568 CHAPTER 42: IGMP SNOOPING CONFIGURATION
Configuring IGMP
Report Suppression
When a Layer 2 device receives an IGMP report from a multicast group member,
the device forwards the message to the Layer 3 device directly connected with it.
Thus, when multiple members of a multicast group are attached to the Layer 2
device, the Layer 3 device directly connected with it will receive duplicate IGMP
reports from these members.
With the IGMP report suppression function enabled, within each query cycle, the
Layer 2 device forwards only the first IGMP report per multicast group to the Layer
3 device and will not forward the subsequent IGMP reports from the same
multicast group to the Layer 3 device. This helps reduce the number of packets
being transmitted over the network.
Follow these steps to configure IGMP report suppression:
Configuring Maximum
Multicast Groups that
Can Be Joined on a Port
By configuring the maximum number of multicast groups that can be joined on a
port, you can limit the number of multicast programs on-demand available to
users, thus to regulate traffic on the port.
Follow these steps to configure the maximum number of multicast groups that
can be joined on a port or ports:
n
■ When the number of multicast groups a port has joined reaches the maximum
number configured, the system deletes all the forwarding entries persistent to
that port from the IGMP Snooping forwarding table, and the hosts on this port
need to join the multicast groups again.
■ If you have configured static or simulated joins on a port, however, when the
number of multicast groups on the port exceeds the configured threshold, the
system deletes all the forwarding entries persistent to that port from the IGMP
Snooping forwarding table and applies the static or simulated joins again, until
the number of multicast groups joined by the port comes back within the
configured threshold.
To do… Use the command… Remarks
Enter system view system-view -
Enter IGMP Snooping view igmp-snooping -
Enable IGMP report
suppression
report-aggregation Optional
Enabled by default
To do… Use the command… Remarks
Enter system view system-view -
Enter the
corresponding
view
Enter Ethernet port
view
interface interface-type
interface-number
Use either command
Enter port group
view
port-group { manual
port-group-name |
aggregation agg-id }
Configure the maximum number of
multicast groups that can be joined on
the port(s)
igmp-snooping
group-limit limit [ vlan
vlan-list ]
Optional
The default is 1024.
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