Periodically, the Mrouter sends Membership Queries to ensure that the host wants to continue
receiving the multicast. If the host fails to respond with a Membership Report, the Mrouter stops
sending the multicast to that path.
The host can send an IGMPv2 Leave report to the switch, which sends a proxy Leave report to the
Mrouter. The multicast path is terminated immediately.
A maximum of 8 VLANs can be configured for IGMP Snooping. The switch can learn up to 16 multicast
routers, and supports up to 1,000 multicast groups.
IGMPv3 includes new membership report messages to extend IGMP functionality. The switch provides
snooping capability for all types of IGMP version 3 (IGMPv3) Membership Reports, as described in
IGMPv3 supports Source-Specific Multicast (SSM). SSM identifies session traffic by both source and group
addresses. The switch uses source filtering, which allows hosts to report interest in receiving multicast
packets only from specific source addresses, or from all but specific source addresses.
The switch supports the following IGMPv3 filter modes:
INCLUDE mode: The host requests membership to a multicast group and provides a list of IP
addresses from which it wants to receive traffic.
EXCLUDE mode: The host requests membership to a multicast group and provides a list of IP
addresses from which it does not want to receive traffic. This indicates that the host wants to receive
traffic only from sources that are not part of the Exclude list.
To disable snooping on EXCLUDE mode reports, use the following command:
By default, the switch snoops the first eight sources listed in the IGMPv3 Group Record. Use the following
command to change the number of snooping sources:
IGMPv3 Snooping is compatible with IGMPv1 and IGMPv2 Snooping. You can disable snooping on
version 1 and version 2 reports, using the following command:
When the switch with IGMP Snooping enabled receives an IGMPv2 leave message, it sends a Group-
Specific Query to determine if any other devices in the same group (and on the same port) are still
interested in the specified multicast group traffic. The switch removes the affiliated port from that particular
group, if the following conditions apply:
If the switch does not receive an IGMP Membership Report message within the query-response-
If no multicast routers have been learned on that port.
With FastLeave enabled on the VLAN, a port can be removed immediately from the port list of the group
entry when the IGMP Leave message is received, unless a multicast router was learned on the port.
Enable FastLeave only on VLANs that have only one host connected to each physical port.