Traffic Protection in T-SDN-Enabled IP-Optical Core Networks by Adjustable Robust Optimization

Failure recovery in IP-Optical core networks has traditionally applied pure IP-based restoration, which although costly, is fast and recovers from failures in the IP and optical layers. In this paper we show that software-defined transport networks (T-SDN) may enable more efficient recovery through multilayer restoration (MR). T-SDN favors MR by exploiting the flexibility of network elements such as bandwidth variable and tunable transponders (BVTs). To study the benefits derived from this flexibility, we apply the theory of adjustable robust optimization (ARO) to formulate traffic protection methods for T-SDN enabled IP-Optical networks. Our approach protects IP traffic from optical layer failures that reduce the capacities of multiple IP links simultaneously. This is achieved by optimum routing rules in the IP layer that minimize the capacity required to protect high-priority and best-effort IP traffic. The ARO-based approach performs capacity dimensioning and IP routing that result in cost-efficient, adaptive and robust MR. For a German network scenario, the results show that cost efficiency is accomplished by the minimization of the number of BVTs and regenerators in the optical layer. For unforeseen optical failures, the ARO-based method performs robust MR by minimizing the amount of unserved traffic. The proposed approach pioneers the design of adjustable and robust MR in IP-Optical networks vulnerable to multiple partial link failures.