Adding new alternative paths for restoration in WSON network

A method of managing pre-planned alternative paths in a wavelength switched optical network having a number of nodes, the method having the steps of:

• receiving an indication of a fault affecting a traffic flow, the traffic flow having a working path and a number of pre-planned alternative paths from a source node to a destination node,
• determining if a number of available pre-planned alternative paths for the respective traffic flow drops to a threshold, the threshold being at least one,
• if the threshold is reached, determining a new alternative path through the nodes of the network for the respective traffic flow from the same source node to the same destination node, and
• setting up the new alternative path in the nodes, to enable one or more of them to move the traffic flow onto the new alternative path in the event of further faults.

A non-transitory computer readable storage medium storing instructions for managing pre-planned alternative paths in a wavelength switched optical network having a number of nodes, the instructions when executed by a set of processors cause the set of processors to:

• receive an indication of a fault affecting a traffic flow, the traffic flow having a working path and a number of pre-planned alternative paths from a source node to a destination node;
• determine if a number of available pre-planned alternative paths for the respective traffic flow drops to a threshold, the threshold being at least one;
• if the threshold is reached, determine a new alternative path through the nodes of the network for the respective traffic flow from the same source node to the same destination node;
• and
• set up the new alternative path in the nodes, to enable one or more of them to move the traffic flow onto the new alternative path in the event of further faults.