H3C Technologies H3C S10500 Series Switches - Manual (Page 48)

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To do... Use the command... Remarks
Enable the function of dropping
multicast data
drop-unknown
Required
Disabled by default.
Configuring the function of dropping unknown multicast data in a VLAN
Follow these steps to configure the function of dropping unknown multicast data in a VLAN:
To do... Use the command... Remarks
Enter system view system-view —
Enter VLAN view vlan vlan-id —
Enable the function of dropping
unknown multicast data
igmp-snooping drop-unknown
Required
Disabled by default.
NOTE:
•
The configuration in IGMP snooping view and the configuration in VLAN view are mutually exclusive.
Namely, after this function is enabled in IGMP snooping view, it cannot be enabled or disabled in VLAN
view, and vice versa.
• Configurations that you make in IGMP snooping view are effective for all VLANs, and configurations
that you make in VLAN view are effective only for the ports that belong to the current VLAN.
• If the function of dropping multicast packets is enabled globally in IGMP snooping view, multicast
packets that are sent to IGMP snooping-enabled VLANs are all dropped. The multicast packets
mentioned here include both multicast data packets and protocol packets, such as PIM, OSPF, and VRRP
messages.
• After the function of dropping unknown multicast data packets is enabled in VLAN view, the switch
forwards unknown multicast data packets to its router ports, if any, instead of flooding them in the
VLAN. Otherwise, if no router ports exist, the switch drops these multicast data packets. Currently, the
switch supports processing unknown multicast data packets destined for up to 2000 unknown multicast
addresses at a time. The switch floods excessive unknown multicast data packets directly.
• The switch supports the function of dropping unknown multicast data packets configuring in up to 500
VLANs.
Configuring 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 from these members.
With the IGMP report suppression function enabled, within each query interval, the Layer 2 switch
forwards only the first IGMP report per multicast group to the Layer 3 device. It will not forward the
subsequent IGMP reports from the same multicast group. This helps reduce the number of packets being
transmitted over the network.
Follow these steps to configure IGMP report suppression:
To do... Use the command... Remarks
Enter system view system-view —