Routing and Scheduled Spectrum Allocation for transfer-based datacenter connections

Creating datacenter (DC) federations allows DC operators to reduce costs and increase their revenues from using under-utilized resources as well as to expand their geographical coverage aiming to improve users´ Quality of Experience. Since huge capacity is needed to interconnect the DCs in a federation, elastic optical networks can be used. Taking advantage of an intelligent control plane, connectivity can be requested on demand. To that end, the Application-Based Network Operations (ABNO) architecture, standardized by the IETF, can be used. Notwithstanding, connection requests can be blocked in the case that no optical resources are available at the time they are needed. In view of that, an Application Service Orchestrator (ASO) on top of the ABNO architecture can be used to coordinate resource utilization among services. Under that approach, DC resource managers request data transferences using an application-oriented semantic, including data volume and completion time. Those requests are transformed into connection requests by the ASO, which solves the Routing and Scheduled Spectrum Allocation (RSSA) problem that might involve performing elastic operations over on-going transferences while ensuring their committed completion time. In this paper, we detail an algorithm for solving the RSSA problem under scenarios where spectral resources are highly utilized reducing thus spectrum fragmentation.