Telecommunications Research in the United States and Selected Foreign Countries: a Preliminary Survey. Report to the National Science Foundation (1973) / Chapter Skim
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SWITCHING, ROUTING AND CONTROL
SWITCHING, ROUTING AND CONTROL
Pages 152-199
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From page 152... ...
Ubiquitous telephone networks were attractive resources for providing data communications services throughout the United States and the rest of the world. The voice network, however, was designed for the transmission of continuously changing "analog" waveforms spanning a frequency range from about 200 to 3000 hz.
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From page 153... ...
Specialized data processing services were also established along industry lines, for example, airline reservations, hotel reservations, stock quotations, credit card checking, bank operations, and many others. These all make use of the public telephone network to link thousands of terminals to central computerized data bases which can be examined and updated appropriately for each transaction.
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From page 154... ...
The Bell System is supporting substantial R&D with the objectives of improving performance and lowering costs of data communications services. A significant commercial step was taken in November l972 with the filing of tariffs for a digital data service, an all-digital private line data network that is expected to serve 96 major cities by l976.
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From page 155... ...
They have long been strong advocates of packet switching and digital transmission for data applications. In Canada a limited data network is already in operation.
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From page 156... ...
End-to-end digital transmission becomes desirable to reduce error rates, to obtain rapid switching and to make full use of available transmission bandwidths. Demand multiplexing and packet switching must be thoroughly evaluated as alternatives to present techniques involving line switching and synchronous time division multiplexing.
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From page 157... ...
Special attention must be paid to standards at all levels. New national data networks should be mutually compatible.
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From page 158... ...
In a primitive version one would just enter a move statement. For instance if Phil Dauber was transferred from San Jose to Yorktown Heights, a move statement would cause the appropriate payroll records to be copied from the San Jose file to the Yorktown Heights file.
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From page 159... ...
S Dauber IBM Corporation Yorktown Heights, N.Y.
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From page 160... ...
Besides serving as the vehicle for the development and exploitation of multi-computer resource sharing, it has demonstrated the effectiveness and economy of an important new form of communications technology, packetswitched communications. Within the next five years, the extension of packet communication concepts into the areas of radio and satellite communication should revolutionize as well the effectiveness and economy of both local and international data communications.
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From page 161... ...
The TIP permitted a whole new class of network use, i.e., a group or centers on the network could now look to the network for all its computation requirements instead of operating a local computer service. This strategy for obtaining the optimum mix and balance of computer capability from large, costeffective computer centers without the many problems associated with running a local center has been so successful that about half the network nodes are now of this type.
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From page 162... ...
IV. Network Traffic Figure l shows the internode network traffic over the first l4 months of user access.
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From page 163... ...
l63 10M r ARPA NETWORK TRAFFIC (INTERNODE) Sept 1971 -Oct 1972 CURRENT NETWORK CAPACITY 1 M 100K Growth Rate = 26%/Month or X 10 per 10 Months I _L JUL 1971 JAN 1972 JUL 1972 JAN 1973 JUL 1973 Figure l
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From page 164... ...
V Cost-Effectiveness In order to fully support computer resource sharing reliably and responsively on a nationwide basis, the communications network must be approximately the size and cost of the current ARPANET (34 nodes and $2 million/yr)
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From page 165... ...
165 I? i° 5 # 83 100 80 60 40 20 10 8 COST-EFFECTIVENESS OF NATIONWIDE NETWORKS I I I I I 8 10 20 40 60 80 100 TOTAL ANNUAL VALUE OF COMPUTER RESOURCES SHARED VIA NETWORK (In Millions)
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From page 166... ...
This review included contacts with overseas associates, and reviews of overseas publications, the minutes of the United States Independent Telephone Association Manufacturers SubCommittee, and papers presented at the International Switching Symposium in Boston and the International Conference on Communications in Philadelphia, both in June l972. In summarizing the results of this review, the remainder of this document will provide suggestions for further research, review the funding of research in telecommunications and switching overseas and in the United States, and review the relative positions overseas and in this country in five main sectors: public telephone switching; private telephone switching (common carrier and interconnect)
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From page 167... ...
This is in effect a natural outcome of the organization of telecommunications overseas where Government departments, or corporations with total or partial Government ownership operate the telecommunications services. Research leading to products covering all principal sectors of the telecommunications switching market are included in these countries' programs.
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From page 168... ...
S Switching Research Funding Switching research in this country is significantly funded by the Bell Telephone System for public and private telephone switching and for data switching.
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From page 169... ...
While there will be some fallout from the substantial work in support of the computer area, which will have an application in communications switching, by and large, these NSF programs are unlikely to have more than limited effect on communications switching. In the industrial sector, funding by the computer manufacturers of work on message switching is a natural adjunct of the primary computer business and seems likely to maintain a leading U.S.
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From page 170... ...
Some ten other countries will get such exchanges within the next three years. However, the research work of BTL leading to the Electronic Switching System #4 appears to be substantially ahead of any published information on analogous Time Division Switching Systems in Japan, United Kingdom, France (8)
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From page 171... ...
have recently introduced their second generation stored program control electronic switching system (SP-l)
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From page 172... ...
industry capable of exporting products and technology (l4) In addition, the character of the private telephone switching market is in the process of change as a consequence of the decision of the FCC to open this field to competition through allowing interconnection of customer owned or leased equipment to the public telephone network under certain conditions.
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From page 173... ...
For the purposes of this review the term "message switching" is applied to the former services and the term "packet switching" to the latter in accordance with present usage by ARPA and the CCITT. The term "message switching" is often also called store and forward switching.
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From page 174... ...
It can be anticipated that this speed of service will spread to the North American markets as a minimum to service requirements of international companies. Traditionally telex switching has been a direct circuit type of switching and has been derived from public telephone exchange designs for the reasons discussed above under Private Telephone Switching.
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From page 175... ...
This latter point results from the cost of direct circuit switching being affected in only a minor way by an increase in transmission speed, whereas cost of the packet switch's processor and memory increase in direct proportion to bit rate. Packet switching is a natural derivative of message switching in that the equivalent of circuit switching is obtained by providing sufficient throughput capacity achieved by fast links and short message units (packets)
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From page 176... ...
Thus, to the U.S. domestic record carrier, the three international record carriers, and the one data oriented miscellaneous common carrier, the choice is currently left to looking for foreign products, or of themselves financing a U.S.
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From page 177... ...
manufacturers would operate on a comparable basis with foreign suppliers when bidding on the future requirements of the record carriers. Most of the research necessary to support data switching is of a type analogous to that supporting the computer industry.
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From page 178... ...
balance of payments of reducing imports and fostering exports. It should be emphasized that in the limited time allowed for this study, only a superficial look could be taken at the area of telecommunications switching.
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From page 179... ...
E Pinet "Introduction of Integrated PCM Switching in the French Telecommunication Network", International Switching Symposium, l972, Boston, June l972, Conference Record, IEEE Catalog No.
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From page 180... ...
R Reynier, "Electronic Switching Network of the IBM 2750", IBM J
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From page 181... ...
funding. An overriding consideration of rail transportation is safety, both for reasons of preservation of human life and for the high cost of a failure in potential damage to property.
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From page 182... ...
In recent years gross investment in rail transportation has been low as the high technology fields of air and space have preoccupied governments, as the poor financial condition of the U.S. railroads and metropolitan subways has kept down the incentive to invest, and as the high tax revenues derived from vehicles and the petroleum products they use have tended to be plowed back into roads, thus worsening the competitive position of the railroads and their capability to invest.
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From page 183... ...
B Command and Control for Two Dimensional Route Structures j The advent of "People Movers" strengthens the need for traffic flow research into effective sharing of common route sections under criteria of human dissatisfaction with delays substantially different from normal telecommunications traffic.
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From page 184... ...
High Speed Interurban Systems Modern rail transport systems employing heavy trains with substantial headways at speeds up to 200 km/hour (l20 MPH) over linear route structures comprising arrays of loosely interacting lines with infrequent intersections.
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From page 185... ...
* over linear route structures comprising arrays of loosely interacting lines." (8-Cat.I)
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From page 186... ...
systems over essentially linear routes. In common with other linear route systems, technology is required for longitudinal control, automatic protection, and automatic operation.
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From page 187... ...
Its automatic operation is carried out by a number of integrated sub-systems (designed by Westinghouse Electric, except where noted) : - An automatic vehicle control system in each car provides the functions of decoding the speed command sent from the wayside, automatically maintaining speed at the level set by the central computer, protecting against over speed, braking, generating identification signals, and stopping at the midpoint of each station platform.
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From page 188... ...
- Despite the complexity of the computer center, it optimizes four linear routes separately and does not attempt to manage the entire system from a traffic flow aspect under major disruption of schedules. Enumeration of the points immediately above is not a criticism of the B.A.R.T.
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From page 189... ...
2. West Germany In categories D (Personal Rapid Transit)
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From page 190... ...
It should be noted that the approach in West Germany is for indirect computer control through existing signal towers. It has not yet been determined whether direct computer control of signals without local interlocking equipments is possible with safety, or if it is economical.
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From page 191... ...
systems and D (Personal Rapid Transit) systems a slow speed (30km/hour monorail has been proposed for Tokyo (32)
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From page 192... ...
handling secure telegrams over 2400 baud data links, and providing l6,000 indications and 6,000 controls. This remote indication and control system provides a function analogous to the digital transmission system in B.A.R.T.
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From page 193... ...
This is wired-logic technology applied to a transposed inductive loop as described above for West Germany.
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From page 194... ...
IV. Comparative Assessment of Research Work The research overseas on command and control of rail transportation appears most advanced in West Germany and Japan.
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From page 195... ...
195 aggressive efforts in speeding up service in Category A and the design of command and control systems potentially applicable to both Category A and B use in those countries, No comparative statistics were obtained on systems in Categories C (Urban Distribution) system and D (Personal Rapid Transit)
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From page 196... ...
U.K. France West Germany Japan Indirectly Computer Controlled Systems in use or trial X XXX Maximum Speed (km/hour)
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From page 197... ...
G Lentz, "The Automatic Train Control System for High Speed Trains in use on The Deutsche Bundesbahn", Technical Meeting of the IEE,.December l5, l966.
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From page 198... ...
W Birkby, "Developments in Train Control on British Railways", paper presented in London, October l3, l97l.
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From page 199... ...
38. "Not-So-Rapid Transit", Wall Street Journal, Nov.
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