Congestion Notification Control Loop Parameter Adjustment

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Solution Overview

Problem

Network congestion leads to increased delays and potential application failures due to overloaded network pathways, where existing congestion management mechanisms like Backward Congestion Notification (BCN) struggle to effectively adjust traffic rates across the network.

Innovation Solution

A system and method to adjust Congestion Notification (CN) control loop parameters by monitoring the congestion point queue, generating feedback messages with responsiveness data, and applying rate limiting at reaction points to mitigate congestion, shifting traffic load from network cores to edges where resources are more available.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If rate-based closed loop feedback control mechanism is implemented with core detector integrated in hardware, then congestion detection capability is improved, but device complexity increases

Engineering Contradiction:
Improvecongestion detection capabilityVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The congestion detection system uses self-service by having the network infrastructure automatically monitor and report its own congestion state through BCN messages, eliminating the need for external monitoring devices and reducing overall system complexity while maintaining high detection capability

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent implements feedback by having core detectors send BCN messages back to reaction points when congestion is detected, creating a closed-loop control system that automatically adjusts traffic rates based on real-time congestion measurements, resolving the contradiction between detection precision and system complexity

Inventive Principle:
Principle #23Feedback

2Measurement precision

If BCN messages include congestion change information and instantaneous measures, then control precision is improved, but loss of information increases due to message overhead

Engineering Contradiction:
Improvecontrol precisionVSAvoidmessage overhead
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent extracts only the essential congestion parameters needed for control decisions into BCN messages, separating critical information (congestion state, queue length) from detailed raw data, thereby achieving precise control while minimizing message overhead and information loss

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system changes parameters by encoding congestion information in standardized BCN message formats with specific fields for congestion state and queue metrics, optimizing the balance between control precision and message size to reduce overhead while maintaining necessary control accuracy

Inventive Principle:
Principle #35Parameter changes

3Reliability

If rate limiters shape individual flows at reaction points, then congestion mitigation effectiveness is improved, but device complexity increases

Engineering Contradiction:
Improvecongestion mitigation effectivenessVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by implementing rate limiters that shape individual flows separately at reaction points, dividing the congested traffic into manageable per-flow controls rather than treating all traffic uniformly, which improves mitigation effectiveness while keeping each rate limiter component relatively simple

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Reaction points perform self-service by automatically adjusting their own rate limiting parameters based on received BCN messages, eliminating the need for centralized control logic and reducing overall system complexity while maintaining effective congestion mitigation through distributed autonomous control

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2258077B1Adjusting congestion notification control loop parameters
Publication Date: 2013.11.06 CISCO TECHNOLOGY INC
  • EP2258077B1 patent drawingFigure 1
  • EP2258077B1 patent drawingFigure 2
  • EP2258077B1 patent drawingFigure 3

AI summary

A method and system to adjust Congestion Notification control loop parameters at a congestion point are provided. The system comprises a monitor to sample a state of a congestion point the congestion point being to receive messages from a reaction point; a history generator to generate an updated reaction to congestion history by consolidating the state of the congestion point with a current reaction to congestion history, the current reaction to congestion history being associated with a current feedback message; a message generator to generate an updated feedback message based on the updated reaction to congestion history; a message update module to replace the current feedback message with the updated feedback message; and a communications module to communicate the updated feedback message to the reaction point.