ZyXEL Communications OLT2406, Руководство пользователя

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Chapter 25 Multicast
OLT2406 User’s Guide
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Figure 124 MVR Network Example
25.4.1 Types of MVR Ports
In MVR, a source port is a port on the OLT that can send and receive multicast traffic in a multicast VLAN
while a receiver port can only receive multicast traffic. Once configured, the OLT maintains a
forwarding table that matches the multicast stream to the associated multicast group.
25.4.2 MVR Modes
You can set your OLT to operate in either dynamic or compatible mode.
In dynamic mode, the OLT 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 OLT does not send any IGMP reports. In this case, you must manually configure
the forwarding settings on the multicast devices in the multicast VLAN.
25.4.3 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 OLT. Multiple
subscriber devices can connect through a port configured as the receiver on the OLT.
When the subscriber selects a television channel, computer A sends an IGMP report to the OLT to join
the appropriate multicast group. If the IGMP report matches one of the configured MVR multicast group
addresses on the OLT, an entry is created in the forwarding table on the OLT. 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 OLT
to leave the multicast group. The OLT sends a query to VLAN 1 on the receiver port (in this case,
an uplink port on the OLT). 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 OLT removes the receiver port from the forwarding table.