ABSTRACT
Lightpath control is one of the key issues in wavelength-routed wavelength division multiplexing (WDM) networks. To achieve good network perfor-
mance, the network must employ a lightpath control mechanism to efficiently establish lightpaths for connection requests. In general, lightpath establishment can be performed under either centralized or distributed control. Although centralized control is relatively simple to implement and works well for static traffic, it is not scalable and reliable. For this reason, centralized control is not considered suitable for large networks with dynamic traffic. In contrast, distributed control improves network scalability and reliability, and is highly preferred for large WDM networks; however, distributed control increases the complexity in implementation, which presents a big challenge for network designers.
