H3C Technologies H3C S7500E Series Switches - Manual (Page 281)

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z When the number of IPv6 multicast groups that can be joined on a port reaches the
maximum number configured, the system deletes all the forwarding entries persistent to
that port from the MLD snooping forwarding table, and the hosts on this port need to join
IPv6 multicast groups again.
z If you have configured static or simulated joining on a port, however, when the number of
IPv6 multicast groups on the port exceeds the configured threshold, the system deletes all
the forwarding entries persistent to that port from the MLD snooping forwarding table and
applies the static or simulated joining again, until the number of IPv6 multicast groups
joined by the port comes back within the configured threshold.
Configuring IPv6 Multicast Group Replacement
For some special reasons, the number of IPv6 multicast groups passing through a switch or
port may exceed the number configured for the switch or the port. In addition, in some specific
applications, an IPv6 multicast group newly joined on the switch needs to replace an existing
IPv6 multicast group automatically. A typical example is “channel switching”, namely, by joining
the new multicast group, a user automatically switches from the current IPv6 multicast group to
the new one.
To address this situation, you can enable the IPv6 multicast group replacement function on the
switch or certain ports. When the number of IPv6 multicast groups a switch or a port has joined
exceeds the limit.
z If the IPv6 multicast group replacement is enabled, the newly joined IPv6 multicast group
automatically replaces an existing IPv6 multicast group with the lowest IPv6 address.
z If the IPv6 multicast group replacement is not enabled, new MLD reports will be
automatically discarded.
Configuring IPv6 multicast group replacement globally
Follow these steps to configure IPv6 multicast group replacement globally:
To do... Use the command... Remarks
Enter system view system-view —
Enter MLD snooping view mld-snooping —
Enable IPv6 multicast group
replacement
overflow-replace [ vlan
vlan-list ]
Required
Disabled by default
Configuring IPv6 multicast group replacement on a port or a group of ports
Follow these steps to configure IPv6 multicast group replacement on a port or a group of ports: