The Telecom Corner: Ethernet Configuration and Wiring

Ethernet Topology and Cabling

A variety of cabling schemes are available for Ethernet LAN configurations and are described in the following sections:

10Base5

This interface is also known as “Thick Ethernet” and is based upon the use of thick, inflexible, coaxial cable. The coaxial cable has an impedance of 50 ohms, and is terminated with Male “Type N” coax connectors. The center conductor is solid.

- Taps per segment      : 100
- Maximum separation    : 5 segments, 4 repeaters
- Maximum segment length: 500 meters
- Total network span    : 2500 meters
- Minimum length between
  transceivers          : 2.5 meters
- Max transceiver drop
  length                : 50 meters

Each end of a coaxial segment must be terminated into a 50 ohm impedance.

10Base2

This interface is also known as “Thin Ethernet” and is based upon the use of thin, flexible, coaxial cable. The coaxial cable has an impedance of 50 ohms, and is terminated with Male “BNC” (Bayonet- Niell and Concelman) type coax connectors. The center conductor is stranded.

- Taps per segment      : 30
- Maximum separation    : 5 segments, 4 repeaters
- Maximum segment length: 185 meters
- Total network span    : 925 meters
- Minimum length between
  transceivers          : 0.5 meters

Each end of a coaxial segment must be terminated into a 50 ohm impedance. There can be no more than TWO 50 ohm termintors per segment, or else the collision detection function may not operate properly. Multiport repeaters may include a 50 ohm termination.

10BaseT

This interface is very popular since it is based upon the use of twisted pair cable. Regular “Silver Satin” phone cable CANNOT be used, since the pairs in this cable are NOT twisted. The interface used for this type of wiring is a RJ-45, 8-pin modular jack. With this cabling scheme, twisted pair cable connects ONLY two MDIs; usually the workstation and a “concentrator” or “hub”. The maximum length between any device and the hub or concentrator is 100 meters.

- Nodes per segment     : 512
- Maximum separation    : 5 segments, 4 repeaters
- Concentrators in
  sequence              : 4
- Maximum node to
  concentrator length   : 100 meters