SR-TE policies are used for Traffic Engineering (TE) in Segment Routing (SR) networks. SR-TE provide ways to define traffic engineered paths by means of “Explicit Candidate paths” and “Dynamic Candidate paths”. With the former, operator can determine the paths and configure them as Segment List (SID-list) at head-end. Currently, the candidate path selection method specified by SR policy architecture defined by IETF is based on preference. The proposed approach factors in hop-count along with preference as best path selection criteria. A head-end can determine the hop-count of an explicit path by running IGP SPF based on its topology database. However, this approach cannot be used for inter-area/level/AS paths as well as path containing binding SIDs. The proposed approach enables operators to deploy SR policies with explicit paths such that inefficient use of bandwidth due to elongated post-failure path is minimized. Also, the proposed mechanism can minimize the impact of network failure on SLA (e.g., end-to-end latency bound).
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Anonymous, "OAM linked SR-TE policy to prevent longer explicit path due to network failure", Technical Disclosure Commons, (April 20, 2022)