5-4-3 Rule

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. It means that in a collision domain there should be at most 5 segments tied together with 4 repeaters, with 3 segments containing active senders (i.e. terminals).