Survivable WDM mesh networks, part I - Protection

This investigation, considers optical networks which employ wavelength cross-connects that enable the establishment of wavelength-division-multiplexed (WDM) channels, between node-pairs. In such and other networks, the failure of a network element (e.g., fiber link, cross-connect, etc.) may cause the failure of several optical channels, thereby leading to large data losses. This study examines different approaches to protect mesh-based WDM optical networks from single-link failures. These approaches are based on two basic survivability paradigms: (a) path protection/restoration, and (b) link protection/restoration. lit path- and link- protection schemes, backup paths and wavelengths are reserved in advance at the time of call setup. Path- and link-restoration schemes are dynamic schemes in which backup paths are discovered (from the spare capacity in the network) upon the occurrance of a failure. In part 1 of this study presented in this paper, we formulated Integer Linear Programs to determine the capacity requirements for the above protection schemes for a static traffic demand. In part 2 of Mis study presented in [1] we analyse the protection-switching times for different protection schemes, propose distributed restoration protocols, and analyse the restoration-time, and restoration efficiency characteristics of the different restoration protocols.