H3C Technologies H3C S10500 Series Switches - Manual (Page 291)

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Setting the maximum number of multicast groups that a port can
join
The maximum number of IPv6 multicast groups that a port can join can limit the number of multicast
programs available to VOD users to control the traffic on the port.
Follow these steps configure the maximum number of IPv6 multicast groups that a port can join:
To do... Use the command... Remarks
Enter system view system-view —
Enter Layer 2 Ethernet interface
view, Layer 2 aggregate interface
view, port group view
Enter Layer 2 Ethernet interface
view or Layer 2 aggregate
interface view:
interface interface-type
interface-number
Enter port group view:
port-group manual
port-group-name
Required
Use either command
Configure the maximum number of
IPv6 multicast groups that a port
can join
mld-snooping group-limit limit
[ vlan vlan-list ] Required
1000 by default.
NOTE:
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 the 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 port, the system
establishes corresponding forwarding entry for the port after receiving a report from the simulated
member host.
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 that the switch
newly joins must replace an existing IPv6 multicast group automatically. A typical example is channel
switching: To view a new channel, a user 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 a certain
port. 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 not enabled, new MLD reports will be automatically
discarded.
• If the IPv6 multicast group replacement is enabled, the IPv6 multicast group that the switch or a port
newly joins automatically replaces an existing IPv6 multicast group that has the lowest IPv6 address.
Configuring IPv6 multicast group replacement globally
Follow these steps to configure IPv6 multicast group replacement globally: