Effect of routing convergence time on lightpath establishment in GMPLS-controlled WDM optical networks

In this paper we consider routing and wavelength assignment of primary and shared backup lightpaths using OSPF-TE routing information and CR-LDP signalling in GMPLS-based WDM optical mesh networks. In the emerging generalized multi-protocol label switching (GMPLS) based WDM transport networks, called intelligent optical transport networks, WDM-based optical components like add-drop multiplexers (ADMs) and optical cross connects (OXCs) will have full knowledge of the wavelengths in the network, status, and traffic carrying capacity of each wavelength. With such intelligence, these intelligent optical networks could create self-connecting and self-regulating connections on-the-fly. In these networks, after a lightpath establishment or release, the routing protocol may take considerable amount of time to update the routing database at all the nodes in the network, known as routing convergence time (T_o). In case of dynamic traffic, where lightpath requests arrive to and depart from the network randomly; the routing and wavelength assignment for a new lightpath request may be carried out based on non-updated (old) link state information resulting in conflicts and hence leads to higher blocking probability. In this paper we evaluate the blocking performance for different scenarios, such as primary and shared backup lightpath establishment, with full and partial information. The simulation results show that the partial information case over performs the full information case with respect to connection blocking probability.