Segment Routing Traffic Engineering Local Protection Advertisement
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Solution Overview
Problem
Current Segment Routing Traffic Engineering (SR-TE) systems lack the capability to effectively advertise and utilize local protection information, such as protected elements and backup paths, which hinders the computation of paths with guaranteed local protection and hampers the detection of faulty backup paths before network failures.
Innovation Solution
The advertisement of local protection information via Interior Gateway Protocols (IGP), Border Gateway Protocol Link-State advertisement (BGP-LS), and Path Computation Element Protocol (PCEP), including identity of protected elements, type of protection, and Binding SID for backup paths, along with a new SR OAM message to activate/deactivate backup paths for testing purposes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If conventional IGP and BGP-LS are used to advertise link protection capability, then basic protection information is available, but additional information required to compute paths with guaranteed local protection is not provided
Solution Approach 1:
The patent segments local protection information into distinct components including protected element identifiers, protection types (node, link, SRLG), backup path identifiers, and binding SIDs. Each component is advertised separately through IGP/BGP-LS extensions, allowing receivers to process only the specific information needed for their path computation requirements without overwhelming complexity
Solution Approach 2:
The patent introduces a Path Computation Element (PCE) as an intermediary that collects local protection information from multiple nodes, processes it centrally, and provides computed paths with guaranteed local protection to head-end nodes. This intermediary simplifies the complexity by performing the complex path computation centrally rather than requiring each node to independently process all protection information
2Reliability
If TI-LFA provides local protection against link and node failure, then destination protection is achieved, but the head-end node lacks information to compute paths with guaranteed local protection
Solution Approach 1:
The patent implements preliminary action by having nodes pre-compute and advertise local protection information including backup path identifiers and binding SIDs before any failure occurs. This allows head-end nodes to have all necessary information available in advance to compute paths with guaranteed local protection, eliminating the information gap that exists in conventional TI-LFA where protection exists but computation information is unavailable
3Reliability
If SR OAM enables probing paths, then path availability can be tested, but local backup paths cannot be probed for local protection
Solution Approach 1:
The patent enables self-service by allowing head-end nodes to autonomously probe local backup paths using the advertised binding SIDs and protection information. The system provides all necessary information (backup path identifiers, binding SIDs) that enables head-end nodes to perform their own backup path validation without requiring external OAM infrastructure, making the testing process as easy as conventional path probing
Data Source
AI summary
Systems and methods for Segment Routing Traffic Engineering (SR-TE) with awareness of local protection include the advertisement of local protection information in effect at each SR capable node via Interior Gateway Protocol (IGP), Border Gateway Protocol Link-State advertisement (BGP-LS), telemetry, etc. A method includes determining local protection in effect at a node in a Segment Routing network; and advertising information based on the local protection via extensions in a routing protocol, e.g., IGP, BGP-LS, etc., associated with the Segment Routing network, wherein the information includes identity of protected elements and a type of the local protection.