Ethernet cables and standards

Ethernet cables and standards

May.06, 2011 in Networks

The cabling is a fundamental part of networking. It provides the physical connection between computers. The cable you choose must be suited for the distance between your computers. You also choose the type of cabling to match the network cards and other networking hardware. For example,
if you choose the Ethernet protocol with a spanning tree, or star, topology, you also must use Ethernet network interface cards, Ethernet cabling, and Ethernet hubs. But what cables to use for your network?
Because of the wide variety of cable types, your decision depends on the speed you want for your network. You also must consider how difficult or easy the cable is to install, how expensive the cabling solution is, the distance between computers, and security issues. Depending on the type of cabling you use, you need to buy appropriate connectors.  Cable connectors are necessary for attaching the cable to certain pieces of computer hardware, such as the network card, hubs, switches, and so on. The many terms that identify cabling types and cabling hardware can be confusing. The following is an  explanation of each cabling type in detail.
Each cabling type uses specific pieces of hardware to terminate the ends or connect two pieces of cabling together. These connectors make it possible for the network cables to transmit data efficiently throughout the network. All LAN cable can be divided into three basic types: twisted pair, coax, and fiber optic. Below is short description for each of them.
Coaxial cable.
Coaxial cable looks like the cable that runs between your VCR and television set. Coax cable consists of a plastic jacket surrounding a braided copper shield, plastic insulation, and a solid inner conductor. The cabling is secure and generally free from external interference.  This type of cabling  uses BNC and T-connectors. A T-connector attaches two coaxial, or thin Ethernet cables and provides a third connection for the network interface card. A BNC connector is an end piece that connects two or three cables together.  Coaxial cabling is also called ThinNet, or Thin Ethernet cabling and it’s used with 10Base-2 and 10Base-5 standards, which are  implementation of an Ethernet standard for coaxial cabling. The data transfer rate, or network speed, for 10Base-2/5 is 10 Mbps.

Twisted-pair.
Twisted-pair wiring is the most common type of LAN wiring cable in use today. It is versatile, easy to install, inexpensive, and has favorable performance characteristics. Twisted-pair cable is available with or without shielding. It consists of one or more pairs of insulated wires that are twisted together and joined in a common sheath. The main characteristics of twisted-pair cable are wire gauge, stranding, twist pitch, insulation type, characteristic impedance, and sheath material. Each of these items may affect the suitability of a cable for a particular application. LAN twisted-pair cable,  usually comes as 4-pair cable. Most LAN topologies actually use only two of the four pairs, however, so some installations place two LAN connections on each 4-pair cable. Telephone connections often use two pairs and may sometimes be wired in the same cable with a 2-pair LAN connection. You should be cautious in using pairs from the LAN cable, because some of the 100 Mbps and higher LAN schemes may use all four pairs of the cable . As we mentioned earlier the twisted pair cables came in two variations : UTP (unshielded twisted pair) and  STP (shielded twisted pair). These cables use a RJ45 connector. RJ-45 connectors consist of an eight-wire connection jack that is used to join the four pairs of networking cable in twisted-pair cable.
Fiber optic .
Functionally, fiber optic systems are similar to the copper wire systems they are rapidly replacing. The principle difference is that fiber optics use light pulses (photons) to transmit data down fiber lines, instead of electronic pulses to transmit data down copper lines.

Fiber-optic cables are used mostly  for higher-speed networks or for transmission of signals at very long distances. Fiber-optic cable has a construction similar to some multi-conductor wire. It functions as a light guide, guiding the light introduced at one end of the cable through to the other end. The light source can either be a light-emitting diode (LED) or a laser. The light source is pulsed on and off, and a light-sensitive receiver on the other end of the cable converts the pulses back into the digital ones and zeros of the original signal.

A typical fiber-optic cable consist of several components.

• core
• cladding
• coating
• strength member/material
• jacket

There are three types of fiber optic cable: single mode, multimode, and plastic optical fiber (POF). Single-mode cable is a single stand of glass fiber with a diameter of 8.3 to 10 microns. Multimode cable is made of multiple strands of glass fibers, with a combined diameter in the 50-to-100 micron range. Each fiber in a multimode cable is capable of carrying a different signal independent from those on the other fibers in the cable bundle. POF is a newer plastic-based cable that promises performance similar to single-mode cable, but at a lower cost. While fiber optic cable itself is cheaper than an equivalent length of copper cable, fiber optic cable connectors and the equipment needed to install them remain, at least for now, more expensive than their copper counterparts. The main disadvantage of fiber optics is that the cables are expensive to install and difficult to splice.
Cabling standards:
10Base-2 -    10 Mbps  Ethernet over coaxial cable limited to  maximum distance of 185 meters. Also known as Thin Ethernet or Thinnet or Thinwire.
10Base-5    – 10 Mbps  Ethernet over coaxial cable limited to maximum distance of 500 meters. Also known as Thick Ethernet or Thicknet or Thickwire.
10Base-36   – 10 Mbps  Ethernet over multi-channel coaxial cable limited to  maximum distance of 3,600 meters.
10Base-F    – 10 Mbps  Ethernet over optical fiber.
10Base-FB – 10 Mbps  Ethernet over two multi-mode optical fibers using a synchronous active hub.
10Base-FL – 10 Mbps  Ethernet over two optical fibers and can include an optional asynchronous hub.
10Base-FP    – 10 Mbps  Ethernet over two optical fibers using a passive hub to connect communication devices.
10Base-T    – 10 Mbps  Ethernet over twisted pair cables with a maximum length of 100 meters. Requires only two pairs.
10Broad-36    – 10 Mbps  Ethernet over coaxial cable with a maximum cable length of 3,600 meters.
100Base-FX    – 100 Mbps  Ethernet over two  optical fibers. Maximum length is 400 meters (1,310 ft) for half-duplex connections  or 2 kilometers (6,600 ft) for full-duplex over multimode optical fiber.
100Base-T    – 100 Mbps  Ethernet over twisted pair cable limited to 100 meters (328 ft).
100Base-T2    – 100 Mbps  Ethernet over two pairs of Category 3 or higher  twisted pair cable.
100Base-T4    – 100 Mbps  Ethernet over four pairs of Category 3 or higher  twisted pair cable.
100Base-TX    – 100 Mbps  Ethernet over two pairs of CAT5 or above  twisted pair  cable with a maximum length of 100 meters (328 ft).
100Base-X -    specifications for Fast Ethernet local-area network (LAN) cabling and related equipment.
1000Base-CX -    1000 Mbps  Ethernet over two pairs  with maximum distances of 25 meters using balanced shielded twisted pair.
1000Base-LX    – 1000 Mbps Ethernet over two multimode or single-mode optical fibers using long wavelength laser.
1000Base-SX    – 1000 Mbps Ethernet over two multimode optical fibers using shortwave laser optics.
1000Base-T    – 1000 Mbps  Ethernet over four pairs of Category 5 or better  twisted pair cable (CAT-5, CAT-5e, CAT-6, or CAT-7).
1000Base-X – A generic name for  gigabit Ethernet transmission over fiber.
10Gigabit Ethernet    – Ethernet at 10 Gigabits per second over optical fiber. Multimode fiber supports distances up to 300 meters and single mode fiber supports distances up to 40 kilometers (10GBASE-ER).