Network Cable Types and Specifications

This tutorial explains network cable types and specifications in details. Learn what type of network cable is used in what type of computer network. Understanding network cable type and specification will help you in selecting the right cable type for your network.

Category 3

cable, commonly known as Cat-3, is an unshielded twisted pair (UTP) cable designed to reliably carry data up to 10 Mbit/s, with a possible bandwidth of 16 MHz. It is part of a family of copper cabling standards defined jointly by the Electronic Industries Alliance and the Telecommunications Industry Association. Category 3 was a popular cabling format among computer network administrators in the early 1990s, but has since been almost entirely replaced by the very similar Cat-5 standard, which offers higher top speeds.

Category 5

Cable, commonly known as Cat 5, is an unshielded twisted pair type cable designed for high signal integrity. The actual standard defines specific electrical properties of the wire, but it is most commonly known as being rated for its Ethernet capability of 100 Mbit/s. Its specific standard designation is EIA/TIA-568. Cat 5 cable typically has three twists per inch of each twisted pair of 24 gauge copper wires within the cable. The twisting of the cable reduces electrical interference and crosstalk.

Another important characteristic is that the wires are insulated with a plastic (FEP) that has low dispersion, that is, the dielectric constant of the plastic does not depend greatly on frequency. Special attention also has to be paid to minimizing impedance mismatches at connection points.

Cat 5 cables are often used in structured cabling for computer networks such as Fast Ethernet, although they are also used to carry many other signals such as basic voice services, token ring, and ATM (at up to 155 Mbit/s, over short distances).

Category 5e

cable is an enhanced version of Cat 5 for use with 1000BASE-T (gigabit) networks, or for long-distance 100 Base-T links (350 m, compared with 100 m for Cat 5). It must meet the EIA/TIA 568A-5 specification. Virtually all cables sold as Cat 5 are actually Cat 5e. The markings on the cable itself reveal the exact type.

Category 6

A cable standard for Gigabit Ethernet and other interconnect that is backward compatible with Category 5 cable, Cat-5e and Cat-3. Cat-6 features more stringent specifications for crosstalk and system noise. The cable standard is suitable for 10BASE-T / 100BASE-TX and 1000BASE-T (Gigabit Ethernet) connections.

The cable contains four twisted copper wire pairs, just like earlier copper cable standards, although each twisted pair is made up of slightly larger 23 gauge copper wire as opposed to Cat 5's 24 gauge wire. When used as a patch cable, Cat-6 is normally terminated in RJ-45 electrical connectors. If components of the various cable standards are intermixed, the performance of the signal path will be limited to that of the lowest category. The distance without losing data is 220 m.

Category 7

(CAT7), (ISO/IEC 11801:2002 category 7/class F), is a cable standard for Ultra Fast Ethernet and other interconnect technologies that can be made to be backwards compatible with traditional CAT5 and CAT6 Ethernet cable. CAT7 features even more stringent specifications for crosstalk and system noise than CAT6. To achieve this, shielding has been added for individual wire pairs and the cable as a whole.

The CAT7 cable standard has been created to allow 10-gigabit Ethernet over 100 m of copper cabling. The cable contains four twisted copper wire pairs, just like the earlier standards. CAT7 can be terminated in RJ-45 compatible GG45 electrical connectors which incorporate the RJ-45 standard, and a new type of connection to enable a smoother migration to the new standard. When combined with GG-45 connectors, CAT7 cable is rated for transmission frequencies of up to 600 MHz.

STP (Shielded Twisted Pair)

This cable has a conductive braided or foil casing for each pair and theoretically offers very good protection from interference and crosstalk. It was commonly used for token ring networks.

Shielded Twisted Pair is rarely used due to the fact that the potential performance increase over UTP is not worth the much greater cost of STP. STP, which is limited to 100-meter lengths (the same as UTP), is used in token ring networks and for IBM mainframe and minicomputer environments. There is no standard for it. Since token ring networks do not require STP, it is used less and less. These are few reasons for this:

  • Higher cost due to greater complexity for the cabling and connectors
  • Larger size and less flexibility of the cabling
  • Longer installation time
UTP (Unshielded Twisted Pair)

UTP is the most commonly used type of networking cable. UTP cables are often called "ethernet cables" after Ethernet, the most common data networking standard that utilizes UTP cables, although not the most reliable.

In contrast to FTP and STP cabling, UTP cable is not surrounded by any shielding. It is the primary wire type for telephone usage and is very common for computer networking, especially in patch cables or temporary network connections due to the high flexibility of the cables.

Coaxial cable


Coaxial cable is an electrical cable consisting of a round conducting wire, surrounded by an insulating spacer, surrounded by a cylindrical conducting sheath, and usually surrounded by a final insulating layer.

Most common use of coax (the short form of coaxial cable) today is in standard cable TV. If you have the chance to examine a cable, you will find that it has a fairly simple design. A copper conductor lies in the center of the cable, which is surrounded by insulation. A braided or mesh outer covering surrounds the insulation. This is also a conductor.

A PVC plastic jacket encases the covering The cable is designed to carry a high-frequency or broadband signal, as a high-frequency transmission line. Because the electromagnetic field carrying the signal exists (ideally) only in the space between the inner and outer conductors, it cannot interfere with or suffer interference from external electromagnetic fields.

ThickNet, or RG-8,

is older and one of the first types of coaxial cable used in networks. RG-8 is strung in a physical bus topology. Its thick shielding makes it fairly immune to noise but also very rigid and difficult to work with. RG-8 requires connectors, called vampire taps, that pierce through its thick outer shielding. Both ends of the bus must be terminated with a 50-ohm resistor; without both functioning resistors, the network will fail.

ThinNet or RG-58

cable is far more flexible than ThickNet and much easier to work with. RG-58 cabling is also strung as a physical bus. It is capable of connecting a maximum of 30 devices on up to a 185-meter length of cable. ThinNet is constructed like ThickNet, except that the central conductor and the insulation are much thinner. British Naval Connectors (BNCs) are crimped onto the cable for connectivity, and 50-ohm resistors are required at each end of the cable. They used to be common for implementing computer networks, in particular Ethernet, but twisted pair cables have replaced them in most applications.

SMF (Single Mode Fiber) optic cable

Single-mode optical fiber is an optical fiber in which only the lowest order bound mode can propagate at the wavelength of interest. Single mode fibers are best at retaining the fidelity of each light pulse over longer distances and exhibit no dispersion caused by multiple spatial modes; thus more information can be transmitted per unit time giving single mode fibers a higher bandwidth in comparison with multi-mode fibers. A typical single mode optical fiber has a core radius of 5-10 micrometers and a cladding radius of 120 micrometers. Currently, data rates of up to 10 Gigabits/second are possible at distances of over 60 km with commercially available transceivers. Equipment for Single mode fiber is more expensive than equipment for Multi-mode optical fiber, but the single mode fiber itself is usually cheaper in bulk.

MMF (Multimode Fiber) optic cable

Multi-mode optical fiber (multimode fiber or MM fiber) is a type of optical fiber mostly used for communication over shorter distances, e.g. within a building. It can carry 1 Gbit/s for typical building distances; the actual maximum speed depends upon the distance. It is easier to connect to than single-mode optical fiber, but its limit on speed. Multi-mode fiber has a larger center core than single-mode fiber, which allows it to support more than one propagation mode, or path within the fiber. The equipment used for communications over multi-mode optical fiber is less expensive than that for single-mode optical fiber. Typical transmission speeds/distances limits are 100 Mbit/s up to 2 km (100BASE-FX), 1 Gbit/s for distances up to 500-600 meters (1000BASE-LX, 1000BASE-SX), and 10 Gbit/s for distances up to 300 meters (10GBASE-SR).

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