Wiley - Frame Relay for High Speed Networks.pdf - Wiley - andri98z

Table of Contents

Frame Relay for High

Speed Networks

by Walter

Goralski

ISBN:

0471312746

pages

Everything you need to

know about frame relay

technology, in plain-

spoken English.

Pete Loshin

Frame Relay for High-Speed Networks

Introduction

Chapter 1 : What Frame Relay Can Do

Chapter 2 : The Public Data Network

Chapter 3 : Frame Relay Networks

Chapter 4 : The Frame Relay User-

Network Interface

Chapter 5 : Frame Relay Signaling and

Switched Virtual Circuits

Chapter 6 : Congestion Control

Chapter 7 : Link Management

Chapter 8 : The Network-Network Interface

(NNI)

Chapter 9 : Voice over Frame Relay

Chapter 10 : Systems Network

Architecture and Frame Relay

Chapter 11 : Internet Protocol and Frame

Relay

Chapter 12 : Asynchronous Transfer Mode

and Frame Relay

Chapter 13 : The Future of Frame Relay

Bibliography

Acronym List

Frame Relay for High-Speed Networks

Walter Goralski

Published by John Wiley & Sons, Inc.

Published simultaneously in Canada.

No part of this publication may be reproduced, stored in a retrieval system or transmitted in any

form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise,

except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without

either the prior written permission of the Publisher, or authorization through payment of the

appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA

01923, (978) 750-, fax (978) 750-4744. Requests to the Publisher for permission should be

addressed to the Permissions Department, John Wiley & Sons, Inc., 605 Third Avenue, New York,

NY 10158-, (212) 850-, fax (212) 850-, E-Mail: PERMREQ@WILEY.COM.

This publication is designed to provide accurate and authoritative information in regard to the

subject matter covered. It is sold with the understanding that the publisher is not engaged in

professional services. If professional advice or other expert assistance is required, the services of a

competent professional person should be sought.

Publisher: Robert Ipsen

Editor: Marjorie Spencer

Assistant Editor: Margaret Hendrey

Managing Editor: Micheline Frederick

Text Design & Composition: North Market Street Graphics

Designations used by companies to distinguish their products are often claimed as trademarks. In

all instances where John Wiley & Sons, Inc. is aware of a claim, the product names appear in initial

capital or all capital letters. Readers, however, should contact the appropriate companies for more

complete information regarding trademarks and registration.

Acknowledgments

There are a number of people who should be thanked for their assistance in making this book.

First I would like to thank Hill Associates, Inc. for creating an intellectual work environment where

personal growth is always encouraged and for a climate that makes the writing of books like this

possible in the first place. I owe special thanks to the Hill reviewers who painstakingly waded

through the individual chapters and found many of my errors. These are Clyde Bales, Rod Halsted,

Gary Kessler, Hal Remington, Harry Reynolds, Ed Seager, Tom Thomas, and John Weaver. Any

mistakes which remain are my own.

On the publishing side, Marjorie Spencer supplied the vision that produced this text. Margaret

Hendrey saw the book-writing process through, although my primitive figure-drawing skills must

have been a real challenge. Finally, Micheline Frederick has produced this fine volume from my

raw material.

My family, Jodi, Alex, and Ari, has also come to grips with the fact that I am now a writer in addition

to all the other roles I play from day to day, and that I am now entitled to all the rights and privileges

that a writer of my stature deserves (such as quiet). Thank you one and all.

Introduction

What do an accountant sitting in a small home office accessing the Web, a sales representative at

a branch office checking the latest home office price list, and a hospital worker ordering medication

from a supplier’s remote server all have in common? Whether they are aware of it or not, more and

more often the links from place to place in these environments are provided by a frame relay

network. In the near future, this list might easily extend to corporate executives holding a

videoconference, commercial artists manipulating images, and even college students calling home.

In fact, all three of these things are done on frame relay networks now, just not routinely or in all

environments.

At a lower level than the user application scenarios above, a frame relay network can support LAN

interconnectivity for Intranet router-to-router traffic, carry financial transactions for a corporate SNA

network, or carry digital voice overseas, and all faster than before and at a fraction of the price of

almost any alternative. How can frame relay do all of this so well? That is what this book is about.

It should come as no surprise that networking needs have changed radically in the past few years.

After all, the end systems that perch on almost every worker desktop and in every home, school,

and library has changed drastically. Systems that were considered state-of-the-art 2 or 3 years ago

struggle mightily even to run the games of today, let alone the new applications. Audio and video

support is not a luxury, but a must, if only so that the multimedia tutorial for a new application can

be appreciated (and no one reads the manual anyway). A video game requires more power than a

supercomputer had 20 years ago. A palmtop assistant draws on more computing power than an

IBM mainframe could in 1964. In 1991, a 66 MHz computer with color monitor and 500-megabyte

hard drive and 16 Meg of RAM and a modest 2x CD-ROM cost more than $13,000. And so on. And

in computing, as in almost nowhere else outside of the electronics industry in general, prices fall as

power rises.

As illuminating (or boring) as these examples might be, the sole point is that the typical device that

uses a network has changed radically in the past 10 or 20 years, from alphanumeric display

terminal to multimedia color computer. Yet how much has the network changed in that same time

period? Hardly at all, and most of those changes apply to the local area network (LAN), where the

cost of use is minimal after installation, and not to the wide area network (WAN), where the cost of

use in the form of monthly recurring charges can be crippling. In a very real sense, frame relay (and

other fast packet WAN technologies like ATM) represents the application of modern computing

power not to the devices at the endpoints of the network, but inside of the network itself.

Computer networks are so common today that it is hard to imagine a time when they were not. Yet

the history of computer networks could be said to begin with the invention of what eventually

became the Internet in 1969. This was only four years after Time magazine, in a story about

computers (remarkable in itself), boldly predicted that “eventually” computers would be able to talk

to each other over “communication links.” In the 1980s, the idea of networking computers was not

so new, and by the end of that decade, it was more or less expected. In the 1990s, the rise of the

whole client/server phenomena has enabled a whole raft of new applications requiring both

networks and computers, from electronic messaging to remote database access to training videos.

Of course, this new emphasis on clients and servers and the networks that connected them led to

the creation of many networks. In fact, there turned out to be perhaps too many networks. It

seemed like every application, not only voice and video but the many types of data, required a

slightly different network structure in terms of bandwidth (speed), errors, and delay (latency). In the

expanding economy of the 1980s, the immediate reaction when faced with a new network

application was to build a completely new network specifically groomed for that application. This

typically meant employing time division multiplexing (TDM) to share the total bandwidth available

among sites by dedicating the maximum amount available or the minimum amount required to

adequately support the application. This form of channelized networking came to dominate the

WAN scene in the 1980s.

But just as the economy needed to regroup before it could advance to new heights in the 1990s, so

did networking. Maintaining all of these essentially parallel networks proved wasteful and

enormously costly. Few people used the tie-lines between office PBXs at 3 a.m. Yet the bandwidth

these channels represented was still dedicated to the voice network. Many organizations,

attempting to perform out-of-hours tasks such as backing up remote servers over the channelized

networks, were unable to utilize the bandwidth locked up in other channels. Frame relay solves this

problem by flexibly, or dynamically, allocating the total bandwidth based on the instantaneous (well,

within a few milliseconds) demand of all active applications. Idle applications consume no

bandwidth at all.

Frame relay is not the only way to solve the problems posed by the time-consuming and wasteful

task of maintaining parallel networks; it has just proved to be the most popular. And frame relay

addresses more than just the need to integrate the total communications infrastructure. Frame

relay can also:

1. Reduce costs. A great deal of this cost reduction comes from the elimination of the need for

parallel communications networks. But there is more to it than that. Frame relay replaces a

complex, incomplete web of dedicated private lines with a “cloud” of general and total connectivity,

not only within the United States, but around the world. Organizations who could only dream of

leasing a dedicated private line to Europe now enjoy affordable communications with major

European capitals thanks to frame relay.

2. Improve network performance. It used to be true that everyone involved in a network was so

happy that it worked at all that they had little inclination to care how the network was performing.

And even if they did care, there was little in the way of performance tuning methodologies or

software to assist them in their task. The problem with creating custom networks for each

application is that there were all slightly different in their performance tuning needs. But frame relay

is the same network for all its various applications. Not only is frame relay faster than almost

anything else, it is also more tunable than a collection of individual, parallel networks.

3. Make the network as a whole more reliable. In a network composed of an interconnected mass of

individual leased private lines, the failure of one critical link can be devastating to the network as a

whole. Part of the allure of public networks is that they are more resilient and robust than private

networks. Everyone knows that the public voice network suffers internal link failures all the time.

Yet with a few widely publicized exceptions, notable only due to their rarity, these failures have no

impact on overall voice network service. Since frame relay is almost always a public network

service, it shares this characteristic with the public voice network.

4. Make the network more future-proof. Many networks are difficult to scale for new and more

applications in terms of speed and connectivity. Even simple reconfiguration can be a time-

consuming and costly process. Frame relay networks can react to sudden changes quite rapidly,

often within 24 hours and as the result of a simple telephone call. And nothing is more painful than

watching competing organizations become more successful while one’s own organization is

saddled with technology that is outdated and perhaps even considered obsolete. Frame relay is not

only a member of the fast-packet family, but is intended to be interoperable with the other major

fast-packet network technology, ATM.

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