5-4-3 rule LastModified: Tuesday, January 27, 2004
Ethernet and IEEE 802.3 implement a rule, known as the 5-4-3 rule, 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 rule mandates that between any two nodes on the network, there can only be a maximum of five segments, connected through four repeaters, or concentrators, 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 Ethernet, 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. Also see the Ethernet Designations chart in the Quick Reference section of Webopedia.
Large Networks: 5-4-3 rule Diagrams of network setups.	related categories: Ethernet Network Topologies Networks related terms: 1000Base-T 100Base-T 10Base-2 10Base5 10Base-T 2-205 rule 802.3ae ATM AUI Gigabit Ethernet IEEE 802 standards local-area network logical topology network physical topology segment shared Ethernet switched Ethernet switching hub topology 5 4 3 rule Products : Top Store Offers: Instawares, LLC  79.55One-subject notebook is ideal for taking notes in class. Each notebook has a durable board back cover. Features three-hole punched format, side openin... eBay  12.44antonline Search PN Continental US Orders Only. Store Search Search by SKU/PN Store Pages Payment Terms and Shipping Info Store Policies About the Sel... Shoplet.com  1.51Subject Notebooks Memo. Wirebound Notebook, 1-Subject, Gregg Ruled, 7-3/4"x5" (ROA12016) Shoplet.com  2.06Value Pack 3 X 5 Ruled Index Cards, White, 500 Cards/Pack. Value Pack 3 x 5 Ruled Index Cards Amazon Marketplace  7.95Sold Individually Compare all matches: 51 Store Offers