Priority Order-Based Key Distribution in QKD-Secured Optical Networks

In quantum key distribution (QKD)-secured optical networks, blocking increases with the number of QKD lightpath requests as well as with the number of times modification required to improve the security level of QKD lightpath requests. The blocking is severe problem in such networks because of the limited number of resources (wavelengths and time-slots) in each fiber link. In this paper, we propose a priority order-based routing wavelength and time-slot allocation (POB-RWTA) scheme to reduce the blocking of QKD lightpath requests. In the proposed POB-RWTA scheme, the QKD lightpath requests are served according to their priority order. The priority order of each QKD lightpath request is based on the security level. The blocking of high priority lightpath requests (HPLRs) and total incoming QKD lightpath requests due to limited resources can be reduced using the above criterion of priority order. The performance analysis of the proposed POB-RWTA scheme is made in terms of the success probability of QKD lightpath requests considering different wavelengths for QSCh and the probability of secret key update failure. We compared the proposed POB-RWTA scheme with a non-priority order-based routing wavelength and time-slot allocation (NPOB-RWTA) scheme. Simulations performed on NSFNET topology show that by using the POB-RWTA scheme, the success probability of HPLRs and total incoming QKD lightpath requests are significantly improved as compared to NPOB-RWTA.