F-G0-A | B | C-Cn | Co-Cz | D | E | F-G | H-I | J-L | M | N-O | P-Q | R | S | T | U-Z
0-A | B | C-Cn | Co-Cz | D | E | F-G | H-I | J-L | M | N-O | P-Q | R | S | T
- F: Frequency.
Frequently Asked Questions
- Farad: A unit of capacitance, Usually
expressed in microfarads which is one millionth of a farad. A 1 Farad capacitor
would take in 1 coulomb of electrons when 1 volt is applied to it.
: (Fire Alarm & Signal Cable)
- Fast Ethernet: A
100BaseT 802.3u standard, Fast Ethernet merely reduces the "bit time" (duration
of each bit transmission) by a factor of ten resulting in 10 times the
performance of 10BaseT. Because 100BaseT uses the same CSMA/CD access method
used on all Ethernet products, the solution can be deployed into existing
networks without requiring massive cabling changes.
- Fault: A
condition that causes any physical component of a system to fail to perform in
an acceptable manner.
- Fault Management: 1 of 5 basic network
management functions defined by the International Standards Organization (ISO).
It involves the detection isolation & correction of fault on the network
- Fault Tolerance: The ability to operate properly in the even
of a failure. These types of systems are designed to ensure that in the event
of a power failure, disk crash, or a major user error, data is not lost & the
system can continue to operate.
- FC: See Frame
- FCC: See Federal Communications
- FCS: See Frame Check
- FDDI: See Fiber Distribution Data
- FDM: See Frequency-Division
- FDX: See Full Duplex
- Federal Communications Commission: (FCC) Government agency
that supervises, licenses, & controls standards for all forms of radio &
- Federal Networking
Council: (FNC) A collection of federal agencies that have heavy interests
in federal networks using TCP/IP & the Internet. Representatives from DOD, DOE,
DARPA, NSF, NASA & HHS are the major members of the FNC.
- Feeder Cable: In a CATV system, the transmission cable from
the head end (signal pickup) to the trunk amplifier. Also called a trunk
- FEP: See Fluorinated Ethylene Propylene or
Front End Processor
- Ferrous: Composed of and/or
containing iron. A ferrous metal exhibits magnetic
- Fiber: A single. separate optical transmission
element characterized by a core & a cladding.
Distribution Data Interface: (FDDI) Established by American National
Standards Institute (ANSI), this standard specifies a data transfer rate of 100
Mbps over fiber & limits network to approximately 200 km in length.
Loss: The attenuation (deterioration) of the light signal in optical fiber
- Fiber Optics: The transmission of light through
optical fibers for communications & signaling.
- Field: A group of bits
(bytes, words) that typically serves a single function. An example of TCP's
sequence number: 32-bit field indicating the number of the first byte of data
in a packet.
- FIFO: A form of buffer that is used in communication
circuits, on a transmitter side, the program writes data into the FIFO while
the transmitting circuit reads at a different rate. On a receiving circuit,
received data is stored in the FIFO in case the program isn't yet ready to read
- Figure 8 Cable: An aerial cable configuration in which the
conductors & the steel strand which supports the cable are integrally jacketed.
A cross section of the finished cable approximates the figure
- File: A collection of related data stored on a disk &
treated as a single unit.
- File Server: A computer which provides file
storage for workstations on the network. The workstations can use the disks on
the file server as though they were attached to the workstation. File Transfer
Access & Management: See FTAM
- File Transfer Access &
Management: (FTAM) An application level protocol governing file
- File Transfer Protocol: (FTP) The
application-level protocol used to transfer files between two hosts on a TCP/IP
based network system.
- Filled Cable: A telephone cable construction in
which the cable core is filled with a material that will prevent moisture from
entering or passing through the cable.
- Fillers: Nonconductive
components cabled with the insulated conductors or optical fibers to impart
roundness, flexibility, tensile strength, or a combination of all three, to the
- Filter: Used in reference to a function performed by a bridge.
It involves comparing each packet received with the specification set by the
network manager. Packets are forwarded or rejected according to these
specifications. Filtering allows a network manager to conduct several tasks
including limiting protocol specific traffic to one network segment, isolating
electronic mail domains. & performing several other traffic control
- Finger: A UNIX command that shows information about a user
or group of users on the Internet. The Finger command usually returns the
user's real name, whether or not they have unread mail, & the time & date of
their last login. Finger also displays two files (if they exist) located in the
home directory of the user you fingered. These two files (the .PLAN & the
.PROJECT files.) are simply ASCII text files that can be entered by the user to
display any information upon being fingered.
- Fire Alarm & Signal
- Firewall: A term used in reference to the router's
ability to contain a fault to the area of the network that it occurs
- Firmware: A computer program or software stored permanently in
PROM or ROM or semi-permanently in EPROM.
- Flag: In communications, a
bit pattern of six consecutive "1" bits (character representation is 01111110)
used in many bit-oriented protocols to mark the beginning (& often the end) of
- Flame: A negative response to an e-mail message or newsgroup
posting. The most common recipients of flames are users who post commercial
message in public forums, adult material in non-adult areas of the Internet, or
racial or gender-biased comments. The worst sort of flame is known as a
"mail-bomb," which occurs when the user bearing flamed open his or her e-mail &
receives a flood of letters with unusually long file attachments that make his
or her computer "crash."
- Flame Resistance: The ability of a material
not to propagate flame once the heat source is removed.
The measure of the material's ability to support combustion.
ROM: Read only memory (ROM) that is electronically reprogrammable &
non-volatile (remains in memory when the unit is powered down for normal
periods of time).
- Flat Cable: A cable with two smooth or corrugated,
but essentially flat surfaces.
- Flex Life: The ability of a cable to
bend many times before breaking.
- Flexibility: The ability of a cable
to bend in a short radius.
- Floating: Referring to a circuit which has
no connection to ground.
- Flourinated Ethylene
Propylene: (FEP) Was formally called X-100 or FEP-100. This "Teflon" FEP
fluorocarbon resin in a register trademark of the DuPont de Nemours
- Flow Control: Any of several hardware or software techniques used
to prevent a source node's transmission from over- running the destination
node's capacity to receive & process the information. Flow control can use
physical hardware techniques, e.g. dedicated signal lines between a modem &
computer, or software techniques, such as windowing information used by a
network protocol such as TCP.
- FM: See Frequency
- FNC: See Federal Networking
- Forwarding: Process whereby an Ethernet switch or bridge
creates the contents of a packet & then passes that packet on to the
appropriate attached segment. A forwarding rate is the time that it takes the
device to execute all the steps.
- Four-Wire Lines: A telephone line
(circuit) between two DTE's using two pairs of wires. One pair is used for
sending & the other pair used for receiving signals.
The process of dividing a datagram into smaller datagrams. Fragmentation is
required to transmit large datagrams through network which can only transmit
smaller datagrams. The Internet Protocol includes facilities for
- Frame: A block of data consisting of its own set of
control information, including transmission address & data for error
- Frame Check Sequence: (FCS) In
bit-oriented protocols, a 16-bit field that contains transmission
error-checking information, usually appended at the end of a frame.
- Frame Control: (FC) On Token Ring networks, this data
supplies the frame type.
- Frame Relay: A packet switching concept
designed to maximize throughput & minimize costs by simplifying network
processing. It is particularly suitable for applications in which the endpoints
are intelligent devices & where transmission lines are of high
- Frame Switch: A multiport device that receives variable
length LAN frames & creates point-to-point connections to deliver a unicast
frame to only the output associated with the destination address identified in
the LAN frame.
- Freenet: A network system made up of community-based
bulletin board systems with e-mail, information services, interactive
communications, & conferencing. they are usually funded & operated by
individuals or organizations much like public television. Freenet providers are
part of the National Public Telecomputing Network (NPTN), a Cleveland-based
organization that works to make computer networking services as freely
available as public libraries.
- Frequency: Rate of cycles per second.
The unit of measurement is Hertz (Hz): cycles per second.
- Frequency Modulation: (FM) A modulation technique. The
frequency of the carrier signal is modified to carry the digital
- Frequency Response: The characteristic of a device
denoting the range of frequencies over which it may be used
- Frequency Shift Key: (FSK) Frequency
modulation of the character which varies between a fixed number of
- Frequency-Division Multiplexor: (FDM)
A device that divides the available transmission frequency range into narrower
banks, each of which is used for a separate channel.
- Front End Processor: (FEP) A dedicated computer linked to
one or more host computers or multi-user minicomputers; performs data
communications functions & serves to off-load attached computers of network
processing; in IBM SNA networks, an IBM 3704, 3705, 3725 or
- FSK: See Frequency Shift
- FTAM: See File Transfer Access &
- FTP: See File Transfer
- Full Duplex: (FDX) Simultaneous
- Fusion Splice: A permanent joint accomplished
by the application of localized heat sufficient to fuse or melt the ends of
- Gain: Increased signal power, usually the result of
- Gateway: A device that allows communication between
dissimilar LANs by translating information from one to the other (e.g. Ethernet
to Token Ring).
- Gauge: A term used to denote the physical size of a
- GHz: see Gigahertz
- Gig: Shortened
prefix for one billion. Usually short for Gigabyte.
- Giga: Prefix meaning billion.
- Gigabyte: (Gbyte, Gig, or G) 1,073,741,824 bytes, equal to
1024 megabytes; basic unit of measurement of mass storage.
- Gigahertz: (GHz) A unit of frequency equal to one billion
- GND: See Ground
- Gopher: An
information search & retrieval tool used widely for research. Gopher
information is stored hierarchically on computers across the Internet. It uses
a simple protocol that allows a client to access information from a multitude
of numerous Gopher servers at one time, creating what's known as "gopher
space." The most common search tools in gopher are Veronica & Jughead. Gopher
clients exist for most platforms.
- GOSIP: See Government OSI Profile
- Government OSI
Profile: (Government OSI Profile) A version of
the OSI (Open Systems Interconnection) model designed specifically for the U.S.
- Graded-Index Fiber: A type of fiber where the refractive
index of the core is lower toward the outside off the fiber. It bends the rays
inward & also allows them to travel faster in the lower index of refraction
region. This type of fiber provides high bandwidth capabilities.
- Ground: (GND) A conducting connection, whether intentional
or accidental, between an electrical circuit or equipment & the earth, or to
some conducting body that serves in place of the earth.
- Ground Loop:
A completed circuit between shielded pairs of a multiple pair created by random
contact between shields. An undesirable circuit condition in which interference
is created by ground currents when grounds are connected at more than one
- Ground Potential: The potential of the earth, A circuit,
terminal, or chassis is said to be at ground potential when it is used as a
reference point for other potentials in the system.
- Group Addressing:
In transmission, the use of an address that is common to two or more stations;
on a multiport line, where all stations recognize addressing characters, but
only one station responds.