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When the function of dropping unknown IPv6 multicast data is disabled, the switch floods
unknown IPv6 multicast data in the VLAN that the data belongs to, causing network bandwidth
waste and low forwarding efficiency.
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When the function of dropping unknown IPv6 multicast data is enabled, the switch forwards
unknown multicast data to its router ports instead of flooding it in the VLAN. If no router ports
exist, the switch drops the unknown multicast data.
Configuration procedure
To enable dropping unknown IPv6 multicast data in a VLAN:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter VLAN view.
vlan
vlan-id
N/A
3.
Enable dropping unknown
IPv6 multicast data.
mld-snooping drop-unknown
Disabled by default.
Enabling 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 directly connected Layer 3 device. When multiple members of an
IPv6 multicast group are attached to the Layer 2 switch, the Layer 3 device might receive duplicate
MLD reports for the IPv6 multicast group.
With the MLD report suppression function enabled, within a query interval, the Layer 2 switch
forwards only the first MLD report for the IPv6 multicast group to the Layer 3 device. It does not
forward subsequent MLD reports for the same IPv6 multicast group to the Layer 3 device. This helps
reduce the number of packets being transmitted over the network.
On an MLD snooping proxy, MLD reports for an IPv6 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 MLD report suppression:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter MLD-snooping view.
mld-snooping
N/A
3.
Enable MLD 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 IPv6 multicast groups that a port can join to regulate the traffic
on the port.
When you configure this maximum number, if the number of IPv6 multicast groups the port has
joined exceeds the configured maximum value, the system deletes all forwarding entries for the port
from the MLD snooping forwarding table, and the hosts on this port join IPv6 multicast groups again
until the number of IPv6 multicast groups that the port joins reaches the maximum value. When the
port joins an IPv6 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
