Efficient label encoding in segment-routing enabled optical networks

The currently standardized GMPLS protocol suite for packet over optical networks relies on hierarchical instances of signaling sessions. Such sessions have to be established and maintained also in transit nodes, leading to complex and weighty control plane implementations. A novel technology called Segment Routing (SR) has been recently proposed to address these issues. SR relies on the source routing paradigm to provide traffic engineering solutions. In particular, the computed route for a given request is expressed as a segment list applied as an header to data packets at the ingress node. Specific algorithms are then required to perform the path computation and express the computed path through an effective segment list encoding (i.e., label stack), minimizing the segment list depth (SLD) (i.e., the number of labels included in the segment list). So far, no algorithms have been proposed to jointly provide path and segment list computation in SR-based networks. In this study, an efficient segment list encoding algorithm is proposed, guaranteeing optimal path computation and limited SLD in SR-based networks. The algorithm also accounts for equal-cost multiple paths and multiple constraints. The proposed algorithm is successfully applied to different network scenarios, demonstrating its flexibility in several use cases and showing effective performance in terms of segment list depth and introduced packet overhead.