31.4.3 Connection with the multicast router

In addition to the hosts that have already joined a group, the forwarding destinations for multicast packets also include neighboring multicast routers. When the Switch and a multicast router are connected and MLD snooping is used, the port connected to the multicast router to forward multicast packets to the router (abbreviated hereafter to a multicast router port) can be specified by configuration.

The Switch forwards all multicast packets to the specified multicast router port.

Also, because MLD is a protocol for sending and reception between routers and hosts, MLD messages are accepted by routers and hosts. The Switch forwards MLD messages as shown in the following table.

Table 31-5 Operation for MLDv1 Messaging
MLDv1 message type	Transfer port within the VLAN	Remarks
Multicast Listener Query	Forwarded to all ports.
Multicast Listener Report	Forwarded only to multicast router ports.
Multicast Listener Done	Not forwarded to any port when group members still exist for other ports. Forwarded to multicast router ports when no group members exist for other ports.	^#

#: Relay operation is performed when a querier is set for the local device and another device is a representative querier. If the local device is a representative querier, MLDv1 Done messaging is not forwarded. If no querier has been set, forwarding is always performed to multicast router ports. However, if a port that has not received an MLDv1 or MLDv2 Report (membership request) message receives an MLDv1 Done message, the MLDv1 Done message is not forwarded regardless of the querier settings.

Table 31-6 Operation for MLDv2 Messaging
MLDv2 message type		Transfer port within the VLAN	Remarks
Version2 Multicast Listener Query		Forwarded to all ports.
Version2 Multicast Listener Report	Membership Request Report	Forwarded only to multicast router ports.
Version2 Multicast Listener Report	Leave Request Report	Not forwarded to any port when group members still exist for other ports. Forwarded to multicast router ports when no group members exist for other ports.	^#

#: Relay operation is performed when a querier is set for the local device and another device is a representative querier. If the local device is a representative querier, MLDv2 Report (detachment req) messageis not forwarded. If no querier has been set, forwarding is always performed to multicast router ports. However, if a port that has not received an MLDv1 or MLDv2 Report (membership request) message receives an MLDv2 Report (leave request) message, the MLDv2 Report (leave request) message is not forwarded regardless of the querier settings.