Wavelength routing and switching mechanism for a photonic transport network

A connection between a source node and a destination node is automatically routed and switched in a WDM photonic network 1 , on receipt of a connection request. A switching and routing mechanism selects a plurality of valid link paths using a path tree, where invalid branches are eliminated based on constraints received with the connection request, and on a link and path cost functions. A regenerator placement tree 25 is used for determining a plurality of viable regenerator paths for each valid link path. On the regenerator placement tree 25 , non-viable branches are eliminated based on constraints received with the request and on regenerator availability at the intermediate nodes along the respective path. Next, the switching and routing mechanism assigns a set of wavelengths to each viable regenerator path, and estimates the performance of the path using a Q calculator 39. The regenerator paths are ordered according to their performance and the switching and routing mechanism 30 attempts to setup a path to serve the request.