Cross-Layer Congestion Marking via Data Link Feedback

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Solution Overview

Problem

Current congestion control mechanisms in data networks, such as ECN and PCN, operate independently in different layers of the protocol stack and do not effectively utilize early congestion detection from lower layers to prevent network congestion.

Innovation Solution

The method involves feeding congestion information from the data link layer, generated through mechanisms like BCN, upstream to the network layer for congestion marking, allowing for earlier detection and remedial action by using this information for higher-layer congestion control functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If congestion marking operates independently in different layers (ECN at network layer, BCN at data link layer), then each layer can perform its own congestion control functions, but the system cannot effectively utilize early congestion detection from lower layers to prevent network congestion

Engineering Contradiction:
Improvecongestion detection accuracyVSAvoidprotocol stack integration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements feedback by having the data link layer send congestion information upstream to the network layer. The BCN mechanism at the data link layer detects congestion conditions and transmits this information to higher layers, enabling them to take preventive action. This cross-layer feedback loop resolves the contradiction by allowing early congestion detection while maintaining a manageable integration approach through standardized information exchange protocols.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent introduces a new dimension of interaction between protocol layers by enabling information flow from the data link layer (layer 2) to the network layer (layer 3). This vertical integration across dimensions allows congestion detection at the lower layer to influence higher layer decisions, preventing congestion before it occurs rather than reacting after independence was maintained.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Loss of time

If early congestion detection is implemented at the data link layer, then preventive action can be taken before network congestion occurs, but the congestion information must be fed upstream to higher layers which increases protocol complexity

Engineering Contradiction:
Improvecongestion response timeVSAvoidcongestion information processing
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by detecting congestion at the data link layer before it propagates to the network layer and causing broader network issues. The BCN mechanism identifies early signs of congestion and triggers preventive marking actions upstream, reducing the time loss by acting before the problem escalates rather than waiting for network layer congestion to manifest.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses congestion information as an intermediary that bridges the data link layer and network layer. This information acts as a mediator, carrying congestion state from the lower layer to the higher layer without requiring direct complex integration of control logic. The intermediary approach reduces overall system complexity while enabling timely preventive action.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If congestion information from lower layer is fed to higher layer for congestion marking, then earlier detection and mitigation is enabled, but the protocol stack integration becomes more complex

Engineering Contradiction:
Improvenetwork throughputVSAvoidlayered protocol integration
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing the congestion information feedback mechanism to serve multiple functions: it enables early congestion detection, facilitates preventive marking actions, and maintains compatibility with existing ECN and PCN frameworks. This multi-functional approach increases network throughput while avoiding the need for entirely new complex integration protocols.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The feedback mechanism from data link layer to network layer creates a closed-loop system that improves productivity by enabling continuous monitoring and adaptive congestion control. The feedback information allows higher layers to adjust their marking behavior in real-time, optimizing network throughput without requiring complex rearchitecture of the protocol stack.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP2095576B1Method and system for congestion marking
Publication Date: 2016.03.09 BRITISH TELECOM PLC
  • EP2095576B1 patent drawingFigure 1
  • EP2095576B1 patent drawingFigure 2
  • EP2095576B1 patent drawingFigure 3

AI summary

The present invention provides a method and system wherein congestion information is taken from a lower level in the protocol stack and used for congestion marking in a higher layer. In particular, the method and system of the invention from a first aspect provide for congestion information in the lower layer to be generated downstream at a congested node, and to be fed back upstream to a source node. The source node then passes the congestion information, or information derived therefrom, up to the corresponding network element responsible for higher layer functions in the protocol stack, where higher level congestion marking can then be performed in dependence on the received lower level congestion information. Thus, congestion information from the lower layer which can typically be generated earlier before significant congestion occurs can be used in higher layer congestion control functions. Preferably the lower layer is the data link layer, and the higher layer is the network layer.