ABBREVIATION DICTIONARY Networks and Telecommunications/Electronics --> F

F

FAQ
Frequently asked questions. Documents that list and answer the questions most often asked about a particular subject. The World Wide Web contains thousands of FAQs on subjects as diverse as pet grooming and cryptography.







FC/APC
Face Contacted / Angled Polished Connector







FDDI
Fiber Distributed Data Interface. A standard for transmitting data on fiber optic cable at rates of up to 100 million bits per second - 10 times as fast as Ethernet, and about twice as fast as T3. FDDI networks are typically used as backbones for wide area networks.







FDL
Facilities Data Link







FECN
Forward Explicit Congestion Notification







FR
Frame Relay. A form of packet switching, but using smaller packets and less error checking than traditional forms of packet switching (such as X.25). Now a new international standard for efficiently handling high-speed, bursty data over wide area networks.







FRAD
Frame Relay access device. A network device that links any non-Frame Relay wide area network.







FT1
See Fractional T1







FTP
File Transfer Protocol Filter







FTP Server
A server that a user can contact in order to transfer files by means of the File Transfer Protocol (FTP) over a TCP/IP network.







FTTC
Fiber to the curb







FTTH
Fiber to the home







Fabrication
In chip making, the manufacturing devices and integrated circuits in silicon wafers. The actual chip making facility is also sometimes called a fab.
See ezine for details.







Facility
An optional service offered by an X.25 packet-switching network. The user can request a facility when subscribing to a network service or when establishing a call.







Facsimile (fax)
An abbreviation for facsimile.







Fallback/fall-forward Line Sensing
A feature that enables a high-speed analog modem to monitor the quality of the phone line and to step down to the next lower speed if the line quality deteriorates. The modem falls forward to the next higher speed as line quality improves.







Fanout
The ability of a digital access cross-connect (DAC) to split and switch channels between incoming and outgoing circuits.







Far-end Block Error (FEBE)
FEBE is a signal that remote end sends to indicate that it has received DS2 or E1 frames with either framing errors (FERR) or C-bit parity errors (CPERR). A block error is detected each time the calculated checksum of the received data does not correspond to the control checksum transmitted in each successive superframe. One block error indicates that one superframe has not been transmitted correctly. No conclusion with respect to the number of bit errors can be drawn from the block-error counter.







Fast Ethernet
A LAN transmission standard with a data rate of 100 Mbps. A workstation with a 10-Mbps (10Base-T) Ethernet card can be connected to a Fast Ethernet network.







Fast Packet Switching
A term covering various packet switching and processing technologies that handle data at rates of 1.5 Mbps or greater and include frame relay, and ATM technologies.







Fatal Error
An error that cause the abrupt termination of a program.







Fault Tolerance
A way to provide redundancy in hardware systems to protect against downtime if one of the redundant systems or components fails. For the B-STDX products, fault tolerance is provided by means of redundancy I/O modules and power supplies, and by the capacity of hot swapping parts that the switch is running. To increase reliability beyond that provided by the hardware and networking service, Lucent provides additional software-based services designed to support mission-critical applications. This added reliability is critical to financial institutions where any interruption in service could be devastating to business.







Fault-Tolerant PVC
An ISDN fault-tolerant service that enables a set of backup ports on the switch to restore connections from a failed data center to the backup data center. When enabled, fault-tolerant PVC reroutes all affected frame relay permanent virtual circuits (PVCs) to the backup set of ports.







Fax Server
1. A computer that resides on a local area network and has one or more PC fax boards in its slots. 2. A specialized interactive voice response system that sends facsimile messages to a fax machine that the user designates via the telephone dialpad.







Federal Communications Commission (FCC)
A regulatory authority for telecommunication in the US.







Ferrule
A component of a fiber optic connection that holds the fiber in place and aids in its alignment.







Fiber
In fiber optics terms, refers to fiber made of very pure glass.







Fiber Distributed Data Interface (FDDI)
FDDI is a proposed ANSI standard for a network architecture that uses high-speed fiber-optic lines and supports transmission rates of up to 100 Mbps.







Fiber In The Loop (FITL)
A system for delivering services to contiguous groups of residential and small business customers using fiber optic media in either all or a portion of the loop distribution network. FITL is an umbrella term that encompasses various systems, such as Fiber to the Curb and Fiber to the Home.







Fiber Optics
A technology which uses light to transmit information from one point to another.







Fiber length
The physical length of the fiber. This length can then be translated to optical loss.







Fiber optics
A term that describes the technology used to transmit infrared and visible light frequencies through a hair-thin strand of glass fiber, with a laser or light-emitting diode. The glass fiber, also known as an optical fiber, is to light what copper wire is to electricity.







Field Programmable Gate Array (FPGA)
A specialized microprocessor that has no physical connections between its logic gates when manufactured, but has potential connections which can be made by a programmer/user.







File Server
A process running on a computer that provides access to files on that computer to programs running on remote machines.







File Transfer Protocol (FTP)
A feature of the Internet that allows users to transfer files from other hosts. See Internet.







Filter
Generally, a process or device that screens network traffic for certain characteristics, such as source address, destination address, or protocol, and determines whether to forward or discard that traffic based on the established criteria.







Filter Presence
A method of enabling a firewall to persist across connection-state changes. With filter persistence, the firewall rules stay in force even when a connection goes offline.







Filtering
One type of filtering transmits a selected range of energy to suppress unwanted frequencies or noise. Another type of filtering removes specific characters received in a data communications channel. Filtering in a network is the assignment of parameters to block transmissions from one LAN to another. See Filter.







Finger
A command used to gather information about a network user - such as name, login name, office location, telephone number, email address, and account activity.







Firewall
A hardware/software tool that allows a network administrator to determine what type of users can access the resources on the network. The firewall provides a mechanism to monitor and funnel data from authorized users (only) through the firewall to and from the network. A firewall may be a software program that runs on UNIX or other platforms, or it may be a part of a proprietary operating system. A firewall by itself does not perform the routing function. See also Filter, Secure Access Firewall, Secure Access Manager.







Flash
Quickly depressing and releasing the plunger in or the actual handset-cradle to create a signal to a PBX or Centrex that special instructions will follow such as transferring the call to another extension.







Flatness
The peak-to-peak deviation in amplitude of a signal over a given frequency or wavelength range.







Flow Control
A method of compensating for differences in the flow of incoming and outgoing data for a modem or other device. If one system receives more data than it can hold in its buffers or process at any given time, it signals the sender to pause the transmission. Flow control can take place by means of hardware or software.







Forward Error Correction (FEC)
An error correction technique in which redundant bits are transmitted along with the payload enabling the receiving station to detect error and to correct the message.







Forward Explicit Congestion Notification
FECN is a bit set in a frame relay header to notify a destination node that there is traffic congestion on the network.







Fractional T1
Service offering data rates between 64 kbit/s (DS0 rate) and 1.536 Mbit/s (DS1 rate), in specified intervals of 64 kbit/s.







Fractional T1 Line
A T1 line that contains both switched and nailed-up channels. T1 PRI and ISDN BRI lines can also be fractional T1 lines.







Fragment
One of the pieces that results when a Internet gateway divides an IP datagram into smaller pieces for transmission across a network that cannot handle the original datagram size.







Frame
A segment of a digital signal that has a repetitive characteristic in that corresponding elements of successive frames represent the same things. In a time-division multiplex system, a frame is a sequence of time slots, each containing a sample from one of the channels served by the multiplex system; the frame is repeated at the sampling rate, and each channel occupies the same sequence position in successive frames.







Frame Relay
A form of packet switching, but using smaller packets and less error checking than traditional forms of packet switching (such as X.25). Now a new international standard for efficiently handling high-speed, bursty data over wide area networks.







Frame Relay Concentrator
A device that concentrates many low-speed, dial-in connections into one high-speed, nailed-up connection to a frame relay switch. As a frame relay concentrator, the Lucent unit forwards many lower-speed PPP connections onto one or more high-speed frame relay interfaces.







Frame Relay Inband Network Management
A management feature that enables the Network Management Station (NMS) operator to remotely manage the network over frame relay. Frame relay inband network management supports Simple Network Management Protocol (SNMP) packet transports within the Internet Protocol (IP) on User Datagram Protocol (UDP) envelopes. Lucent supports frame relay inband network management through the configuration of a management data link connection indicator (DLCI). The NMS uses the management DLCI when it is connected to the same LAN as a router with a frame relay connection to the gateway switch.







Frame Relay Link Management
A feature that enables you to retrieve information about the status of the frame relay interface by means of a special management frames with a unique data link connection indicator (DLCI) address. (DLCI 0 is the default for link-management frames.) On a user-to-network interface (UNI) to frame relay, link-management procedures occur in one direction. The UNI-DTE device requests information, and the UNI-DTE device provides it. On a network-to-network interface (NNI), link-management procedures are bidirectional. Switches perform both the DTE and DCE link-management functions, because both sides of the connection request information from their peer switches.







Frame Relay Network
A network in which every access point connects directly to a frame relay switch. Depending on how a device such as a Lucent unit is integrated into the frame relay network, the device can operate as a frame relay terminating unit (Customer Premises Equipment or CPE) or as a frame relay switch.







Framed Protocol
A synchronous protocol that encapsulates data into frames.







Framing
At the physical and data link layers of the OSI model, bits are fit into units called frames. Frames contain source and destination information, flags to designate the start and end of the frame, plus information about the integrity of the frame. All other information, such as network protocols, and the actual payload of data, is encapsulated in a packet, which is encapsulated in the frame.







Frequency
Number of cycles per unit of time, measured in units called Hertz (Hz). One Hz equals one cycle per second.







Frequency Division Multiple Access
A technique used in cellular communications in which channels are assigned specific frequencies.







Frequency Division Multiplexing (FDM)
A method of dividing a transmission channel into several parallel paths. All signals are carried simultaneously.







Frequency Modulation (FM)
A radio transmission scheme in which the message signal joins with the carrier, changing the carrier's frequency. See Modulate.







Frequency Shift Keying (FSK)
In transmitting binary data, a technique that uses a specific frequency to represent the 1 bit, and another frequency to represent the 0 bit.







Frequency Stacking
The process in which allows two identical frequency bands to be sent over a single cable. This occurs by up converting one of the frequencies and "Stacking" it with the other.







Frequency-Hopping
A transmission technology in which packets of information hop along the clearest frequencies in a bandwidth.







Full Duplex
Circuit in telecommunications with channels for both sending and receiving.







Full Status Reporting
In frame relay, a link-management message function that provides the user device with the complete status of all permanent virtual circuits (PVCs) configured on the link.







Fusion Splice
A splice created by applying heat to fuse or melt the ends of two optical fiber cables, forming a continuous single fiber.