Overview

Multicast VLAN Registration (MVR) is designed for different end user devices, such as IPTVs to receive the same source multicast traffic across the Ethernet network with different service VLAN tags. Usually, different end users are isolated with different service VLAN ID for security reason. Multicast stream from the upstream port is forwarded to multi-access ports tagged with different service VLAN ID.

On the other hand, the IGMP report packets from access ports for joining or leaving the multicast group, are tagged with different service VLAN IDs. When forwarding the IGMP packets to multicast router, the VLAN ID of the packets should be changed to upstream VLAN ID so as to talk to IGMP router.

Terminology

MVR

Multicast VLAN Registration is designed for delivering IPTV multicast streams over ethernet network from the same source, group and VLAN ID to different receivers in different VLAN. The VLAN ID translation should be done for the multicast traffic data and IGMP control packets between the upstream port and access ports.

MVR VLAN

It is the VLAN ID of the multicast traffic from the upstream ports connected to the multicast router. The IGMP control packets from the multicast router also use the same VLAN ID to talk to any receiver devices.

Receiver VLAN

It is the service VLAN ID allocated for one end user/device, which is connected to access port of the switch for receiving the multicast traffic.

Mrouter Port

Mrouter port is the upstream port of the switch that is connected to the multicast router for delivering the multicast traffic to end users.

IGMP Snooping

IGMP Snooping listens to IGMP packets between router and access ports of the interested multicast groups, so as to do L2 forwarding accordingly without flooding.

IGMP Packet

IGMP packet is the control message packets between IGMP router and receiver devices for joining or leaving the multicast stream.

MVR Operation Mechanism

MVR does the VLAN translation of multicast traffic on both directions from mrouter to user access port, and from access to mrouter port. There are two types of packets, multicast IGMP control packets and multicast data packets.

The multicast protocol control packets from upstream router, such as IGMP Query packets from mrouter port will be intercepted and sent out to all ports in the mapped VLAN list of the corresponding multicast group. On the other hand, the IGMP multicast group join/leave packets from receiver devices will be intercepted and translated to MVR VLAN and sent out from the mrouter port. The upstream multicast router doesn’t feel any difference if the MVR is enabled or not on the switch side.

The multicast data traffic from upstream ports will be translated to the receiver VLAN ID accordingly based on IGMP Snooping messages from each access port.

On the other hand, the multicast traffic will be forwarded to the trunk ports with same VLAN ID as the MVR VLAN.

For example, in Figure 1 sample MVR topology, the multicast router will send IGMP Query packets to Ring Node 1. If RPL link of the ERPS instance VLAN 100 is between Node 1 and Node 4, the IGMP Query packets will be forwarded to Node 2. Node 2 will forward the Query to Host 1 to Host 40, and another ERPS port1 to Node 3, and node 3 to Node 4 as well.

Figure 1. Sample MVR Topology

On ERPS Node 3, the IGMP Query packets will be forwarded to all access ports in the VLAN list with VLAN changed accordingly. When the host sends back the IGMP report packets, the VLAN will be modified to MVR VLAN and sent out from upstream port0 to multicast router.

The multicast data traffic from Node 1 will be forwarded out to Node 3 through ERPS port1 without changing of the data VLAN.