H3C Technologies H3C S3100V2 Series Switches - Manual (Page 84)

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NOTE:
•
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.
• 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
Under special circumstances, the number of IPv6 multicast groups that a switch or a port joins might
exceed the upper limit. In addition, in some specific applications, an IPv6 multicast group newly joined
on the switch must 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, enable the IPv6 multicast group replacement function on the switch or certain
ports. When the number of IPv6 multicast groups that a switch or a port has joined exceeds the limit, one
of the following occurs:
• 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.
• 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:
To do... Use the command... Remarks
Enter system view system-view —
interface interface-type
interface-number
Enter Ethernet interface/Layer 2
aggregate interface view or port
group view port-group manual
port-group-name
Required
Use either approach
Enable IPv6 multicast group
replacement mld-snooping overflow-replace
[ vlan vlan-list ] Required
Disabled by default