5-4-3 Rule

What Does 5-4-3 Rule Mean?

The 5-4-3 rule is a guideline used in the design of shared Ethernet networks which promotes optimal traffic flow. This refers to the number of repeaters and segments that must be present on shared Ethernet backbones set up in a tree topology. The rule states that there should be a maximum of five segments which are connected by four repeaters, and only three of those segments can contain active senders/terminals.

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Techopedia Explains 5-4-3 Rule

The Ethernet protocol dictates that data sent over the collision domain must reach every part on its path toward its destination within a specified length of time. However, each repeater and segment that the signal passes through adds a certain amount of time in the process. The rule was created in the early days of the Ethernet when 10Base5 and 10Base2 were the only Ethernet types available, and shared access backbones were quite slow. The 5-4-3 rule was designed to minimize signal transmission time.

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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.