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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
—
Enter Ethernet interface/Layer 2
aggregate interface view or port
group view
interface
interface-type
interface-number
Required
Use either approach
port-group
manual
port-group-name
Enable IPv6 multicast group
replacement
mld-snooping overflow-replace
[
vlan
vlan-list
]
Required
Disabled by default
CAUTION:
Be sure to configure the maximum number of IPv6 multicast groups allowed on a port before
enabling IPv6 multicast group replacement. Otherwise, the IPv6 multicast group replacement
functionality will not take effect. For more information about the maximum number of IPv6 groups
that a port can join, see "
Configuring maximum multicast groups that a port can join
."
Configuring 802.1p precedence for MLD messages
You can change 802.1p precedence of MLD messages so that they can be assigned higher
forwarding priority when congestion occurs on their outgoing ports.
Configuring 802.1p precedence for MLD messages globally
Follow these steps to configure 802.1p precedence for MLD messages globally: