N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 2 - Data Communications Basics and Legacy Technologies                                                Slide 29 of 45 _________________                                                                                  __________

                                ISDN Elements

                                Network Termination (NT 1, NT2)

                                Terminal Adapter (TA)

                                Terminal Equipment (TE 1, TE 2)

                                Interfaces (R, U, S/T)

_________________                                                                                  __________

ISDN elements include Network Termination, Terminal Adapter, Terminal Equipment and Interfaces. The functions of all elements are defined by the CCITT.

Network Termination - Network termination equipment lies at the periphery of the ISDN network. It interfaces  either with non-ISDN equipment or directly to user.
NT1 - Does not perform functions above layer1, used for 2B+D service
NT2 - Performs layer2 and layer3 functions, used for multiple line device, PABX and LAN 23B+D connections

Terminal Adapters - A Terminal Adapter is a device providing functionality of upper level OSI protocols to connect voice terminals and data terminals to ISDN network.

Terminal Equipment - ISDN compatible (TE 1) and Non-ISDN compatible (TE 2), requires a TA to convert rate to 64 K bps

Interfaces _  The ISDN line card is the entry point to R, S, or U interfaces. The interface function is confined to layer 1 tasks.
            S - four wire connection
            U - Central office connection to subscriber using 2-wire connections
            R - RS-232, V.35, X.21 and X.25 connections - adapts bit rate to 64 K bps