Energy-efficient traffic grooming in sliceable-transponder-equipped IP-over-elastic optical networks [invited]

The sliceable optical transponder, which can transmit/receive multiple optical flows, was recently proposed to improve a transponder´s flexibility. The upper-layer traffic can be offloaded onto an optical layer with “just-enough transponder” resources. Traffic grooming evolves as the optical transponder shifts from fixed to sliceable. “Optical-layer grooming” enabled by a sliceable optical transponder can reduce the number of power-consumption components (e.g., IP ports and optical transponders). In this paper, energy-efficient traffic grooming in IP-over-elastic optical networks with a sliceable optical transponder is studied. Three bandwidth-variable transponders (BVTs) based on their sliceability, namely, non-sliceable BVTs, fully sliceable BVTs, and partially sliceable BVTs, are investigated. For each transponder, we develop energy-minimized traffic grooming integer linear programming (ILP) models and corresponding heuristic algorithms. Comprehensive comparisons are performed among the three types of transponders, and two interesting observations emerge. First, we find that significant power savings can be achieved by using a sliceable optical transponder. Second, we find that power savings do not keep improving linearly while transponder sliceability is increasing, and traditional electrical-layer grooming is still required to work together with optical-layer grooming to reduce power consumption.