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Glossary

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telco

A common abbreviation for the telephone company.

Telnet

The standard terminal emulation protocol within the TCP/IP pro-

tocol stack. Method of remote terminal connection, enabling users to log in
on remote networks and use those resources as if they were locally connected.
Telnet is defined in RFC 854.

terminal adapter (TA)

A hardware interface between a computer

without a native ISDN interface and an ISDN line. In effect, a device to
connect a standard async interface to a non-native ISDN device, emulating
a modem.

terminal emulation

The use of software, installed on a PC or LAN server,

that allows the PC to function as if it were a "dumb" terminal directly
attached to a particular type of mainframe.

TFTP

Conceptually, a stripped-down version of FTP, it's the protocol of

choice if you know exactly what you want and where it's to be found.
TFTP doesn't provide the abundance of functions that FTP does. In par-
ticular, it has no directory browsing abilities; it can do nothing but send
and receive files.

TFTP host

Trivial File Transfer Protocol is used to send files using IP

at the Network layer and UDP at the Transport layer, which makes it
unreliable.

thicknet

Also called 10Base5. Bus network that uses a thick cable and runs

Ethernet up to 500 meters.

thinnet

Also called 10Base2. Bus network that uses a thin coax cable and

runs Ethernet media access up to 185 meters.

three-way handshake

Term used in a TCP session to define how a virtual

circuit is set up. It is called a "three-way" handshake because it used three
data packets.

token

A frame containing only control information. Possessing this con-

trol information gives a network device permission to transmit data onto the
network. See also: token passing.

token bus

LAN architecture that is the basis for the IEEE 802.4 LAN

specification and employs token passing access over a bus topology. See
also: IEEE.

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