Communications system with protection switching using channel identities and individual selectors.

摘要

An optical fiber communications system with a plurality of bidirectional channels (1, 2) and a protection channel (P) 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 (42). 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 (24) back to the transmit end of the span, and using this request in a controller (38) for the channel to effect a protection switch, using an individual selector (36) for the channel, if a priority scheme allows. The controllers (38, 39) 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.