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`Page 1 of 4
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`Page 1 of 4
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`Library of Congress Cataloging-in-Publication Data
`
`Summers, Charles K.
`ADSL: standards. implementation, and architecture I Charles K. Summers.
`p.
`cm.-—— (Advanced and emerging communications techniques)
`Includes bibliographical references and index.
`ISBN O-8493-9595-X
`1. Data transmission systems. 2. Telecommunicationsfiflandards. 3. Modems.
`4. Telephone switching systems, Electronic. 1. Title. II. Series.
`TK5105.S86 1999
`621.38—dc2l
`
`99-26897
`CIP
`
`This book contains information obtained from authentic and highly regarded sources. Reprinted material
`is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable
`efforts have been made to publish reliable data and information, but the author and the publisher cannot
`assume responsibility for the validity of all materials or for the consequences of their use.
`
`Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic
`or mechanical, including photocopying, microfilming, and recording, or by any information storage or
`retrieval system, without prior permission in writing from the publisher.
`
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`for such copying.
`
`Direct all inquiries to CRC Press LLC, 2000 N.W. Corporate Blvd., Boca Raton, Florida 33431.
`
`Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are
`used only for identification and explanation, without intent to infringe.
`
`© 1999 by CRC Press LLC
`
`No claim to original U.S. Govemmeni works
`lntemational Standard Book Number 0-8493—9595X
`Library of Congress Card Number 99-26897
`Printed in the United States of America
`2 3 4 5 6 7 8 9 0
`Printed on acid-free paper
`
`For r.
`
`children Che;
`
`Page 2 of 4
`
`

`
`ADSL: Standards, Implementation, and Architecture
`
`The XDSL Family of Protocols
`
`TABLE 2.1
`ADSL Standards Bodies and Standards
`
`Standards Body Working Group
`ADSL Forum
`Many, including
`UAWG SNAG
`TlEl .4
`TM6
`Study Group 15
`
`ANSI Tl
`ETSI
`ITU—T
`
`Standard
`TR-00x
`
`Purpose
`Industry Advisory Papers
`
`Basic ADSL Standard
`Close interworking with ANSI
`International Standards
`
`T14413’ Issue 2
`
`G.992.l
`G.992.2
`G.994.1
`G.995 .1
`G.996.1
`G.997.]
`
`2.4.2.1 ADSL Forum and UAWG
`
`The ADSL Forum (http://www.adsl.co1n/), formed in 1994, has been in the forefront
`in publicizing ADSL and acting as a working group to explore architectural issues
`not yet covered by the standards bodies. It also acts as a “prod” to the standards
`bodies to get them working on standards. Most of the technical issues, addressed
`by the industry participants of the forum, deal with interworking. There are four
`subgroups that are particularly active. These are the UAWG (mentioned above), the
`System Network Architecture Group (SNAG), the Management Information Base
`(MIB) group, and the test group which Coordinates test environments between forum
`participants and other manufacturers of equipment. Many of the issues being looked
`at by the ADSL Forum are also of interest to the Asynchronous Transfer Mode
`(ATM) Forum (http://www.atmforum.com/).
`
`2.4.2.2 ANSI
`
`The American National Standards Institute (http://web.ansi.org) oversees various
`committees composed primarily of industry technical people. The comIn_ittee T1
`and, more specifically, the subcommittee TlEl is associated with ADSL standards.
`The TlEl subcommittee has the responsibility of overseeing standards work for
`interfaces, power, and protection for networks.
`Each subcommittee may be broken down into working groups. The T1E1.4
`working group is actually the group responsible for DSL access, including ADSL.
`DSL access includes physical layer standards and transmission techniques for inter-
`faces. The TIE1.4 working group was responsible for the TL413 ADSL standard,
`which will be covered in detail in the next chapter. T1.4l3 was published in 1995.
`A new version (Tl.413, release 2) is now available, in draft form, which incorporates
`some of the UAWG simplification issues.
`
`2.4.2.3
`
`ETSI
`
`ETSI (http://www.etsi.fr) is also
`Transmission and Multiplexing ('
`which roughly corresponds to T1}
`that international issues are addre;
`
`2.4.2.4
`
`TU-T
`
`The International Telecommunic at
`
`the last body to get involved with :
`T did join ADSL standardization
`international desire to incorporat
`recommendations, such as L325 11
`recommendations being worked 0]
`fall into physical layer protocol ca
`are G.DMT which is largely a re‘
`of the work of the UAWG, G.te
`G.OAM concerning operations, a
`and G.HS for handshaking protoc
`G.lite has now been informal
`
`during the next meeting of ITU—T I
`in June 1999. It is currently avail.
`Forum. The standard is not expects
`is guaranteed. The versions of G.]
`as G.992.1, G.992.2, G.994.l, G.9f
`T recommendations at present are
`
`G.992.1 (G.dmt)
`
`G.992.2 (G.lite)
`
`G.994.1 (G.hs)
`
`G.995.1 (G.ref)
`
`G.996.1 (G.test)
`
`G.997.1 (G.ploam)
`
`2.5 THE XDSL FAMILY OF
`
`The ADSL Forum refers to the pri
`Technologies.” Although pure ana
`
`Page 3 of 4
`
`

`
`Implementation, and Architecture
`
`The XDSL Family of Protocols
`
`2.4.2.3
`
`ETSI
`
`Pu rpose
`Industry Advisory Papers
`
`Basic ADSL Standard
`Close interworking with ANSI
`International Standards
`
`in 1994, has been in the forefront
`up to explore architectural issues
`acts as a “prod" to the standards
`of the technical issues, addressed
`vith interworking. There are four
`ie UAWG (mentioned above), the
`re Management Information Base
`; test environments between forum
`t. Many of the issues being looked
`he Asynchronous Transfer Mode
`
`)://web.ansi.o1'g) oversees various
`Jnical people. The committee T 1
`. associated with ADSL standards.
`of overseeing standards work for
`
`nto working groups. The TlE1.4
`for DSL access, including ADSL.
`. transmission techniques for inter-
`le for the Tl.4l3 ADSL standard,
`er. T1.413 was published in 1995.
`3, in draft form, which incorporates
`
`ETSI (http://www.etsi.fr) is also broken down into groups and subgroups. The
`Transmission and Multiplexing (TM) group contains the working subgroup TM6
`which roughly corresponds to T1El.4. TM6 often works with T1E1.4, making sure
`that international issues are addressed.
`
`2.4.2.4
`
`TU-T
`
`The International Telecommunications Union (ITU, http://www.itu.int) is sometimes
`the last body to get involved with a new technology. However, the fact that the ITU-
`T did join ADSL standardization efforts in 1998 is an indication of the growing
`international desire to incorporate such services. The lTU-T generates technical
`recommendations, such as 1.325 mentioned above. The present set of ADSL—related
`recommendations being worked on by the ITU-T are named by ‘G’ prefixes, as they
`fall into physical layer protocol categories. Recommendations currently under study
`are G.DMT which is largely a rewrite of ‘Tl.4l3, G.lite which incorporates much
`of the work of the UAWG, G.test which concerns test specifications for xDSL,
`G.OAM concerning operations, administration, and maintenance aspects of XDSL
`and G.HS for handshaking protocols to allow startup negotiation.
`G.lite has now been informally accepted by the ITU-T and will be voted on
`during the next meeting of ITU-T Study Group 15 to be held in Geneva, Switzerland
`in June 1999. It is currently available via special user’s groups, such as the ADSL
`Forum. The standard is not expected to change much in that process although nothing
`is guaranteed. The versions of G.DMT, G.OAM, G.HS, and G.lite will be released
`as G.992.1, G.992.2, G.994.1, G.995.1, G.996.l, and G.997.l. Specifically, the ITU-
`T recommendations at present are:
`
`G.992.1 (G.dmt)
`
`Asymmetrical Digital Subscriber Line (ADSL)
`Transceivers
`
`G.992.2 (G.lite)
`
`G.994.1 (G.l1s)
`
`G.995.1 (G.ref)
`
`Splitterless Asymmetrical Digital Subscriber
`Line (ADSL) Transceivers
`Handshake procedures for Digital Subscriber
`Line (DSL) Transceivers
`Overview of Digital Subscriber Line (DSL)
`Recommendations
`
`G.996.1 (G.test)
`
`Test procedures for Digital Subscriber Line (DSL)
`Transceivers
`
`G.997.1 (G.ploam)
`
`Physical layer management for Digital Subscriber Line
`(DSL) Transceivers
`'
`
`2.5 THE XDSL FAMILY OF PROTOCOLS
`
`The ADSL Forum refers to the protocols covered in this section as “Copper Access
`Technologies.” Although pure analog modems are also included in this category, we
`
`Page 4 of 4