One of the challenging issues in optical networks is call blocking and it increases with the number of connection requests due to the limited number of wavelength channels in each fiber link. In this paper, we propose a priority based routing and wavelength assignment scheme with incorporation of a traffic grooming mechanism (PRWATG) to reduce call blocking. In this scheme, the connection requests having the same source–destination (s–d) pair are groomed first to avoid intermediate optical–electrical–optical conversation and then these groomed connection requests are served for routing and wavelength assignment according to their priority order. The priority order of each groomed connection request is estimated based on type of path (direct link physical path or indirect link physical path) first and then the traffic volume. If the priority order of connection requests is estimated using these criteria, blocking of connection requests due to wavelength continuity constraints can be reduced to a great extent, which will in turn lead to better performance of the network in terms of lower blocking probability and congestion. The performance analysis of our proposed scheme is made in terms of blocking probability and congestion and compared with a similar non-priority based routing and wavelength assignment scheme (NPRWATG). It is seen that using the PRWATG scheme, the blocking probability and the congestion of the network are significantly reduced compared to NPRWATG. It is also seen that the performance of the proposed scheme is better compared to NPRWATG when the number of connection requests increases in the network.
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