The 5-4-3 rule, also referred to as the IEEE way, is a design guideline for Ethernet computer networks covering the number of repeaters and segments on shared-medium Ethernet backbones in a tree topology.[1][2] It means that in a collision domain there should be at most 5 segments tied together with 4 repeaters, with up to 3 mixing segments (10BASE5, 10BASE2, or 10BASE-FP). Link segments can be 10BASE-T, 10BASE-FL or 10BASE-FB. This rule is also designated the 5-4-3-2-1 rule with there being two link segments (without senders) and one collision domain.[3]
An alternate configuration rule, known as the Ethernet way, allows 2 repeaters on the single network and does not allow any hosts on the connection between repeaters.[4]
The rules were created when 10BASE5, 10BASE2 and FOIRL were the only types of Ethernet networks available. The rules only apply to shared-medium 10 Mbit/s Ethernet segments connected by repeaters or repeater hubs (collisions domains) and FOIRL links. The rules do not apply to switched Ethernet because each port on a switch constitutes a separate collision domain. With mixed repeated and switched networks, the rule's scope ends at a switched port.[5]
- ^ "IEEE 802.3-2012 13. System considerations for multisegment 10 Mb/s baseband networks". IEEE 802.3. 8 December 2012. Archived from the original on 5 December 2012. Retrieved 15 November 2015.
- ^ Helmig, Johannes (28 October 1997). "Large Networks: 5-4-3 Rule". WindowsNetworking.com. Archived from the original on 18 August 2010.
- ^ Mitchell, Bradley. "The 5-4-3-2-1 Rule". About.com. Archived from the original on 6 December 2010.
- ^ IEEE 802.3 13.4 Transmission System Model 2
- ^ IEEE 802.3 13. System considerations for multisegment 10 Mb/s baseband networks