SR Flex Algorithm Plane for Low-Latency Layer 1 Services
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Solution Overview
Problem
Existing solutions for providing low latency paths in Segment Routing (SR) networks are inefficient, requiring large segment identifier (SID) label stacks and are not dynamically adaptable to network changes, leading to configuration-intensive and fragile systems.
Innovation Solution
Implementing a Flex Algorithm Definition (FAD) for latency information using a new sub-Type-Length-Value (TLV) to dynamically build a flexible algorithm plane, restricting SID stack scope and automatically adjusting to network events, ensuring accurate latency-based path computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If colored links are used to compute low latency paths in SR network, then latency information can be incorporated into topology, but SID label stack depth increases to unusable sizes
Solution Approach 1:
The patent segments the routing information by introducing Flexible Algorithm (Flex Algo) identifiers that group links with similar latency characteristics. Instead of requiring individual SIDs for every possible path combination, the network is segmented into different Flex Algo planes (e.g., Flex Algo 0 for default, Flex Algo 1 for low-latency paths), allowing routers to select appropriate segments based on service requirements without stacking excessive SIDs.
Solution Approach 2:
The patent changes the routing parameter from traditional IGP metrics to latency-based metrics by introducing a new sub-TLV that carries latency information. This parameter change enables the computation of paths based on actual latency measurements rather than administrative metrics, allowing the network to dynamically adjust paths based on real-time latency conditions while maintaining manageable SID stacks through Flex Algo grouping.
2Device complexity
If multiple SR policies are stitched together to avoid large SID stacks, then stack size is reduced, but configuration becomes intensive and system becomes fragile
Solution Approach 1:
The patent creates a universal Flex Algo framework that can handle multiple routing objectives (low latency, low cost, custom metrics) through a single standardized mechanism. Instead of requiring separate SR policies for different scenarios, the Flex Algo sub-TLV provides a universal interface that can encode various routing preferences, reducing configuration complexity and improving system robustness while maintaining low SID stack depths.
3Productivity
If latency information is collected at packet level, then path computation can be performed, but accuracy is insufficient for low latency services
Solution Approach 1:
The patent introduces an intermediary mechanism at the data link layer (Layer 2) that measures latency between adjacent nodes and reports this information to the network layer (Layer 3) through the Flex Algo sub-TLV. This intermediary measurement approach provides more accurate latency data than packet-level measurements because it occurs at a lower layer with more direct control over the transmission path, enabling precise latency-based path computation while maintaining manageable routing table sizes.
Data Source
AI summary
Systems and methods for providing layer 1 services over a Segment Routing (SR) network include maintaining a Flexible Algorithm Definition (FAD) for Layer 1 services with the FAD across the SR network; receiving a request for a Layer 1 service and determining a Segment Identifier (SID) label stack based on the advertised FAD; and providing the Layer 1 service using the determined SID label stack.