Co-Routed SR Paths for Accurate OAM Fault Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing network systems lack a mechanism to ensure co-routed bidirectional paths for Operations, Administration, and Maintenance (OAM) packets, leading to unnecessary path switchovers due to faults on non-co-routed reverse paths, which is particularly problematic for Segment Routing (SR) networks.

Innovation Solution

The proposed solution involves determining and advertising a co-routed reverse path Segment Identifier (SID) list using Border Gateway Protocol (BGP) speakers, ensuring that OAM packets traverse the same forward and reverse paths by computing paths with color extended communities and appending Binding Segment Identifiers (BSIDs) in BGP updates, thereby preventing unnecessary path switchovers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If OAM mechanisms are used to detect faults on TE paths, then fault detection capability is improved, but unnecessary path switchovers occur when reverse path faults are detected

Engineering Contradiction:

Improvefault detection capabilityVSAvoidpath switchover accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces reverse path SIDs as an intermediary mechanism to steer OAM packets specifically over the reverse TE path. This allows independent control and monitoring of the reverse path, enabling accurate fault detection without triggering unnecessary switchovers when only the reverse path is affected.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the bidirectional TE path into separate forward and reverse paths with independent SID lists. This segmentation allows OAM packets to be steered independently over each direction, enabling precise fault localization and preventing false positives in fault detection.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If co-routed bidirectional paths are established, then fault detection accuracy is improved, but path establishment complexity increases

Engineering Contradiction:

Improvefault detection accuracyVSAvoidpath establishment complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements dynamic path computation where the reverse path SID list is automatically generated by reversing the forward path SIDs. This dynamic approach ensures co-routed paths for accurate fault detection while reducing manual configuration complexity through automated path derivation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent uses path inversion to generate the reverse path SID list from the forward path SID list. By reversing the sequence of SIDs, the system automatically creates co-routed reverse paths without manual intervention, maintaining fault detection accuracy while simplifying path establishment.

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If OAM packets are sent over different forward and reverse paths, then path utilization is improved, but false fault detection occurs

Engineering Contradiction:

Improvepath utilizationVSAvoidfault detection accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent uses reverse path SIDs as intermediaries to explicitly steer OAM packets over the reverse TE path. This intermediary mechanism ensures that OAM packets traverse the actual reverse path used by data traffic, enabling accurate fault detection while maintaining proper path utilization.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12500832B2Establishing and advertising co-routed bidirectional paths across multiple domains

Publication Date: 2025.12.16 CIENA CORP

AI summary

Establishing and advertising co-routed bidirectional paths across multiple domains includes determining a path from the router to a BGP peer, in a Segment Routing (SR) network, as a reverse path SR policy; appending a Binding Segment Identifier (BSID) of the reverse path SR policy in a BGP update message; and sending the BGP update message to the BGP peer. This can be used to ensure an Operations, Administration, and Maintenance (OAM) packet is guaranteed to traverse the same forward and reverse path for fault detection thereon.