BGP Routing Policy Debugging via Live Simulation

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Solution Overview

Problem

Network device users face difficulties in debugging routing policies due to the lack of clear insights into why unexpected outcomes occur during the application of routing policies, making it challenging to identify and fix issues without manual, time-consuming assessments.

Innovation Solution

A new CLI command, 'show BGP debug policy,' is introduced, allowing users to specify options like neighbors, route attributes, and VRF instances, which simulates the code path of the routing policy to display step-by-step evaluations, enabling users to identify the exact cause of unexpected outcomes and make necessary modifications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If manual assessment of routing policies is performed, then debugging can be done, but it is time-consuming and inefficient

Engineering Contradiction:

Improvedebugging efficiencyVSAvoidtime for manual assessment

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent creates a copy of the routing policy configuration and simulates its execution on test data. This allows debugging without affecting the live system, enabling efficient iteration and testing of policy modifications.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent performs preliminary simulation and validation of routing policies before deploying them to the live system. This includes testing policy rules against sample route data to identify issues beforehand, preventing time-consuming manual debugging later.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If detailed analysis of routing policy code path is provided, then debugging accuracy is improved, but system complexity increases

Engineering Contradiction:

Improvedebugging accuracyVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the routing policy evaluation process into discrete, traceable steps. Each policy rule evaluation is logged separately, allowing precise identification of which specific rule caused an unexpected outcome without requiring analysis of the entire policy complex.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary simulation layer that sits between the routing policy configuration and the live system. This intermediary captures and logs detailed execution information without modifying the core routing logic, providing debugging accuracy while isolating complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11245611B2Analysis of routing policy application to routes

Publication Date: 2022.02.08 ARISTA NETWORKS INC

AI summary

Techniques described herein relate to performing an analysis of application of a routing policy to a route. Specifically, the techniques relate to a command that may be executed to evaluate the steps of the routing policy (e.g., a route map). A copy of a live route map may be made. Receipt of the command may cause the steps of the routing policy to be simulated using the copy. The simulation may return results of analyzing the outcome of each step in the routing policy. Based on the results, an updated routing policy copy may be generated that changes one or more steps in the routing policy. The updated routing policy copy may then be re-simulated to determine if the changes caused the intended effect. If so, the live routing policy may be replaced with the updated routing policy copy.