Chapter 45 Multicast
XGS2220 Series User’s Guide
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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.
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
, through 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, an uplink port on the Switch). If there is another subscriber device connected to this port in the
same subscriber VLAN, the receiving port will still be on the list of forwarding destination for the multicast
traffic. Otherwise, the Switch removes the receiver port from the forwarding table.
Figure 202
MVR Multicast Television Example
45.2 IPv4 Multicast Status
Click
SWITCHING
>
Multicast
>
IPv4 Multicast
>
IPv4 Multicast Status
to display the screen as shown. This
screen shows the IPv4 multicast group information. See
for more information
on multicasting.
Figure 203
SWITCHING > Multicast > IPv4 Multicast > IPv4 Multicast Status
