Fiber & Data Center Cabling Glossary | Hardline Field Services

As-built

Documentation that records what was actually installed — rack positions, cable routes, port assignments — rather than what was designed.

Attenuation

Loss of optical power along a fiber, measured in dB per kilometre. See loss budgets.

Backbone cabling

Cabling between main distribution areas, telecom rooms and data halls, or between buildings. Usually high-count fiber.

Badging

The site owner's process for approving and issuing access credentials to workers. Often the longest step in mobilizing a crew.

Bi-directional OTDR

Taking OTDR measurements from both ends of a fiber and averaging them to get the true loss of each splice.

Cable tray / ladder rack

Overhead or underfloor pathway that supports cables in a data hall or telecom room.

Cassette

A module that transitions an MPO trunk to individual LC ports, usually mounted in a patch panel.

Change control

The process for approving any change inside a live facility before work starts.

Cleaver

A precision tool that cuts a fiber end flat before splicing. Ribbon cleavers cut a whole ribbon at once.

Cross-connect

A patch connection between two cabling segments, often in a meet-me room, linking customers and carriers.

dB (decibel)

The logarithmic unit used to measure optical loss.

Fusion splicing

Joining two fibers permanently by melting them together with an electric arc. See fiber splicing crews.

FTTH

Fiber to the home: fiber networks running to individual residences. See OSP and FTTH crews.

Innerduct

A small flexible conduit placed inside a larger conduit to protect and organize fiber cables.

Launch cable

A length of fiber attached between the OTDR and the link under test so the first connector can be measured. A receive cable does the same at the far end.

Liquidated damages (LDs)

Contract penalties per day of delay, a major reason schedules cannot slip.

Loss budget

The maximum total optical loss allowed in a link, calculated from its components. See the guide.

Mass fusion splicing

Splicing a full fiber ribbon — usually 12 fibers — in one operation. See ribbon vs single-fiber.

Meet-me room (MMR)

The room in a data center where carriers and customers interconnect.

MOP

Method of procedure: the approved, step-by-step plan for work in a live environment.

MPO / MTP

Multi-fiber push-on connectors carrying 8, 12, 16, 24 or more fibers. MTP is a brand of MPO. See MPO polarity.

Multimode fiber (OM3, OM4, OM5)

Fiber with a larger core used for short links inside data centers. OM4 jackets are usually aqua.

OSP

Outside plant: cabling outside buildings — aerial, underground, between buildings.

OTDR

Optical time-domain reflectometer: a tester that sends pulses of light down a fiber and reads the reflections to locate and measure splices, connectors and faults. See OTDR testing.