Notes:
From http://www.faqs.org/faqs/LANs/ethernet-faq and http://www.ethermanage.com/ethernet/enet-faqs/ethernet-faq.html
Then there are limitations on the number of repeaters and cable segments allowed between any two stations on the network. There are two different ways of looking at the same rules: 1. The Ethernet way: A remote repeater pair (with an intermediate point-to-point link) is counted as a single repeater (IEEE calls it two repeaters). You cannot put any stations on the point to point link (by definition!), and there can be two repeaters in the path between any pair of stations. This seems simpler to me than the IEEE terminology, and is equivalent. 2. The IEEE way: There may be no more than five (5) repeated segments, nor more than four (4) repeaters between any two Ethernet stations; and of the five cable segments, only three (3) may be populated. This is referred to as the "5-4-3" rule (5 segments, 4 repeaters, 3 populated segments).