1-11 IPv6 Multicast VLAN ConfigurationWhen configuring IPv6 multicast VLAN, go to these sections for information you are interested in:z Introduction to IPv6 Multicast VLANz IPv6 Multicast VLAN Configuration Task Listz Configuring IPv6 Sub-VLAN-Based IPv6 Multicast VLANz Configuring Port-Based IPv6 Multicast VLANz Displaying and Maintaining IPv6 Multicast VLANz IPv6 Multicast VLAN Configuration ExamplesIntroduction to IPv6 Multicast VLANAs shown in Figure 1-1, in the traditional IPv6 multicast programs-on-demand mode, when hosts, HostA, Host B and Host C, belonging 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 userVLAN to the Layer 2 device, Switch A. This results in not only waste of network bandwidth but also extraburden on the Layer 3 device.Figure 1-1 Multicast transmission without IPv6 multicast VLANThe IPv6 multicast VLAN feature configured on the Layer 2 device is the solution to this issue. With theIPv6 multicast VLAN feature, the Layer 3 device needs to replicate the multicast traffic only in the IPv6multicast VLAN instead of making a separate copy of the multicast traffic in each user VLAN. This savesthe 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 VLANAs 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 IPv6multicast VLAN, and enable MLD snooping in the IPv6 multicast VLAN.
