Combining Midpoint Optimization and Conventional End-to-End Segment Routing for Traffic Engineering

A recent innovation in the context of Segment Routing (SR) Traffic Engineering (TE) is the use of the Midpoint Optimization (MO) concept to substantially reduce the number of SR policies required to implement TE solutions. However, these benefits come at the price of a potential deterioration of traffic steering capabilities as the individual, per-demand traffic control of end-to-end (E2E) SR is lost. In this paper, we show that a hybrid SR approach utilizing both MO as well as E2E SR allows to combine the individual benefits of both approaches. It results in improved TE capabilities and, thus, enables better TE solutions. Besides discussing this with theoretical examples, we also confirm our findings in an extensive evaluation on real-world network topologies. For this, we propose a TE algorithm based on the hybrid SR approach and show that it outperforms state-of-the-art algorithms that rely solely on MO or E2E SR. Furthermore, we demonstrate that the hybrid SR approach is also suitable for the use-case of time-constrained, tactical TE.