Wavelength division multiplexed (WDM) networks are matured to provide, scalable data centric infrastructure, capable of delivering flexible, value
added, high speed and high bandwidth services directly from the optical (WDM)
layer. But, providing fault-tolerance at an acceptable level of overhead in these
networks has become a critical problem. Several methods exist in the literature
which attempt to guarantee recovery in a timely and resource efficient manner.
These methods are centered around a-priori reservation of network resources called spare resources along a node disjoint protection path. This protection path is usually routed from source to destination along a totally link disjoint path from primary path. This paper considers the problem of routing and wavelength
assignment (RWA) in wavelength routed WDM optical networks. In particular, we propose an efficient algorithm to select routes and wavelengths to establish dependable connections (D-connections), called segmented protection paths. Our algorithm does not insist on the existence of totally disjoint paths to provide full protection. We present
experimental results which suggest that our scheme is attractive enough
in terms of average call acceptanc ratio, spare wavelength utilisation, and number of requests that can be satisfied for a given number of wavelengths assuming that the requests come one at time, and wavelengths are assigned according to fixed ordering.