Ring interworking between bidirectional line-switched ring transmission

Abstract

The possibility of passing off apparent 'good' higher level digital signals that may include corrupted or failed lower level digital signals because of inter-ring grooming of the lower level digital signals from a bidirectional line-switched ring to a path-switched ring and vice versa which employ first and second shared nodes is minimized by dual feeding communications circuits from the bidirectional line-switched ring to the path-switched ring and vice versa via the shared nodes. An inter-ring groomed communications circuit is provisioned from a secondary ring node in the line-switched ring of one of the shared nodes (secondary communications circuit) to be supplied to a primary ring node in the other of the shared nodes of the line-switched ring. A replica of the secondary communications circuit is demultiplexed to obtain the lower level digital signals, which are evaluated on a pair-wise basis with corresponding lower level digital signals from the primary ring node. The least corrupted of the evaluated lower level signals are selected to be combined into a new primary communications circuit which is to be inserted in the line-switched transmission path. An inter-ring groomed communications circuit is provisioned from a secondary ring node of one of the shared nodes in the path-switched ring to be supplied to a primary ring node in the other shared node of the path-switched ring. The secondary communications circuit is demultiplexed to obtain the lower level signals which are evaluated on a pair-wise basis with lower level signals from a corresponding primary communications circuit to determine which of the lower level signals are least corrupted. The selected least corrupted lower level signals are combined into a new primary communications circuit which is then dual fed in the path-switched ring primary ring node.