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FDB See forwarding database (FDB).
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.
A database maintained on a Wireless Switch (WX) 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 WX is restarted or loses power),
or dynamic (learned dynamically and removed through aging or when
the WX is restarted or loses power).
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.
glob See MAC address glob; user glob; VLAN glob.