Cabletron Systems CSX100 series User Manual - Isdn Concepts

ISDN and Ordering Issues

5

Chapter 1. ISDN and Ordering Issues

ISDN Concepts

This chapter explains several ISDN line configuration key concepts and tells

you how to order your ISDN services

Basic Rate Interface ISDN Line (U.S. only)

You will need to order one Basic Rate Interface (BRI) ISDN line from your

service provider.  It will provide:

•

 Two full-duplex 64-Kbits-per-second B-channels used for voice, data,

fax, etc.

•

 One full duplex 16Kbps channel used for signaling.

Each B-channel can be used for a call; i.e., two calls can occur at the same

time.  Services vary from individual service providers.

Note: The full 64 Kbps for each channel (called clear channel) may however

not be available across the entire communications link: many providers still

use in-band signaling (the 8-Kbps signaling is taken from the B-channel

bandwidth) so that you may only achieve a 56-Kbps channel speed.

Network Terminator

Network Terminator equipment (NT1) is required to interface between the

router and the ISDN line.  The NT1 offers conversion between the two-wire

twisted pair (U-loop interface) used by telephone companies and the four-wire

terminal equipment (S/T interface) as well as line-testing capabilities.

In North America

U Interface: The router comes with only one U interface

S/T Interface: You can order the router with an internal NT1 or use your

own NT1 equipment.  External Network Terminator equipment comes

with a power supply (built-in or external).