Alcatel Lucent

Alcatel

Hans-Jörg Jäkel

Pierre A Humblet

Dieter Beller

Luigi Ronchetti

Werner Beisel

Martin Huck

Hartmut Borschel

Brian William Schoenherr

Walter Kailbach

Kerstin Skerra

A method of restoring an active path between two nodes of a transport network upon occurrence of a failure includes the steps of determining an alternate path through the network and establishing a path protection involving the failed active path and the alternate path. If in layered networks, a failed path is restored at a lower layer and at a higher layer concurrently, the restoration actions in the higher network layer can thus be reverted easily.

Network restoration

A network element for a transport network contains a multistage lower order switching matrix with at least an input matrix stage and an output matrix stage designed to switch lower order multiplex units and with a center stage capable of switching higher order multiplex units, only, thereby connecting the input and output stages.

Network element with multistage lower order switching matrix

An 1:n or m:n path protection mechanism is provided. Rather than defining an automatic protection protocol, use is made of the existing tandem connection monitoring function, tandem connection reverse defect indication, and tandem connection trail trace identifier. Upon detection of a failure on the working path segment, the occurrence of this failure is communicated to the far end node by inserting forced RDI into the tandem connection as long as the failure persists. In the case of more than one protected paths, the failed path is identified by means of the unique trail trace identifier received on the protection path. In the case of several protection paths, one network node is defined as slave node which has to follow the switch-over initiated by the master node and choose the same protection path as the master node. Preferably, a combination of two timers enables return from failure condition to normal operation.

M:N path protection

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Stuttgart, Germany

Hans-Jörg Jäkel