814 Appendix F:Glossary
NN47250-500 (Version 03.01)
Extensible Authentication Protocol See EAP.
Extensible Markup Language See XML.
failover In a redundant system, an operation by which a standby (or secondary) system component
automatically takes over the functions of an active (or primary) system component when the active component
fails or is temporarily shut down or removed for servicing. During and after failover, the system continues its
normal operations with little or no interruption in service.
FCC Federal Communications Commission. The United States’ governing body for telecommunications,
radio, television, cable, and satellite communications.
FDB See forwarding database (FDB).
Federal Communications Commission See FCC.
FHSS Frequency-hopping spread-spectrum. One of two types of spread-spectrum radio technology used in
wireless LAN (WLAN) transmissions. The FHSS technique modulates the data signal with a narrowband
carrier signal that “hops” in a predictable sequence from frequency to frequency as a function of time over a
wide band of frequencies. Interference is reduced, because a narrowband interferer affects the spread-spectrum
signal only if both are transmitting at the same frequency at the same time. The transmission frequencies are
determined by a spreading (hopping) code. The receiver must be set to the same hopping code and must listen
to the incoming signal at the proper time and frequency to receive the signal. Compare DSSS.
forwarding database (FDB) A database maintained on a WLAN—Security Switch (WSS) for the
purpose of making Layer 2 forwarding and filtering decisions. Each entry consists of the media access control
(MAC) address of a source or destination device, an identifier for the port on which the source or destination
station is located, and an identifier for the virtual LAN (VLAN) to which the device belongs. FDB entries are
either permanent (never deleted), static (not aged, but deleted when the WSS is restarted or loses power), or
dynamic (learned dynamically and removed through aging or when the WSS is restarted or loses power).
frequency-hopping spread-spectrum See FHSS.
GBIC Gigabit interface converter. A hot-swappable input/output device that plugs into a gigabit Ethernet
port, to link the port with a fiber-optic or copper network. The data transfer rate is 1 gigabit per second (Gbps)
or more. Typically employed as high-speed interfaces, GBICs allow you to easily configure and upgrade
communications networks.
gigabit interface converter See GBIC.
GMK Group master key. A cryptographic key used to derive a group transient key (GTK) for the Temporal
Key Integrity Protocol (TKIP) and Advanced Encryption Standard (AES).
greenfield network An original deployment of a telecommunications network.
GRE tunnel A virtual link between two remote points on a network, created by means of the Generic
Routing Encapsulation (GRE) tunneling protocol. GRE encapsulates packets within a transport protocol
supported by the network.
GTK Group transient key. A cryptographic key used to encrypt broadcast and multicast packets for
transmissions using the Temporal Key Integrity Protocol (TKIP) and Advanced Encryption Standard (AES).
group master key See GMK.