Communications system with protection switching and channel identities

摘要

An optical fiber communications system with a plurality of bidirectional channels and a protection channel is disclosed. Each channel has a respective identity which is transmitted in the traffic of that channel and in the event of a protection switch is identified in the protection channel traffic. A protection switch is effected by detecting a channel failure at the receive end of a span, transmitting a protection request on the return channel back to the transmit end of the span, and using this request in a controller for the channel to effect a protection switch, using an individual selector for the channel, if a priority scheme allows. The controllers are enabled or disabled under software control following a protection switch in accordance with the prevailing priority scheme. The arrangement provides for rapid protection switching.