Traffic Engineering with Joint Link Weight and Segment Optimization

Most ISPs use sophisticated traffic engineering strategies based on link weight optimizations to efficiently provision their backbone network and to serve intra-domain traffic. While traditionally, traffic is split among the shortest weighted paths using ECMP, recently, an additional dimension for optimization arose in the context of segment routing: traffic can be steered away from congested shortest paths by inserting intermediate destinations, so-called waypoints. This paper investigates the benefits of jointly optimizing the link weights and waypoints for traffic engineering both analytically and empirically. In particular, we formulate the joint optimization problem and formally quantify the benefits of joint optimizations over separate link-weights and waypoints optimizations, using a rigorous analysis. We also present an efficient joint optimization algorithm and evaluate its performance in realistic and synthetic scenarios.