ADTRAN user manual Chapter Understanding ISDN and the Express L128/L128T, Isdn Overview

Chapter 1

Understanding ISDN and

the Express L128/L128T

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 L128/L128T

The Express L128/L128T 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 L128T has two plain old telephone service (POTS) connectors used for voice/modem applications

See Figure 1-1 for an illustration of the Express L128/L128T. The 10BaseT con- nector operates at 10 megabits per second half duplex and accepts standard Ethernet 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 con- nect to either a hub-concentrator or network interface card without the need for special cabling. The maintenance port can connect to any asynchronous terminal emulating a VT 100 terminal for configuration.

	TX/RX	B1	B2	PWR
LI
EXPRESSL128T
			TEST	LINE

Figure 1-1

Express L128/L128T

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