Telecommunications Lingo

In the telecom community, we have our own little language. Here are a few terms, just a short list of some commonly used items. I’m sure there are enough telecom terms to fill a dictionary or even an encyclopedia – this is just a tiny sampling ;-).

  • CPE – Customer Premises Equipment
  • NNI – Network to Network Interface
  • Demarc or MPOE – Point at which carrier wire enters building, The “demarcation point” or “minimum point of entry”.
  • TDM – Time Division Multiplexing, the classic high-quality way to deliver telecom service such as voice circuits, leased serial lines (T1/DS1, DS3, …), etc.
  • WDM & DWDM – Wavelength Division Multiplexing & Dense WDM, techniques used by carriers to provide multiple optical circuits on the same fiber (using advanced prism tricks).
  • SFP, SFP+, XFP, Optical Transciever module – Small Form-factor Pluggable standardized sockets and associated modules to provide optical connections on telecom equipment. The “+” version is 10G capable, and XFP is an older larger socket that is also 10G capable.
  • MMF, SMF – Multi-mode fiber & Single-mode fiber. Multi-mode is cheaper and only used for short distances within buildings (usually up to 300 meters). Single-mode fiber is more expensive and is used for long distance connections usually greater than 300 meters).
  • Twisted Pair Copper – popular type of wiring used to connect old fashioned phones, T1/DS1 circuits, PRI voice circuits, elecrical ethernet connections (non-optical), etc.
  • MUX – “Multiplexer” used to provide many smaller capacity circuits from one or more high-capacity carrier backbone lines. Usually present in the building “Demarc” or MPOE telecom wiring room.
  • DTE & DCE – Data Terminal Equipment & Data Carrier Equipment. Usually used to describe how a serial port is wired. On a PC, Server, Router, or switch the serial port is usually wired as DTE. On a Modem, the serial port is usually wired as DCE. For communication to occur between DTE ports, a serial crossover or “null modem” cable must be used. Standard Cisco serial cables are wired as “null modem.” To connect between DTE and DCE, you need a straight-through serial cable (Usually PC or Server to Modem).
  • Rollover cable – A flat 8-wire cable commonly used for serial port connections. Each wire is aligned for easy crimp into a special RJ45 (8P8C) connector. If you flip or “roll over” the flat cable before crimping, it will make the difference between a “straight-through” or “null modem” serial connection if equipment uses the standard Cisco serial pinout.

I may come back here and add some more if time allows. These types of terms give us telecom people “warm fuzzies”. We’re right at home with our alien language ;-).

About notesbytom

Keeping technology notes on to free up my mind to solve new problems rather than figuring out the same ones repeatedly :-).
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