ai OD. 'YEE viii Sle z j —- - z mna ee: lg a aje oo ae o ea Pi o ea ie (ISDN), a com- munication tech- have great stra- tegic impor- tance in the future. It's no longer practical to think of computing and telecommunications as separate en- tities. Both are based on the same mi- croprocessor technology and both han- dle information. Information is input at one end and output at the other, with only the physical transportation mecha- nism in between. The existing analog telecommunications network has been able to handle this type of traffic be- Cause computer output is in digital for- mat. Relatively low-speed data commu- nications (at speeds from 1,200 bits per second to 9.6K bps and up to 19.6K bps) are easily possible via modems over the analog network. However, analog net- works are not able to offer the high- speed communication links necessarv to support effective communications and video transmission. Design Changes The incorporation of digital switching and transmission technigues into tele- communications has begun to alter the foundation upon which networks are de- signed. Although voice communication is, and will continue to be, the primary means by which information is trans- mitted, the philosophy of network de- sign is changing. Voice is no longer the dominant feature around which net- works are designed; data communica- tions now plays the major role. This is not to say that voice communication is decreasing in importance; it is just that, in a digital network, voice or data no longer become issues, Al] communica- tions, including digitized voice, are con- sidered to be data. The key concept of a digital network is that it lays the foundation for creat- ing a ubiguitous, integrated network ca- pable of handling all our communica- tilons reguirements—from a simple tele- phone call to the broadcasting of high- MARTIN - definition television. Economic Factors The scale of the task involved in con- verting networks from analog to digital is guite daunting, The telephone net- work has evolved over the past 100 years. By the mid-1990s, the majority of telecommunications networks in the ma- Jor industrial countries of the world will be fully digital. This reguires the replacement, of all VIH and transm ssion facilities, se and the introduction of a wide e of m zača opici in addition to ole (adi inge | alog to dig: ing the change from an pe rninications are thr KA pe nomic factors: cost-effectiveness ar" na lability; expandable JE koki The first SEK toka 'below; wider k bandwidth is the gubject of next week S column. Cost-Effectiveness PTTs (state-controlled A tions facilities), common carriers an network operators of all types, sklene public or private, have long had prob lems associated with running and main: taining an analog network; some of the basic principles date back to the early: part of this century. The cost of operat: Of CorntnunicatioH BNO, Iteriace — The Natwotk: The different tYpeš of Hetworka ate physically sepadrata The Move Towatti lntegtatlon nj ze bi ta te ME f ra: KJE A ah A s MA ] dari 14 uji, bution to the economic and Zeta NEK ; sine f a country and its pe pni neo mputer is a relative y. m a piiča, we have become on computers v" gone ithout them woU RE EEA. pe Fuiše economic prospetii peli ly depends upon the continued p le plation is one of the world : et valuable traded commodities, and a | fective use of information meja se and communications technologies Le to improving effectivenesS and pr ke tivity across all sectors of industry : commerce. In order to ens ure kan country's investment in a digital JE iz structure is compatible with anotner S, | | ore FTE, ki | sd Pil niž J | | ra Z a V. si di: Xu - Pi ig k | i m; k kai I tudi [Ai , zaji, H 5 j $ G- ki k 1 x] il a 7 Ml! NA nea P AP 11H k i gt side (ip pav : Mi tih Pes k s h H it ha Moe j s 1 Ev Ha | nee bob sa fa < 41 | 4 iti AM pode kai kih | HE. ii] ah o F4 | | l na I 4 hi gu? La diši 4 " 1 1 d I MM MSEBIE viii m Ada " | P laš 8 gi. f' | k 4 ed A J - ZA. iza | ka | ' BE Hi | d i fi ja f ; dli lj K | ni ai k a | ME: ] H | a ap nes v di pi . ž peso, a 7 : X S a f | I ki 4 l ij sd: 4 fi | b ii [Jeri k | | i u dl | H M4 PU i šad ' i i A digital network lays the foundation for creating an integrated network capable of o | ing and maintaining large analog net: works is becoming prohibitive. The older type of mechanical switching systems have many moving parts, are unreliable and reguire a large number of trained engineers to maintain them. Modern dig- ital switching systems are inherently much more reliable as many of the old moving parts have been replaced with microprocessor-controlled circuitry, . Expandable Infrastructures - A major economic factor governing ture. A communications net. taroduction of ISDN relates to in... yet been resolved, One of the mest ja the application of common, internation- ally agreed-upon network standards js critical, The creation of and adherence to standards for digital networks by all countries is vital. Tariffs Because both voice and data will be transmitted over the same ISDN net. - Work, the network operator will have no means of distinguishing between the - two types of traffic. This raises a num. ber of potential problems that have not portant is the guestion of tariffs for — ISDN. An ordinary circuit-switched — Volce call is charged on the basis of con. Data calis over rk are char ged nect time and distance. d the "vet.switched netwo! a pa rar of connect LEA an olume of da transmi žre oči x in most case$, it iS more ae naavover send data over a VOICE ak mk: acket-switched data netwo!r pobi z zi k operator have to see d ns k Ne large investment in ISDN s lbeči vices are tariffed is erucial to the de? opment of ISDN. Transition to ISDN A number of major ISDN issues are tand: for broadband unresolved standar traffic that oper: ISDN, circuits lo kan 64K bps, and ate at a speeds less than 9" IN net: the operation of international ISDN ne works, for example. Many of zlet ste 3 sues will be clarified following ti A operator experience, user a a and additional standards recommenici" tions from CCITT, the international standards-making body. ME During the initial stages of ISDN im- plementation, access to varl0us ISDN circuit- and packet-switched services will be via a single network interface. At this stage, individual traffic types will still be switched separately, as illus- trated. Progress toward the integration of both switching and transmission facil- ities is not generally expected until the mid-1990s with the integration of high- speed circuits and the completion of the transition to digital packet-switched networks. Throughout the development of ISDN, the level of services, facilities and de- gree of network integration will depend upon the individual PTT or network op- erator. The speed at which each opera- tor develops his or her network will de- pend upon many factors, not the least of which will be financial/investment considerations, guality of an existing plant, as well as user demand and the willingness to pilot new services. Depending on the individual network operator, ISDN will develop at different speeds and provide different levels of sophistication. In North America, it is | likely that operating companies will de- velop ISDN at; different speeds and with different priorities. How and in what way this development, takes place will be due in no small part to the pressure exerted on the local operator by the business Community. It is the business Community that potentially will benefit most during the early stages of ISDN: therefore, it, is up to it to ensure that the network operator makes the right planning and implementation decisions based on present and anticipated corpo- rate telecommunications reguirements Next. week, we will look at, broadband ISDN channels that operate on Very high-capacity optical-fiber circuits. S The James Martin Productivit le an information service ANA INO terly, is avatlable through High Pro- ductivity Software Ine., of Marble- head, Mass. ( 800) 2942-1240. For infor- matton. on seminars, please contact (in ihe United States and Canada) Tech- nology Transfer Institute, 741 10th St., Santa Monica, Calif. 90402 (213) 394. 8305. In Europe, contact Savant, 2 New St., Carnforth, Lancs., LA5 9BX United Kingdom (0524) 734 505.