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61200.070L1-1 Express XL/XLT User Manual 7
Chapter 1
Understanding ISDN and
the Express XL/XLT
ISDN OVERVIEW
The Integrated Services Digital Network (ISDN) is a public or private switched
digital network. ISDN is an international standard for digital communica-
tions, allowing a full range of enhanced services supporting voice, data, and
image applications through standard interfaces over a single telephone wire.
ISDN provides a means of integrating these services and modernizing com-
munication networks for information movement and management efficiency.
THE EXPRESS XL/XLT
The Express XL/XLT is a standalone device that links two Local Area Net-
works (LANs) using a high-speed ISDN public network or leased two-wire
line. Optionally, the Express XLT has a plain old telephone service (POTS)
connector that is used for voice/modem applications
See Figure 1-1 for an illustration of the Express XL/XLT. The 10BaseT connec-
tor operates at 10 megabits per second half duplex and accepts standard eth-
ernet packets encapsulated using IEEE 802.3 or Ethernet II (DIX). Because the
10BaseT is a four-wire interface, a crossover switch permits the user to connect
to either a hub-concentrator or network interface card without the need for
special cabling. The maintenance port can connect to any asynchronous termi-
nal emulating a VT 100 terminal for configuration.
Figure 1-1
Express XL/XLT
RX
TX
LI
COL
JAB
ERR
LNK
B1
B2
TEST
Express XL
LOOP
PWR
SELECT
TEST