5-4-3 rule

The standard requires generation of sufficient preamble bits to make sure a frame can be received when operated within specification limits (i.e. applying the 5-4-3 rule).

At this point in the evolution of Ethernet, multiple network segments could be connected with repeaters (in accordance with the 5-4-3 rule) to form a larger collision domain.

The 5-4-3 rule also referred to as the IEEE way (contrary to the Ethernet way) is a design guideline for Ethernet computer networks covering the number of repeaters and segments on shared-access Ethernet backbones in a tree topology.