3Com S7906E Configuration Manual page 1388

multicast VLAN instead of making a separate copy of the multicast traffic in each user VLAN. This saves
the network bandwidth and lessens the burden of the Layer 3 device.
The IPv6 multicast VLAN feature can be implemented in two approaches, as described below:
Sub-VLAN-based IPv6 multicast VLAN
As shown in Figure 1-2, Host A, Host B and Host C are in three different user VLANs. On Switch A,
configure VLAN 10 as an IPv6 multicast VLAN, configure all the user VLANs as sub-VLANs of this IPv6
multicast VLAN, and enable MLD snooping in the IPv6 multicast VLAN.
Figure 1-2 Sub-VLAN-based IPv6 multicast VLAN
IPv6 Multicast packets
VLAN 10 (IPv6 Multicast VLAN)
VLAN 2
VLAN 3
VLAN 4
Source Router A
MLD querier
After the configuration, MLD snooping manages router ports in the IPv6 multicast VLAN and member
ports in the sub-VLANs. When forwarding multicast data to Switch A, Router A needs to send only one
copy of multicast traffic to Switch A in the IPv6 multicast VLAN, and Switch A distributes the traffic to the
IPv6 multicast VLAN's sub-VLANs that contain receivers.
Port-based IPv6 multicast VLAN
As shown in Figure 1-3, Host A, Host B and Host C are in three different user VLANs. All the user ports
are hybrid ports. On Switch A, configure VLAN 10 as an IPv6 multicast VLAN, assign all the user ports
to this IPv6 multicast VLAN, and enable MLD Snooping in the IPv6 multicast VLAN and all the user
VLANs.
Switch A
1-2
VLAN 2
Receiver
Host A
VLAN 3
Receiver
Host B
VLAN 4
Receiver
Host C