1-19To do... Use the command... RemarksConfigure the maximumnumber of multicast groupsallowed on the port(s)igmp-snooping group-limitlimit [ vlan vlan-list ]OptionalBy default, the maximumnumber of multicast groupsallowed on the port(s) is 1000z When the number of multicast groups a port has joined reaches the maximum number configured,the system deletes all the forwarding entries persistent to that port from the IGMP Snoopingforwarding table, and the hosts on this port need to join the multicast groups again.z If you have configured static or simulated joins on a port, however, when the number of multicastgroups on the port exceeds the configured threshold, the system deletes all the forwarding entriespersistent to that port from the IGMP Snooping forwarding table and applies the static or simulatedjoins again, until the number of multicast groups joined by the port comes back within theconfigured threshold.Configuring Multicast Group ReplacementFor some special reasons, the number of multicast groups that can be joined on the current switch orport may exceed the number configured for the switch or the port. In addition, in some specificapplications, a multicast group newly joined on the switch needs to replace an existing multicast groupautomatically. A typical example is “channel switching”, namely, by joining a new multicast group, a userautomatically 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 orcertain ports. When the number of multicast groups joined on the switch or a port has joined reaches thelimit:z If the multicast group replacement feature is enabled, the newly joined multicast groupautomatically replaces an existing multicast group with the lowest address.z If the multicast group replacement feature is not enabled, new IGMP reports will be automaticallydiscarded.Configuring multicast group replacement globallyFollow these steps to configure multicast group replacement globally:To do... Use the command... RemarksEnter system view system-view —Enter IGMP Snooping view igmp-snooping —Enable multicast groupreplacementoverflow-replace [ vlanvlan-list ]RequiredDisabled by defaultConfiguring multicast group replacement on a port or a group of portsFollow these steps to configure multicast group replacement on a port or a group of ports:
