ZyXEL Communications Dimension GS-3012, User Manual, Page: 146 / 259

GS-3012/GS-3012F User’s Guide
20-6 Multicast
Figure 20-4 MVR Network Example
20.5.1 Types of MVR Ports
In MVR, a source port is a port on the switch that can send and receive multicast traffic in a multicast VLAN while
a receiver port can only receive multicast data. Once configured, the switch maintains a forwarding table that
matches the multicast stream to the associated multicast group.
20.5.2 MVR Modes
You can set your switch to operate in either dynamic or compatible mode.
In dynamic mode, the switch sends IGMP leave and join reports to the other multicast devices (such as multicast
routers or servers) in the multicast VLAN. This allows the multicast devices to update the multicast forwarding
table to forward or not forward multicast traffic to the receiver ports.
In compatible mode, the switch does not send any IGMP reports. In this case, you must manually configure the
forwarding settings on the multicast devices in the multicast VLAN.
20.5.3 How MVR Works
The following figure shows a multicast television example where a subscriber device (such as a computer) in
VLAN 1 receives multicast traffic from the streaming media server,
S , via the switch. Multiple subscriber devices
can connect through a port configured as the receiver on the switch.
When the subscriber selects a television channel, computer A sends an IGMP report to the switch to join the
appropriate multicast group. If the IGMP report matches one of the configured MVR multicast group addresses on
the switch, an entry is created in the forwarding table on the switch. This maps the subscriber VLAN to the list of
forwarding destinations for the specified multicast traffic.
When the subscriber changes the channel or turns off the computer, an IGMP leave message is sent to the switch to
leave the multicast group. The switch sends a query to VLAN 1 on the receiver port (in this case, a DSL port on the
switch). If there is another subscriber device connected to this port in the same subscriber VLAN, the receiving port