LOOP-BACK IN DUAL RING NETWORK

摘要

This invention aims at making a loop-back recovery when a failure takes place in a ring network for transmitting information to a path indicated with a path ID number or. the time slot position from a periodic frame. This is achieved by establishing working paths on one of the dual ring line between a transmission node and a receiving node thereof, establishing ring-formed protection paths in a ring line of the direction opposite to the working line, and a loop-back is made from the working paths to the corresponding protection paths at a node which detected the failure.