H3C Technologies H3C S7500E Series Switches - Manual (Page 54)

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To do... Use the command... Remarks
Enable the function of dropping
unknown multicast data packets
igmp-snooping drop-unknown
Required
Disabled by default
z For devices that support both drop-unknown and igmp-snooping drop-unknown
commands at the same time, the configuration made in IGMP snooping view and the
configuration made 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.
z Configurations made in IGMP snooping view are effective for all VLANs, while
configurations made in VLAN view are effective only for ports belonging to the current
VLAN.
z If the function of dropping multicast packets is globally enabled in IGMP snooping view,
multicast packets 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.
z 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 S7500E 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.
z The S7500E supports the function of dropping unknown multicast data packets configuring
in up to 500 VLANs.
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:
To do... Use the command... Remarks
Enter system view system-view —