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 one bidirectional line-switched ring to another bidirectional line-switched ring, employing at least a first shared node and a second shared node, is minimized by dual feeding communications circuits from one line-switched ring to the other via the shared nodes. An inter-ring groomed communications circuit is provisioned from a secondary ring node of one of the shared nodes (secondary communications circuit) of a particular ring to be supplied to a primary ring node in the other shared node of the same ring. Additionally, a replica of the secondary communications circuit is demultiplexed in the primary ring node to obtain the lower level digitals signals therefrom. Then, the lower level digital signals in the secondary communications circuit are evaluated on a pairwise basis with corresponding lower level digital signals in a corresponding communications circuit (primary communications circuits) being supplied from the inter-ring grooming apparatus associated with the primary ring node to determine the least corrupted signal in each pair. The least corrupted lower level signals are selected and combined into a 'new' primary communications circuit which is inserted in the primary ring node.