Xem mẫu
- Networks and Telecommunications: Design and Operation, Second Edition.
Martin P. Clark
Copyright © 1991, 1997 John Wiley & Sons Ltd
ISBNs: 0-471-97346-7 (Hardback); 0-470-84158-3 (Electronic)
40
Technical Standards for
Networks
In the past, telecommunications networks have been evolved in the minds of their designers to
meet well defined but changing user demands. These broadly innovative influences are bound to
persist and users can look forward toever more sophisticated telecommunications services in the
future. Itwas onlyin themid-1960s that customer-dialled international telephone callsfirst became
possible, and in those days such calls were for therich alone. Nowadays the advance of technology
has made themso much cheaper thateveryone takes them for granted. In late 1960s everyone
the
marvelled at thefirst live satellite broadcasts; now there areso many satellites in space that many of
them no longerhavenames,only longitudinal geographic location references. Every day the
world’s communicators move larger and largervolumes of video, text, speech, and data informa-
tion around theglobe, and all without a second thought. The revolution in communications that
we haveseen, and theever-wideningscope forinformationtransfer, have only come about
through an almost fanatical emphasis on the internationalcompatibility of telecommunications
networksandequipment,underpinned by worldwideagreement onthe technical standards
without which interconnection between networks in different countries and the interworking of
different network types would be impossible. This chapterdiscusses the variousbodies involved in
setting these standards. It outlines inparticulartherecommendations of ITU (International
Telecommunications Union), the world’s most authoritative
body on telecommunications
technical standards.
40.1 THE NEED FOR STANDARDS
Whenevertwo or more pieces of equipment,built by different people or different
manufacturing companies, arecalled on towork harmoniously together within the same
network, there is a need for technical standards. The standard defines comprehensively
the interface, or set of interfaces to be used between various equipments. It describes
the functions that each of the equipments are required to perform, and it ensures that
the signals passed between the equipments are fit for their purpose, and unambiguous.
Only a network designed and built in isolation could exist without carefully defined
and documented technical standards for the interfaces. Such networks are extremely
723
- 724 STANDARDS TECHNICAL FOR NETWORKS
rare,for even whenmanufacturersdeveloptheirownspecialinterfacesforinter-
connecting two pieces of their own equipment, these interfaces usually conform to their
own documented proprietary standards. An example of a proprietary standard is the
systems network architecture ( S N A ) (described in Chapter 18) which can be used as the
basis for network design(called an architecture) interconnecting computer systems.
SNA is similar to ITU’s (or ISO’s) OS1 model, but was developed by the IBM cor-
poration and was in use by their customers before the ITU standards had been agreed.
Most networks are from equipment supplied by many different manufacturers, who
usually cooperate with the network operators and other interested parties to define the
standards necessary to ensure correct interworking of equipment. The application or
potential of any particular standard is usually the determining factor in how many
partiesneed to beinvolvedindeveloping and documenting it. Consequentlymany
slightly different groupings of manufacturers, network operators, users, and regulatory
bodies, both national and international, have sprung up over the years to address the
developmentofvariousdifferentsets of standards.Eachgrouping(often calleda
standards body) tends to specialize in the interfaces required between particular types of
equipment(saycomputers,orfacsimilemachines, or customerpremisesequipment
( C P E ) or safety). The remainder of the chapter describes a number of the most prom-
inent ones.
40.2 WORLDWIDE INTERNATIONAL STANDARDS
ORGANIZATIONS
International network interconnectionshave always presented somethingof a challenge
forthe engineers developingthem.Historically,
international
telecommunications
between different countries have been provided by means of gateway switches, which
have provided a means for interfacing and interworking a common international stand-
ard with the plethora of slightly differing national networks. International standards
have thus provided the foundationof the recent boom in international communication.
The boom is likely to continue so long as each national network evolves slowly towards
the international standard, leading ultimately to a homogeneous worldwide network.
However, this is only one of the benefits to be derived from international standards; no
less important, withusers of even thesmallestnetworksinsisting on conformance,
terminal equipment manufacturers will beobliged to produce devices of worldwide
compatibility.
The amount and quality of international standardization has improved rapidly in
recent years. One of the practices which has improved standards is the definition not
only of interfaces andprotocols,butalso of theproceduresfor conformance and
compatibility testing. Such procedures are defined in standards called PICS (protocol
implementation conformance statements) and PIXITs (protocol informationextra
information f o r testing).
The most important worldwide standards organizations in telecommunications are
the International Organization for Standardization ( I S O ) (colloquially the International
Standards Organization)and theInternational Telecommunications Union (ZTU).A third
body, but only important in the agreement of standards for satellite working, is the
International Telecommunications Satellite Organization, called I N T E L S A T .
- INTERNATIONAL
WORLDWIDE STANDARDS ORGANIZATIONS 725
International Organization for Standardization (ISO)
The I S 0 is a ‘voluntary’ organization, composed of and financed the national stand-
by
ards organizations (e.g. British Standards Institute ( B S I ) , American National Standards
Institute ( A N S I ) , etc.) of each of the member countries. Like each of its component
national organizations, the I S 0 lays down standards for practically every conceivable
item, not only telecommunications, but also colour scheme for electrical wiring, and
the
even the standard sizes for paper (e.g. A3, A4, etc.). The organization has a number of
sub-committees, but in the main it does not produce standards from scratch. It tends
merely to ‘brush-up’ standards submitted by its member organizations. In this way the
local area network ( L A N ) standard I S 0 8802 started life as IEEE802, generated initially
by the American Institution o Electrical and Electronic Engineers ( I E E E ) .
f
Address
International Organization for Standardization
Rue de Varembe, 1
Case Postale 56
CH-l21 1
Geneve 20
Switzerland
Tel: (41) 22 749 0111
International Telecommunications Union ( I T U )
The ITU is an agency of the United Nations, responsible for overseeing all aspects of
telecommunications. Organizationally, theITU is split into four permanent parts, all of
which are headquartered in Geneva.Theseareshown in Figure 40.1. TheGeneral
Secretariat is responsible for overall administration, finance, and publication of regula-
tions, journals and technical recommendations (their name for standards). The Radio-
communication Bureau ( B R or I T U - R ) serves in two functions, first as a ‘custodian of
international public trust’, regulating the assignment of radio frequencies throughout
the world, and so preventing interference between radio stations (this responsibility
used to be carried out by the ITU under the organization called IFRB (International
(radio) Frequency Registration Board). Second, the ITU-R acts as a consultative com-
mittee which generates technical standards and reports regarding radiocommunication
(thisfunctionwasformerlycarriedout by thepredecessorbodyknown as CCIR
The
(Consultative Committee for Radiocommunication)). Telecommunications Standardi-
zationBureau ( T S B or I T U - T ) is themain consultative committee whichgenerates
INTERNATIONAL TELECOMMUNICATIONS UNION (ITU)
Standardization
(BR or ITU-R)
(TSB or ITU-T)
Figure 40.1 Organization of the ITU
- 726 STANDARDS TECHNICAL FOR NETWORKS
technical standards for telephone/telegraph networks (including data networks). The
I T U - T ( I T U standardization sector) replaces the former body, known as the C C I T T
(International Telegraph and Telephone Consultative Committee). The fourth partof the
ITU, set up by the plenipotentiary meeting in June 1989 is the BDT (Bureau for the
Development of Telecommunications). The BDT has the same status as the ITU-R and
ITU-T in its aimis to secure ‘technical cooperation’ but in addition it has a prime role in
raisinghelp and finance to helpthe less-industrialized countriesdeveloptheir tele-
communicationsnetworks.Morethan 150 countriesaremembers of the ITU and
participate in the workof the consultative committees. Delegatesto the individual study
group meetings comprise not only the main public network operators, but alsoscientific
and industrial organizations, private companies and equipment manufacturers. In the
main, the study groups generate recommendations from scratch, based on the contribu-
tions of delegates.
ITU-Tapproves new recommendations at the WTSC (World Telecommunications
Standardization Conference) which has replaced the four yearly C C I T T plenipotentiary
meeting which formally approved the coloured ‘books’ of technical standards.
Address
International Telecommunications Union
Place de Nations
CH-1211
Geneve 20
Switzerland
(Same address for ITU-R, ITU-T and BDT)
Tel: (41) 22 730 5111
(Sales and Marketing Service)
Tel: (English): (41) 22 730 6141
Tel: (French): (41) 22 730 6142
Tel: (Spanish): (41) 22 730 6143
International Electrotechnical Commission ( I E C )
Also known as the Commission Electrotechnique Internationale ( C E I ) , the IEC exists to
promote international cooperation on electrical and electronic standards. It works in a
similar manner to the ISO, gaining an international consensus of opinion and issuing
standards in main
nine fields, the important
most to us being those affecting
Telecommunicationsand Electroniccomponents andthoseon Telecommunications
equipment and information technology. The IEC has equal status and works in close
cooperation with the ISO, whose prime interest is in the non-electrical fields.
Address
International Electrotechnical Commission
Rue de Varembe, 3
CH- 1202
Geneve 20
Switzerland
Tel: (41) 22 919 02 11
- REGIONAL AND NATIONAL STANDARDS ORGANIZATIONS 727
INTELSAT
The International Telecommunications Satellite organization is run by subscription
between the world’s main international public network operators. Its prime purpose is
to develop, procure, and operatesatellite services between countries. In support of these
aims it develops its ownstandards specifically for the satellite service (e.g. from satellite
earth station to satellite in space, or for multiple access operation (see Chapter 33)).
Address
INTELSAT
3400 International Drive NW
Washington D C 20008
United States of America
Tel: (1)-202-944-6800
40.3 REGIONAL AND NATIONAL STANDARDS ORGANIZATIONS
A number of regional and national standards organizations are also in existence. In
some cases these duplicate the international standards, and may even be at variance
with them, a situationwhich is bound to persist, because it takes a long time to agree on
an international standard. However, some users cannot wait but feel obliged to develop
their own ‘interim’ standards, and these too tend to persist even after the emergence of
the world standard, because of the investment tied up in them. Notable regional and
national organizations involved in such standards are as follows.
Comite‘ Europe‘en de Normalisation ( C E N )
The CEN is theEuropean equivalent of the ISO; constituted of membernational
standards bodies, it generates European Norms (ENS), but unlike I S 0 standards ENS
are mandatory standards in the signatory countries to the CEN. CENELEC, a related
organization, is theEuropean equivalent of theIEC, generatingEuropeanelectro-
technical standards.
Addresses
Comite Europeen de Normalisation
Rue de Stassart 36
B- 1050
Brussels
Belgium
Tel: (32) 2 550 08 11
CENELEC
Rue de Stassart 35
B- 1050
Brussels
Belgium
Tel: (32) 2 519 68 71
- 728 TECHNICAL STANDARDS FOR NETWORKS
European Conference for Posts and Telecommunications ( C E P T )
The Telecommunications Commission (T Com) of the CEPT was until 1988 promi-
nent, in muchthesame way asthe CCITT (the forerunner of theITU-T), in the
developmentofEuropean telephone telegraph anddatanetworksstandards,and
manyCEPTrecommendations haveformedthebasis of the CCITT (now ITU-T)
recommendations. However, in 1988, prompted by the desires of the European Union
( E U , thencalledthe EuropeanEconomicCommunity, E E C ) to quicklydevelopthe
network interfaces
needed for establishment
the of pan-European
a network
infrastructure,the CEPT elected tohand overallitstechnical standards develop-
mentwork to a new permanentlystaffedorganizationcalledthe ETSI(European
Telecommunications Standards
Institute). Nevertheless,
the CEPT lives on, an
as
organizationofEuropean public telecommunications operators discussingmutual
strategy and planning, including management of the radio spectrum in the European
region.
Address
CEPT Information Desk
European Telecommunications Office (ETO)
Holsteinsgade 63
DK-2100 Copenhagen
Denmark
Tel: (45) 35 43 25 52
European Telecommunications Standards Institute (ETSI)
Funded in part by EuropeanUnion money, theETSI wasfoundednearNicein
France in 1988 to develop network
the interfaces andother technical standards
necessary for a homogeneous, and pan-European telecommunications network. It has
over 370 members from more than 30 countries in the CEPT and the European Free
Trade Association (EFTA), as well as European Union states. The technical work is
undertaken by full time staff, seconded from public network operators, manufacturers,
trade associations, users, research bodies and national standards bodies. In addition, a
number of special voluntary working parties have been established to deal with priority
items.
The ETSI is composed of a technical assembly and a permanent secretariat, but the
standardsdevelopmentwork is carried out by workingpartiesand projectteams.
Technical documents produced by ETSI may become one of three types of document,
as listed below
e E N or E N V (European Norm) Standards;to become ENSortemporaryENS
(ENVs), the standard needs to be put up for formal adoption by CENjCENELEC
e E T S (European
Telecommunication
Standards) ETSs are voluntarily
accepted
standards and guidelines
e NETS (Normes EuropPenesde Tklkcommunications), these are the most important
standards, because they are mandatory across Europe
- REGIONAL AND NATIONAL STANDARDS ORGANIZATIONS 729
In addition, ETSI also issues ETRs (European Technical reports) which provide useful
technical information for the design of equipment and telecommunications networks,
but these do not have the status of standards.
Address
European Telecommunications Standards Institute
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex
France
Tel: (33) 4 92 94 42 00
secretariat@etsi.fr
Tel: (Publications office): (33) 92 94 42 41
European Computer Manufacturers Association ( E C M A )
A consortium of European computer manufacturers, working on a voluntary basis to
develop computer interconnection standards. The ECMA often debated standards
have
within Europe before contributingto the ITU.An example is the OS1 transport
protocol, ECMA-72 and I S 0 8072.
Address
European Computer Manufacturers Association
Rue du Rhone, 114
CH- 1204
Geneve
Switzerland
Tel: (41) 22 849 6000
American National Standards Institute ( A N S I )
ANSI is a voluntary national standards organization of the United States of America,
and is a member the It
of ISO. is theUnitedStates clearing house stand-
for
ards, generally adopting standards proposed by smaller companies and organizations
withintheUnitedStates. Notable achievementsof ANSI have been the computer
character code ASCII (American standard code f o r information interchange) and the
computerprogramminglanguages, COBOL and F O R T R A N . ASCIIwasthefore-
runnertoITU-T’sinternationalalphabetnumber 5 (IA5,ITU-Trecommendation
T.50) which defines the alphabet in which computers ‘talk’ to one another.
Address
American National Standards Institute
11 West 42nd Street
New York
NY 10036
United States of America
Tel: (1)-2 12-642-4900
- 730 TECHNICAL STANDARDS FOR
NETWORKS
Electronic Industries Association ( E I A )
The EIA is a national trade association, developing electrical standards primarily for
North America. Notable achievements of the EIA havebeen the RS-232 (forerunner to
ITU-T V.24) and RS-449 (forerunner to ITU-T V.36) interfaces used between computer
equipment.
Address
Electronic Industries Association
2500 Wilson Boulevard
Arlington
Virginia VA2220 1
United States of America
Tel: (1)-703-907-7500
Institute of Electrical and Electronics Engineers (IEEE)
This is a professional institution based in the United States but for electrical engineers
based anywhere in the world. It lays down professional and technical standards and
codes of conduct. A notable achievement of IEEE was the IEEE local area network
( L A N ) standards inthe 802 series, first published in 1983. These are now used
throughout the world as the standards for localarea networks (LANs). Theyhave
subsequently been adopted by the International Organization for Standardization as
I S 0 8802.
Address
Institution of Electrical and Electronic Engineers
United Engineering Centre
345 East 47th Street
New York
NY 10016
United States of America
Tel: (1)-212-705-7900
Publications from Customer Services
Tel: (1)-908-981-0060
Exchange Carriers Standards Association (United States)
Commonly calledtheT1-Committee,aleadingbodyinagreeingstandardsforthe
deregulatednetworks of theUnitedStates.The TI-committee (formerlyExchange
carriersstandardsassociation) is opentoanysubscribingmembers,buttheseare
mainly United States exchange carriers.Standards under the auspice T1 include most
of
United States PTO (or exchange carrier) networking standards (e.g. T1-ISUP, the T1
version of the number integrated
7 services
digital
network user partsignalling
described in Chapter 12. T1-ISUP is used mainly in the United States). Another T1
standard is the B-ICI (Broadband Inter-Carrier Interface) used to interconnect ATM
networks of different carriers. The standards work itself is carried out by a number of
sub-committees called variously T1-D1, Tl-XI, etc.
- REGIONAL AND NATIONAL STANDARDS ORGANIZATIONS 731
Address
Alliance for Telecommunications Industry Solutions
(Standards Committee T1)
1200 G Street NW
Suite 500
Washington DC 20005
United States of America
Tel: (1)-202-434-8845
Society o Manufacturing Engineers ( S M E )
f
This is an American society formed of subscribing manufacturing organizations. It is
responsible for the early development work on the manufacturing automation protocol
( M A P ) and the technical and ofice protocol TOP).
Address
Society of Manufacturing Engineers
PO Box 930
1 SME Drive
Dearborn
Michigan 48 12 1
United States of America
Tel: (1)-313-271-1500
Telecommunication Technology Committee (TTC) (Japan)
This body (set up in Japan at thetime of liberalization of telecommunications network
services) is responsible for laying down network interface standards. It is composed
primarily of leading Japanese scientists and engineers from network operators and
equipment manufacturers. same way that T1 and ETSI the
In the set pace for
telecommunications standards in North America and Europe, respectively, so the TTC
sets the de facto standards for the South East Asian region.
Address
The Telecommunication Technology Committee
Hamamatsu-cho Binato-Ku
1-2-1 1Hamamatsu-cho
Susuki Building
Minato-Ku
Tokyo 105
Tel: (81) 33 43 21551
British Standards Institution ( B S I )
As an example of the many other national standards organizations, the British Stand-
ardsInstitution ( B S I ) producestelecommunications andotherstandardsand is a
member of the ISO.
- 132 TECHNICAL STANDARDS FOR NETWORKS
Address
British Standards Institution
Linford Wood
Milton Keynes
MK14 6LE
United Kingdom
Customer service and sales,
Tel: (44) 181 996 7000
40.4 REGULATORY STANDARDS
ORGANIZATIONS
As many of the world’s governments have recently become keen to deregulate their
telecommunicationsmarkets,allowingfreecompetitionparticularlybetweenmanu-
facturers of customer premises equipment ( C P E ) as well as between network operators,
there been
has an increasing need forcertainnetworkinterfacestandards to be
mandated by law, and ‘policed’ by a regulating body. (Customer premises equipment
( C P E ) is the general name applied to any type of equipment connected to the public
network. Thus telephones, computer terminals and other similar devices are all CPE.)
The use of a mandated standard for the interface between network and CPEensures the
protection of the network operator’sstaff and equipment,meanwhile also assuringCPE
manufacturersthat theirequipmentoperatessatisfactorilyoverthenetwork.The
following organizations are active in laying down mandatory technical standards.
European Telecommunications Standards Institute (ETSI)
Already mentioned in this chapter, one of the first jobs of the ETSI was to lay out the
CPE-to-network interfaces that become mandatory in each of the European Union
member states and other signatories of the CEPT’s memorandum of understanding.
Thestandardsareknown as NETs(Normes EuropPennes de Telecommunications,
French for ‘Europeantelecommunications standards’). Once a NET has been adopted,
both public network operators and CPE manufacturersneed to prove that their equip-
ment conforms to the interface, before legal
NET of
approval is given either for the launch
a new network service or for the saleof CPE. TheNET programme, however, is signifi-
cant in that CPE approval and certification (the‘green dot’) will be valid Europe-wide (in
any one of the signatory countries). Table 40.1 lists the original mandatory NETs.
Federal Communications Commission (FCC)
The FCC is the regulatory body in the United States, reporting directly to congress,
which lays down the code practice to which network operators and equipment manu-
of
facturers must conform.
Address
Federal Communications Commission
1919 M Street NW
Washington DC 20554
United States of America
Tel: (1) 202-418-0260
- DARDS REGULATORY 733
Table 40.1 MandatoryEuropeanTelecommunications Inter-
face Standards
~~ ~
Normes Europeenes de Telecommunications (NETS)
Access Group
NET 1 X.21 (Chapter 9 )
NET 2 X.25 (Chapter 10)
NET 3 ISDNbasic rate interface(Chapter 10)
NET 4 PSTNnormaltelephoneaccess
NET 5 ISDN primary interface
rate (Chapter 10)
NET 6 X.32 (Chapter 10)
NET 7 ISDNterminaladaptor
(Chapter 10)
Mobile Group
NET 10 Cellular network access
NET 11 Telephonyterminal
Modems Group
NET 20 General
modem
NET 21
V.21 modem
NET 22 V.22 modem
NET 23 V.22 bis
modem
NET 24 V.23 modem
NET 25
V.32 modem
Terminals Group
NET 30 Group 3 facsimile terminal
NET 31 Group 4 facsimile terminal
NET 32 Teletex
terminal
NET 33 Telephonyterminal
Ofice of Telecommunications (Oftel)
Oftel is theregulatorybodyfortelecommunicationswithintheUnitedKingdom,
overseeing the activities of all public and private telecommunications operators and
users. It is part of the UK government’s Department of Trade and Industry. Of late,
Oftel has focussed its regulations on controlling the conduct of operators in the U K
rather than on technical standardization. Standardization of technical interfaces for
interconnection of networks has been delegated to the Network Interconnection
Coordination Committee (NZCC) while questions of quality and network design have
been left to individual user choice.
Address
The Office of Telecommunications
50 Ludgate Hill
London
EC4M 755
United Kingdom
Tel: (44)-171-634 8700
- 734 NETWORKS FOR STANDARDS TECHNICAL
British Approvals Board for Telecommunications ( B A B T )
BABT is the independent body in the United Kingdom which undertakes customer
premises equipment (CPE) approvals, confirming that submitted equipment conforms
to thenational
network interface.
BABT is the UK’s main registered bodyfor
approvals which will apply throughout the European Union and other NET signatory
countries.
Address
British Approvals Board for Telecommunications
Claremont House
34 Molesey Road
Hersham, Walton-on-Thames
Surrey KT12 4RQ
United Kingdom
Tel: (44) 932 251200
Bundesamt fir Zulassung in der Telekommunikation ( B Z T )
BZT is the German equivalent of BAPT, being the responsible agency in Germany for
testing and issuing of technical approvals certificates.
Address
Bundesamt fur Zulassung in der Telekommunikation
TalstralJe 34-42
66 119 Saarbrucken
Germany
Tel: (49) 681 598-0
40.5 OTHER STANDARDS-PROMOTING ‘FORA’
Towards the end of the 1980s a number of organizations were becoming increasingly
frustrated because of the bureaucratic manner in which the official standards organiza-
tions operated, because of the constraining rules of procedure, and particularly by the
long maturation time then required to develop and agree new technical standards. For
equipment manufacturers this was resulting in lost sales, as potential purchasers held
off until the standards were agreed. For network operators this meant a hold-up in the
opening dates of new services. In a number of fields the frustration was so great that a
number of like-minded organizations set about forming debating and lobbying fora to
promote the quicker development of standards. Also typical is a permanent member-
financed company to organize the work of the forum and promote its results. Typical
also is a less formal procedure of meetings and contributions. Much of the work and
communication within the working groupsis instead conducted via electronic mail, and
members may be obliged to own an electronic mailbox as a condition of membership.
The most well-known of such fora are the Frame Relay Forum, the Network Manage-
ment Forum and the ATM Forum.
- OTHER STANDARDS-PROMOTING ‘FORA’ 735
Frame Relay Forum
TheFrame Relay Forum was establishedwiththeobjective to develop,agree and
promote frame relay networks
Address
Frame Relay Forum
303 Vintage Park Drive
Foster City
California CA94404
United States of America
Tel: (1) 415 578 6980
www.frforum.com
Network Management Forum
The Network Management Forum (NMF) was established in 1989 with the objectiveto
speed progress in the development of standardized ‘umbrella’ network management
systems. The members are drawn broadly from two camps, major network operators
(e.g. British Telecom, which played a leading role in the initial establishment of the
forumand provided first
the president) and computermanufacturers DEC,
(e.g.
Hewlett Packard,IBM,SUN, etc.).Valuable outputs of the N M F have been the
OMNIpoint and SPIRIT (service providers integrated requirements for information
technology)specifications.The OMNIpoint specifications were thefirst attemptto
consolidatethemanyemergingcomputerandnetworkmanagementstandardsand
specifications into a meaningful and realizable whole.
Address
Network Management Forum (NMF)
1201 Mount Kemble Avenue
Morristown
New Jersey NJ 07960
United States of America
Tel: (1) 201 425 1900
A T M Forum
The ATM Forum came about through the interest of four major manufacturers who
wanted to speed up the standardization process of ATM. It was set up in October 1991
by Northern Telecom(nowcalledNortel),Sprint,SunMicrosystems and Digital
Equipment Corporation (DEC). In January 1992 membership was opened to wider
participation from the telecommunication industry. The purpose of the ATM forum is
to promote the development of technical standards for ATM and to raise awareness in
the market of its capabilities. Many ATM standards adopted by ITU-T are heavily
based on (if not identical to) those previously issued by the ATM forum.
Address
The ATM Forum
2570 West El Camino Real
Suite 304
- 736 TECHNICAL STANDARDS FOR
NETWORKS
Mountain View
California CA 94040
United States of America
Tel: (1) 415 949 6700
info@atmforum.com
Internet Engineering Task Force (IETF)
The IETF is the group which develops the technical standards (RFCs (requests for
comment)) for the Internet. The RFCs themselves can be obtained from
Jon Poste1
RFC Editor
USC Information Sciences Institute
4676 Admiralty Way
Marina del Rey
CA 90292-6695
United States of America
Tel: (1) 213 822 1511
postel@isi.edu
RFCs may also be viewed using FTP on the host nisc.sri.com
40.6 PROPRIETARY STANDARDS
Despite the phenomenal number of standards organizations around theworld, a few of
whichhavebeenmentioned,somecompaniesnonetheless feel that they can steala
march on their competitors by developing their own proprietary (as opposed to open)
technical standards. By proprietary we mean that the standards are not available for
free use by any manufacturer;either they may not be published at all, or alternatively a
‘licence fee’ is demanded when the standards are used in the design of new equipment.
It is usuallyonlylarge and powerfulorganizationswhocanaffordtoretaintheir
standards as proprietary. The markets that such companies can command for their
proprietary technology make it worthwhile to protect technical
the rights.
Other
companies may find it lucrative to ‘buy-into’ these standards, so that they in turn may
sell compatible ‘add-on’ equipment, but the lead company retains an edge. Examples of
companies who have been successful in retaining control of proprietary standards are
AT&T and IBM.
American Telephone and Telegraph Company ( A T & T )
One of the world’s largest telecommunications carriers (based in the United States),
AT&T and the new equipment manufacturer, Lucent, which was created by spin-off
fromAT&T, draw technical
their strengthfrom famous
their research arm, Bell
Laboratories. Anexample of one of AT&T’s proprietarystandards is the UNIX
operating system, used as the operating software in many modern computer systems.
- PROPRIETARY STANDARDS 737
Address
Lucent Technologies
Customer Information Centre
2855 North Franklin Road
Indianapolis
Indiana 46219
United States of America
Tel: (1)-800-432-6600
(1)-888-582-3688
Bell Communications Research (Bellcore)
Bellcore is the jointly owned research arm of the seven United States Regional Bell
Operating Companies (RBOCs). It was formed partly with staff from AT&T’sBell
Laboratories at the time of AT&T divestiture in the mid-1980s. Bellcore initially gained
considerable respect for its networking standards called Technical References ( T R s ) , in
particular in the field of intelligent networks and services (Chapter 11). Preliminary
versions of TRsare called TAs (TechnicalAdvisories). In recentyears,however,
Bellcore has suffered from a lack of clear direction and funding from its owners, who
see themselves increasingly in competition with one another.
Address
Customer Service, Technical Publications
Bellcore
444 Hoes Lane
Piscataway
New Jersey 08854
United States of America
Tel: (1)-908-758-2142
British Telecom ( B T )
BT is thelargestpublictelecommunications operator in the United Kingdom. It is
descended from the state-owned Post Ofice Telecommunications (formerly known as
GPO (GeneralPost Ofice)). BritishTelecomremainsa predominant force in UK
network standards setting. The standards are nowadays catalogued as British Telecom
NetworkRequirements (or BTNRs). Examplesinclude BTNR 190 ( D P N S S , Digital
Private Network Signalling System, a widely used standard in private networking of
PBXs).
Address
British Telecom Network Secretariat
Postpoint 2C07
403 Saint John Street
London EClV 4PL
United Kingdom
Tel: (44) 171 843 51 88
- 738 NETWORKS FOR STANDARDS TECHNICAL
International Business Machines (IBM)
Perhaps the world’s most important computer manufacturer, it was IBM who gave us
thestandardhardwareandbusconfigurationformanymainframeandpersonal
computers and the systems network architecture ( S N A ) to communicate data between
interconnected computers.
UK Address
IBM Technical Publication Centre
Alencon House
Alencon Link
Basingstoke
Hampshire RG21 7EJ
United Kingdom
Tel: (44) 1256 478166
European Address
IBM Software Manufacturing Solutions
IBM Denmark A/S
Sortemosevej 2 1
Alleroed
DK 3450 Denmark
Tel: (45) 2 33 000
United States Address
IBM Mechanicsburg Distribution Centre
180 Kost Road
Mechanicsburg
Pennsylvania
PA 17055-0786
United States of America
Tel: (1)-717-796-3200
(1)-800-879-2755tpb -1
40.7 THESTRUCTUREAND CONTENT OF
ITU-T RECOMMENDATIONS
Finally, we takealookintothestructureandcontent of the recommendations of
the
world’sleading authority networking
on standards, ITU-T. ITU-T
the The
recommendations used to be approved every four years (at CCITT plenary assemblies
of all thememberorganizations).Thisused to be theculminationoffouryears
development work, establishing new recommendations, improving existing,
and
deletingobsolete
ones. recommendations then
The were published in aseries of
coloured volumes, a process taking an entire year because all the transcripts had to be
translatedand publishedinalltheworkinglanguages.Each four yearly issue was
- THE STRUCTURE AND CONTENT OF ITU-T
RECOMMENDATIONS 739
given a‘colour’ which wasassigned to each of the bound volumesinwhichthe
recommendationsappeared, and every four yearswitheachsubsequent issue the
colour was changed. The whole set of volumescorresponding to aparticularyear
thus became colloquially known as The Blue Book (1988), or The Red Book (1984).
Thus
e the yellow book was approved in 1980
e the red book was approved in 1984
e the blue book was approved in 1988
Table 40.2 ITU-T seriesof recommendations
Recommendation
series Subject coverage
A Organization of the work of the ITU-T
B Means of expression (symbols, terms, vocabulary, etc.)
C General telecommunications statistics
D Recommendations for general application, including general tariff principles and
charging and accounting in international telecommunication services and
recommendations for regional application
E International telephone network and ISDN: operation, numbering routing, mobile
services, quality of service, network management and traffic engineering
F Operations and quality of service: telegraph services, mobile service, telematic service,
message handling services, directory services, document communication, data
transmission services, audiovisual services, ISDN services, universal personal
telecommunication, human factors
G Transmission systems and media
H Transmission of non-telephone signals
i Integrated services digital network (ISDN)
J Transmission of sound-programme and television signals
K Protection against interference
L Construction, installation and protection of cables and other elements of outside plant
M Maintenance and telecommunications management network (TMN)
N Maintenance of international sound-programme and television transmission circuits
0 Specifications for measuring equipment
P Telephone transmission quality
Q General recommendations on telephone switching and signalling
R Telegraphy
S Alphabetical telegraph terminal equipment
T Telematic services
U Telegraph switching
V Data communication over the telephone network
X Public data networks
Z Programming languages (including SDL, specification and description language;
CHILL, CCITT high level language; and MML, man-machine language)
- 740 TECHNICAL STANDARDS FOR
NETWORKS
The four year cycle of issueing new recommendations was ended in 1992, when the
plenary assembly restructured the ITU. One of the objectives of the re-organization of
the CCITT into the ITU-T to speed up the process of agreement and publication of
was
standards. Thus itbecamepossible to issue new recommendations as soonas they
becameavailable. Therecommendations issued since 1992 havethereforeappeared
individually as separate recommendations on plain white paper. Colloquially these are
known as the white book.
Each updated recommendation is an improvement over its predecessor, but there is
no guarantee of compatibility between equipments which have been designed to differ-
ent versions of the same recommendation. Thus, for example, there no guarantee that
is
themessage handling system (MHS) of theX.400recommendation of
1988 was
compatible with the version of 1984 (and indeed it was not),
One of theproblems of the new publishing regime is that the overview of the
standards has to some extent been lost. Each book of recommendations used to be
generally cohesive and compatible within itself. Nowadays, it is difficult to obtain a full
picture of all the otherrelevant recommendations, because some of these may not yet be
fully complete and thus published.
Table 40.2 provides an overview of the subject areas, covered by the various series of
recommendations, which make up each book. Recommendations are usually known by
their series letter and a number; X.25 for example is a particular type of datu com-
munications network interface in the X-series of recommendations, in fact the one used
in packet switched networks.
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