Cabling Glossary


CAT3, CAT5E, CAT6, CAT6A are all Category Cables. These are copper computer networking cables that handle anything from telephone grade signals to gigabit ethernet signals. These cables typically contain 2+ twisted wire pairs. The wires are twisted because this helps cancel out electromagnetic interference (EMI). The CATs come Shielded (STP) or Unshielded (UTP). The shield is usually an Aluminum Foil that protects from EMI. The jackets can have various levels of fire resistance, and can also be outdoor rated.


Media Converters are networking devices that convert a signal between two dissimilar media types, for example, twisted pair to fiber optic.


Attenuation is the reduction in intensity of a number of different things. It is the opposite of amplification. In physics or electronics the change is usually referred to using decibels (dB), noting the number of decibels by which a particular signal is reduced as it passes through a particular medium a certain distance. This concept is used quite a bit in the telecom industry because of its importance in determining where a repeater is needed.


A backbone network or network backbone is a part of computer network infrastructure that interconnects various pieces of network, providing a path for the exchange of information between different LANs or subnetworks. A backbone can tie together diverse networks in the same building, in different buildings in a campus environment, or over wide areas.


Bandwidth is a measure of data flow rate in digital networks typically in bits per second.

Bend-Insensitive Fiber (BIF)

In regular fiber there are many rays of light (modes) transmitted down the fiber. The inner modes are more strongly guided while the outer modes are weakly guided.

Bend-Insensitive Fiber adds a layer of glass around the core of the fiber – a protective type coating – so that if light tries to get out of the core it is reflected back, thus minimizing data loss, even if bent beyond the bend-radius.

Bend Radius

Bend radius, measured to the inside curvature, is the minimum radius one can bend a pipe, tube, sheet, cable or hose to without kinking it, damaging it, or shortening its life.


BICSI - Building Industry Consulting Service International.

Central Patching

Central Patching is the patching done at the core of a structured cabling system. A Central Patching area simplifies equipment moves, adds and changes. For example if a new equipment switch will use an LC connector (instead of an SC) you would just need to change the cable or harness from the enclosure, not the whole more expensive trunk.


A cleave in an optical fiber is a deliberate, controlled break, intended to create a perfectly flat endface. A good cleave is required for a successful splice of an optical fiber, whether by fusion or mechanical means.  


A conduit is a general term for a means of conveying something from one location to another or between persons. An electrical conduit is a purpose-designed electrical piping system used for protection and routing of electrical wiring. Electrical conduit may be made of metal, plastic, fibre, or fired clay. Flexible conduit is available for special purposes.


The Core is the center part of the fiber cable through which light is transmitted. The fiber consists of a core surrounded by a cladding layer.

Decibel (dB)

The standard unit used to express gain or loss of optical power. A standard logarithmic unit for the ratio of two powers, voltages or currents. In fiber optics, the ratio is power.

EDA (Equipment Distribution Area)

In these spaces you will find the cabinets and racks that house the equipment – servers, storage devices, mainframes, tape drives, etc. Horizontal cabling is terminated here in patch panels.


EIA - Electronic Industries Alliance is a standards organization that defines standards for telecommunications cabling systems.


Extrusion - Plastics extrusion is a high volume manufacturing process in which raw plastic material is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, weather stripping, window frames, plastic sheeting, adhesive tape and wire insulation.  


Ferrule is the protruding portion of a fiber connector. Materials: ceramic, stainless steel, polymer  

Furcation Tubing

Furcation Tubing - A protective tubing that protects exposed fiber. Commonly used in terminating multi-fiber cable or "fan-out" situations.  

HDA (Horizontal Distribution Area)

Supports all cabling to the EDA, includes the horizontal cross-connects, and switches (LAN, SAN, KVM) for the equipment in the EDA.

Insertion Loss

Insertion Loss is the total power loss caused by insertion of an optical component (such as a connector, splice, or coupler) into a previously continuous path.

IDA (Intermediate Distribution Area)

This area contains a second-level backbone that connects the MDA and an HAD.


ISDN (Integrated Services Digital Network) is an international standard for transmitting digital information (text, sound, voice, data, video, etc.)  


Kevlar is the registered trademark for a light, strong synthetic fiber. Kevlar is widely used as a protective outer sheath for fiber optic cable, as its strength protects the cable from damage and kinking. 

Loose Tube Buffering

In Loose Tube Buffering construction the fiber is laid into semi-rigid tubes, allowing the cable to stretch without stretching the fiber itself. This protects the fiber from tension during laying and due to temperature changes.  



Loss Budget

The Loss Budget is the total acceptable loss for a given system from transmitter to receiver; includes cables, splices and connectors.

Low Smoke Zero Halogen (LSZH)

Low Smoke Zero Halogen (LSZH or LSOH) is a type of cable jacketing used in the manufacture of industrial and network cabling. LSZH cable jacketing is composed of thermoplastic or thermoset compounds that emit limited smoke and no halogens when exposed to high sources of heat. Most network cables are insulated with PVC plastic. In fires, this plastic material releases chlorine, a poisonous gas, which forms caustic hydrochloric acid when it comes in contact with water. Halogen-free cable, on the other hand, is made of a different material called polypropylene, which doesn't produce a dangerous gas/acid combination. Low smoke zero halogen cable reduces the amount of toxic and corrosive gases emitted during combustion. Typically used in poorly ventilated areas, low smoke zero halogen is becoming very popular where the protection of people and equipment from toxic and corrosive gasses is critical.  

MDA (Main Distribution Area)

MDA is the central (main) point of distribution, includes the main cross-connect and may include horizontal cross connects. Core routers, backbone, LAN/SAN switches, PBX are located here. This is the central point for the data center structured cabling system.


Mode is a path of light through a fiber.

Multi-mode Fiber

Multi-mode Fiber is a type of optical fiber mostly used for communication over shorter distances, such as within a building or on a campus. Typical multi-mode links have data rates of 10 Mbit/s to 10 Gbit/s over link lengths of up to 600 meters, more than sufficient for the majority of premises applications.  

Near End Crosstalk (NEXT)

Is the measurement of noise interference that is transmitted from one cable pair to another pair on the near end. An example of crosstalk is when a second conversation can be heard in the background over the phone while you are talking. This same thing happens with data transmission. If the crosstalk is great enough, it will interfere with signals. Crosstalk is measured in dB. The higher the dB the better the performance as more of the signal is being transmitted.


Multi-mode fibers are identified by the OM ("optical multi-mode") designation as outlined in the ISO/IEC 11801 standard. OM3 is a laser optimized Aqua 50/125 multi-mode fiber for high bandwidth applications. OM3 fiber allows 10Gb data transmission over a distance up to 300m. 


Multi-mode fibers are identified by the OM ("optical multi-mode") designation as outlined in the ISO/IEC 11801 standard. OM4 is a laser-optimized, high bandwidth 50/125 multi-mode fiber. OM4 fiber allows data transmission of up to 550 meters at 10 Gb/s for ultra long building backbones and medium length campus backbones. OM4 has a significantly higher bandwidth than OM3. This Aqua fiber is also backward compatible with OM3.

(The TIA-942-A recommends OM4 fiber for backbone and horizontal cabling in the data center, this will most likely be approved in 2012.)

Plenum Cable

Plenum Cable refers to structured cabling permitted under building codes for plenum spaces. Plenum rated cable has slow-burning, fire-resistant casing that emits little smoke.

Point to Point

Point to Point refers to when there is a direct connection between two active communications devices (switches to servers, servers to storage, server to server, etc.).

Punch Down

is when the copper wires are “punched down” into the 110 block or patch panel. A special punch down tool is used to push the wire down firmly and properly. Time consuming punch downs can be avoided with the use of preterminated copper trunking.

Return Loss

Return Loss is a measure of power reflected from imperfections in an electrical or optical communications link. Return loss is usually expressed in decibels. The return loss value describes the reduction in the amplitude of the reflected energy, as compared to the forward energy. It will always be a loss, and therefore a negative dB. However one can write -3 dB as simply 3 dB of loss, dropping the negative sign and adding loss.

Riser Cable

Riser Cable which is to be run between floors in non-plenum areas is rated as riser cable. The fire requirements on riser cable are not as strict. Thus, plenum cable can always replace riser cable, but riser cable cannot replace plenum cable in plenum spaces.


SAN: Storage Area Network (SAN) is a high-speed network of shared storage devices. A SAN permits storage devices attached to the SAN to be used by servers attached to the SAN.


Sheath - A cable is one or more wires or optical fibers bound together, typically in a common protective jacket or sheath.

Single-mode Fiber

Single-mode Fiber optical fiber (SMF) is an optical fiber designed to carry only a single ray of light (mode).


Splice -Fusion splicing is the act of joining two optical fibers end-to-end using heat. The goal is to fuse the two fibers together in such a way that light passing through the fibers is not scattered or reflected back by the splice, and so that the splice and the region surrounding it are almost as strong as the virgin fiber itself. The source of heat is usually an electric arc, but can also be a tungsten filament through which current is passed.

Strength Member

Strength Member - For indoor applications, the jacketed fiber is generally enclosed, with a bundle of flexible fibrous polymer strength members like Aramid (e.g. Twaron or Kevlar), in a lightweight plastic cover to form a simple cable. Each end of the cable may be terminated with a specialized optical fiber connector to allow it to be easily connected and disconnected from transmitting and receiving equipment.

Structured Cabling

Structured Cabling is defined as building or campus telecommunications cabling infrastructure that consists of a number of standardized smaller elements (structured). A properly designed and installed structured cabling system provides a cabling infrastructure that delivers predictable performance as well as has the flexibility to accommodate moves, adds and changes; maximizes system availability, provides redundancy; and future proofs the usability of the cabling system.

Tensile Strength

Tensile Strength - measures the engineering stress applied (to something such as rope, wire, or a structural beam) at the point when it fails. It is an intensive property of the material, which not only depends on the type of material but also the preparation of the specimen and the temperature of the test. In other words, the amount of force the material can withstand when being stretched. (Picture tug-of-war, the amount of force required to break the rope would be it's tensile strength)


TIA/EIA-568-B attempts to define standards that will enable the design and implementation of structured cabling systems for commercial buildings, and between buildings in campus environments. The bulk of the standards define cabling types, distances, connectors, cable system architectures, cable termination standards and performance characteristics, cable installation requirements and methods of testing installed cable.

Tight Buffer

In Tight Buffer construction the fiber may be embedded in a heavy polymer jacket. These fiber units are commonly bundled with additional steel strength members, with a helical twist to allow for stretching.


TIA-942 is the structured cabling standard developed by the Telecommunications Industry Association (TIA) to define guidelines for designing, planning and building data centers, particularly with regard to the cabling systems and network design. The standard deals with both copper and fiber cabling infrastructure; site space and layout; and environmental considerations, including power and cooling.

The standard specifies the usage of data center pathways and spaces. The TIA 942 standard defines a structured cabling system where everything leads back to the MDA, not point to point.

The standard specifies the usage of data center pathways and spaces. A basic data center topology will consist of the Entrance Room, MDA, HDA, ZDA


Usually when people are talking about Virtualization they are referring to Server Virtualization. When you partition one physical server into several virtual machines, you can operate and manage multiple operating systems at once on that single server. This helps reduce the number of physical servers a company needs. This also will cut down on energy (power and cooling) consumption. Virtualization lets a single physical source (server, operating system or storage device) appear as multiple resources; or lets multiple physical sources (servers or storage devices) to appear as a single source.

ZDA (Zone Distribution Area)

The ZDA acts as a consolidation point for high-fiber-count cabling from the main distribution area (MDA) or horizontal distribution area (HDA) to regional areas or zones within the data center. Incorporating this architecture into one’s data center cabling design allows for a one-time installation of the backbone cabling and provides flexibility to accommodate frequent reconfigurations at the zone required for moves, adds and changes.