British Telecommunications Public Limited Company

Raymond S Chng

Christopher P Botham

Mark C Sinclair

A distributed restoration process operated by nodes in a communications network, the process being run in a background mode, i.e. at times when a node is not operating at full capacity, the each end node of an existing path and having a higher network ID will act as master and broadcast path-finder signatures on its spans. Each node receiving a path-finder signature adds the path length of the span to the node from which it received the path-finder signature and, in turn, forwards the amended signature on its spans. The slave node on receiving path-finder signatures selects the signature corresponding to the lowest path length, this being referred to as the restoration path, and sends a return signature to notify the nodes along the existing path of the path length of the restoration path.

Restoration in communications networks

Restoration of connections by a distributed restoration process in a fully or partly meshed communications network of nodes, the restoration method comprising the steps of responding at a first end node of a path in the network to receipt of an indication that the path has failed to retrieve the identity of one or more nodes stored in the first end node in association with the identity of the path and constituting a stored restoration path for the path, sending a connection signature to the node at the other end of the path via the stored restoration path, responding at the other end node to receipt of a connection signature to send a confirmation signature to confirm establishment of the stored restoration path, broadcasting from the first end node in response to the receipt of the indication a path-finder signature to find a restoration path for the failed path by real-time restoration process, sending from the other node a real-time restoration path confirmation signature identifying a real-time restoration path selected by the other end node from one or more received path-finder signatures, and in the first end node switching traffic data for the other end node from the failed path to either the stored restoration path or the selected real-time restoration path, depending upon which confirmation signature is first received at the node.

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Colchester, United Kingdom

Raymond S Chng