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`Telecommunications
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`Essentials
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`The Complete Global Source
`for Communications Fundamentals,
`Data Networking and the Internet,
`and Next-Generation Networks
`
`Lillian Goleniewski
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`vfiAddison—Wesley
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`Boston 0 San Francisco 0 New York - Toronto - Montreal
`London - Munich - Paris - Madrid
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`Capetown - Sydney - Tokyo - Singapore - Mexico City
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`Page 1
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`AT&T v. VoIP, IPR 2017-01382
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`AT&T Exhibit 1016
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`AT&T Exhibit 1016
`AT&T v. VoIP, IPR 2017-01382
`Page 1
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`Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trade-
`marks. Where those designations appear in this book, and Addison—Wesley, Inc. was aware of a trademark claim,
`the designations have been printed with initial capital letters or in all capitals,
`
`Lido Telecommunications Essentials® is the registered trademark of The Lido Organization, Inc.
`
`The author and publisher have taken care in the preparation of this book, but make no expressed or implied ware
`rarity of any kind and assume no responsibility for errors or omissions. No liability is assumed for incidental or con-
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`Library of Congress C(iltiltiglHg—ill—PullliCflElflil Data
`
`Goleniewski, Lillian.
`Telecommunications essentials : the complete global source for communications
`fundamentals, data networking and the internet, and next-generation networks / Lillian Goleniewski.
`p. cm.
`Includes bibliographical references and index.
`ISBN 0—201-7603270
`1. Telecommunication. I, Title.
`
`TKSIOI G598 2002
`621.382rdc21
`
`Copyright © 2002 by Pearson Education, Inc.
`
`2001053752
`
`All rights reserved. No part of this publication maybe reproduced, stored in a retrieval system, or transmitted, in
`any Form, 'or by any means, electronic, mechanical. photocopying, recording, or otherwise, Without the prior con
`sent of the publisher. Printed in the United States of America. Published simultaneously in Canada.
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`For information on obtaining permission for use of material from this work, please. submit a written request [0:
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`Pearson Education, Inc.
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`isBN 07201160320
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`Text printed on recycled paper
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`1 2 3 4 5 6 7 8 9 lO—CRS—050403020l.
`
`First printing, December 2001
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`AT&T Exhibit 1016
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`AT&T v. VoIP, IPR 2017-01382
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`Page 2
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`AT&T Exhibit 1016
`AT&T v. VoIP, IPR 2017-01382
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` Establishing Connections: Switching Modes and Networking Modes
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`certain position and are switched to a different position. The position to which bits
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`are switched is determined by a combination of one or more of three dimensions:
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`space (that is, the interface or port number), time, and wavelength. Packet switch—
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`ing is based on labels; addressing information in the packet headers, or labels, helps
`to determine how to switch or forward a packet through the network node.
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`l 99
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`Circuit Switching
`Circuit switchng has been the basis of voice networks worldwide for many years.
`You can apply three terms to the nature of a circuit-switched call to help remember
`what this is: continuous, exclusive, and temporary. One of the key attributes of a
`circuit-switched connection is that it is a reserved network resource that is yours
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`and only yours for the full duration of a conversation. But when that conversation
`is over, the connection is released. A circuit-switched environment requires that an
`end-to-end circuit be set up before a call can begin. A fixed share of network
`resources is reserved for the call, and no other call can use those resources until the
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`original connection is closed. A call request signal must travel to the destination
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`and be acknowledged before any transmission can actually begin. As Figure 4.1
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`illustrates, you can trace the path from one end of the call to the other end; that
`path would not vary for the full duration of the call, and the capacity provisioned
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`on that path would be yours and yours alone.
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`Advantages and Disadvantages of Circuit Switching Circuit switching uses
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`many lines to economize on switching and routing computation. When a call is set
`up, a line is dedicated to it, so no further routing calculations are needed.
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`Exchange
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`Intermediate Switching Offices
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`Trunk that stays in place
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`------------ Connection set up when call is placed
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`Figure 4.1 A circuitfiswitched call
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`Since they were introduced in the mid-1980s, digital cross-connect systems
`(DCSs) have greatly eased the process of reconfiguring circuit-switched networks
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`and responding to conditions such as congestion and failure. DCSs create pre—
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`defined circuit capacity, and then voice switches are used to route calls over circuits
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`that are set up by these DCSs. DCSs are analogous to the old patch panels. You may
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`have seen a main distribution frame (MDF) on which twisted-pair wiring is termi~
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`nated. The MDF is a manual patch panel, and before DCSs were introduced, when
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`it was necessary to reconfigure a network based on outage, congestion, or cuse
`tomer demand as a result of shifting traffic patterns, technicians had to spend days
`or even weeks, manually making changes at the MDE The DCS is a software patch
`the software are databases that define alternate routes—alternate
`panel, and within
`s a con-
`connections that can be activated in the event'that the network encounter
`dition that requires some form of manipulation. DACSs are one of the elements of
`the PSTN that contribute to its reliability: When network conditions change, in a
`matter of minutes, a DCS can reconfigure the network around those changes. With
`such tools, the PSTN is able to offer five 95 reliability—in other words, 99.999016
`guaranteed uptime. (DCSs are discussed in more detail in Chapter 5.)
`Circuit switching offers the benefits of low latency and minimal delays because the
`on the path is made only once, at the beginning of the call, and
`routing calculation
`there are no more delays incurred subsequently in calculating the next hop that should
`be taken. Traditionally, this was sometimes seen as a disadvantage because it meant that
`the circuits might not be used as efficiently as possible. Around half of most voice calls
`is silence. Most people breathe and occasionally pause in their speech. So, when voice
`being continuously held, and half
`communications are conducted over a circuit that’s
`eing used very efficiently. But
`the time nothing is being transmitted, the circuit is not b
`remember that this is an issue that is important when bandwidth is constrained. And as
`mentioned earlier in the book, through the optical revolution, bandwidth is being
`released at an astounding rate, so the efficient use of circuits because of bandwidth con-
`straints will not present the same sort of issue in the future that it once did. Hence, the
`low latencies or delays that circuit switching guarantees are more important than its
`potential drawbacks in bandwidth efficiency.
`Circuit switching has been optimized for real-time voice traffic for which Quality of
`Service (Q05) is needed. Because it involves path calculation at the front end, you know
`how many switches and cables you’re going to go through, so you can use a pricing
`mechanism that’s based on distance and time. The more resources you use, either over
`time or over distance, the greater the cost. Again, developments in fiber economics are
`changing some of the old rules, and distance is no longer necessarily an added cost ele-
`ment. (QoS is discussed in more detail in Chapter 10, “Next-Generation Networks”)
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`Chapter 4
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`5 Establishing Communications Channels
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`Generations of Circuit Switches Circuit switches have been around for quite
`some time. We’ve already been through three basic generations, and we’re begin—
`AT&T Exhibit 1016
`ning to see a fourth generation.
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