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Configuring IPv6 multicast VLANs
Overview
As show in Figure 74, Host A, Host B, and Host C reside in different VLANs and join the same IPv6
multicast group. When Switch A (Layer 3 device) receives IPv6 multicast data for that group, it sends
three copies of the data to Switch B (Layer 2 device). This occupies large bandwidth and increases the
burden on the Layer 3 device.
Figure 74 Multicast transmission without the IPv6 multicast VLAN feature
After an IPv6 multicast VLAN is configured on Switch B, Switch A only sends one copy of the IPv6
multicast data for the IPv6 multicast VLAN on Switch B. This saves network bandwidth and lessens the
burden on the Layer 3 device.
IPv6 multicast VLANs include sub-VLAN-based IPv6 multicast VLANs and port-based IPv6 multicast
VLANs.
Sub-VLAN-based IPv6 multicast VLAN
As shown in Figure 75:
• Host A, Host B, and Host C are in VLAN 2 through VLAN 4, respectively.
• On Switch B, VLAN 10 is an IPv6 multicast VLAN. VLAN 2 through VLAN 4 are sub-VLANs of
VLAN 10.
• MLD snooping is enabled for the multicast VLAN and its sub-VLANs.
Source
Receiver
Host A
IPv6 Multicast packets
VLAN 2
VLAN 3
VLAN 4
VLAN 2
VLAN 3
VLAN 4
Switch B
Receiver
Host B
Receiver
Host C
Switch A
MLD querier