Ethernet Way versus IEEE Way

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Ethernet and IEEE 802.3 implement a rule, known as the 5-4-3 rule is also known as the IEEE way, for the number of repeaters and segments on shared access Ethernet backbones in a tree topology. 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 IEEE way mandates that there can only be a maximum of five segments, connected through four repeaters, or hubs, and only three of the five segments may contain user connections. 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 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.

The 5-4-3 rule is also known as the IEEE way and is sometimes compared to the Ethernet way which is having 2 repeaters on the single network without having any hosts connected to a repeater.