What Is Thicknet and Thinnet?

By David Dunning

Thicknet, also known as Thick Ethernet or 10Base5, and Thinnet, also known as Thin Ethernet or 10Base2, are obsolete Ethernet networking technologies. Both technologies use coaxial cable, which consists of solid copper core surrounded by an insulator; a shield of braided wire is wrapped around the insulator and further insulator is wrapped around the shield to complete the cable.

Physical Cable

Thicknet uses a type of coaxial cable known as Radio Grade 8, which conforms to the original Xerox Ethernet specification and has a diameter of approximately half an inch. Thinnet, on the other hand, uses a thinner type of coaxial cable known as Radio Grade 58, which is similar to the Radio Grade 6 cable used for cable TV.

Bandwidth

The official name for Thicknet, 10Base5, indicates that the technology supports a data transfer speed, or bandwidth, of up 10 megabits per second and a maximum segment length of 500 meters (approximately 1,640 feet). All devices connect to a single cable, known as a segment or bus, and Thicknet supports up 100 devices per second. The official name for Thinnet, 10Base2, is not quite so informative. Thinnet also supports a bandwidth of up to 10 megabits per second, but a maximum segment of just 185 meters (approximately 606 feet); originally this was supposed to be 200 meters (approximately 656 feet), but the maximum segment length was reduced. Thinnet supports a maximum of 30 devices per segment.

Connection

Devices connect to Thicknet cable with a transceiver -- a device that transmits and receives electronic signals -- known as a vampire connector, which physically pierces the cable. Thicknet also requires an external transceiver, known as an access unit interface, which connects the cable to the appropriate port on each network interface card. Devices connect to Thinnet cable with T-shaped connectors, known as Bayonet Neill Concelman connectors. Each BNC connector has two small knobs on the female connector, which lock into spiral slots in the male connector when the two are twisted together.

Limitations

Thicknet cable is expensive and difficult to work with. Each Thicknet segment must be terminated with a 50 ohm terminator to prevent reflection of the signal from destroying the data. If a Thicknet cable breaks, data transfer to the whole network stops. Thinnet is cheaper and easier to work with, but also requires termination and any break brings the entire network to a halt. Thinnet was popular for home and small business networks in its time, but, like Thicknet, is no longer used for modern networks.