Join Greg Sowell for an in-depth discussion in this video Exploring cable types and their characteristics, part of Networking Foundations: Network Media (LANs).
- Copper cable is the most commonly used connection media in local area networks. It provides high bandwidth at a low price and is easy to install. The vast majority of networks utilize unshielded twisted pair or UTP. UTP is a cable that has eight wires inside. The wires are twisted into pairs, leaving you with four groups of distinctly colored wires. Since these cables are unshielded, they rely on the twisting effect for protection. Twisted pair cable is used to carry both voice and network traffic.
The wires inside of the cables are twisted at varying rates to prevent crosstalk, or the electrical interference produced by adjacent wires. When an electrical current is sent across a wire, it produces a magnetic field. If another wire is caught in that magnetic field, interference will be generated. By twisting pairs of wires together, the magnetic fields are cancelled out. This is not to be confused with STP, or shielded twisted pair. STP is nearly identical to UTP, save for the additional foil shielding added around the pairs.
This helps to insulate the cable from external electromagnetic radiation and RF interference. STP requires the shielding to be grounded at both ends. Otherwise, the shielding can act as an antenna, possibly creating even more interference than would have been experienced otherwise. The additional shielding also makes the cable more expensive. STP is used in noisy environments or spaces where heavy machinery or other equipment produces exceptional amounts of interference. UTP and STP generally come in three flavors, riser, plenum, or outdoor.
Riser is your everyday cable. It is used for standard patch cables as well as within cabinets and racks. A plenum is the space that circulates air for heating and air conditioning systems. Cable rated to run in the plenum is specifically formulated to put out fewer toxins when burned. Outdoor cable is generally thicker jacketed and UV protected. It can be dry inside, gel filled, shielded, and can contain a grounding wire. The wire inside of the cable can also vary in a couple of ways.
A wire made up of many small wires that have been twisted together is called stranded wire. This makes the cables very flexible and more durable when bent frequently. Stranded is usually used in patch cables. If you have an ethernet cable in your bag, chances are it's stranded wire. Solid core, on the other hand, is made from one solid copper wire. Solid is cheaper to make and better able to carry current, which makes it great for most fixed infrastructure. A more legacy cable in the network world is coax.
Coaxial cable is often seen in home cable tv systems or home satellite connections. It is comprised of a center copper wire surrounded by a flexible insulation. Around the insulation, shielding foil surrounded by a steel mesh, and finally a jacket. Coax cable is rated on a system called RG. The term "RG" or "radio guide" comes from old military jargon. The number following the RG only loosely determines the size of the center conductor and not much else.
Each manufacturer will produce it differently and often you get what you pay for. Most often, RG6 is used, though RG58 and 59 are seen on occasion. Coax was the benchmark connection method for legacy networks, but it is rarely used today. In modern applications, coax is used as waveguide, to connect radios to antennas, to connect cable modems, or to terminate Digital Service 3 connections which provide speeds up to 45 megabits. Each type of cable is used for unique purposes.
- Exploring cable types
- Creating coaxial cable
- Terminating Cat 5 cable
- Mitigating EMI
- Setting up wireless LANs
- Comparing Wi-Fi frequencies
- Securing a wireless network
- Using fiber-optic cable in LAN and WAN applications