3Com Switch 8800 Advanced Software V5 Configuration Guide

554 CHAPTER 41: IGMP SNOOPING CONFIGURATION
n
■ When the number of multicast groups a port has joined reaches the maximum
number configured, the system deletes this port from all the related IGMP
Snooping forwarding entries, and hosts on this port need to join the multicast
groups again.
■ If you have configured a port to be a static member port or a simulated
member of a multicast group, the system deletes this port from all the related
IGMP Snooping forwarding entries and applies the configurations again, until
the number of multicast groups the port has joined reaches the maximum
number configured.
Configuring Multicast
Group Replacement
For some special reasons, the number of multicast groups that can be joined on
the current switch or Ethernet port may exceed the number configured for the
switch or the port. In addition, in some specific applications, a multicast group
newly joined on the switch needs to replace an existing multicast group
automatically, namely, by joining a new multicast group, a user automatically
switches from the current multicast group to the new one.
To address such situations, you can enable the multicast group replacement
function on the switch or certain Ethernet ports. When the number of multicast
groups joined on the switch or an Ethernet port has joined reaches the limit:
■ If the multicast group replacement feature is enabled, the newly joined
multicast group automatically replaces an existing multicast group with the
lowest address.
■ If the multicast group replacement feature is not enabled, new IGMP reports
will be automatically discarded.
Configuring multicast group replacement globally
Follow these steps to configure multicast group replacement globally:
Configuring multicast group replacement on a port or a group port
Follow these steps to configure multicast group replacement on a port or a group
ports:
To do... Use the command... Remarks
Enter system view system-view -
Enter IGMP Snooping view igmp-snooping -
Configure multicast group
replacement
overflow-replace [ vlan
vlan-list ]
Required
Disabled by default
To do... Use the command... Remarks
Enter system view system-view -
Enter the
correspon
ding view
Enter Ethernet
interface view
interface interface-type
interface-number
Use either command
Enter interface
group view
port-group { manual
port-group-name |
aggregation agg-id }
Configure multicast group
replacement
igmp-snooping
overflow-replace [ vlan
vlan-list ]
Required
Disabled by default