H3C Technologies H3C S10500 Series Switches - Manual (Page 290)

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NOTE:
•
Configurations that you make in MLD snooping view and configurations that you make in VLAN view
are mutually exclusive. Namely, after this function is enabled in MLD snooping view, it cannot be
enabled or disabled in VLAN view, and vice versa.
• Configurations that you make in MLD snooping view are effective for all VLANs. Configurations that you
make in VLAN view are effective only for ports that belong to the current VLAN.
• If the function of dropping IPv6 multicast packets is globally enabled in MLD snooping view, IPv6
multicast packets sent to MLD snooping-enabled VLANs are all dropped. The IPv6 multicast packets
mentioned here include both IPv6 multicast data packets and protocol packets, such as IPv6 PIM,
OSPFv3, and IPv6 VRRP messages.
• After the function of dropping unknown IPv6 multicast data packets is enabled in VLAN view, the switch
forwards unknown IPv6 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 IPv6 multicast data packets. Currently,
the switch supports processing unknown IPv6 multicast data packets destined for up to 1000 IPv6
unknown multicast addresses at a time. The switch floods excessive unknown IPv6 multicast data packets
directly.
• The switch allows you to configure the function of dropping unknown IPv6 multicast data packets in up
to 500 VLANs.
Configuring MLD report suppression
When a Layer 2 switch receives an MLD report from an IPv6 multicast group member, the Layer 2 switch
forwards the message to the Layer 3 device directly connected with it. When multiple members of an IPv6
multicast group are attached to the Layer 2 switch, the Layer 3 device might receive duplicate MLD
reports from these members.
With the MLD report suppression function enabled, within a query interval, the Layer 2 switch forwards
only the first MLD report of an IPv6 group to the Layer 3 device. It will not forward the subsequent MLD
reports from the same multicast group. This helps reduce the number of packets being transmitted over
the network.
Follow these steps to configure MLD report suppression:
To do... Use the command... Remarks
Enter system view system-view —
Enter MLD-snooping view mld-snooping —
Enable MLD report suppression report-aggregation
Required
Enabled by default.
CAUTION:
On an MLD snooping proxy, MLD membership reports are suppressed if the entries for the corresponding
groups exist in the forwarding table, regardless of whether the suppression function is enabled or not.