Greater Challenges in U.S. Required More Than a Single Digital Network Approach.
Worldwide, the international standards body, the International Telegraph and Telephone Consultative Committee (CCITT), has undertaken a standardization program for worldwide agreement on a unified network approach...an Integrated Services Digital Network (ISDN)...A single network to handle voice and data equally effectively while providing sophisticated services and features demanded by the business world. The US is supporting the efforts. Last August, for example, the FCC initiated Docket 83-841 to explore the major issues.
But perhaps what will work in other countries won't work as well in the US. At least that's the view presented in a two-hour, 15-projector, sound-synchronized program put on by ITT Telecom in a special opening session at USTA's Kansas City Showcase. Basically, ITT sees a need for USDN-- US Digital Networks (note the plural on the last word). According to ITT Telecom, competitive pressures, deregulation and market-driven technological advances make a conventional ISDN impractical in the US, noting that, whereas the ISDN concept promotes integrated services on a single network, USDN--ACKNOWLEDGING the dramatically different telecommunications environment of the US--IMPLIES integrated access to multiple networks and services.
After opening remarks by John Guilfoyle, president of ITT Telecommunications, details of the concept and its rationale were presented by ITT executives, portions of which are excerpted in the following sections.
Henry Macchio, vice president and director of product marketing, ITT Telecom Network Systems Division: The objectives of the international and US telecommunications communities are similar--the creation of a multi-function information transport capability needed to address the rapidly growing demands for voice, data and video transport. However, what is becoming increasingly clear is that the implementation of a US ISDN is taking several intermediate near-term steps towards the realization of this capability. These near-term steps will give the US ISDN a somewhat different personality than its international counterpart.
In the September 1983 Monterey Conference on Integrated Services Digital Networks, the US users were heard from, in force, for the first time. The needs of these users differ considerably from the ISDN planning of the CCITT and related standards groups. While the CCITT and others are planning as ISDN by defining standards and protocols necessary for the ultimate definition and evolution of this network, little attention is being paid to the near-term service needs of the end users. The business users in the United States, on the other hand, are more concerned with near-term service provision. They are not necessarily willing to wait for complete standards definitions prior to implementing multi-function voice and data transport networks.
There are several market-pull, technology-push network environmental forces at work today that differ significantly between the US and international marketplaces. Consequently, a different approach to implementing a multifunction information transport network is not surprising. What is surprising is the speed at which these forces aer shaping the US network and affecting the planning, service and application dynamics of that network.
There are major differences between the US and international telecommunications markets. Sizes, distances and geography are quite different. Since capital investment tends to be related, perhaps non-linearly, to the geographic area covered, the size differences alone cause major differences in the in-place investment required to service a mostly-analog plant.
The US regulatory environment has encouraged competition and many competitor networks are now in place or planned for imminent service. In contrast, telecommunications in most European markets is a nationalized industry.
We have no single group governing the standards in the US network. Although many of the Bell System and USTA documents serve as de facto standards, they are not necessarily enforceable.
One result is that the US market ends up being largely market-driven. When the customer cannot satisfy his requirement through public service offering, he is able to set up his own private service. The only impediment to private service has been an economic impediment--that is, communication volume had to be sufficiently large to justify a private network.
With the divestiture of the Bell System operating companies by AT&T and the impact of Computer Inquiry II, the environment is changing so that the small businessman can have access to sophisticated communication services--once the sole province of the large user.
The most important network trend shaping the evolution of the US digital network is the growth of data traffic. Data communications is expanding at a rate of 25 to 35 percent per year.
For the foreseeable future, this growth rate is expected to continue, such that, by 1990, the bandwidth dedicated to data communication will be approximately 10 percent of the total long distance bandwidth.
Voice service will also continue to grow. However, the comparative saturation of the local telephone market in the United States will not permit dramatic growth. On the other hand, growth in special services--such as WATS lines, foreign exchange lines, business services and Centrex services--is fueled by the continual penetration of PABX and office communication products into the business marketplace. Special services will achieve a 10 to 15 percent per year compounded growth.
The important factor of USDN is that these special service facilities presently require special handling and conditioning by the telephone companies. By 1990, it is expected that over 50 percent of the bandwidth allocated to circuits leaving local wire centers will typcially use some kind of special service.
The downward trend in the cost of bandwidth experienced over the past 20 years in the United States continues--now fueled by low-cost single-mode fiber optics. In addition to decreasing the cost of long distance bandwidth, we can expect to see the inherent bandwidth of the copper loop plant enhanced by fiber loop additions--making local bandwidths available at lower and lower costs.
The market forces--particularly the competitive and regulatory forces at work now in the United States--will stimulate a multiplicity of specialized service networks. The challenge will be one of integrating a number of these specialized networks into an integrated services network.
This then is the key issue of the US digital networks; namely, the requirement to bring together the many complementary specialized networks that are now in existence, in order to provide integrated services. USDN means integrated access to multiple networks and services rather than integrated services on a single digital network.
Lee Thomas, vice president of BOC Customer Systems Engineering, ITT Telecom Network Systems Division: The key technologies in the information age are microelectronics, fiber optics, digital techniques, advanced packaging, software and control structures and, last but not least, human factors.
The new system technologies can be applied in two ways: a replacement of existing plant with the new integrated system to provide revenue enhancement and bypass protection, or using the flexibility of deployment made possible by the new technology to augment existing plant for new services, with ultimate capping and replacement occurring as business factors dictate. One is where these information systems are having the highest revolutionary impact is the capabilities provided to networks by digital switching technologies.
Traditional switching can be grouped into four generations--the first generation being electromechanical: the second generation stored-program analog telephone siwtching; the third generation central control store-program digital switching; and the fourth generation distributed control digital switching.
I believe all manufacturers are striving to reach a fourth generation of digital switch gear, characterized by complete decentralization of the control and consequent decoupling of the feature content from the traffic capacity. This will enable the free addition of major features such as Centrex, or Common-Channel Signaling without depletion of the switch capacity. It will also enable connections to be switched equally for milliseconds in a packet-like connection or for hours or days in a semi-permanent-type connection without affecting the traffic-handling capacity of the switching system.
Two inventions are necessary in my view to reach a true four-generation switching system. These are a new digital switching network approach, different from the conventional time/space/time, and a control structure, which allows for the decoupling I just mentioned.
These are the characteristics required of the digital switching network. It is extremely important that the network contains all of the intelligence for the network functions integral to itself, thereby placing no demands on any external control mechanisms--even for diagnostics and maintenance. Such as netowrk must be transparent to all types of traffic, from very short holding times to very long holding times...both voice and data, including multiple quantums of digital bandwidth built up to serve fullmotion video. The network should be substantially non-blocking, once again increasing the decoupling between different services.
Allan Gerard, vice president of product marketing, ITT Telecom Business & Consumer Communications Division: Business demands for information are insatiable and information delivery via electronic means is expanding.
The most significant growth in information demand is in the so-called public information area. From law to medicine, finance to news, marketing to politics, retrieval of public subscription, or peruse information is now increasingly availab.e But private or proprietary information is also growing.
Underlying both of these growths is the increasing data communications necessary to satisfy this demand.
Information media is changing dramatically because of technology-based improvements in cost performance. Voice use will grow over the next two decades, with much of this growth in the messaging area and in the voice input/output to systems. Paper will remain strong, but will decline slowly in favor of electronic delivery of information.
Users are demanding bandwidth and, even more, demanding simultaneous voice and data capability, not alternate transmission. This message was made clear at the 1983 Monterey ISDN- USDN Conference, with the rapid proliferation of voice-prompted transactions in banking, retail, manufacturing and insurance. Meeting this bandwidth challenge will be a necessity for both the network and the PABX.
The net effect to our customer is that they are faced with the big bills in transitioning to the future. The issue is how to push forward to these newer capabilities given a large investment in incompatible equipment, software and, most significant, people.
Generically simple solutions to such a complex issue are not believable. There are no revolutionary answers. What is required is careful step-by-step evolutionary solutions which need to be tested in the crucible of the marketplace.
Let us now step back to the network opportunities by recapping the needs of major business customers. They are: simultaneous voice and data transmission; a better match between business systems and network service capabilities; improved price performance of communications via the network; and greater customer control over the network.
Let us pick up on the idea of local CCIS (Common-Channel Inter-Office Signaling)...local all the way down to the PABX. The network topology extended to the local level, say via CCITT7 signaling, can provide the PABX and network with a new source of information and the possibility for new and improved features.
These possibilities include improved telemarketing services, personalized service for business, lower-cost point of sales, point of transaction credit checking, lower-cost DID, improved customer network control and routing, including look-ahead signaling and dynamic bandwidth control and, finally, improved value-added network and information service access.
I'm positive that many more applications exist for local common-channel signaling, but more thought and experimentation will be required.
Communications to the PABX will be improving in the next decade. We will be rapidly moving beyond the traditional use of twisted-pair to the use of T-carrier DS-1 and, in the future, a light-pipe bulk facility at 45 megabits per second and beyond.
If we applique USDN onto the twisted-pair that already exists, then we can expand communications and improve costs and derive a multitude of additional services. These include low-cost, low-speed data, telemetry and the CCIS packet, value-added network and information-provider access.
To close, remember that fourth-generation architecture allows us the flexibility and freedom to move gracefully to the future, through enhancement versus replacement and USDN provides a vehicle for exploring between us new services and capabilities, both in a technical and market sense.
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|Author:||Macchio, H.; Thomas, L.; Gerard, A.|
|Date:||Mar 1, 1984|
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