Faces fan-out-unit FAQ
FARNET Fast Ethernet fast switching
fault management FAX FCC
FCS FDDI FDDI II
FDHD FDM FDx
FEC Feeder Network
FEP Fiber Opticus
fiber-optic-cable FICIX FID4
FIFO FIFO Buffer file-creation mode mask
file system file transfer filter
Finger FIPS Firewalls
FIX Flame flapping Flash EPROM
flash update flooding flow control
FNC FOIRL FORTHnet
forward channel forwarding Fourier transform
Fourth-Generation Language Four-Wire Circuit
FPD FPI FPU
FQDN Fractional T1 Fragment
Fragmentation Frame Frame Relay
France Telecom frequency freenet
FRICC Front End FSK
FST/IP FT FTAM
FTP Full Duplex full pathname
FUNET Fuzzball FXO
Faces (:-)). This odd
symbol is one of the ways a person can portray "mood" in the very flat
medium of computers by using "smiley faces". This is "metacommunication",
and there are literally hundreds of such symbols, from the obvious to the
obscure. This particular example expresses "happiness". Don't see it? Tilt
your head to the left 90 degrees. Smiles are also used to denote sarcasm.
[Source: ZEN]. See the italian archive of "smiley
that allows multiple devices on a network to communicate using a single
FAQ (Frequently Asked Question)
FARNET A non-profit corporation,
established in 1987, whose mission is to advance the use of computer networks
to improve research and education. [Source: RFC1392].
Fast Ethernet A
proposed specification in the 802.3
Ethernet working group to boost Ethernet speeds to 100 Mbps, and referred
to as 100BaseTX. Early implementations promise to offer automatic sensing
of LAN speeds between 10 Mbps and 100 Mbps. See also 100VG
fast switching Cisco-supported
feature whereby a route cache is used to expedite packet switching through
FAT (File Allocation Table).
A record maintained by an operating system that indicates the status of
disk space (e.g. flawed disk segments).
fault management One
of five categories of network management defined by ISO
for management of OSI networks. Fault
management attempts to ensure that network faults are detected and controlled.
See also accounting management, configuration
management, performance management,
and security management.
FAX (Facsimile). Long distance
copy; Transfer of graphical data between two fax units. The graphical data
is compressed during transfer (G3).
FCC (Federal Communications
Commission). The regulatory agency established in the United States for
all interstate radio and electronic communications.
FCS (Frame Check Sequence).
HDLC term adopted by subsequent link
layer protocols and referring to extra characters added to a frame for
error control purposes.
FDDI (Fiber Distributed
Data Interface). A high-speed (100Mb/s) LAN standard. The underlying medium
is fiber optics, and the topology is a dual-attached, counter- rotating
token ring. See also: Local Area Network,
Token ring. [Source: RFC1208].
FDDI II The proposed
ANSI standard to enhance FDDI. FDDI
II will provide isochronous transmission
for connectionless data circuits
voice and video circuits.
FDHD (Floppy Disk High-Density).
FDM (Frequency Division
Multiplexing). A technique whereby information from multiple channels can
be allocated bandwidth on a single wire based on frequency.
FEP (Front End Processor).
A dedicated computer designed for communications control of a mainframe.
Also a node or software program that requests services of a back end. See
also: Client and Server.
FEC (Forward Error Correction).
A technique for detecting and correcting errors in transmission without
requiring retransmission of data by the transmitter.
Feeder Network That
part of a public switched network which connects access nodes to the core
network. [Source: ADSL Forum]
Fiber Opticus Thin
filaments of glass or plastic carrying a transmitted light beam (generated
by an LED or laser).
flexible, medium capable of conducting modulated linght transmission. Compared
with other transmission media, fiber-optic cable is more expansive, not
susceptible to electromagnetic interference, and capable of higher data
FICIX (Finnish Commercial
Internet Exchange). An exchange point for EUnet Finland, Datanet (Telecom
Finland), LanLink (FINNET group)
FID4 (Format Indicator
4). One of several formats that an SNA
transmission header (TH) can use. An FID4TH encapsiulates messages between
SNA subarea nodes that are capable
of supporting virtual and explicit
routes, as well as transmission
FIFO (First In, First Out).
FIFO Buffer (First-In-First-Out
Buffer). A buffer of this type is used in the 16650 type of UARTs
wich allows higher data troughput rates on PCs.
file-creation mode mask In
UNIX a number consisting of three octal digits which is subtracted from
a similar number used by the system to create files and directories.
file system In UNIX the physical
or logical device that holds a collection of files and directories. This
might be a hard disk drive or a partition on a disk drive.
file transfer The
copying of a file from one computer to another over a computer network.
See also: File Transfer Protocol, Kermit.
See also: protocol (file transfer)
filter Generally, a
process or device that screen incoming information for certain characteristics,
allowing a subsety of that information to pass through. A function in Cisco
Works (Cisco's network-management product) that limits the data Cisco
Works receives for transfer to NetView.
finger A program that
displays information about a particular user, or all users, logged on the
local system or on a remote system. It typically shows full name, last
login time, idle time, terminal line, and terminal location (where applicable).It
may also display plan and project files left by the user. [Source: RFC1392].
FIPS (Federal Information
are designed specifically to control unwarranted access to your network,
and usually embrace a much more conservative security philosophy: "That
which is not expressly permitted is denied." They can also deal with some
of the trickier protocols. Besides providing stronger logging capabilities,
many firewalls can provide features like network address translation, authentication
and virtual private networks.
firmware Software instructions
set permanently or semipermanently in ROM.
FIX (Federal Information
eXchange). One of the connection points between the American governmental
internets and the Internet. [Source: SURA].
Flame A strong opinion
and/or criticism of something, usually as a frank inflammatory statement,
in an electronic mail message. It is common to precede a flame with an
indication of pending fire (i.e., FLAME ON!). Flame Wars occur when people
start flaming other people for flaming when they shouldn't have. See also:
Electronic Mail. [Source: RFC1392].
flapping Routing problem
where the advertised route between two nodes alternates (flaps) back and
forth between two paths due to a network problemthat causes intermittent
Flash EPROM A PROM
(Programmable Read-Only Memory) technology developed by Intel and licensed
to other semiconductor companies. Flash EPROM is novolatile storage that
can be electrically erased in the circuit and reprogrammed. Used in Cisco
routers to allow downline loading and subsequent nonvolatile retention
of software images.
flash update A routing
update sent asynchronously in response to a change in the network topology.
Normal routing updates are sent at fixed intervals.
flooding Routing tehnique
by which routing information received by a routing device is sent out each
of that device's interfaces except (usually) the interface on which the
information was received.
flow control A technique
for ensuring that a transmitting entity does not overwhelm a receiving
entity. In IBM networks, this technique is called pacing.
FNC (Federal Networking Council).
The coordinating group of representatives from those federal agencies involved
in the development and use of federal networking, especially those networks
using TCP/IP and the
Internet. Current members include
representatives from DoD, DOE,
DARPA, NSF, NASA, and HHS. See also: Defense
Advanced Research Projects Agency, National
Science Foundation. [Source: RFC1392].
FOIRL (Fiber-Optic Inter-Repeater
Link). Fiber-optic signaling methodology based on the IEEE
802.3 fiber-optic specification.
for Research and Technology - Hellas (FO.R.T.H)
forward channel The
communications path carrying information from the call initiator to the
forwarding The process
of sending a frame toward its ultimate destination by an internetworking
Fourier transform Technique
used to evaluate the importance of various frequency cycles in a time series
4GL (Fourth-Generation Language).
Four-Wire Circuit A
communications path consisting of two pairs of conductors (wires), one
pair for transmitting and one pair for receiving.
FPD (Full-Page Display).
FPI (Floating-Point Interface).
FPU (Floating-Point Unit).
FQDN (Fully Qualified Domain
Name). The FQDN is the full name of a system, rather than just its hostname.
For example, "venera" is a hostname and "venera.isi.edu" is an FQDN. See
also: hostname, Domain
Name System. [Source: RFC1392].
Fractional T1 A
service provided by North American carriers where a full T1
link is given to the customer, but the service charge is calculated based
on the number of timeslots used.
Fragment A piece of
a packet. When a router is forwarding an IP
packet to a network that has a maximum packet size smaller than the packet
size, it is forced to break up that packet into multiple fragments. These
fragments will be reassembled by the IP layer at the destination host.
IP process in which a packet is broken
into smaller pieces to fit the requirements of a physical network over
which the packet must pass. See also: Reassembly
Frame A frame is a datalink
layer "packet" which contains the header and trailer information required
by the physical medium. That is, network layer packets are encapsulated
to become frames. See also: Datagram,
Encapsulation, Packet. [Source:
Frame Relay A protocol
used across the interface between user devices (for example, hosts and
routers) and network equipment (for example, switching nodes). Frame Relay
is more efficient than X.25, the
protocol for switch it is generally considered a replacement.
France Telecom (FT) French
in Hertz(Hz), the number of cycles of an alternating current signal per
bulletin board system with email, information services, interactive communications,
and conferencing. Freenets are funded and operated by individuals and volunteers
-- in one sense, like public television. They are part of the National
Public Telecomputing Network (NPTN), an organization based in Cleveland,
Ohio, devoted to making computer telecommunication and networking services
as freely available as public libraries. [Source: LAQUEY].
FRICC (Federal Research
Internet Coordinating Committee). Now replaced by the FNC.
FSK (Frequency Shift Keying).
A frequency modulation scheme.
FST/IP Fast Sequenced
Transport encapsulation for source-route bringing on IP
FT (France Telecom;). French
FTAM (File Transfer
Access and Management). The OSI
remote file service and protocol
developed for network file exchange and management. Similar to FTP
FTP (File Transfer Protocol).
A protocol which allows a user on one host to access, and transfer files
to and from, another host over a network. Also, FTP is usually the name
of the program the user invokes to execute the protocol. It is defined
See also: Anonymous FTP. [Source:
Full Duplex (FDx).
A circuit or device permitting transmission in two directions in the same
full pathname In UNIX the
name of a directory or file in relation to the root(/) directory.
The Finnish University Network. The academic computer network
Fuzzball Digital's LSI-11
computer system running IP gateway software.
The NSFnet used these systems as a backbone
FXO (Foreign eXchange Office).
A voice interface emulating a PABX
trunk line, as it appears to the C.O. (Central Office). Also emulating
regular telephone set, as it appears to the PABX extension interface.
FXS (Foreign eXchange Subscribe).
A voice interface, emulating the extension interface of a PABX
(or subscriber interface of a C.O.) for connecting a regular telephone
set to a multiplexer.
Your Information). A subseries of RFCs
that are not technical standards or descriptions of protocols. FYIs convey
general information about topics related to TCP/IP or the Internet. See
also: Request For Comments, STD.
G.703 G3 Fax
GATE Gated gateway
gateway NCP GB GCLisp
GDDM GDI GEM
geosynchronous orbit GGP GIF
GIS GIX Gopher
Gopherspace GOSIP GPI
GPIB GPSS GPU
grade of service ground station group
group address group delay guard band
G.703 A CCITT
standard for the physical and electrical characteristics of various digital
interfaces, including those at 64 kbps and 2.048 Mbps.
G3 Fax (Group 3 fax). One
of several fax standards. Most available fax machines use the group 3 (G3)
standard. This standard defines the compression of graphic data and transmission
speed of up to 14400 bps with an automatic fallback to 2400 bps if the
telephone line is bad.
GAL (Generic Array Logic).
(Gruppo Armonizzazione Reti della Ricerca). The Italian Research
GATE General Access to X.25
Gated (Gatedaemon). A program
which supports multiple routing protocols and protocol families. It may
be used for routing, and makes an effective platform for routing protocol
research. The software is freely available by anonymous FTP from "gated.cornell.edu".
Pronounced "gate-dee". See also: Exterior
Gateway Protocol , Open Shortest Path
First..., Routing Information Protocol,
Routed. [Source: RFC1392].
Gateway The term "router"
is now used in place of the original definition of "gateway". Currently,
a gateway is a communications device/program which passes data between
networks having similar functions but dissimilar implementations. This
should not be confused with a protocol converter. By this definition, a
router is a layer 3 (network layer) gateway, and a mail gateway is a layer
7 (application layer) gateway. See also: mail
gateway, router, protocol
converter. [Source: RFC1392].
gateway NCP An NCP
that connects two or more SNA networks
and performs address translation to allow cross-network session traffic.
GB (GigaByte). A gigabyte
equals approximately 1 billion bytes.
GCLisp (Golden Common
GDDM (Graphical Data Display
GDI (Graphical Device Interface).
GEM (Graphics Environment
geosynchronous orbit Term
referring to an orbit taken by satellites where the satellite's orbit velocity
matches the rotation of the earth, causing the satellite to remain stationary
relative to a position on the earth's surface.
Protocol). A MILNET protocol specifying
how core gateway (routers) should exchange rachability and routing information.
GGP uses a distributed shortest-path algorithm.
GIF . (Graphics Interchange
Format). Is the CompuServe(TM)
image format for image files.
GIS (Geographic Information
GIX (Global Internet eXchange).
Note: some confusion may arise here, if you see the term "the GIX", this
usually means the MAE-East Internet exchange point in Washington DC, USA,
which could also be referred to as a "de-facto NAP". There has been plans
to physically distribute the GIX and thereby create a "D-GIX". The technical/strategic
plan is to create a market for providing bandwidth at layer 2 between the
individual GIX installations. However, this has not yet happened, at least
not as an operational infra- structure. The internet exchange located at
KTH is however usually referred to as "the Stockholm D-GIX" or "the D-GIX
at KTH" or possibly simply "the D-GIX" (which could be confusing).
Gopher A distributed information
service that makes available hierarchical collections of information across
the Internet. Gopher uses a simple protocol that allows a single Gopher
client to access information from any accessible Gopher server, providing
the user with a single "Gopher space" of information. Public domain versions
of the client and server are available. See also: Archie,
Archive Site, Prospero,
Wide Area Information Servers.
for the interconnected Gopher servers.
GOSIP (Government OSI Profile).
A subset of OSI standards specific
to U.S. Government procurements, designed to maximize interoperability
in areas where plain OSI standards are ambiguous or allow excessive options.
GPI (Graphics Programming
GPIB (General Purpose Interface
Bus). The IEEE-488 interface, designed primarily to provide communications
between test equipment, supports several peripherals and 8-bit data transmission
in both directions.
GPSS (General Purpose Simulation
GPU (Graphics Processing
grade of service Measure
of telephone service quality based on the probability that a call will
encounter a busy signal during the busiest hour of the day.
ground station Collection
of communications equipment designed to receive (and usually transmit)
signals from/to satellites. Also called a downlink station.
group In UNIX a collection
of users who have protected access to their resources.
group address A single
address that refers to multiple network devices.
Synonymous with multicast address.
group delay See distortion
guard band Unused frequency
band between two communications channels that provides separation of the
channels to prevent mutual interference.
GUI (Graphical User Interface).
Refers to the techniques involved in using graphics, along with a keyboard
and a mouse, to provide an easy to use interface to some program
Hacker Half Duplex half gateway
handset handshake Handshaking
hardware address H channel HDH
headend header HEAnet
heartbeat HELLO helper addresses
HEMS HEPnet Hertz
heterogeneous network HFS hierarchical routing
Highspeed Modem HIPERLAN HIPPI
history list HLLAPI HMAC
HMMU HOB holddown
home directory home page homologation
hop hop count host
host address hostname host node
host number hotlist HPCC
HPFS HPGL HP-IB
HPPI HP Probe HSCI
HSSI HSYNC HTML
.html HTTP hub
HUNGARnet hybrid network hyperlink
hypermedia Hypertext Hz
Hacker A person who
delights in having an intimate understanding of the internal workings of
a system, computers and computer networks in particular. The term is often
misused in a pejorative context, where "cracker" would be the correct term.
See also: Cracker. [Source: RFC1392].
Half Duplex A circuit
or device capable of transmitting in two directions, but not at the same
half gateway Literally,
a device that performs the functions of half of a gateway. Gateways are
often divided into two functional halves to simplify design and maintenance.
handset Part of a telephone
containing the transmitter and receiver thatb is handled during use.
of messages exchanged between two or more network devices to ensuretransmission
of predetermined signals between two devices establishing a connections
hardware address Also
called physical address or MAC-layer
address, a data link layer address associated with a particular network
device. Contrasts with network or protocol address, which is network layer
H channel Full-duplex ISDN
primary rate channel operating at 384 Kbps.
Distant Host). A means of running the 1822 protocol over synchronous serial
links instead of over special-purpose 1822 hardware. HDH is essentially
1822 headers and data encapsulated in LAPB
(X.25 Level 2) packets.
HDLC (High level Data Link Control).
Popular ISO standard bit-oriented, link-layer
protocol derived from SDLC. HDLC specifies an encapsulated method of data
on synchronous serial data links.
HDSL (High data rate Digital Subscribe
Line). Modems on either end of one or more twisted pair wires that deliver
T1 or E1
speeds. At present T1 requires two lines and E1 requires three. See SDSL
for one line HDSL. [Source: ADSL Forum]
HDTV (High-Definition TeleVision).
HDx (Half DupleX).
headend The end point of a broadband
network. All stations transmit toward the headend the headend then transmit
toward the destination stations.
header The portion of a packet, preceding
the actual data, containing source and destination addresses, and error
checking and other fields. A header is also the part of an electronic mail
message that precedes the body of a message and contains, among other things,
the message originator, date and time. See also: Electronic Mail, packet.
The Higher Education Authority's Network in Ireland.
heartbeat See SQE
HELLO A routing protocol used
principally by NSFnet nodes. Hello allows
trusting packet switches to discover minimal delay routes. Also, the Hello
protocol (different than the NSFnet Hello protocol) is used by OSPF
systems for establishing and maintaining neighbor relationships.
helper addresses The address configured
on an interface to which broadcasts received in the interface will be sent.
HEMS (Higher-level Entity Management
System). A technically intriguing network management protocol that was
a candidate for Internet standardization until it was withdrawn by its
designer during the evaluation process in deference to SGMP
(which evolved into SNMP) and CMOT.
HEPnet (High-Energy Physics network).
Research network that originated in the U.S., but has spread to most places
where high-energy physics is done. Well-known sites include Argonne National
Laboratory, Brookhaven National Laboratory, Lawrence Berkeley Laboratory,
and the Stanford Linear Accelerator Center (SLAC).
Hertz Abbreviated "Hz", a measure
of frequency or bandwidth. Synonymous with cycles/second.
A network running multiple network layer protocols. See also: DECnet,
HFS (Hierarchical File System). The
Apple Macintosh storage system in switch files are stored in folders. HFS
offers no default paths for applications to find files.
The complex problem of routing on large networks can be simplified by reducing
the size of the networks. This is accomplished by breaking a network into
a hierarchy of networks, where each level is responsible for its own routing.
The Internet has, basically, three levels: the backbones, the mid-levels,
and the stub networks. The backbones know how to route between the mid-levels,
the mid-levels know how to route between the sites, and each site (being
an autonomous system) knows how to route internally. See also: Autonomous
System, Exterior Gateway Protocol,
Interior Gateway Protocol, sub
network, transit network. [Source:
Highspeed Modem A modem that works
at bit rates higher than 9600 bps.
HIPERLAN (HIgh PErformance Radio
Local Area Networks)> Are radio based local area networking (RLAN) solutions,
intended for connectivity between PCs, laptops, workstations, servers,
printers and other networking equipment. HIPERLANs thus enable the replacement
of physical cables for the connection of data networks within a building,
providing a more flexible and, possibly, a more economic approach to the
installation, reconfiguration and use of such networks within the business
and industrial environments. Source [ERC]
HIPPI (High Performance Parallel Interface).
An emerging ANSI standard which extends the computer bus over fairly short
distances at speeds of 800 and 1600 Mb/s. HIPPI is often used in a computer
room to connect a supercomputer to routers, frame buffers, mass-storage
peripherals, and other computers. See also: American
National Standards Institute [Source: MALAMUD].
history list In NCSA
Mosaic, a list of recently visited
HLLAPI (High-Level Language Application
HMAC (Keyed-Hashing Message Authentication).
a mechanism for message authentication using cryptographic hash functions.
HMAC can be used with any iterative cryptographic hash function, e.g.,
MD5, SHA-1, in combination with a secret shared key. The cryptographic
strength of HMAC depends on the properties of the underlying hash function..
HMMU (Hardware Memory Management Unit).
HOB (High-Order Byte).
holddown A state into which a
route can be placed whereby routers will neither advertise the route nor
believe advertisements about the route for a specific length of time (the
olddown period) in order to flush bad information about that route from
all routers in the network. A route can be placed holddown when a link
in that routefails.
home directory In UNIX the directory
you are placed in immediately after you login to the system. H
home page The document
initially displayed when starting up NCSA
homologation Conformity of a product
or specification to international standards, such as CCITT,
CS, and TUV. Enables portability
across company and international boundaries.
hop A term used in routing. A path to
a destination on a network is a series of hops, through routers, away from
the origin. [Source: RFC1392].
hop count A routing metric used
to measure the distance between a source and a destination. RIP uses hop
count for RIP is 16. See also RIP.
host A computer that allows users to
communicate with other host computers on a network. Individual users communicate
by using application programs, such as Electronic
Mail, Telnet and FTP.
host address See: Internet
host name The name given to a machine.
(See also: FQDN). [Source: ZEN].
host node An SNA
subarea node that contains an SSCP.
host number See: Internet
hotlist A personal online reference
of WWW documents
HPCC (High Performance Computing and
Communications). High performance computing encompasses advanced computing,
communications, and information technologies, including scientific workstations,
supercomputer systems, high speed networks, special purpose and experimental
systems, the new generation of large scale parallel systems, and application
and systems software with all components well integrated and linked over
a high speed network. [Source: HPCC].
HPFS (High-Performance File System).
An OS/2 file system that accomodates
complex data structures, multiple levels of caching, and long filenames
that include both uppercase and lowercase characters.
HPGL (Hewlett-Packard Graphics Language)
HP-IB (Hewlett-Packard Interface Bus).
HPPI (High Performance Peripheral Interface).
HP Probe See: Probe.
HSCI (High-Speed Communications
Interface). A controller developed and marketed by Cisco Systems. The HSCI
is a single-ported interface providing full-duplex synchronous serial communications
capability at up to 52 Mbps. It install some routers.
HSSI (High-Speed Serial
Interface). Network standard for high-speed (up to 52 Mbps) serial communications
over WAN links.
HSYNC (Horizontal Synchronization).
Markup Language). The coding language used create Hypertext documents
for use on the World Wide Web. HTML looks a lot like old-fashioned typesetting
code, where you surround a block of text with codes that indicate how it
should appear, additionally, in HTML you can specify that a block of text,
or a word, is "linked" to another file on the Internet. HTML files are
meant to be viewed using a World Wide Web Client program, such as Mosaic,
.html The extension used on
a file that is coded using HTML (myfile.html).
Transport Protocol). The protocol (RFC
1945) for moving hypertext files across the Internet. Requires a HTTP
client program on one end, and an HTTP server program on the other end.
HTTP is the most important protocol used in the World Wide Web (WWW).
hub A device connected to several
other devices. In ARCnet, a hub
is used to connect several computers together. In a message handling service,
a hub is used for the transfer of messages across the network. In Ethernet/IEEE
802.3 terminology, a hub is an Ethernet multiport repeater, which is
sometimes referred to as a concentrator. The term is also used to refer
to a hardware/software device that contains multiple independent but connected
modules of network and internetwork equipment. Hubs can be active (where
they repeat signals sent through them) or passive (where they do not repeat,
but merely split, signals sent through them).
The association and computer network of Hungarian institutes of
higher education, research and development, libraries and other public
hybrid network Term used
to describe an internetwork made up of more than one type of network technology,
including LANs and WANs.
hyperlink A hotspot that
links one document to another; in Mosaic,
Netscape, a hyperlink is displayed
as a highlighted word or graphic (colour and/or underlining); clicking
on a hyperlink takes to you to the linked document
hypermedia Richly formatted
documents containing hyperlinks.
Hypertext Generally, any
text that contains "links" to other documents - words or phrases in the
document that can be chosen by a reader and which cause another document
to be retrieved and displayed.
Hz See: Hertz