Layer 2 Switch Path Tracing Using Reply Frames

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Solution Overview

Problem

Existing methods for tracing a path between source and destination nodes in a network comprising multiple Layer 2 switch devices are cumbersome and resource-intensive, lacking efficient techniques to determine the path without logging into each switch device.

Innovation Solution

A method and apparatus that utilize Layer 2 frames to include switch IDs, sequence numbers, and port information in reply frames, allowing nodes to trace the path without requiring login into each switch device, using EtherType fields to indicate request and reply frames.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual login to each switch device is used to trace path, then path information can be obtained, but operation time and resource consumption increase significantly

Engineering Contradiction:
Improvepath tracing accuracyVSAvoidtracing operation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The switch devices automatically generate and send reply frames containing path information when they receive request frames, eliminating the need for manual login and commands. Each switch device serves itself by autonomously participating in the path tracing process, embedding its identification and port information in the reply frames it generates.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Reply frames act as intermediaries to transfer path information from switch devices to the tracing source. Instead of requiring direct manual access to each switch device, the intermediary reply frames carry the necessary path tracing data (switch ID, port information, hop count) back to the source, enabling indirect information retrieval.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If manual login to each switch device is used to trace path, then path information can be obtained, but operational complexity increases

Engineering Contradiction:
Improvepath tracing accuracyVSAvoidtracing operation simplicity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

Switch devices automatically generate and send reply frames containing path information when they receive request frames, eliminating the need for manual login and commands. Each switch device serves itself by autonomously participating in the path tracing process, embedding its identification and port information in the reply frames it generates.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Reply frames act as intermediaries to transfer path information from switch devices to the tracing source. Instead of requiring direct manual access to each switch device, the intermediary reply frames carry the necessary path tracing data (switch ID, port information, hop count) back to the source, enabling indirect information retrieval.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If traditional L2 path tracing methods are used, then path information can be obtained, but resource consumption increases

Engineering Contradiction:
Improvepath tracing accuracyVSAvoidnetwork resource consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent uses only the necessary minimum actions for path tracing: sending a request frame and receiving reply frames. It avoids excessive actions such as manual login to each device, executing multiple commands per device, and processing unnecessary data, thereby reducing network resource consumption while achieving complete path information retrieval.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3952250B1Methods and apparatuses in a network comprising a plurality of switch devices
Publication Date: 2026.03.18 TELIASONERA AB
  • EP3952250B1 patent drawingFigure 1
  • EP3952250B1 patent drawingFigure 2
  • EP3952250B1 patent drawingFigure 3

AI summary

The embodiments herein relate to method and apparatuses in the form of switch device (1, 300) and a source host node (10, 500) respectively. A method perform by the switch device (1) includes receiving (210), from a source host node (10), a frame including a MAC address of the source host node (10) as a source MAC address; a MAC address of a destination host node (17) as a destination MAC address, and information indicating a type of the frame as a request frame; sending (220) the received frame towards the destination host node (17); generating (230) a first reply frame including the MAC address of the source host node (10), and information indicating a type of the frame as a reply frame, wherein the information, indicated in a source MAC address field of the first reply frame, includes a switch ID, a sequence number with a value equal to 0, a hop number with a value equal to 1, and an incoming port information that the switch device (1) uses to forward at least one frame towards the source host node (10); and sending (240) the generated first reply frame towards the source host node (10).