SR-TE computation and Signaling

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Segment Routing Traffic Engineering (SR-TE) refers to the computation and installation of constraint-based Segment Lists used to steer traffic along optimized paths. SR Policies provide the general framework for associating traffic with one or more candidate paths, while SR-TE specifically focuses on computing paths that satisfy explicit traffic-engineering constraints. In deployments with a centralized controller, a Path Computation Element (PCE) can compute such paths based on a global view of the network topology. This enables the instantiation of paths that meet requirements such as disjointness, affinity constraints, or cumulative metric bounds, which cannot always be efficiently solved by local router-based computation alone.

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In this test, we verified the interoperability between the PCE and PCC of the SR-TE computation and signaling workflow.

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We covered both PCE-initiated SR-TE and PCC-initiated, delegated SR-TE over PCEP. In the delegated scenarios, the headend router requested path computation from the PCE and installed the returned Segment Lists. The validation used SR-MPLS as the primary dataplane, with additional runs over SRv6-µSIDs.

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The primary constraint used in the test runs was delay. The PCE computed paths that minimized end-to-end latency, and in selected scenarios, a delay bound was applied. In those cases, a path was considered valid only if its cumulative delay remained below a configured threshold. In all scenarios, the PCC installed the computed paths and reported their operational state to the PCE, confirming correct signaling and state synchronization.

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[[~[~[Figure 53: SR-TE Computation and Signaling using BGP-SR~>~>image:485744699448164353_SDN-3-1-v2.png~|~|alt="Figure 53" width="550"~]~]>>attach:485744699448164353_SDN-3-1-v2.png||target="_blank"]]

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|=PCE|=PCC

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|Keysight IxNetwork|HPE MX204

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|Keysight IxNetwork|ZTE ZXR10 M6000-4SE

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