H3C Technologies H3C S12500 Series Switches - Manual (Page 339)

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Configuring IPv6 multicast VLANs
Overview
In this chapter, the switch functions as a Layer 2 device (referred to as the switch in network diagrams);
configurations for a Layer 3 device (referred to as the router in network diagrams) are implemented on
an H3C router device.
As shown in
Figure 87 , in the traditional IPv6 multicast programs-on-demand mode, when receiver hosts
(Host A, Host B, and Host C) that belong to different VLANs require IPv6 multicast programs on demand
service, the Layer 3 device (Router A) needs to forward a separate copy of the multicast traffic in each
user VLAN to the Layer 2 device (Switch A). In this case, a large amount of network bandwidth is used
and an extra burden is added to the Layer 3 device.
Figure 87 Multicast transmission without the IPv6 multicast VLAN feature
The IPv6 multicast VLAN feature configured on the Layer 2 device is the solution to this issue. With the
IPv6 multicast VLAN feature, the Layer 3 device needs to replicate the multicast traffic only in the IPv6
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 switch supports only sub-VLAN-based IPv6 multicast VLANs.
As shown in
Figure 88 , 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.
Source
Receiver
Host A
IPv6 Multicast packets
VLAN 2
VLAN 3
VLAN 4
VLAN 2
VLAN 3
VLAN 4
Switch A
Receiver
Host B
Receiver
Host C
Router A
MLD querier