The revolution in communications that we have seen, and the ever-widening scope for information transfer, have only come about through an almost fanatical emphasis on the international
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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 to ever more sophisticated telecommunications services in the future It was only in the mid-1960s that customer-dialled international telephone calls first became possible, and in those days such calls were for the rich alone Nowadays the advance of technology has made them so much cheaper that everyone takes them for granted In the late 1960s everyone marvelled at the first live satellite broadcasts; now there are so many satellites in space that many of them no longer have names, only longitudinal geographic location references Every day the world’s communicators move larger and larger volumes of video, text, speech, and data informa- tion around the globe, and all without a second thought The revolution in communications that
we have seen, and the ever-widening scope for information transfer, have only come about through an almost fanatical emphasis on the international compatibility of telecommunications networks and equipment, underpinned by worldwide agreement on the technical standards without which interconnection between networks in different countries and the interworking of different network types would be impossible This chapter discusses the various bodies involved in setting these standards It outlines in particular the recommendations of ITU (International Telecommunications Union), the world’s most authoritative body on telecommunications technical standards
Whenever two or more pieces of equipment, built by different people or different manufacturing companies, are called on to work 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
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ISBNs: 0-471-97346-7 (Hardback); 0-470-84158-3 (Electronic)
Trang 2724 TECHNICAL STANDARDS FOR NETWORKS
rare, for even when manufacturers develop their own special interfaces for inter-
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 parties need to be involved in developing and documenting it Consequently many slightly different groupings of manufacturers, network operators, users, and regulatory bodies, both national and international, have sprung up over the years to address the development of various different sets of standards Each grouping (often called a
standards body) tends to specialize in the interfaces required between particular types of equipment (say computers, or facsimile machines, or customer premises equipment
( 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 interconnections have always presented something of a challenge for the engineers developing them 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 foundation of 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, with users of even the smallest networks insisting on conformance, terminal equipment manufacturers will be obliged 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 and protocols, but also of the procedures for conformance and
compatibility testing Such procedures are defined in standards called PICS (protocol
implementation conformance statements) and PIXITs (protocol information extra information f o r testing)
The most important worldwide standards organizations in telecommunications are
the International Organization f o r Standardization ( I S O ) (colloquially the International Standards Organization) and the International 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
Trang 3International Organization for Standardization ( I S O )
The I S 0 is a ‘voluntary’ organization, composed of and financed by the national stand-
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 the colour scheme for electrical wiring, and 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 of Electrical and Electronic Engineers ( I E E E )
Address
International Organization for Standardization Rue de Varembe, 1
Case Postale 56
Geneve 20
Switzerland Tel: (41) 22 749 0111
CH-l21 1
International Telecommunications Union ( I T U )
The ITU is an agency of the United Nations, responsible for overseeing all aspects of
telecommunications Organizationally, the ITU is split into four permanent parts, all of which are headquartered in Geneva These are shown in Figure 40.1 The General 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 (this function was formerly carried out by the predecessor body known as C C I R
(Consultative Committee for Radiocommunication)) The Telecommunications Standardi-
zation Bureau ( T S B or I T U - T ) is the main consultative committee which generates
INTERNATIONAL TELECOMMUNICATIONS UNION (ITU)
Standardization (TSB or ITU-T) (BR or ITU-R)
Figure 40.1 Organization of the ITU
Trang 4726 TECHNICAL STANDARDS 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 part of 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 aim is to secure ‘technical cooperation’ but in addition it has a prime role in raising help and finance to help the less-industrialized countries develop their tele- communications networks More than 150 countries are members of the ITU and
participate in the work of the consultative committees Delegates to the individual study
group meetings comprise not only the main public network operators, but also scientific 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-T approves new recommendations at the W T S C ( W o r l d 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
Geneve 20 Switzerland (Same address for ITU-R, ITU-T and BDT) Tel: (41) 22 730 51 11
CH-1211
(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 nine main fields, the most important to us being those affecting Telecommunications and Electronic components and those on 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
Geneve 20 Switzerland Tel: (41) 22 919 02 11 CH- 1202
Trang 5INTELSAT
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 operate satellite services between countries In support of these aims it develops its own standards 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 N W 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 situation which 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 the European equivalent of the ISO; constituted of member national 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 the European equivalent of the IEC, generating European electro- technical standards
Addresses
Comite Europeen de Normalisation Rue de Stassart 36
Brussels Belgium Tel: (32) 2 550 08 11
B- 1050
CENELEC Rue de Stassart 35 Brussels
Belgium Tel: (32) 2 519 68 71
B- 1050
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European Conference for Posts and Telecommunications ( C E P T )
The Telecommunications Commission (T Com) of the CEPT was until 1988 promi- nent, in much the same way as the CCITT (the forerunner of the ITU-T), in the development of European telephone telegraph and data networks standards, and many CEPT recommendations have formed the basis of the CCITT (now ITU-T) recommendations However, in 1988, prompted by the desires of the European Union ( E U , then called the European Economic Community, E E C ) to quickly develop the network interfaces needed for the establishment of a pan-European network
infrastructure, the CEPT elected to hand over all its technical standards develop- ment work to a new permanently staffed organization called the ETSI (European Telecommunications Standards Institute) Nevertheless, the CEPT lives on, as an organization of European public telecommunications operators discussing mutual 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 ( E T S I )
Funded in part by European Union money, the ETSI was founded near Nice in France in 1988 to develop the network interfaces and other 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 standards development work is carried out by working parties and project teams 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 ENS or temporary ENS (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 EuropPenes de Tklkcommunications), these are the most important standards, because they are mandatory across Europe
Trang 7European
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
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 have often debated standards within Europe before contributing to 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
Geneve Switzerland Tel: (41) 22 849 6000 CH- 1204
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 of the ISO It is the United States clearing house for stand- ards, generally adopting standards proposed by smaller companies and organizations within the United States Notable achievements of ANSI have been the computer
character code ASCII (American standard code f o r information interchange) and the
computer programming languages, COBOL and F O R T R A N ASCII was the fore-
runner to ITU-T’s international alphabet number 5 (IA5, ITU-T recommendation
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
Trang 8730 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 have been 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 ( I E E E )
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 in the 802 series, first published in 1983 These are now used throughout the world as the standards for local area networks (LANs) They have 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)-908-98 1-0060
Exchange Carriers Standards Association (United States)
Commonly called the T1-Committee, a leading body in agreeing standards for the
deregulated networks of the United States The TI-committee (formerly Exchange carriers standards association) is open to any subscribing members, but these are
mainly United States exchange carriers Standards under the auspice of T1 include most United States PTO (or exchange carrier) networking standards (e.g T1-ISUP, the T1 version of the number 7 integrated services digital network user part signalling 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, T l- XI, etc
Trang 9Address
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 of Manufacturing Engineers ( S M E )
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 the time 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 In the same way that T1 and ETSI set the 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 1 Hamamatsu-cho Susuki Building
Minato-Ku Tokyo 105 Tel: (81) 33 43 21 551
British Standards Institution ( B S I )
As an example of the many other national standards organizations, the British Stand-
ards Institution ( B S I ) produces telecommunications and other standards and is a
member of the ISO
Trang 10132 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 telecommunications markets, allowing free competition particularly between manu-
facturers of customer premises equipment ( C P E ) as well as between network operators,
there has been an increasing need for certain network interface standards 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 CPE ensures the protection of the network operator’s staff and equipment, meanwhile also assuring CPE manufacturers that their equipment operates satisfactorily over the network 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 The standards are known as NETs (Normes EuropPennes de Telecommunications,
French for ‘European telecommunications standards’) Once a NET has been adopted, both public network operators and CPE manufacturers need to prove that their equip- ment conforms to the NET interface, before legal approval is given either for the launch of
a new network service or for the sale of CPE The NET 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 of practice to which network operators and equipment manu- facturers must conform
Address
Federal Communications Commission
1919 M Street NW
Washington D C 20554 United States of America Tel: (1) 202-418-0260