Joint banding-node placement and resource allocation for multigranular elastic optical networks

The fine-grained grid of elastic optical networks (EONs) facilitates flexible bandwidth allocation and increased spectrum utilization efficiency and is seen as a promising solution to handle ever-increasing traffic demands. Despite this, fiber capacity exhaustion is imminent, and multifiber links are expected to be prevalent in future optical networks. A challenge this brings about is the high port count of optical cross-connects (OXCs). Conventional OXCs built using flex-grid wavelength selective switches do not scale well. To achieve scalability of OXCs, a flexible wavebanding OXC architecture (FLEX) has been proposed recently. FLEX reduces the complexity and cost of OXCs while sacrificing some performance in terms of limited switching flexibility. Taking the reduced switching capability into consideration, a cost-function pluggable auxiliary layered-graph framework has been proposed in our previous work to solve the routing, fiber, waveband, and spectrum assignment (RFBSA) problem in multifiber-based EONs with flexible wavebanding nodes. In this paper, we address the following problem. Given the total number of available WSSs for the network as a budget, we determine how many FLEX nodes to deploy and where to deploy them, and solve the RFBSA problem jointly to optimize the network performance. An integer linear programming formulation is proposed for a set of traffic requests. We also propose a heuristic algorithm to solve this joint problem efficiently. The results show that our algorithm achieves good network performance, which is indicated by the average maximum spectrum usage as well as considerably reducing hardware costs. We also evaluate our algorithm for dynamically arriving traffic requests in terms of demand blocking ratio.