3Com S7906E - Switch, Configuration Manual

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For devices that support both drop-unknown and mld-snooping drop-unknown commands at
the same time, the configuration made in MLD snooping view and the configuration made 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.
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Configurations made in MLD snooping view are effective for all VLANs, while configurations made
in VLAN view are effective only for ports belonging to the current VLAN.
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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.
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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 S7900E 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.
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The S7900E supports the function of dropping unknown IPv6 multicast data packets configuring in
up to 500 VLANs.
Configuring MLD Report Suppression
When a Layer 2 device receives an MLD report from an IPv6 multicast group member, the Layer 2
device forwards the message to the Layer 3 device directly connected with it. Thus, when multiple
members belonging to an IPv6 multicast group exist on the Layer 2 device, the Layer 3 device directly
connected with it will receive duplicate MLD reports from these members.
With the MLD report suppression function enabled, within a query interval, the Layer 2 device forwards
only the first MLD report of an IPv6 group to the Layer 3 device and will not forward the subsequent
MLD 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 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
Optional
Enabled by default