F
Fast Ethernet

The 100Mbps Standard for 802.3 Ethernet. Fast Ethernet has been implemented on several different physical media including varieties of copper and fiber cabling.



 

FCS

Frame Check Sequence. A Layer 2 checksum applied to Ethernet and Token Ring frames.



 

FDDI

Fiber Distributed Data Interface. A 100Mbps fiber optic token-passing LAN system consisting of dual rings for redundancy.



 

Fiber Optic Inter-Repeater Link

See FOIRL.



 

FIFO

First In First Out. The simplest possible queuing algorithm puts every incoming piece of data into a linear queue and handles them in the order in which they arrived.



 

File Transfer Protocol

See FTP.



 

Firewall

A network security device. Essentially all commercial firewalls are used for securing TCP/IP data streams. Some operate at Layer 2, but most operate at Layer 3. Most firewalls are capable of hiding the internal structure of the network they protect.



 

FOIRL

An early version of a fiber optic implementation for 802.3 Ethernet. FOIRL was later updated and replaced by the newer 10BaseFL standard. The acronym has remained in casual use and loosely refers to any fiber optic Ethernet implementation.



 

Frame

In most Layer 2 networks (excluding ATM), the basic chunk of information. The networks generally include source and destination information (including the possibility of broadcast and multicast destinations). When transporting user- application data, a frame generally holds the packet from a higher-layer protocol. See also Packet.



 

Frame Check Sequence

See FCS.



 

Frame Relay

A Wide Area Network protocol that is capable of connecting one circuit to many other circuits. Frame Relay is a Non-Broadcast Multiple Access (NBMA) medium.



 

FTP

File Transfer Protocol. FTP is one of the earliest applications built using TCP/IP. It uses a TCP connection and is capable of transferring an arbitrary stream of data from one host to another.



 

Full Duplex

A Full Duplex link is one that is capable of sending and receiving data simultaneously.