| Glossary: F |
| Facilities Assignment Control System (FACS) |
Database system for assigning and controlling cable pairs.
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| FAD |
See Facility Access Digroup.
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| Facility access digroup (FAD) |
This term refers to the DS1 path(s) between the DTAU and the test system.
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| Far-end Alarm and Control (DS3 FEAC) |
A DS3 C-bit subframe used to send alarm or status information from the far-end terminal to the near-end terminal. The channel is also used to initiate DS3 loopbacks at the far-end terminal from the near-end terminal (or mid-point test resource).
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| Far-end block error (FEBE) |
An indication sent to a transmitting node that a flawed block has been detected at the receiving node.
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| FAS |
Frame Alignment Signal
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| FBE |
See Framing Bit Error.
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| FC |
Framing Conversion
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| FCIF |
Flexible Computer Interface Format
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| FCS |
See Frame Check Sequence.
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| FDDI |
Fiber Distributed Data Interface
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| FDL |
Facility Data Link
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| FDM |
See Frequency Division Multiplexing.
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| FDS1 |
Fractional DS1 (or FT1)
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| FE1 |
Fractional E1
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| FEC |
Forward Error Correction
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| FECN |
Forward Explicit Congestion Notification
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| FEP |
See Front-End Processor.
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| FEV |
Far-End Voice
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| FEXT |
Far-End Cross-Talk
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| FIFO |
"First In |
| Flag |
The unique bit pattern (01111110) in a data stream at the data link layer used to mark the start or end of a frame. Requires bit stuffing so strings of ones in the data do not erroneously indicate a start or end to a frame.
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| FLC |
Function Level Code
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| Foreign exchange |
A circuit between a customer's main station or private branch exchange and a central office. This circuit is different than the one that normally serves the exchange area in which the customer is located.
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| Format errors |
"Any deviations from the prescribed format of the signal. This includes bipolar violations |
| Four-wire circuit (4W) |
A circuit which uses two electrically separated paths to carry data signals. One path is used for each direction.
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| FPS |
Framing Pattern Sequence
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| FPU |
FADplus Line Interface Unit
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| Fractional T1 |
"A technology that combines several individual channels on a T1 and uses them as a single channel. This action provides channels of a greater bandwidth (multiples of 64 or 56 kbps) than the typical 64-kbps channel |
| FRAD |
Frame Relay Access Device
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| Frame check sequence (FCS) |
A checking code used to detect data corruption.
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| Frame error |
(DS1): A frame synchronization bit error which occurs in either a terminal framing (Ft) bit or signaling framing (Fs) bit of the superframed format.
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| Frame relay |
"A high-speed |
| Frame slip |
The deletion or duplication of a frame of data. You detect a frame slip by the following event sequence:
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| Frame sync loss |
"In SF |
| Framing bit |
A bit introduced into a bit stream that identifies where one frame ends and the next one begins. This bit helps separate the characters at the receiving end of a transmission.
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| Framing bit error (FBE) |
"In SF |
| Framing bit error ratio |
"The number of framing bits in error divided by the total number of framing bits. This computation does not include any second where there is LOS |
| Frequency division multiplexing (FDM) |
The process of combining a number of analog signals onto a single transmission facility by an orderly assignment of frequency bands.
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| FRMBE |
Framing Bit Errors
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| Front-end processor (FEP) |
"A communications processor |
| Ft |
Terminal Framing
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| FT1 |
Fractional T1 (aka Nx64k)
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| FT3 |
Fractional T3
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| Full-duplex |
A transmission mode in which information can travel in both directions at the same time.
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| FX |
See Foreign Exchange. |
