Routing and spectrum allocation method for immediate reservation and advance reservation requests in elastic optical networks

Numerous studies have investigated elastic optical networks (EON) with the aim of expanding the transmission capacities of core networks. To achieve this goal, it is necessary to solve the issue of wastage of spectrum resources caused by spectrum fragmentation. Moreover, considering the potentially high traffic demands of future networks, it is important to handle not only requests that need to be reserved immediately (IR: Immediate Reservation) but also those that can be reserved in advance (AR: Advance Reservation). In networks that support the coexistence of IR requests and AR requests, ensuring fair reservation of spectrum resources for both IR requests and AR requests becomes a challenging task. In this paper, we propose a novel dynamic routing and spectrum allocation method to reduce spectrum fragmentation and to improve the fairness in reservation for IR requests and AR requests. We verify the effectiveness of the proposed method through computer simulations.