Northern Telecom Limited

Dino Cosimo DiPerna

Kim Bryon Roberts

David Michael Goodman

Donald Russell Ellis

David Wright Martin

Wang-Hsin Peng

David John Nicholson

Adonios Bitzanis

John B Mills

Clifford Townsend

An engineering order wire arrangement is provided for a synchronous telecommunications network comprising a plurality of nodes interconnected via transmission paths, each path accommodating a plurality of transmission channels. Engineering voice traffic is carried on a first overhead channel having a defined network route topology. A second overhead channel is used to define a model network having a a route topology identical to that of the first overhead channel. The model network is tested to determine its integrity, i.e. the absence of loops. If the model network is found to be defective, both networks are reconfigured.

Engineering order wire

A communications system is provided having SONET communications channels extending between first and second locations. The channels include pairs of forward and reverse channels for carrying traffic in normal operation between first and second locations and a protection channel for carrying traffic of one channel in the event of a fault. Each pair of forward and reverse channels is provided on a shelf at each location, the shelves having the same relative position at both locations and the protection channel is provided on a protection shelf. The protection channel includes, between the first and second locations, a forward optical link and a reverse optical link and at each of the first and second locations, a single protection loop, coupling the forward and reverse optical links, that forms the protection channel. The protection loop is used to provide, at each location, a local virtual protection loop for indicating the protection requirements and status of the respective location, and a remote virtual protection loop for indicating the protection requirements and status of the location remote from the respective location. The local protection loop is provided by inserting K1 and K2 bytes into E1 slots of STS-1 #25 and #2, respectively. The remote protection loop is provided by inserting K1 and K2 bytes into E1 slots of STS-1 #26 and #3, respectively.

Communications system with a single protection loop

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Stittsville, Canada

Dino Cosimo DiPerna