ELSA TanGo 1000, User Manual

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Appendix: Glossary
40
ELSA TanGo 1000
Operating Manual © 1997 ELSA GmbH
TEI TEI ( T erminal E ndpoint I dentifier)
is an identification code negotiated with the
exchange in the
→
D channel protocol, in order to distinguish several terminal
devices connected to the same S
0
interface.
MicroLink TLpro
has a green LED that
indicates whether a TEI has been assigned to the terminal adapter.
Terminal Endpoint Identifier
→
TEI
Terminal adapter Terminal adapters
(TA) are used to connect non-ISDN devices to the ISDN.
An a/b terminal adapter, for example, can be used to connect devices designed for
analog telephone networks, such as analog telephones, class 2 and 3 fax devices,
modems etc.
MicroLink ISDN/TLpro
is an external RS-232/V.24 terminal adapter,
allowing the access of the ISDN through the serial RS-232/V.24 interface of a
computer.
Transmission protocol
To transmit data files from one computer to another, a range of
transmission protocols
exists in order to provide a trouble-free file transfer. Over
the years, protocols of different efficiency and convenience have been developed.
In principle, they all work as follows: Data are usually transmitted as data blocks
and are checked for errors and incompleteness on the receiving side. If an error has
been detected, the defective block is requested once more and transmitted again.
The
→
communications software
Telix
(supplied with every ELSA
MicroLink
®
product that uses the AT command set), supports many common transmission
protocols, such as
→
Xmodem, Xmodem-1k, Ymodem and
→
Zmodem.
V.110
V.110 (also referred to as I.463) is an
→
ITU-T standard for the adaptation of
asynchronous or synchronous serial data streams to the ISDN line bit rate of
64,000 bps for the transmission over an ISDN
→
B channel.
V.120
V.120 (also referred to as I.465) is an
→
ITU-T standard for the packing of
asynchronous or synchronous data in (error-corrected) HDLC frames on an ISDN
→
B
channel. Unlike
→
X.75, V.120 also supports a line bit of 56,000 bps as commonly
used in the USA.
V.42bis
The
→
ITU-T standard V.42bis describes a data compression method which can
increase the
→
effective transfer rate of (previously uncompressed) data by a factor
up to four.
MicroLink ISDN/TLpro
supports V.42bis. Thus effective line transfer
rates of (theoretically) up to 256,000 bps can be achieved, if the serial interface
supports these high rates.
X.75
Similar to
→
V.120, X.75 is an
→
ITU-T standard for the error-corrected transmission
of data with HDLC frames on an ISDN
→
B channel (64,000 bps).