An agile transparent network with a trail routing and switching (also called "engineering") mechanism is provided that enables efficient use of regenerators and wavelengths available in the network, while maintaining a very efficient time-to-service. The trail engineering mechanism allows fast, automatic establishment of new connections based on the current network architecture, connectivity and loading and also on conditions in the connection request. Selection of regenerator sites and of the wavelengths used on each regenerator segment is performed with optimal use of current network resources, while ensuring that the quality of the selected trail is adequate for the respective call. The mechanism provides for both distance and performance balancing, and it optimizes the network response time.