Distance-adaptive online RSA algorithms for heterogeneous flex-grid networks

Flex-grid elastic optical networks are an enabling technology for future heterogeneous on-demand optical bandwidth services. Heterogeneous means that optical connection requests for different services requiring different data rates would coexist in the network. In this context, Routing and Spectrum Assignment (RSA) algorithms face the challenge of making a fair allocation of resources, providing a similar blocking performance to all the services. In this paper, we review existing RSA proposals applicable to heterogeneous flex-grid networks, evaluating (i) their blocking performance averaged among services, and (ii) the fairness in the blocking observed by each individual service. In addition, we propose the Partial-Sharing-Partitioning (PSP), a scheme to balance both aforementioned metrics. We concentrate on a distance-adaptive scenario, where the same connection request can be carried with different modulations, associated to different spectral efficiencies and optical reaches. Our simulation results in the Net2Plan tool explore the interplay between average blocking and fairness. We observe that many classical RSA algorithms produce unfair allocations, while PSP permits tuning the balance between both metrics. The algorithms developed are publicly available in the open-source Net2Plan repository.