5-4-3 Rule

Ethernet and IEEE 802.3 implement a rule, known as the 5-4-3 rule, for the number of repeaters and segments on shared access Ethernet backbones in a tree topology.

The 5-4-3 rule divides the network

The 5-4-3 rule divides the network into two types of physical segments: populated (user) segments, and unpopulated (link) segments. User segments have users’ systems connected to them. Link segments are used to connect the network’s repeaters together. The rule mandates that between any two nodes on the network, there can only be a maximum of five segments, connected through four repeaters, or concentrators, and only three of the five segments may contain user connections.

Requires a Signal to Reach Every Part of the Network

The Ethernet protocol requires that a signal sent out over the LAN reach every part of the network within a specified length of time. The 5-4-3 rule ensures this. Each repeater that a signal goes through adds a small amount of time to the process, so the rule is designed to minimize transmission times of the signals.

The 5-4-3 rule — which was created when Ethernet, 10Base5, and 10Base2 were the only types of Ethernet network available — only applies to shared-access Ethernet backbones. A switched Ethernet network should be exempt from the 5-4-3 rule because each switch has a buffer to temporarily store data and all nodes can access a switched Ethernet LAN simultaneously.

Recommended Reading: Webopedia’s Ethernet Designations chart.

Vangie Beal
Vangie Beal
Vangie Beal is a freelance business and technology writer covering Internet technologies and online business since the late '90s.

Top Articles

Huge List Of Texting and Online Chat Abbreviations

From A3 to ZZZ we list 1,559 text message and online chat abbreviations to help you translate and understand today's texting lingo. Includes Top...

How To Create A Desktop Shortcut To A Website

This Webopedia guide will show you how to create a desktop shortcut to a website using Firefox, Chrome or Internet Explorer (IE). Creating a desktop...

The History Of Windows Operating Systems

Microsoft Windows is a family of operating systems. We look at the history of Microsoft's Windows operating systems (Windows OS) from 1985 to present...

Hotmail [Outlook] Email Accounts

  By Vangie Beal Hotmail is one of the first public webmail services that can be accessed from any web browser. Prior to Hotmail and its...

Common Business-Oriented Language (COBOL)...

What is COBOL? COBOL stands for Common Business-Oriented Language. It is a 60-year-old programming...

Shared Hosting Definition &...

Shared hosting is a web hosting model in which multiple sites occupy the...

Database Integration Definition &...

Database integration consolidates data from multiple sources to provide businesses with more comprehensive...