Fast Ethernet
Any of a number of 100-Mbps Ethernet specifications. Fast Ethernet offers a speed increase 10 times that of the 10BaseT Ethernet specification while preserving such qualities as frame format, MAC mechanisms, and MTU. Such similarities allow the use of existing 10BaseT applications and network management tools on Fast Ethernet networks. Based on an extension to the IEEE 802.3 specification.
FDDI
Fiber Distributed Data Interface. LAN standard, defined by ANSI X3T9.5, specifying a 100-Mbps token-passing network using fiber-optic cable, with transmission distances of up to 2 km. FDDI uses a dual-ring architecture to provide redundancy.
fiber optics
A method for the transmission of information (audio, video, data). Light is modulated and transmitted over high purity, hair-thin fibers of glass. The bandwidth capacity of fiber optic cable is much greater than that of conventional cable or copper wire.
fiber-optic cable
Physical medium capable of conducting modulated light transmission. Compared with other transmission media, fiber-optic cable is more expensive but is not susceptible to electromagnetic interference, and is capable of higher data rates. Sometimes called optical fiber.
firewall
A security device designated as a buffer between any connected public networks and a private network. A firewall uses access lists and other methods to ensure the security of the private network.
flapping
Routing problem where an advertised route between two nodes alternates (flaps) back and forth between two paths due to a network problem that causes intermittent interface failures.
flat addressing
Scheme of addressing that does not use a logical hierarchy to determine location. For example, MAC addresses are flat, so bridging protocols must flood packets throughout the network to deliver the packet to the appropriate location. Compare with hierarchical addressing.
flooding
Traffic passing technique used by switches and bridges in which traffic received on an interface is sent out all the interfaces of that device except the interface on which the information was receivedoriginally.
FQDN
fully qualified domain name. FQDN is the full name of a system, rather than just its host name. For example, aldebaran is a host name, and aldebaran.interop.com is an FQDN.
fragment
Piece of a larger packet that has been broken down to smaller units.
fragmentation
Process of breaking a packet into smaller units when transmitting over a network medium that cannot support the original size of the packet.
frame
Logical grouping of information sent as a data link layer unit over a transmission medium. Often refers to the header and the trailer, used for synchronization and error control, that surround the user data contained in the unit. The terms cell, datagram, message, packet, and segment also are used to describe logical information groupings at various layers of the OSI reference model and in various technology circles.
Frame Relay
Industry-standard, switched data link layer protocol that handles multiple virtual circuits using HDLC encapsulation between connected devices. Frame Relay is more efficient than X.25, the protocol for which it generally is considered a replacement.
FTP
File Transfer Protocol. Application protocol, part of the TCP/IP protocol stack, used for transferring files between network nodes. FTP is defined in RFC 959.
full duplex
Capability for simultaneous data transmission between a sending station and a receiving station. Compare with half duplex and simplex.
full mesh
Term describing a network in which devices are organized in a mesh topology, with each network node having either a physical circuit or a virtual circuit connecting it to every other network node. A full mesh provides a great deal of redundancy but because it can be prohibitively expensive to implement, it usually is reserved for network backbones.
FXO
Foreign Exchange Office. An FXO interface connects to the Public Switched Telephone Network (PSTN) central office and is the interface offered on a standard telephone. Cisco’s FXO interface is an RJ-11 connector that allows an analog connection at the PSTN’s central office or to a station interface on a PBX.
FXS
Foreign Exchange Station. An FXS interface connects directly to a standard telephone and supplies ring, voltage, and dial tone. Cisco’s FXS interface is an RJ-11 connector that allows connections to basic telephone service equipment, keysets, and PBXs.
Leave a Reply