Planning Low-Cost SDN Transport Networks with Integrated, Fast and Robust IP-Optical Restoration

Abstract:
This paper studies the design of fast, robust and low-cost software-defined Metro/Core networks that implement IP-Optical restoration. This strategy restores in the optical layer IP links affected by optical failures. When an optical failure occurs, optical restoration is first applied to restore the affected IP links. During this process, the IP layer applies a fast-reroute mechanism to temporarily protect high-priority (HP) traffic. Best-effort (BE) traffic is not protected in this stage. Once the IP links are restored, IP restoration is applied to recover HP and BE traffic by a robust mechanism that adjusts the routing and capacity of the IP tunnels carrying the traffic. This mechanism applies decision rules for online adjustment of the capacity and routing of the IP tunnels, thereby the network restores IP traffic from unforeseen optical failures. The techno-economic benefits of the approach are assessed for a realistic German network scenario. The results show that, w.r.t pure IP restoration, IP-Optical restoration introduces high capacity cost savings for low and moderate HP traffic loads. Besides, in case of unexpected optical failures, the approach – regardless of the HP traffic contribution, and after applying optical restoration – minimizes the amount of unserved traffic w.r.t pure IP restoration.