H3C Technologies H3C S10500 Series Switches - Manual (Page 50)

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To address such situations, enable the multicast group replacement function on the switch or on a certain
port. When the number of multicast groups joined on the switch or on a port reaches the limit, one of the
following occurs:
• If the multicast group replacement feature is not enabled, new IGMP reports are automatically
discarded.
• If the multicast group replacement feature is enabled, the multicast group that the switch or a port
newly joins automatically replaces an existing multicast group that has the lowest address.
Configuring multicast group replacement globally
Follow these steps to configure multicast group replacement globally:
To do... Use the command... Remarks
Enter system view system-view —
Enter IGMP-snooping view igmp-snooping —
Enable multicast group
replacement
overflow-replace [ vlan vlan-list ]
Required
Disabled by default.
Configuring multicast group replacement on a port or a group of ports
Follow these steps to configure multicast group replacement on a port or a group of ports:
To do... Use the command... Remarks
Enter system view system-view —
Enter Layer 2 Ethernet interface
view or Layer 2 aggregate
interface view:
interface interface-type
interface-number
Enter Layer 2 Ethernet interface
view, Layer 2 aggregate interface
view, or port group view
Enter port group view:
port-group manual
port-group-name
Required
Use either command
Enable multicast group
replacement igmp-snooping overflow-replace
[ vlan vlan-list ] Required
Disabled by default.
CAUTION:
Be sure to configure the maximum number of multicast groups allowed on a port (see “ Setting the
maximum number of multicast groups that a port can join ”) before enabling multicast group
replacement. Otherwise, the multicast group replacement functionality will not take effect.
Configuring 802.1p precedence for IGMP messages
You can change 802.1p precedence of IGMP messages so that they can be assigned higher forwarding
priority when congestion occurs on their outgoing ports.
Configuring 802.1p precedence for IGMP messages globally
Follow these steps to configure 802.1p precedence for IGMP messages globally: