Netgear M4100-50G (GSM7248v2h2) - 46‐port GE + 4 GE Combo L2 Managed Switch Guía De Administador

The IGMP Layer 3 protocol is widely used for IPv4 network multicasting. In Layer 2 networks, 
the IGMP protocol uses resources inefficiently. For example, a Layer 2 switch multicast traffic 
to all ports even if there are receivers connected to only a few ports.

To address this problem, the IGMP Snooping protocol was developed. But the problem 
reappears when receivers are in different VLANs. Multicast VLAN registration (MVR) is 
intended to solve the problem of receivers in different VLANs. It uses a dedicated manually 
configured VLAN, called the multicast VLAN, to forward multicast traffic over Layer 2 network 
in conjunction with IGMP snooping.

MVR, like the IGMP Snooping protocol, allows a Layer 2 switch to snoop on the IGMP control 
protocol. Both protocols operate independently of each other. Both protocols can be enabled 
on the switch interfaces at the same time. In such a case, MVR listens to the join and report 
messages only for groups configured statically. All other groups are managed by IGMP 
snooping.

There are two types of MVR ports: source and receiver.

The source port is the port to which the multicast traffic flows using the multicast VLAN. 

The receiver port is the port where a listening host is connected to the switch. It can utilize 
any (or no) VLAN, except the multicast VLAN. This implies that the MVR switch performs 
VLAN tag substitution from the multicast VLAN source port to the VLAN tag used by the 
receiver port.

The Multicast VLAN is the VLAN that is configured in the specific network for MVR purposes. 
It has to be manually specified by the operator for all source ports in the network. It is a VLAN 
that is used to transfer multicast traffic over the network to avoid duplication of multicast 
streams for clients in different VLANs. A diagram of a network configured for MVR is shown in 
the following illustration. SP is the source port and RP is the receiver port.