Virtual Queue Marking for Early Congestion Signaling

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Solution Overview

Problem

Current network congestion management techniques in packet-switched networks, such as IP and Ethernet networks, fail to timely signal congestion until real queues grow in size, leading to increased latency and packet loss, as they rely on inspecting real queues rather than anticipating imminent congestion.

Innovation Solution

Implementing a Virtual Queue Marking mechanism using two registers that simulate a virtual queue, where the size of the virtual queue builds up faster than the real queue, allowing for earlier congestion signaling by marking packets when the virtual queue exceeds a threshold, which can be achieved by modifying existing Single Rate Three Colour Marking (srTCM) hardware.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If real queue inspection is used for congestion marking, then implementation is simple with current switches and routers, but congestion signaling starts only when the real queue grows, leading to increased latency and packet loss

Engineering Contradiction:
Improvecongestion signaling timelinessVSAvoidlatency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent implements a virtual queue that builds up faster than the real queue, allowing congestion marking to begin before the real queue grows. This preliminary action enables early congestion signaling, reducing latency and packet loss by marking packets in advance of actual queue buildup.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces a virtual queue as an intermediary mechanism between packet arrival and real queue inspection. This virtual queue acts as a mediator that accumulates load data and provides early congestion indicators, bridging the gap between actual traffic load and real queue state for timely congestion management.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a virtual queue mechanism is implemented to enable earlier congestion signaling, then latency and packet loss are reduced, but device complexity increases

Engineering Contradiction:
Improvecongestion signaling timelinessVSAvoidqueue management complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent creates a virtual queue as a simplified copy or representation of the real queue dynamics. This virtual queue replicates essential queue behavior characteristics without requiring full real queue inspection, enabling early congestion detection while maintaining manageable complexity through abstraction.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent modifies queue management by changing the parameters used for congestion detection - using virtual queue metrics rather than real queue size. This parameter change enables earlier congestion signaling while the complexity is managed through configurable virtual queue parameters such as build-up rate and marking thresholds.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2195973B1Methods and apparatus for providing congestion information
Publication Date: 2014.07.30 BRITISH TELECOM PLC
  • EP2195973B1 patent drawingFigure 1
  • EP2195973B1 patent drawingFigure 2
  • EP2195973B1 patent drawingFigure 3

AI summary

Methods and systems for providing information relating to congestion at a network element caused by data units intended to be forwarded across a telecommunications network by the network element, the apparatus comprising: load-data receiving means for receiving load data relating to data units intended to be forwarded by the network element; rate-data obtaining means for obtaining data indicative of a configurable rate; first and second registers for storing first and second metrics; first and second updating means operable to update the metrics in said first and second registers in dependence on said load data and on the configurable rate; and a congestion indication provider operable to provide indications of congestion in dependence on the metrics stored in the registers; said apparatus being configured in such that it may provide behaviour equivalent to a virtual queue marking scheme by virtue of a minor modification to hardware provided for Single Rate Three Colour Marking.