable IGMP Snooping in VLAN view first.
z The port to be configured must belong to the specified VLAN; otherwise the configuration does not
take effect.
z You can use the source-ip source-address command to specify a multicast source address that
the port will join as a simulated host. This configuration takes effect when IMGPv3 Snooping is
enabled in the VLAN.