Broadcast Message Filtering in Local Area Network Topology

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Solution Overview

Problem

In local area networks, wireless communication coverage extension systems fail to properly filter messages intended for specific subnetworks, leading to security risks and operational issues, such as unintended data reception by clients connected via wired links, which can result in loss of access to the primary subnetwork due to mismatched IPv6 configurations.

Innovation Solution

A method and device that analyze the local network topology to determine filtering rules, applying these rules to broadcast packets to ensure only legitimate recipients receive messages by identifying virtual networks, dropping or transforming packets as necessary to prevent unauthorized access, using nodes capable of applying filtering rules and potentially connected switches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If nodes transmit broadcast messages across all subnetworks without filtering, then message delivery coverage is maximized, but security risks increase and operational problems occur due to unintended data reception by clients

Engineering Contradiction:
Improvemessage delivery coverageVSAvoidsecurity risks and operational problems
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent segments the local network into multiple virtual subnetworks (VLANs) including primary subnetwork, secondary subnetwork, and guest subnetwork. Each subnetwork is isolated at the data link layer, allowing broadcast messages to be confined to their intended subnetwork only. This segmentation resolves the contradiction by enabling targeted message delivery while preventing unauthorized access across subnetwork boundaries.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces VLAN tags as intermediary identifiers that are inserted into Ethernet frames to mark the source and destination subnetworks. These tags act as mediators that enable routers and switches to intelligently forward or filter broadcast messages based on subnetwork identity, thus achieving secure segmented delivery without requiring complex reconfiguration of network devices.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If devices receive all broadcast messages from primary and secondary subnetworks equally, then configuration simplicity is maintained, but clients may lose access to the primary subnetwork due to incorrect IPv6 configurations

Engineering Contradiction:
Improvemessage reception simplicityVSAvoidsubnetwork access reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent implements preliminary filtering of broadcast messages at the network infrastructure level (routers and switches) before they reach client devices. By pre-processing messages and applying VLAN-based filtering rules upstream, the system prevents clients from receiving unwanted broadcast traffic in the first place, thus maintaining device simplicity while ensuring reliable subnetwork access.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where nodes analyze network topology and automatically determine appropriate filtering rules based on the VLAN configuration. This closed-loop approach ensures that broadcast filtering adapts to the actual network structure, preventing configuration errors that could lead to subnetwork access loss while maintaining operational simplicity.

Inventive Principle:
Principle #23Feedback

3Reliability

If filtering rules are applied to broadcast packets to ensure only legitimate recipients receive messages, then security and operational reliability are improved, but network device complexity increases

Engineering Contradiction:
Improvemessage delivery accuracyVSAvoidfiltering rule implementation
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the parameter of message identification by introducing VLAN tags into the Ethernet frame structure. Instead of requiring complex analysis of message content or destination addresses, the system uses these standardized tags as simple identifiers that routers and switches can process efficiently. This parameter change enables reliable filtering while minimizing the complexity of implementation in network devices.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4366252A1Method and device for managing broadcast messages in local area network
Publication Date: 2024.05.08 SAGEMCOM BROADBAND SAS
  • EP4366252A1 patent drawingFigure 1~2
  • EP4366252A1 patent drawingFigure 3a~3b
  • EP4366252A1 patent drawingFigure 4~5

AI summary

The present invention relates to a method and device for managing messages broadcast in a local network comprising nodes allowing an extension of wireless communication coverage and stations, the nodes being connected to each other by a routing subnetwork, at least one node transmitting at least one wireless network called the front end network to which the stations connect, the local network comprising a primary subnetwork and a secondary subnetwork, the primary subnetwork being a subnetwork to which the links of the routing network and the nodes belong, the secondary subnetwork being a subnetwork composed of at least one station and which is isolated from the rest of the local network by a virtual network.According to the invention, a node capable of applying filtering rules: - commands (E300) an analysis of the local network topology, - determines (E301) from the local network topology the filtering rules to be applied, - applies (E302) the filtering rules determined on the broadcast packets containing at least one piece of information identifying the virtual network.