3Com S7902E, Configuration Manual

Page: 308 / 2621

3-8
To do... Use the command... Remarks
Enable IGMP snooping globally
igmp-snooping
Required
Disabled by default
Return to system view
quit
—
Enter VLAN view of a multicast
VLAN
vlan vlan-id
—
Enable IGMP snooping
igmp-snooping enable
Required
Disabled by default
Drop unknown multicast traffic
igmp-snooping
drop-unknown
Optional
Configuring the IGMP snooping mode
In the IGMP snooping mode, the OLT and ONUs mainly use IGMP report, leave, and query messages
to manage dynamic multicast group membership. The OLT can implement simple user multicast access
control through the multicast VLAN configuration on UNI ports of the ONU. More complex service
access control is realized through the IPTV service platform.
You can use the OLT to remotely configure the aging timer of the ONU router port, the aging timer
of multicast group member ports, and the query response timer.
Table 3-1
Timers used by IGMP snooping
Timer name Time
Messages received
within timer expiry
Action upon timer
expiry
Router port aging timer
Aging time of a router
port
IGMP general query
message, PIM
message, Dvmrp
Probe message
Considers the port not
a router port
Aging timer for
multicast group
member port Aging time of the
multicast group
member port
IGMP host report
message
Sends an IGMP
group-specific query
message to the
multicast member port
Query response timer
Maximum
response-to-query
time
IGMP report message
Removes the port from
the member port list of
the multicast group
Configuring IGMP membership report suppression
When an ONU receives an IGMP membership report from a multicast group member, the ONU
forwards the message to the OLT. Thus, when multiple members of a multicast group are attached to
the ONU, the OLT will receive duplicate IGMP reports from these members.
With the IGMP report suppression function enabled, within each query cycle, the ONU forwards only the
first IGMP report of a multicast group to the OLT and will not forward the subsequent IGMP reports from
the same multicast group to the OLT. This helps to reduce the number of packets being transmitted over
the network.
Follow these steps to configure multicast in IGMP snooping mode: