Video bridging enables video packets to be forwarded over bridges from a headend device down to downstream device. In this case, the video travels from the source, or head-end device, using one video stream to passively traverse the Zhone device backplane. This lowers the bandwidth requirements for video packets traversing the device.
Video bridging requires configuring an uplink bridge and a downlink bridge. On the uplink bridge, the Forward Via Multicast Paths function is associated with a location that contains the video content that allows the Zhone device to receive video streams from the network. An interface with this value set to true only transmits multicast traffic for which a JOIN request was received. A bridge interface with the Forward Via Multicast Paths parameter set to false discards multicast traffic from that interface. By default, the Forward Via Multicast Paths parameter is set to true on uplink bridges and false on downlink bridges.
On the downlink bridge, the Multicast Address Learning function is associated with interfaces that have hosts connected to them and allows the Zhone device to send video groups from downlink interfaces to the network. By default, the Multicast Address Learning parameter is set to true on downlink bridges.
Note that JOIN requests enter on a Multicast Address Learning interface associated with a downlink bridge and pass through on a Forward Via Multicast Paths interface associated with an uplink bridge.
The following table describes various video bridge behaviors associated with different combinastions of settings for the bridge parameters.
Multicast Address Learning |
Forward Via Multicast Paths |
Behavior |
False |
False |
The interface discards all incoming multicast packets and does not forward any of the packets. |
True |
False |
The interface forwards both default multicast signaling packets and control multicast packets. |
False |
True |
The interface forwards control packets received on this interface to all other interfaces that have the Multicast Address Learning field set to true that have sent a JOIN message for a group |
True |
True |
Treat the same as an interface with the Multicast Address Learning field set to false and the Forward Via Multicast Paths field set to true. |
For more information about bridging on Zhone devices see the manuals on Zhone website http://www.zhone.com/support/manuals/.
November 6, 2011