Bandwidth-Guaranteed Segment Routing Path Computation
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Solution Overview
Problem
Current Segment Routing (SR) technologies lack the ability to compute bandwidth-guaranteed SR Paths that consider multi-path capabilities and resource utilization on traversed links, particularly for Equal Cost MultiPath (ECMP) segments, which is essential for efficient traffic engineering and load balancing.
Innovation Solution
A method is introduced to determine bandwidth-guaranteed SR paths by receiving a bandwidth demand value, obtaining network information, determining constrained shortest multipaths, and tuning loadshares using per segment-list loadshares, ECMP, and per link residual capacity to maximize bandwidth capacity, ensuring that the bandwidth capacity exceeds a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Segment Routing is used to simplify routing protocols and reduce network complexity, then ease of operation is improved, but the ability to compute bandwidth-guaranteed paths and perform traffic engineering deteriorates
Solution Approach 1:
The patent introduces a Path Computation Element (PCE) as an intermediary component that computes bandwidth-guaranteed SR paths. The PCE receives bandwidth requirements, determines appropriate SR paths considering link capacities and current utilization, and provides these computed paths to SR routers. This mediator enables bandwidth guarantee functionality without requiring complex modifications to the core SR protocol simplicity.
Solution Approach 2:
The patent segments the path computation function from the forwarding function. The PCE handles the complex bandwidth computation and path determination, while SR routers focus on simple packet forwarding using the pre-computed segment lists. This segmentation allows bandwidth guarantee capabilities to be added without complicating the operational simplicity of SR forwarding.
2Productivity
If Equal Cost MultiPath (ECMP) is used for load balancing, then productivity is improved, but the precision of bandwidth allocation and resource utilization tracking deteriorates
Solution Approach 1:
The patent dynamically adjusts load shares across ECMP paths based on real-time bandwidth requirements and link utilization. Instead of static ECMP hashing, the system computes dynamic load share percentages for each path segment, allowing precise control of bandwidth allocation while maintaining load balancing across multiple paths. This dynamic adjustment enables both high productivity through load balancing and precise measurement of bandwidth allocation.
Solution Approach 2:
The patent implements feedback mechanisms where the PCE continuously monitors link utilization and bandwidth consumption on ECMP paths. Based on this feedback, the system recalculates and adjusts load shares to ensure precise bandwidth allocation. The feedback loop maintains measurement precision by tracking actual bandwidth usage and comparing it against allocated quotas, enabling corrective adjustments to load balancing weights.
3Device complexity
If traditional SR paths are used without considering per-link residual capacity, then device complexity is reduced, but the reliability of bandwidth guarantee deteriorates
Solution Approach 1:
The patent performs preliminary path computation that incorporates per-link residual capacity information before traffic is actually routed. The PCE queries link state databases to obtain current utilization and available capacity, then pre-determines SR paths that satisfy bandwidth requirements. This preliminary action ensures bandwidth guarantee reliability by validating capacity availability before commitment, without requiring complex real-time monitoring during packet forwarding.
Solution Approach 2:
The PCE acts as an intermediary that bridges the simple SR forwarding plane and the complex bandwidth management requirements. It accesses link state information from network databases, performs capacity calculations, and translates these into SR policy configurations that the simple forwarding plane can execute. This intermediary approach maintains device complexity at acceptable levels while ensuring reliable bandwidth guarantees through sophisticated pre-computation.
Data Source
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AI summary
At least one bandwidth-guaranteed segment routing (SR) path through a network is determined by: (a) receiving, as input, a bandwidth demand value; (b) obtaining network information; (c) determining a constrained shortest multipath (CSGi); (d) determining a set of SR segment-list(s) Si=sl1i,sl2i..slni that are needed to steer traffic over CSGi; and (e) tuning the loadshares in Li, using Si and the per segment-list loadshare Li=l1i,l2i,..lni, the per segment equal cost multipath ("ECMP"), and the per link residual capacity, such that the bandwidth capacity that can be carried over CSGi is maximized.