Multicast VLAN replication is used to distribute the same multicast data to different user VLANs.
On a Layer 2 broadcast network, multicast data is broadcast to all hosts. Internet Group Management Protocol (IGMP) snooping solves this problem but it takes effect only within a VLAN. If users in different VLANs require the same multicast data, the upstream router still has to send multiple copies of identical multicast data to different VLANs.
Multicast VLAN replication can be configured on a Layer 2 device to implement multicast data replication across VLANs. After this function is configured, the upstream router replicates multicast data in the multicast VLAN and sends only one copy to the Layer 2 device, instead of sending several identical multicast data flows downstream. This saves network bandwidth and reduces the burden on the router.