H3C Technologies H3C S12500 Series Switches - Manual (Page 45)

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NOTE:
•
After you enable dropping unknown multicast data, the switch does not drop the unknown multicast
data with the multicast MAC address of 0100-5E00-00xx (where "x" represents any hexadecimal
number from 0 to F) or 0100-5E00-0101. Instead, the switch floods the multicast data in the VLANs to
which they belong.
• After you enable dropping unknown multicast data, the switch still forwards unknown multicast data to
other router ports in the VLAN.
Enabling IGMP report suppression
When a Layer 2 switch receives an IGMP report from a multicast group member, the switch forwards the
message to the Layer 3 device that directly connects to the Layer 2 switch. When multiple members of a
multicast group are attached to the Layer 2 switch, the Layer 3 device might receive duplicate IGMP
reports for the multicast group from these members.
With the IGMP report suppression function enabled, within each query interval, the Layer 2 switch
forwards only the first IGMP report for the multicast group to the Layer 3 device. It does not forward the
subsequent IGMP reports for the same multicast group. This helps reduce the number of packets being
transmitted over the network.
On an IGMP snooping proxy, IGMP reports for a multicast group from downstream hosts are suppressed
if the forwarding entry for the multicast group exists on the proxy, whether the suppression function is
enabled or not.
To enable IGMP report suppression:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter IGMP-snooping view. igmp-snooping N/A
3. Enable IGMP report
suppression.
report-aggregation Enabled by default.
Setting the maximum number of multicast groups that a port can
join
You can set the maximum number of multicast groups that a port can join to regulate traffic on the port.
When you configure this maximum number, if the number of multicast groups the port has joined exceeds
the configured maximum value, the system deletes all the forwarding entries for the port from the IGMP
snooping forwarding table, and the hosts on this port join multicast groups again until the number of
multicast groups that the port joins reaches the maximum value. When the port joins a multicast group,
if the port has been configured as a static member port, the system applies the configurations to the port
again. If you have configured simulated joining on the port, the system creates corresponding
forwarding entry for the port after receiving a report from the simulated member host.
To set the maximum number of multicast groups that a port can join: