Thick Ethernet (10B5)

One form of cabling supported by Ethernet is low-loss 50 Ohm coaxial cable as shown in the figure below. This type of cable is 0.5" diameter (usually supplied with a yellow outer PVC coating) and rather inflexible. It has become known in the communications industry as "Thick Ethernet". The official name for this cable is 10 Baseband5 (10B5), indicating that it is specified for baseband communications (i.e. not modulated) at 10 Mbps over distances up to 500m.

10B5 Cable or "Thick Ethernet"

The 10B5 cabling system uses thick (low loss) co-axial cable which forms a shared bus. Upto 100 transceivers may be used to connect computers to the bus. The cable is difficult to install (due to its weight, large 0.5" diameter, and constraints on minimum curvature). It's key advantage is the extended transmission distance and the fact that it has good noise immunity. 10B5 cabling was traditionaly used for backbone connections and it is now fairly uncommon to find this type of cabling using to connect user's workstations. An AUI drop cable is then run from the transeiver attached to the cable to a Host AUI port on the network interface card of each computer to be connected.

Network Interface Card for connection of a computer to an Ethernet Network

Since this type of cabling is relatively difficult to install, the cable is normally installed in a communications duct or along a corridor in an office building (see below).

A typical example of the use of 10B5 cabling in an office environment.

A summary of the properties of this type of cabling is given below:


Gorry Fairhurst - Date: 01/3/2007 EG3557