I. Introduction
The significant increase in the availability of high-speed research networks has led to the deployment of large-scale distributed computing environments that are able to serve a large number of geographically separated users by exchanging large amounts of data. Direct communication between sites and computing facilities is now necessary in many working environments. This results in greatly expanded requirements for high-speed, dedicated networks that cross multiple domains. The European Research Network GEANT [1] and National Research and Educational Networks (NRENs) in Europe are high-capacity networks which are based on optical technologies and components that provide wavelength-based services to the research community.