The Intelligent Network the Intelligent Choice

Telenet

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The Telenet® Public Packet-Switched Network

We thought it was time for Telenet is technological What sets Telenet apart communicationsflexibility, data communications to innovation and excellence, from other data communi reliability, and economy. keep pace with data a nationwide data com- cations services? First, Telenet service is fur- processing. munications network, a it's a complete backbone nished on a common carrier dynamic company. The network, already in place, basis, cancellable at any Time to provide a superior technology is called with the unique ability to time on 30 days' notice. alternative to dedicated packet switching. The establish instant connec- You pay for service only networks and the delays network —"the Telenet" — tions between computers as you use it, at low dis- and high costs associated is in operationfrom coast and diverseterminals, tance-independent rates. with their design, instal- to coast. The company, With it you get a complete lation, and operation. A Telenet Communications network management team This is onlythe beginning superior alternative which Corporation, is an FCC- to install and maintain of the story of Telenet, the eliminates problems of regulated common carrier equipment,tailor the intelligent network. More outages, inflexibility, and organization with deep service to your requirrequire- and more users are calling underutilization. roots and many strengths. ments, monitor operations it the intelligent choice in and provide you with data communications. The So we developeda better traffic and accounting following pages will tell way. The Telenet® way. statistics. you why. Tte Oo^tll^Ml ifcfffc points. Long-haul capacity Freedom from errors. MS ww unique characteristics is assignedto the virtual Powerful error detection ""*« ** tech rtf thfi T^lAnAt built into the Telenet connection and the cus- and retransmission which benefit all users, tomer is charged only niques keep the error rate in 10 _ , . , , irrespective of their ap- when data is actually being down around one Telenet is a highly one in 01 2 bits between' ' The licaVlons . transferred. You do not to 1 interconnected network haveto pay for or be nodes. This is one million of programmable switching connections Cus- concerned with idle line rimes betterthan many called Telenet . centers (also tQmer terminals and host time. other available data Offices) and high- Central computerg CO mmumcate communications services. speed digitaltransmission through virtual connec . Adaptive routing. There .. . all constantly „ - Rapid lines t transparent com. are no predefinedroutes transmission/re- by Network speed at monitored our mumcatlons channels between nodes in the ception. The Control Center. with aU the attributes of Telenet . Instead, the whichyour data travels , . dedicated links except routing is selected dynam- depends solelyon your unique network is . andyour This h h cogt and Iqw perform ically by computers in the requirements not on trans- based on packet-switching ance V]rtual connectlons switchingcenters, as each equipment, technology, an advanced may be establishedby the packet of data passes mission bandwidth or but thoroughly proven terminal user or host corn- through the node. The direction. Any network negligible means of achieving effi- puter whenever required, route can be instantly transit delay is cient termmal-to-computer, m may be get up perma . changed duringtransmis- andtransparent to the computer-to-computer, nently between two sion to adaptto traffic user. andterminal-to-termmal loading or bypass con- communication. The gested or failed links Highreliability. Telenet's Telenet is daily demon- without your awareness. extensive use of self- strating itsreliability, performance, and economy.

irm more money it costs. By contrast, Telenet charges for data actually transmitted, independent of distance. The rates are low. We invite your comparison.

Single-source network management responsibility. Telenet furnishes a complete end-to-end network service, taking full responsibility for all network components— no longer the problem of dividedresponsibilities and "finger pointing" among vendors of circuits, modems, multiplexers, concentrators, software, etc. Experienced network management personnel install, operate, and maintain allfacilities, optimizing access lines and tailoring software parameters to meet your traffic and application requirements. Ask any Telenet user how important this is.

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The Telenet isnationwide . . . and l steadily towardcompletion of the 60-city network shown here. Why aren't the switching center locati joined by lines? Because there would be more lines than map, and because it would suggest that there isa "right" way for your data totravel. In fact, data is routed fromCity A to CityB not along a predetermined link but via dynamic, adaptive routing . . . by-passing congested or failed links . . . going thefastest wa in the blink of an eye. o I \f:^j fn (^ ®o©d Ronofitc install several separate Many organizations have ting back-up processors at data communication found Telenet a practical each computation center. fyf UsinQ systems, each oriented and desirable alternative towardtnw^rrl a HiHorontdifferent an.ap- to private nets . . . here You have greater flex- the T&lenet P"cation- administra- are some of thereasons ibility in your choice of ■■ ■ tive message switching, why. terminals . . . you can data in quiry/ select the optimumter- Let's take a look at some entry' typical data response, interactive You can implement new minal for each ofyour communica- locations. tions applications areas and time sharin9- re mote Job teleprocessing applica- entry and so on. Fre- see why Telenet has be- tions quickly and easily, You ter- uentl these networks, can reduce come the intelligent choice

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One of the largest severe strain on its own and eventually established A leading commercial corporations in the U.S. facilities. Telenet carries sales offices in several bank operated various compared the cost and time the overload and provides of these cities. computer systems at its required to developits areliable back-up facility. headquarters location. A leadingpublishing own concentrator net- In order to make partic- An Ivy League college concern with a unique data work and opted to use ular computer known for its exceptional programs Telenet instead as the base offered users access to and data computing capabilities base availableto backbone network for a the data if the users correspondent banks, new in-house sharing wanted to share itsre- furnished their own com- time sources with other academ- the firm electedto use system. munication facilities. Telenet's ic without nationwide institutions The high costs of toll tele- facilities. An international the problems of building phone calls and point-to- engineeringfirm operates and managing a communi- point leased lines pre- An industry associa- interactive and remote cations network. Now vented manyinterested tion had for manyyears batch computers at scholars and researchers parties from using the serv- sought to establish a several locations in the in all parts of the country ice. After connecting the data exchange among the U.S. for text editing of have economical access to host system to Telenet, computer facilities of its client proposals and re- its unique instructional communications cost was members. With Telenet's ports, andfor engineering computer programs no longer a barrier to the assistance, a pilot program analysis and design. through Telenet. successful marketing of wasinitiated with several Access to these systems the service. association members. Im- The dataprocessing was limitedto only a few portant, tangible benefits of the firm's office loca- subsidiary of a major life A leading manufac- have already been realized tions until it began using insurance company wished tunng concern developed Telenet. to offer various computer- a family of computer pro- based services to its in- grams, resident on the A regional computer dependentagents, but was firm's largest computer, to service in the West wanted unableto predict the num- be used by its sales to be cost-competitive in ber or locations of ter- engineers in customer ap- the East, South, andMid- minals, or the traffic from plications. The firm found west as well. With Telenet each. Through Telenet it that customers wished to it is effectively selling was possible to make the use the programs directly services nationwide. service availableto all and that such use would the agents who wished to boost sales as well as re- A minicomputer man- participate. duce selling expenses. ufacturer in New Eng- Telenet was chosen as the land introduceda multi- A small firm in the Mid- means of providing the user interactive system. west developeda minicomputer-based customers with access to By connecting the hard- account- theseprograms. ware/software system at ing service, initially the factory to Telenet, the limiting its marketing to A major aerospace firm's field salespeople the local area. Through company with extensive were able to demonstrate Telenet the firm was able computationalfacilities the system from terminals to test market the service decided to market the use at customer sites. in several other major of its computers and pro- cities without any invest- grams nationwide. An information retrieval ment in communications, service with a nationwide Through Telenet it was private network couldn't able to offer immediate accommodate additional national access to its subscribers without a customers. (address) The terminal is still actively Explanation of Network Messages STILL connected to this address. CONNECTED You must disconnect before How to Use @ A Telenet prompt character initiating another connec- y*l.^.»%.^#The Public indicating that the network tion Wl^^l i^?liPacket-Switched is waiting for a command (address) The terminal has a request Network for Data Communications TERMINAL= Request for user to enter STILL f°r connection to this ad- terminal model identifier PENDING dress pending. You must disconnect before initiating In response to CONNECT command: another connection. Information (address) The connection between SUBPROCESS The specific process In- CONNECTED vour terminal and the com- eluded as part of address puter has been UNAVAIL- for established is not Terminal adic available successfully (address) AH computer ports are in Inresponse to CONTINUE command: Users BUSY use NOT CON- No suspended connection NECTED exists and the command is (address) The computer system is re- ignored DOES NOT fusing the connection be- SUPPORT cause of the terminal model TERMINAL or mode ILLEGAL The computer system ad- ADDRESS dress is invalid because it identifies a non-existent system H Telenet Communications ILLEGAL Connection to this address Corporation DESTINA- is not permitted TION Corporate Headquarters ADDRESS 1050 17th Street, NW ILLEGAL The computer system will Washington, DC 20036 SOURCE not communicate because ADDRESS of the terminal's address Telephone: 202/637-7900 (address) NOT The computer system Is Regional Sales Offices: AVAILABLE operating but is actively refusing to permit the ter- New England minal to connect Boston, MA 617/899-4478 (address) NOT No connection can be made New York-New Jersey-Penn OPERATING because the computer sys- New York, NY 212/594-6644 tem is not operating Central-Southeast (address) NOT The computer system can- Washington, DC 202/637-7900 REACHABLE not be reached because in- tervening components are Southwest-Southern California out of service Los Angeles, CA 213/477-2048 (address) NOT The computer system is Northwest-Northern California RESPOND- operating but not acknowl- Menlo Park, CA 415/854-5845 ING edging the terminal's request to connect Telenet Customer Service (address) The computer system is not Telephone: 202/347-2424 REFUSED willing to accept the charges COLLECT for the connection CONNEC- TION

/ TelenetSign-On Procedure Terminal Model Identifiers Network Commands

The instructions below explain how to connect to your computer through Telenet if you are Enter the identification for your terminal When you are talking to Telenet (in Tele- using an ASCII-type terminal. If you are using a selectric-based terminal (like the IBM 2741), model in response to network inquiry net "command mode"), you may use any or if you are accessing an APL service for either class of terminal, Steps 1 and 3 will be dif- TERMINAL = of the following network commands or ferent. See Notes. In the example: = your response. |CRl= carriage return. All other mes- Terminal Model Identifier their abbreviations (boxed): sages are automatically sent by Telenet.□ Anderson Jacobson 630 AJ63 Anderson Jacobson 841 Steps Example Notes Computer Devices CDI 1030 CD3O JCJONNECT a request for connection to Computer Transceiver Execuport 300 CT3O the computer address that 1. Turn on the terminal and coupler. (1) Selectric-based terminals: switch to Computer Transceiver Execuport 1200 CTI2 follows OFFLINE or LOCAL. 2200 Datapoint DP22 your Datapoint 3000 DP3O MDjISCONNECT to disconnect from 2. Dial local Telenet number. (2) Telenet will have local dial-in service computer system in more than 60 cities in the coming Datapoint 3300 DP33 DECwriter DECW CR @ CR to interrupt your computer months. For a current list, contact Data your computer service or any Tele- 100 73 DT73 conversation and return to office. General Electric TermiNet 30 TN3O Telenet command mode net General Electric TermiNet 120 TNI2 3. Send two carriage returns. fCRIfCR (3) Step three identifies the speed and General Electric TermiNet 300 GE3O Cl|Ol| NllTl INUE to return to your computer code at which your terminal is ope- General Electric TermiNet 1200 GEI2 conversation after you have rating. The appropriate speed/code Hazeltine 2000 HZ2O been in Telenet command IBM 2740/2741 EBCD (with type:) detectors are: , , mode (a) ASCII terminals|CßJ[Cß|—- 963, 996, 998 IBMI ASCII/APL applicationTcßllTifCßl 938, 939, 961, 962, 997 IBM2 (b) Selectric-based terminals 942, 943 IBM3 HHSEE DUPLEX (first switch to REMOTE or 947, 948 IBM4 to stop the network from COMM)nfCRI IBM 2740/2741 Correspondence (with echoing keyboard input on Selectric/APL application[Tl|CR| type:) ASCII terminals 001, 005, 007, 008, 012, 202, 030, 4. Telenet will identify itself and ask TELENET (4) A list of Terminal Model Identifiers is 050, 053, 067, 070, 085 IBMS Firu L L DUPLEX you to identify your terminal. Type 202 DL 9 included in this folder. If it does not 006,010, 015, 019, 059, 090 IBM6 to echo keyboard input in the four character ID for contain ID for 021, on your an your terminal, just 025-029, 031-039, 060, 068, ASCII terminals a return, terminal, followed by carriage re- T-r--.».n.i a i r—ii—ii—ii—l l i enter a carriage return. inIn most cases 086, 123, 129-145, 156, 161 IBM7 turn. TERMINAL=UUUU|__P_JCR| this will work satisfactorily. Use ofof 043, 054 IBMB the four character ID, however, en- IBM 3767 sures the best performance for your IBM 5100 t terminal. Imlac PDS-1 IMLI Infoton Vista Standard IFVS 5. Type a C for "connect", skip a @[C~| QDD DD |CR| (5) The Telenet address for the com- Infoton Vistar Display IFVD space, and type the network ad- puter you wish to reach is available Memorex MRX 1240 MX4O dress of the computer, followed by from your computer service. Research Inc. Teleray 3300 R133 a carriage return. Tektronix 4010 TKIO Tektronix 4013 TKI3 6. Telenet will respond with a connec- (address) (6) If a connection cannot be made im- Tektronix 4023 message. TK23 tion You are now ready CONNECTED mediately, Telenet will print out an Teletype Model 33 TT33 to begin your conversation with the explanation. See list of Network Mes- Model 35 computer. sages. Teletype TT3S Teletype Model 37 TT37 7. To disconnect (7a) Three number groups may appear Teletype Model 38 TT3B Log off as usual. along with the disconnect message. Teletype Model 40 TT4O Teletype Telenet will in most cases send a (address) They indicate: connect time in min- Inktronics TTIN utes and seconds; packets received; Texas Instruments 725 T125 "DISCONNECTED" message, indi- DISCONNECTED Texas Instruments 733 cating that your computer connec- and packets sent. T133 tion through the network has been (7b) The disconnected message returns Texas Instruments 735 T135 terminated. you to Telenet. At this point you may Trendata 1000 t 500 UVSO Hang up to disconnect from Telenet. request a connection to another Univac DCT computer on the network without re- Video Systems 1200 VSI2 dialing. Video Systems 5000 VSSO (7c) If you did not automatically receive t same as IBM 2741 FOR TERMINALS WIRED DIRECTLY a disconnect message—and you wish to use another computer on the net- TO TELENET work—you After your terminal has been turned on, can disconnect from the begin with Step 5. first computer by entering: fgFH |g5) rcßi @ Qs] [CR] (address) DISCONNECTED Telenet Dial-In Access ed s,a,es Numbers Sl!ada

51 Telenet Communications Corporation Corporate Headquarters 1050 17th Street, NW Washington, DC 20036 Telephone: 202/637-7900 Regional Sales Offices: New England Boston, MA 617/899-4478 New York-New Jersey-Penn New York, NY 212/594-6644 Central-Southeast Washington, DC 202/637-7900 Southwest-Southern California Los Angeles, CA 213/477-2048 Northwest-Northern California Menlo Park, CA 415/854-5845 Telenet Customer Service Telephone: 202/347-2424 Effective July 1976 New York Telenet Dial-In Access Numbers Albany 518/445-9111 110-300 bps adaptive speed ports Buffalo 716/847-0600 Long Island 516/292-0320 Arizona New York 212/736-7205 Phoenix 602/257-1552 Rochester 716/454-3430 California White Plains 914/682-8777 Los Angeles Ohio Central & East 213/624-5230 Cincinnati 513/621-7017 West & Valley 213/822-9287 Cleveland 216/241-0940 South & Long Beach 213/549-5150 Columbus 614/463-1400 Orange County 714/558-6061 Oregon San Diego 714/231-1922 Portland 503/243-2800 San Francisco 415/362-6200 San Francisco Pennsylvania Peninsula 415/595-0360 Philadelphia 215/574-0620 San Jose 408/279-8450 Pittsburgh 412/765-2681 Colorado Texas Denver 303/623-0876 Dallas 214/748-0127 Houston 713/224-3380 Connecticut Hartford 203/522-0344 Utah New Haven/ Salt Lake City 801/364-2644 Bridgeport 203/789-0211 Washington Stamford 203/357-1800 Seattle 206/624-9780 District of Columbia Wisconsin Washington 202/347-1400 Milwaukee 414/271-2560 Florida Miami 305/374-6400 Canadian Georgia 404/577-8911 Montreal Atlanta 110 bps 514/878-9975 Illinois 134.5 bps 514/878-9977 Chicago 312/372-4901 300 bps 514/878-9971 Indiana Ottawa Indianapolis 317/635-9630 110 bps 613/563-9625 Louisiana 134.5 bps 613/563-9629 New Orleans 504/568-1840 300 bps 613/563-9639 Maryland Toronto Baltimore 301/962-5010 110 bps 416/361-1728 134.5 bps 416/361-1515 Massachusetts 300 bps 416/361-0011 Boston 617/338-1400 Michigan Detroit 313/961-5115 1200BPS Ports Minnesota Boston 617/338-7495 Minneapolis 612/339-0150 Chicago 312/726-1957 Missouri Dallas 214/748-6371 Kansas City 816/474-1600 Los Angeles 213/624-1521 St. Louis 314/231-8800 New York 212/736-1800 San Francisco 415/956-5777 New Jersey Washington, DC 202/347-6093 Newark 201/623-6818 Telenet AbstractofTariff Communications FCC No. 1 July 1976 Corporation

The charges for Telenet's public packet switched data earning the volume rate. See the reverse side for rate communications service include: classifications of Telenet Central Offices. Network Access Port Charges Traffic Charges Host computers are ordinarily connected to a leased Based on the volume of data transferred, independent channel port at a Telenet Central Office (TCO). Termi- of distance. nal users may access the network either through dial- Dedicated Access Lines in facilities or leased channel ports. On public dial-in Charges for access lines to Telenet Central Offices are ports the connection times of all users of a given host based on common carrier digital facilities where avail- computer system are totaled by TCO for purposes of able, or on analog facilities. I. Network Port Charges Hourly Charge/Per Month/Per TCO Public Dial-In Ports High Density Medium Density Low Density 10-300 bps Adaptive Speed Port $1.40 $2.40 $4.80 (Ist 1200 hrs.) (Ist 500 hrs.) (Ist 200 hrs.) .70 .70 .70 (for addtl. hrs.) (for addtl. hrs.) (for addtl. hrs.) 1200 bps $3.80 $4.80 $5.80 (Ist 300 hrs.) (Ist 600 hrs.) (Ist 600 hrs.) $1.40 $2.40 $2.40 (for addtl. hrs.) (for addtl. hrs.) (for addtl. hrs.) Installation Monthly Charge rivate Dial-In Ports Charge High Density Medium Density Low Density 110-300 bps fixed or ASP $200 $100 $135 $170 1200 bps 400 200 300 350 2000-2400 bps sync. 520 320 4800 bps sync. 600 400 Private Dial-Out/In Ports 10-300 bps fixed 400 200 235 270 200 bps 500 300 400 450 Leased Channel Ports 50-300 bps fixed or ASP 250 75 110 145 1200 bps 350 150 250 300 2400-56000 bps sync. 400 200 Multiple Connection 200 200 elenetAccess Controller Basic equipment 600 400 50-300 bps fixed or ASP 25 25 1200 bps ports 50 50 Located on customer premises Answer only modem for 110-300 bps ports 15 15 Option for mixture of speeds 100 30 Use of additional channel to TCO 400 200 Optional Port Features Each rotary list 50 20 20 20 Privacy List Ist station 25 5 5 5 Additional—stations 5 1 1 1 11. Traffic Charges 111. Canada to U.S. Service $.60 per kilopacket Public Dial-In Ports (110-300 bps) $3.25 per hour (1000 packets, each containing up to Traffic Charges $1.75 per kilopacket 128 characters of user data) Other pricing information for U.S.-Canadian service is available from your Telenet Representative. Telenet Central Offices Rate Classifications

L-D Phoenix M-D Minneapolis

Los Angeles L-D Kansas City H-D Central & East M-D St. Louis H-D West & Valley M-D South & Long Beach M.D Newark M-D Orange County M-D San Diego H-D San Francisco L-D Albany M-D San Francisco Peninsula L-D Buffalo M-D San Jose M Long Island New York Colorado _'° L D Rochester M-D Denver M.D White Plains

Connecticut c L-D Hartford I^.D Cincinnati L-D New Haven/Bridgeport m_d Cleveland L-D Stamford |__q Columbus District of Co H-D Washington |_.q Portland Florida M-D Miami H-D Philadelphia Georgia M-D Pittsburgh M-D Atlanta Texas Illinois H-D Dallas H-D Chicago M-D Houston Indiana L-D Indianapolis |_-D Salt Lake City Louisiana igt L-D New Orleans L-D Seattle Maryland M-D Baltimore M-D Milwaukee Massachusetts H-D Boston Canadian Central Offices Michigan Montreal Ottawa Toronto H-D Detroit 5E Telenet Communications Corporation 050 17th St., N.W. Washington, DC 20036 TELENET PUBLIC DIAL-IN PORT CHARGES $4 80

AVERAGE HOURLY RATE 40 70

40 70 $2 40

80 70 $1 40

CUSTOMER PORT HOURS/CITY / rj| iTr [l®@qgml mm

lovember 1976

/~\ CUSTOMER COMPUTER ( J TELENET CENTRAL OFFICE

' I The Telenet Report JL ® " Telenet Communications Corporation, 1050 17th St. , N.W. , Washington, D.C. 20036, (202) 637-7900 Volume 3, Number 2, September 1 976 Telenet Expands Service Internationally Talking to a computer overseas may are also available in Canada at monthly munications will range from $8.00 to cost as little as 15 to 25 cents a minute in charges of $200 to $1200 per port. $15.00 an hour. the not too distant future. Links between dependingupon transmission speed. This An application for authority to provide public packet networks like Telenet and charge includes access line facilities for overseas service was filed with the similar networks in other countries will for customers within Datapac serving areas, Federal Communications on May 4 and the first time make international data was strongly supported by many Telenet exchange economical for large and small subscribers. However, since Telenet's organizations alike. application has been opposed by the four Telenet has already taken the first IvEßrlI existing U.S. international record car- steps to extend service internationally in _ . _. riers, the FCC's review process is ex- Service between the United States and pected to be delayed by several months, partnership with communications entities in . . „. . . , .. . iU £, .7 begin in ' inter- ...... „. . _ Mexico will a the fall through Canada, Mexico and the United Kingdom. , , according to Philip M. Walker, Telenet connection with packet switching facili- Vice President and General Counsel. |Af ties operated by Teleinformatica de "The fact that Telenet is offering a I Mexico S.A. (TIMSA). TIMSA's initial fundamentally new service not presently Mexico City. By node will be located in provided by the U.S. international record 1977 the Mexican company plans to carriers and one that will bring enormous ■ extend its packet switched services to economies to data communications users In Canada Telenet will interconnect Guadalajara and Monterey in orderto pro- makes us very optimistic that our appli- with Datapac, the public packet network as well as ser- vide domestic international cation will be acted upon favorably," developed by Bell Canada and other yet vice Although a tariff has not been Walker said. member companies of the Trans-Canada fj| ed charges for interactive communica- Interconnecting its facilities with other Telephone System. Scheduled to go into j t ons are expected to range from $5.00 to use operation this year, public packet networks, Telenet will commercial later $10.00 an hour. X.25 interface approved for world- Datapac will initially link Toronto, Ottawa, the wm^^~ wide adoption last spring by Study Group and Calgary. Under an interim Montreal CCITT, arrangement, limited service is already VII of the the international stand- " ards-making organization. being provided in Montreal, Ottawa and Toronto for terminals and computer systems communicating through Telenet. The traffic charge for interactive com- United Kingdom New Tariff Lowers puter communications between coun- In the first commercial extension of tries, under tariffs recently filed by TCTS packet communications overseas, Tele- Volume User Rate and Telenet, will be $1 .75 per kilopacket. net plans to link its domestic network with (Typical usage for interactive terminals packet switching facilities in London Tariff rates have been filed for Tele- ranges from 0.4 to 1.2 kilopackets per operated bythe British Post Office, net's expanded 43-city network along hour.) Network access port charges in Traffic charges for this new overseas with a reduction in public dial-in charges the U.S. will be the same for domestic or service have been tentatively set at for large volume users. international service with public dial-in $10.00 per kilopacket. Added to normal Each Central Office has been classified facilities located in Canada charged at domestic access charges, the hourly rate as a high, medium or low-density service $3.25 per hour. Dedicated access ports for interactive terminal-computer com- point with corresponding access charges for 110-300 bps public ports of $1.40, Telenet Receives $4.8 Million in New $2.40 and $4.80 an hour. The charge at all Central Offices drops to a new low of Equity Financing $.70 an hour after a specified period of In July Telenet completed the third man Inc., founder of Telenet in 1972; usage each month. The volume rate phase of its financing program with a $4.8 Bessemer Securities Corporation, a lead- begins after 1200 hours (high-density), million private sale of common stock to a ing venture capital firm; Time, Inc., the 500 hours (medium-density) and 200 group of institutional investors. Bowne & diversified publishing firm; and Lehman hours (low-density). For purposes of com- the oldest and largest financial Brothers, Inc., Telenet's investment puting the volume rate, the connection printer in the United States, was the prin- banker. times of all users of a given computer cipal participant with a $2 million invest- Dr. Lawrence G. Roberts, President of system are totalled by city. ment. Telenet, said that the funds will be used Roger Goetz, Vice President for Also participating were four organiza- for expansion of network facilities and the Marketing, points out tnat Telenet's tions that have made previous invest- developmentof new data communication sliding rate structure makes the network (continued on page4) ments in Telenet : Bolt Beranek and New- services and servicefeatures. Telenet® and JE areregistered service marks ofTelenet Communications Corporation ©Copyright 1976*Telenet Communications Corporation The sales and systems engineering staff has been expanded in order to a A continue high level of service to both chance to access computer-based National Computer Network of Chicago present and prospective customers. resources throughout the U.S. attracted is proof that a commercial service firm Dick 4,000 Anderson, already well known to over visitors to a unique demon- doesn't have to unique software New stration of offer York customers in his role as Dis- packet networking at the " packages to attract a national clientele trict Manager, National Computer Sales now oversees sales Conference in New and it doesn't have to be big to afford a activities of the New York and New York in June. No one outside of Dartmouth probably knows national network. Sponsored more about the college's computer-based offer- Commodities futures traders are one of England Offices as recently-named by the NCC program com- A4O percent jump in sales is good NCN, of the companies ings than this young student who spent four ,he newest 9rOUDS able t0 obtain reliable one first to Regional Manager. mittee, the "hands on" demonstration days news for a commercial computer service working his way through the DTSS program '"formation on a low-cost, as-needed connect its computer facilitiesto Telenet, A recent addition to the New York was staged by Telenet with the aid of 16 library. provided it is prepared to handle a surge basically offers time basis because f Telenet access. The raw computer and office is Frank Vecchiarello, who is of the data base services, college com- A variety of other business and educa- of new business almost overnight. yet spread from Washington, service is c mmodity its users are responsible for sales in New Jersey and puting centers and commercial service tional applications were featured by Bolt Standard Information Systems of CDIS'° Information D.C. Data Service, operated by MJK to Phoenix and Miami as well as Pennsylvania. During ten-year Army firms that are connected to the network. Beranek and Newman, Bowne Time Shar- Wellesly, Mass., a medium-sized ° Asso- throughout a ciates Moun,ain V|ew, Calif, the midwest. career, Frank was involved in planning Visitors kept more than 50 data termi- ing, Computer Sharing Services, Data company with many Fortune 500 clients, ' One secret to NCN's is MJK Ass ciates has established a data market success and implementing military voice and data nals busy as they searched for medical Resources Inc.,. First Data, Grumman/ signed on to Telenet for justthat reason. pricing. $8.00 base Wlth n 33 major At a flat an hour with no communications in references in the extensive files of the CallData Systems, Interactive Sciences, The company had developed a highly ° corn- systems Vietnam and modlties going back as far as 1970. Cus- minimum and a volume discount on Europe. Prior to joining Telenet, he mar- National Library of Medicine, checked National Computer Network of Chicago, popular new product - the INFORM data ° accounts over $500 a month, the kind ,omers order out sPread histories, point it's keted international communications ser- their knowledge of programming in a sur- New Jersey Institute of Technology, base management system. Its English of service that fits many companies' and figure char,s movin averages, etc. vices and was New York District Manager vey offered by INSCO Systems, or System Development Corporation, Time language, non-technical format enables 9 needs. on command with' their terminals. "Most for Carterphone Communications. became acquainted with Scientific Time Sharing Resources and Dartmouth Time any user to operate the system without Originally customers," explains Michael Marriott, its user base was in the Neil Gottlieb, new Systems Analyst in Sharing's APL-Plus service. Sharing System, Inc. knowledge of conventional programming Illinois-Wisconsin-lndiana area MJK President, "have created their own where the the New York office, strengthens sys- techniques. A wide variety of other busi- company installed multiplexers. Pr°9rams s that they are able to test Soon tems engineering support services for ness and engineering applications had of its large trad n strategies before going the some corporate users wanted customers in that He also been adapted to the INFORM 9 ° into district. has a marketplace.' their branch offices in other parts of the degree in computer science from New language. New sales quickly followed. country use MJK utlllzes a Model 4000 computer to NCN's computers too. York Univeristy. "We are bootstrapping our rapid ex- Telenet, by Basic Timesharing, Inc. with its national coverage, In the northwest John re- pansion through Telenet rather than add- manufactured Peters has "e system u seemed to be the solution to keeping ing to our net- ed extended version placed Peggy Karp as head of systems existing 35-city multiplexer ? A long-distance communications to a mini- of BASIC " BASIC*t"X ~ which BTI ha engineering. (Peggy was promoted to work," says Mike Lowery, SlS's Director mum having prices. developed for use by non-professional* without to raise Manager of Customer Service at the Net- of Distributed Services. Public networking Programmers, has worked so well work Control Center in Washington.) John He views Telenet as a way of accom- in fact that NCN has Customers range from major national more than doubled has two degrees from Stanford a BS in modating new users in new cities and its Telenet ports in the eight — brokerage firms to individuals with termi- access past statistics and computer science and an coping with the peaks and valleys in months and has a third Honeywell " nals In tne,r nomes- com- MBA. Between academic programs he usage as well as providing a nationwide puter on order to handle the extra busi- served as line officer in the Navy where backup for their own system. ness. he helped develop and manage compu- terized message processing and satellite communications systems.

Peter Waal Heads Getting set for opening day are, left to right, Chuck Lizak of National Computer Network of Chicago; Telenet President LawrenceG. Roberts, Public dial-in service for terminals Frank Vecchiarello, demonstration coordinator, and Carolyn Morse, both of Telenet: Ron Knox of Com- considered the architect of packet at 1200 has been extended puter Sharing Services, Denver; and Tony Petritliano, Bowne Time Sharing, New York. operating bps Systems Development switching technology, is the 1976 recipi- to seven U.S. cities. Peter Waal joined Telenet in June as ent of the Harry Goode Memorial Award Originally offered in New York and Vice President of Systems Development. given by the American Federation of In- Washington, D.C, this higher speed ser- In this newly created position, he heads formation Processing Societies. vice is also now available in Boston, the engineering, network design and soft- Presented at the National Computer Chicago, Dallas, Los Angeles and San ware systems groups. Conference in June, the award recog- Francisco. Waal has had more than 18 years of nizes Dr. Roberts' contributions to the in- Access charges are $3.80 per hour for management and systems engineering formation processing sciences. He was the first 300 hours a month, dropping to experience in commercial computer and cited for "his contributions to the archi- $1 .40 for additional hours. The connec- communications projects. Most recently tectural design of computer communi- tion times of all users of a given remote he was Vice President of Technical Ser- cation systems, his leadership in creating computer system are totalled by city for vices and Director of Communications a fertile environment leading to advances purposes of earning the volume rate. Systems at Applied Data Research where in computer and satellite communica- Private dial-in ports and leased channel techniques, his role in the establish- Dr. Anthony Ralston, President of AFIPS, makes he was responsible for the development tions the Goode Award presentation to Dr. Lawrence ports for 1200 bps are available at fixed and management of its time sharing ment of international communication pro- Roberts of Telenet at the National Computer monthly rates in all Telenet Central in system and data communications tocols and procedures, and his accom- Conference New York. Offices. Contact your Telenet representa- network. ments in the development and demon- Award include computer designers tive for further informmtion. stration of packet switching technology Howard Aiken, J. P. Eckert, J.W. Mauchly

and the ensuing networks which grew out and Seymour Cray and / Bill Funderburk of System Development Corporation, at terminal, shows a group of visitors from Mexico programming how to use the SDC Search Service, one of the major bibliographic information retrieval services in the " of this work." language specialists Grace M. Hopper, country. Previous recipients of the Goode Edsger Dijkstra and Kenneth E. Iverson. 2 3 Telenet (continuedfrom page 1) Johnson, Timothy. "Projecting the future Dial-in Access Numbers roles of packet-switching networks" more economical for all classes of data 110-300bps adaptive speed ports communications users. DATA COMMUNICATIONS, July/August 1976. Albany, NY (518)445-9111 In cities where traffic volume is light, Atlanta, GA (404)577-8911 Telenet's public dial-in rates represent Roberts, L.G. "International interconnec- (301)962-5010 substantial savings for organizations that tion of public packet networks" 3rd Inter- Baltimore, MD WATS Boston, MA (617) 338-1400 might otherwise use service at an national Conference on Computer Com- (716)847-0600 average of $12 an hour. In cities where munications. Toronto, 1976. Buffalo, NY Chicago, IL (312) 372-4901 there are a large number of terminal Rybczynski, A., B. Wessler, R. Despres Cincinnati, OH (513)621-7017 users, the volume rate compares favor- and J. Wedlake. "A new communication Cleveland, (216) 241-0940 ably with the cost private multiplexer OH of or protocol for accessing data networks Columbus, OH (614) 463-1400 concentrator networks. — the international packet-mode interface" Dallas, TX (214) 748-0127 The table average below indicates the National Computer Conference. New Denver, CO (303) 623-0876 hourly cost at varying levels of usage. York, 1976. Detroit, Ml (313)961-5115 Telenet Communications Corp. "How to Hartford, CT (203) 522-0344 use Telenet: instructions for terminal Hempstead, NY (516)292-0320 Public Dial-in Charges (713)224-3380 (11 0-300 bps ports) users", July 1976. (Available upon Houston, TX request to Telenet) Indianapolis, IN (317) 635-9630 Total Hours/City AverageCost Per Hour Kansas City, MO (816)474-1600 High- Medium- Low- Long Beach, CA (213)549-5150 Density Density Density Educational Use Los Angeles, CA (213)624-5230 -9 I .-+W VP.C.-+V (213) 500 1.40 2.40 2.34 Of Network Grows Marina delRey, CA 822-9287 Miami, FL (305) 374-6400 1,200 1.40 1.41 1.38 The number of educational institutions 2,000 1.12 1.13 1.11 Milwaukee, Wl (414) 271-2560 sharing computer-based 5,000 .87 .87 .86 that are their Minneapolis, MN (612) 339-0150 0,000 .78 .79 .78 nationally through Telenet resources con- Newark, NJ (201)623-6818 tinues to grow. Rate classifications for each city are as New Haven, CT (203) 789-021 1 follows. Among colleges and universities that New Orleans, LA (504) 568-1840 recently connected computing High-density: Boston, Chicago, have New York, NY (212)736-7205 Dallas, Detroit, Los Angeles, New York, facilities to the network are Cornell Uni- Philadelphia, PA (215) 574-0620 versity College, New Jersey Philadelphia, San Francisco and Medical Phoenix, AZ (602) 257-1552 Institute of Technology, Trinity College of Washington. Pittsburgh, PA (412)765-2681^^ Hartford, and Yale University. Medium-density: Atlanta, Baltimore, Portland, OR (503) 243-2800^P Cincinnati, Cleveland, Denver, Houston, Dartmouth, one of the first colleges to Rochester, NY (716) 454-3430 use Telenet for Long Island, suburban Los Angeles, computer communica- St. Louis, MO (314) 231-8800 tions, presently insti- Miami, Milwaukee, Minneapolis, Newark, serves educational Salt Lake City, UT (801)364-2644 Pittsburgh, St. Louis; San Carlos, San tutions in a dozen states outside the New San Carlos, CA (415)595-0360 England through the network. Other Diego, San Jose and Santa Ana, Calif. ; area San Diego, CA (714) 231-1922 and White Plains, N.Y. universities presently served by Telenet San Francisco, CA (415) 362-6200 University of New Low density: Albany, Buffalo, Colum- include MIT, the State San Jose, CA (408) 279-8450 bus, Hartford, Indianapolis, Kansas City, York and UCLA. Santa Ana, CA (714) 558-6061 New Haven/ Bridgeport, New Orleans, Seattle, WA (206) 624-9780 Phoenix, Portland, Ore. ; Rochester, Salt Telenet Directory Stamford, CT (203) 357-1800 Lake City, Seattle and Stamford, Conn. Washington, DC (202) 347-1400 Corporate Headquarters Pricing information for leased channel White Plains, NY (914) 682-8777 NW and private dial ports in each city is avail- 1050 17thStreet, Montreal able from all regional sales offices. Washington, DC 20036 bps (514)878-9975 202/637-7900 110 134.5bps (514) 878-9977 More Information 300 bps (514)878-9971 Sales Offices Ottawa Switching New England 110bps (613) 563-9625 On Packet Boston, MA 617/899-4478 134.5 bps (613)563-9629 DeMent, Ralph E. "Pricing switched ser- New York-New Jersey-Pennsylvania 300 bps (613) 563-9639 vices" DATA COMMUNICATIONS, May/ New York, NY 212/594-6644 Toronto June 1976. Central-Southeast 110bps (416)361-1728 134.5bps (416)361-1515 Hovey, Richard B. "Packet-switched net- Washington, DC 202/637-7900 300bps (416)361-0011 works agree on standard interface" Southwest-Southern California DATA COMMUNICATIONS, May/June Los Angeles, CA 213/477-2048 1 200 bps ports 1976. Northwest-Northern California Johnson, Timothy. PACKET SWITCHING Menlo Park, CA 41 5/854-5845 Boston, MA (617) 338-7495J^ SERVICES AND THE DATA COMMUNI- Chicago, IL (312)726-1957^ CATIONS USER. London: Ovum Ltd., Network Control Center Dallas,TX (214) 748-6371 Washington, DC 1976. (A 237-page report available for Los Angeles, CA (213)624-1521 $185 from Ovum Ltd., 14 Penn Rd., Lon- Customer Service 202/347-2424 New York, NY (212) 736-1800 don, N7 England) San Francisco, CA (415) 956-5777 Washington, DC (202) 347-6093 4 The Telenet Report JL ® " Telenet Communications Corporation, 1050 17th St., N.W., Washington, D.C. 20036.(202)637-7900 Volume 3, Number 1,February 1976 Profile of Telenet Subscribers: WideRange of Computer Systems Sign Onto Telenet's Public Network Who is a typical Telenet subscriber? tions. Some have extensive networks graphic data baseswhich theircustomers What kind of computer system does he which currently operate in parallel with mayaccess through Telenet. Lockheed's have and how is he using public packet Telenet's, while others utilize no other Dialog" service, for example, permits switching service? network facilities. There are hosts con- searching files containing millions of ab- The logical map of the network on page nected to the network by means of a stracts of scientific, technical, educa- 2 shows the particular host computers single asynchronous communication tional, social, agricultural and business that have been connected to the Telenet line, or multiple asynchronous direct literature and retrieving selected items. network in our first six months of opera- channels into a Telenet Access Con- SUNY's biomedical information retrieval tion. Several dozen additional hosts are troller on their premises. There are other scheduled for service during the first hosts that are connected by means of quarter of 1976, and network expansion synchronous communication lines em- both within Telenet Central Offices and ploying powerful network access proto- into new cities is also underway. cols. Most Telenet subscribers are using the Mostsubscribers made no changes to network to provide remote terminal their systems when connecting to the access to their host computer, but the network, while others either installed range of systems and applications are Telenet-furnished network interface soft- diverse. Some subscriber systems, such ware, or wrote their own. as MlT's IBM 370/168 are very large, Services Offered while others are low-cost minicomputers. Significantly, the network is accommo- A number of hosts are offering commer- dating a wide range of quite different " cial computer services, while others are remote-access computer applications, using Telenet solely for in-house applica- Several subscribers maintain biblio-

Packet Nets Agree on Standard Interface

Substantial progress has been made The X-25 interface protocol is very in reaching worldwide agreement on a similar to the current Telenet host inter- Medical researchers can access "Medline" standard host interface to public packet- face specification. It is based on the con- through Telenet and instantly retrieve bib- switched networks. cept of virtual connections whereby no liographic references on any topic in their A major effort this field. Several computer systems connected toward end has been actual channel capacity is utilized except to Telenet provide this valuable medical undertaken by the CCITT [Consultative when data is being sent. data base service. Committee on International Telephone The new protocol is currently being and Telegraph). Continuing the progress implemented by both Telenet and the service, available to academic and gov- made at the last CCITT meeting in Sep- Trans-Canada System and should be tember, the major countries involved in available to by mid-1976, ernmentorganizations on a membership customers basis, packet networks have jointly prepared Telenet's current host interface will, how- also permits search and retrieval of medical, educational, and agreed upon a complete detailed ever, continue to be supported by biological and the psychological interface specification. Labeled "X-25," network. literature abstracts. At this writing, another bibliographic the protocol has been formally submitted An internationally agreed upon stand- information retrieval system, by Systems to the CCITT by the United Kingdom and ard is seen as a major step in offered De- forward velopment Corporation, France with the concurrence of Telenet providing guidelines for carriers and data is alsoscheduled and the Trans-Canada Telephone Sys- processing equipment to make its service available through manufacturers Telenet facilities. tern. It will be discussed at the organiza- and in hastening the development of " meeting in in late February. worldwide packet-switching page tions Geneva service. tcontinued on 2) Tieienet" and JC *areregistered service marks ot Telenet Communications Corporation Copyright 1976 Telenet Communications Corporation Profile of Network TelenetSubscribers Expands to x tn Telenet will introduce dial-in service for 26Cities 1200 bps terminals this spring. It will be made available in selected Telenet Cen- Ten new cities will be connected to " " tral Offices based on the needsof terminal Telenet by May, making service locally higher operating speed. accessible in 26 cities coast to coast. time-sharing systems that users forthis anal Locations of the Telenet Central Offices want to become national in scope arc At the present time network users can / spring installation are: many operate at 1200 bps and higher over scheduled for typical of Telenet subscribers. Two Anaheim, Baltimore, Cincinnati, Denver, computer private dial and leased channel ports at lortheastern services-one Miami, Milwaukee, Phoenix, Portland, lommercial, the other non-profit- illus- fixed monthly rates, and. several sub- option. San Jose/Palo Alto and Seattle. ate how and why public networking fits scribers have chosen this Host computers connected to the net- The initial seven-city network included into theirfuture growth planj work by means of the network interface Boston, Chicago, Dallas, Los Angeles, protocol will beableto handledial-in 1 200 New York, San Francisco and Washing- any ton, D.C. In late 1975 nine additional specialists than bps terminals immediately without We're more computer switching centers were put into service communications managers." That, ac- changes. Hosts connected by means of . \"T* '"""ciJCo must be in Atlanta, Cleveland, Detroit, Houston, cording to Gene Fucci, Assistant Direc Telenet Access Controllers equippedwith 1 200 bps subchannels (at Minneapolis, Newark, Philadelphia, Pitts- tor the Kiewit Computation Center developments members of his systems engi- of Barry Wessler, atright, goes over new with two month) bps burgh and St. Louis. College, is why it makes more neering staff, Rich Hovey, at left, and Mike Ford. $50 per to handle 1200 Dartmouth New Central Offices will be added on a Telenet handle networking terminals. sense to let Engineers: continuing basis and by early 1977, the time-sharing system Systems Tariff rates for service are presently for its computer network will connect some 60 cities in (DTSS"). being finalized. Contact your Telenet rep- informationregard- the U.S. Located in Hanover, New Hampshire, resentative forfurther and availability. Dartmouth has for several years shared ing rates University of Utah in its exceptional computer resources and As an end-to-end communications ser- neering from the vice, promises MSEEdegreesfrom uniquedata banks with other educational Telenet total communica- additiontoßSEEand Coming Events MIT. With the 1973, in quarter, institutions in the northeast. Some 50 tions support. Part of this package is company since he Also the second Telenet end of If you are attending any of the following This logical map shows the kinds of host computers using Telenet service, as of the to DTSS over a technical consultation, costing analysis was a key figure in the design and devel- public dial ports will accommodate IBM's January. colleges are connected conferences this spring, we invite you to of leased lines and frequency and systems design -all wrapped up in a opmentofthe network. Like many others new 3767 communications terminal and network the Telenet exhibit and meet with our multiplexers. the multi-talented group of people called sys- in the company, he grew up with packet- 5100 desk-top computer, operating in visit (continued trom page 1 ing services through Telenet facilities division With advent of representatives. > engineers. switching technology as a research pro 2741 mode. The 3767 will be supported computing Business Systems of Min- Telenet, it has become practical for DTSS terns Several large commercial Programmed managenn bps, while the will sup- March 29-21, Data Communications to offer its services to universities and In ateameffort unique among common gram the Advanced Research at 300 5100 be service companies with extensive nation- nesota, offering accounting-oriented ser- '76, Miami Beach Conven- " " carriers, a systems engineer and a Tele- Agency (ARPA) of the Department of ported at both 134.5 and 300 bps. The INTERFACE wide private their own also vices and systems implemented on a schools in distant parts of the country as tion networks of representative work with Defense, which operates the first US 3767 is a keyboard/printer intended to Center Time Sharing Prime 300 mini-computer, utilizes the well, without the necessity of installing net sales each utilize Telenet. Scientific right packet-switching network, the ARPANET. replacethe IBM 2740and 2741 May 2-7, ICA Annual Conference, Wash- to to its and maintaining lines. One of its subscriber from the start to plan ultimately Corp., one of Telenet's earliest subscrib- network provide remote access leased group ington Hilton, Washington, D.C. first via Telenet is the out his communications requirements. A senior member of the is terminals. It offers higher transmission ers and a leader in the development and specialized service. One mini-computer users National June 7-10, National Computer Confer- at the Uni- HowmuchwillTelenetcost?Howmuch Richard Hovey, who played a major role and print speeds and local buffering. The use of the APL programming language, manufacturer, Prime Computer Inc., Opinion Research Council ence, New York Coliseum Chicago. will it save7 What type of interface is best? in designing the host computer interface 5100 is a small computer available with offers its APLplus® service through Tele- Telenet's principal supplier of computer versity of In the coming months Telenet staff with being able How can Telenet improve or complement to the network and in developing and the APL and/or BASIC programming net. Data Resources Inc., headed by equipment, saw yet another possibility. Fucci equates Telenet members will also be taking part in sem- "to by the ounce an existing private network7 The systems testingterminal handling procedures. His languages. Professor Otto Eckstein, well-known Their field salesmen have used the net- buy communications inars programs planned by various ratherthan by the pound." He points out engineers are prepared to analyze each Harvard degree in engineering and ap- and Harvard' economist, offers an econo- work to conduct live customer demon- organizations in the United States and the'resulting company's existing facilities and require- plied physics combined with an MBA Karp in San Francisco and Allen Piatt in metric modeling service utilizing a large strations of the Prime 300 interactive that lower communications A partial list includes: economical ments, recommend a technical approach from Dartmouth's Amos Tuck School of Los Angeles. Associated with Bell Labs overseas. file of economic data. By supplementing system from remote locations. costs will now make it more February 19, Data Communications colleges to gain and put together a detailed costing Business, plus several years of practical for seven years, Peggy became a spe- theirown nationwide networks with Tele- In-house computer departments, such for remote smaller access [lEEE), Baden-Baden, Ger- systems" like Dartmouth's analysis. experience with computers, highlight the cialist in packet-switching technology Conference net facilities, STSC and DRI are able to as that of Shawmut Bank in Boston, are to the big many. paper "Telenet- Network equipment and The systems engineer also works with dual business and technical orientation when she served as technical advisor to A on more easily accommodate rapid growth finding Telenet service an advantageous Honeywell 6000 to take Features and Interface Protocols" will be many education-ori- each new subscriber in setting up train- that Telenet systems engineers bring to ARPA in the early 1 970'5. After receiving and provide backup for their own net- way toobtain network capabilities without advantage of the given by Dr. Holger Opderbeck, Director programs developed ing procedures, tailoring network tunc- their jobs. an MS degree in information science at work facilities as well. requiring the capital investment, long ented computer at Design (prepared jointly with Dartmouth the past decade. tions, preparing userdocumentation, and Also located in Washington is Technical the University of Chicago, she continued of Network A number of other Telenet subscribers delays, and maintenance burdens asso- over Richard Hovey, Systems other tasks necessary for a successful Manager Larry Cole, who joined Telenet in the PhD program in computer science Senior who have offered commercial computing ciated with developing and operating a Thecoast-to-coast availability ofTelenet Engineer). numbers is also an important conversion to Telenet. After that, he co- with 16 years experience in the design at Stanford University. services primarily on a regional basis are private network. local dial-in February 25, COMPCON, lEEE Com- particular plus for Dartmouth's faculty and ordinates installation with Telenet's Oper- and implementation of many telecom- Her associate, Allen Piatt, has had over now able to market their services nation- The latter advantages are of own Society, San Peggy ations Department and continues to munication and dataprocessing systems, a decade of experience in software man- puter Francisco. wide. Among them are Interactive Sci- value to universities which seek to have students, 93 percent of whom use com- Engineer, will be guest stand by whenever technical assistance for both industry and government. His agement as applied to time-sharing com- Karp, Systems of Braintree, Mass., First Data the computer resources at all academic puting in their academic work. Since the subject, ences is needed. professional background is supple- puter systems, both in England and the speaker on the "Communica- Corp. of Waltham, Mass, and Computer and research centers available to any college operates on a four-semester sys- fortunate to have gathered mented by a degree in business admmis- United States. As a former management tions Network Interfaces." Sharing Services, Inc. of Denver. individual faculty member or student. tem, many of the faculty are likely to be Telenet is Association, extremely capable and diversified tration from Fairleigh Dickinson Univer- consultant, he specialized in evaluating, March 3, Computer Law Operators of minicomputer-based sys- These are but a few of the ways that off campus at any one time. Now they an group of men and women for its growing sity and graduate studies at the University selecting, and configuring computer Washington, D.C. Philip Walker, Vice are benefiting by the network too. different organizations are using Telenet can conveniently continue their com- terns staff. of Southern California. hardware, terminals, data communica- President and General Counsel, will dis- Computer Network of Chicago, As other novel applications of the net- puting work from any part of the country systems engineering National Dr. Barry Wess- In the western part of the country sup- tions facilities communications cuss tariff concepts relating to data com- using Honeywell sys- emerge, these will be reported in by dialing into a nearby Telenet Central Thegroupis headed by a/id a small-scale 1648 work " Peggy Software, (continued on page 4) munications services. Office, (continuedon page 4) ler, holds PhD in electrical engi- port is provided by people like tern, offers low-cost interactive comput- future issues of the Telenet Reoort. who a r% % I fl H NewPublications ■^ page Telenet:The Intelligent Network . . . The Dntinued from 2 Intelligent Choice First Data Corporation next. And additional DEC equipment is Swithers, Manager of Program- being in A 1 2-page booklet that serves as an in- Bob installed Waltham to handle the ming, Data, Waltham, Mass, cites company's troduction to network services and pack First increased business. entry et-switching technology. "low cost" as a key factor in this Initially, First Data connected its com- commercial time-sharing firm's decision puter facilities to the network through an How to Use Telenet: Information for to expand into a national market via eight-line Telenet Access Controller. Terminal Users Telenet. Based on their users' favorable experi- " A step-by-step guideto accessing Telenet, In its first five years of operation, First ence with the network, the company and Telenet received $1.3 million in addi- prepared for terminal users operating in Data had concentrated on selling its ser- Swithers invested theirtime in implement- tional equity financing during the latter real terminal mode. vices primarilyto government and private ing Telenet's versatile network interface part of 1 975. The five organizations that customers in the northeast and has built protocol in their system and it will one earlier in the year invested $2.1 million, If you would like to receive copies of be a private network in the Boston-New of the first in operation with DEC also participated in this second phase of either of these Telenet publications, new York-Washington area. equipment. Telenet's planned equity capitalization please fill out the enclosed reply card. When Telenet became operational, it A privately-owned corporation with a program. presented an excellent opportunity for staff of over 100, First Data provides Dr. Lawrence G. Roberts, president of First Data to market its services all over facilities managementfor such clients as the company, said that the money will be Telenet Directory the country. Telenet's distance-indepen- the National Institutes of Health, and its used for continuing expansion of the Corporate Headquarters dent traffic charges in effect made the services include data base management, packet-switching network. company cost competitive matter engineering applications, is of 1050 17th Street, NW no financial Telenet an affiliate Bolt Beranek where potential customers were located. models, statistical programs and Newman Inc., Cambridge, Mass., Washington, D.C. 20036 and an ex- January, opened tensive stock market data dating in 202/637-7900 This First Data an base one of the investors the current financ- office in Chicago. A West Coast office is back to 1968. ing The other investors include Time, Sales Offices Inc., the diversified publishing concern; Bessemer Securities Corporation and Boston 617/899-4478 The Palmer Organization, leading ven- Angeles capital firms; Los 213/477-2048 H.U. MTiNNJ^_. ture and Lehman Brothers, Menlo Park(CA) 415/854-5845 nimiaiJß H| Inc., Telenet's investment banker. New York 212/594-6644 STATE univfl ■■■■■■ Washington 202/637-7900

Customer Service 202/347-2424

Network Dial-In Access Numbers Atlanta Systems Engineers: " 404/577-8911 Baltimore 301/962-5010 Boston 617/338-1400 Human Chicago 312/372-4901 etoieiene Cincinnati 513/621-7017 (continued page Cleveland 216/241-0940 from 3 Dallas 214/748-0127 These EDUCOM members talked to computers 3000 miles away at Telenet's demonstration of In the northeastern part of the country, Denver 303/623-0876 aprototype network for educational institutions. Telenet's subscribers have the services Detroit 313/961-5115 of Harvey Baumel and Mike Ford of the Houston 713/224-3380 New York office in addition to staff mem- Los Angeles Colleges Explore Nationwide Edunet bers at the Washington corporate offices. Downtown 213/624-5230 In the next few years a historian in terminals at the meeting site with com- An engineering-physics major at Cor- West 213/937-3580 North Carolina may be able to obtain puter facilities at three east coast univer- nell, Harvey was associated with MlT's Miami 305/374-6400 bibliographic references from a data sities: Dartmouth, MIT and the State Uni- Laboratory for Nuclear Science and the Milwaukee 414/271-2560 bank at Stanford while at the same time versity of New York. Computer centers at Programming Development Office, Minneapolis 612/339-0150 an economist in Chicago might run a all three universities were among the where he was assistant to the director. Newark 201/623-6818 computer-based forecasting model at first subscribers to the Telenet and are While at MIT, he also served as technical New York 212/736-7205 the Wharton School in Philadelphia. already actively sharing their educational liaison to the New England Regional Philadelphia 215/574-0620 EDUCOM, an association of computer data bases and computer resources Computing Program (NerComp). Phoenix 602/257-1552 specialists representing more than 200 through our public network. The newest member of the staff, Mike Pittsburgh 412/765-2681 colleges and universities, is looking Packet-switching technology em- Ford, also comes from MIT where he Portland 503/243-2800 closely at a national educational network ployed by Telenet has erased many of earned his degree in electrical engineer- St. Louis 314/231-8800 that will give scholars like these access to the technical and economic barriers to ing/computer science. Later, as chief San Carlos 415/595-0360 the best of academic computer resources institutionsforming common interest net- systems programmer at the Laboratory San Diego 714/231-1922 coast to coast. works of this kind. Supported by a grant for Nuclear Science, he served as pro- San Francisco 415/362-6200 Just how the network might operate from the National Science Foundation, jectadministratorfor several ERDA-spon- Santa Ana 714/558-6061 was demonstrated by Telenet at the fall EDUCOM will begin development of a sored ARPA network experiments. These Seattle meeting of EDUCOM in Portland, network simulation model this spring. projects were carried out using 206/624-9780 Ore- MlT's "/ Washington, D.C. 202/347-1400 gon. The prototype network linked data MULTICS system. C3l-829-201 r> Transmission v. Facilities Telenet Communications Company Private, Packet-Switched Data Service

MANAGEMENT SUMMARY Leased, private dial-in or dedicated, interstate, Telenet service is unique in that it allows users to transmit packet-switched data transmission service. data across the country or over short distances for the same cost. The system offers a wide range of speeds to The rate structure is based on leased monthly accommodate low-speed terminal data and high-speed charges according to type of access port and data transmission. Charges are directly related to the its speed. Data traffic is charged by according amount of data sent and fixed monthly charges kilopacket, which is equivalent to 128,000 to access port speeds. characters. Rates are related to served centers, which are classified as High-, Medium-, and simple arrangement involves one or more asynchronous A Low-Density centers. links between a host computer and the Telenet, each appearing to the host as an asynchronous terminal. A Telenet Access Controller (TAC) furnished by Telenet and A Telenet Access Controller can be leased, installed on the customer's premises appears to the host as which provides flexibility for network/host multiple asynchronous terminals. A host computer may system functions. be connected to the network by means of a high-speed channel operating synchronously exchanging data according to Telenet's multiple connection network interface CHARACTERISTICS suitable method for protocol. A TAC provides a CARRIER: Telenet Communication! Company, 1666 K systems network for connecting interactive host to the Street NW, Washington, DC 20006. Telephone (202) communication with compatible terminals operating at 785-8444. speeds up to 1200 bps. TARIFF: Telenet #1. of TAC. New A typical example shows the function a In SERVICE TYPE: Leased, private dial-in or dedicated, York, a regional office is connected directly by private interstate, packet-switched datatransmiiaion service. line to the Telenet system to forward order entry data to its Chicago computer center. The Chicago center is SERVICE LOCATIONS: Nationwide,fromTelenet Central Central Offices, which are classified for ratemaking purposes into connected by private line to the Chicago Telenet Low-Density Controller, the High-Density, Medium-Density, and centers. Office. A Telenet Access located on AH offer service up to 1200 bps, and High-Density Centers, customer's premises in New York, is leased to multiplex except Detroit, Marina del Rey, and Philadelphia offer the terminal data over a private line to the New York service up to 56,000 bps. The Telenet central cities to Telenet Central Office and through the Telenet system to which connectionsmay be made for Telenet service are: the Chicago data center. Eight CRT units, operating at 120 cps, are connected to the Telenet Access High -Density Centers displays is used solely for an Controller. One of the eight Boston Detroit New York inquiry-response function; this unit only is permitted this Chicago Los Angeles Philadelphia function, through a Network Privacy Feature offered by Dallas Marina del Rey San Francisco Telenet to assure restricted access to the computer Washington, DC containing data files that may be queried. This feature, Medium-Density Centers incorporated in the Telenet central office equipment, performs an address check that verifies the correct Atlanta Houston St Louis identity of the terminal before allowing connection to the Baltimore Los Angeles San Carlos customer computer center. After a permitted connection, Cincinnati Miami San Diego security procedures under control of the host Cleveland Milwaukee San Jose additional Denver Minneapolis San Pedro computer software may be employed. Hemstead, NY Newark, NJ Santa Ana Pittsburgh White Plains, NY A summary of monthly charges for this network ty-Cen arrangement and for representative monthly usage is as Low-Densi tets follows: Albany, NY Indianapolis, IN Portland, OR Buffalo, NY Kansas City, MO Rochester, NY Fixed charges- Columbus, OH New Haven, CT Salt Lake City, UT Seattle, WA to office, via Hartford, CT New Orleans, LA Chicago center Telenet Phoenix, AZ Stamford, CT access channel, private line: S 400/month (channel Leased access port termina- SERVICE COSTS: All data traffic is measured on the basis $ tion at Telenet): 200 of a kilopacket (1000 packers of 128 characters or 1024 Network privacy feature, at $5 bits each), irrespective of distance. The measured usage for first station: S 5 r> charge is $0.60 per kilopacket. Private dial service charges AUGUST 1976 ©1976 DATAPRO RESEARCH CORPORATION, DELRAN, NJ. 08075 REPRODUCTION PROHIBITED C3l 829 202 Transmission Telenet Communications Company ♦ Fdcilitias V Private, Packet-Switched Data Service

I> Multiple connection function: $ 200 Dedicated access port installation charges are: $250 for 50 $350 for 1200 and New York center to Telenet office, through 300 bps; $300 for 600 bps; bps; for speeds up to 56,000bps. via access channel, private line: $ 400 $400 Leased access port (channel termina- When a leased channel or private dial access port is tion at Telenet): $ 200 equipped to support multiple simultaneous virtual connec- Terminal Access Controller (with tions, a Multiple Connection Charge applies. This charge u multiplexing): $ 400 determined by the actual peak number of simultaneous virtual connections through the port each month. The rate Terminal access ports, for eight 120 per connection at the peak is $4 per month with a cpsCRT units at $50 each: $ 400 minimum of 50 such connections or a monthly minimum of $200. Installation of the multiple connection capability Total monthly fixed charge: $2,205/month is $200. Monthly charges for local access lines supplied by another Usage charge— common carrier are charged at that carrier's rates, as are 2500 kilopackets, at $0.60 each $1,500/month move or modify charges. Telenet applies a one-time charge of $50 additional each move or modify and coordinates the common Total monthly charge $3,705/montho end-to-end service. Installation charges of another carrier are applied in accordance with that carrier'sappli- cable tariff. A Telenet Access Controller (TAC) can be installed at a customer's premises for multiple terminal/host computer accesses to Telenet TAC charges are based on a minimum three-month service period. The TAC requites at least one leased access channel to the nearest High-Density central office. Central office port connections are included in the cost of leased channels.

Telenet Access Controller charges are: access line, and for dial out, the include modem, local Monthly Installation automatic call unit. Private dedicated service does not Equipment include modems and access line; these are additional $400 charges. Basic TAC $400/mo. Each access port— bps 25 25 Monthlyprivate dial-in, access port charges are: 50-300 110-300ASP* 25 25 600 40 40 Rate Center 1200 50 50 Each answer only modem 15 15 Speed High Medium Low Arrangement for more than 100 30 one port speed 110-300bps $100/mo. $135/mo. $170/mo. Arrangement for each additional 400 200 600 175 235 leased channel 1200 200 300 350 2000/2400 320 'Adaptive speed port 4800 400 A minimum of a $200 installation charge applies for installation of one or more access ports at any one time. The monthly charge for dial-in and dial-out access is $100 Minimum installation charge applies to the conversion of more than the charges above, except thatfor Low-Density, access ports to operate at a different speed. the charge is $235 (110-300 bps) and $400 (1200 bps). Dial-in and dial-out applies only to 110 through 1200 bps. TAC ports can be equipped with the Rotary Feature and the Private Network Feature. Installation charges are $200 (up to 300 bps), $350 (600 bps), $400 (1200 bps), $520 (2000/2400 bps), and S6OO The customer must specify those ports which are to operate (4800 bps). Installation charges for both dial-in and dial-out under rotary control, which provides multiple access paths are $400 for up to 300 bps and $500 for 600 or 1200 bps. with a common single network address. A virtual connection initiated by a remote station is established to Monthly dedicated access port charges are: the first available port on the list. Monthly charge for each Rotary list is $20. Installation charge is $50. Rate Center Private access ports and TAC ports may be equipped with control, accepts Speed High Medium Low private network which establishes or connections to or from only stations specified by the a Private bps $ $110/mo. 5145/mo. customer. Monthly charge for first station on 50-300 75/mo. is additional station, $1. Installation 600 125 185 Network list $5; each are for station on list and each 1200 150 250 300 charges $25 first $5 2400-56,000 200 additional station. ■

by A. RYBCZYNSKI BellCanada Ottawa, Canada B. WESSLER Telenet Communication* Corporation Washington, D.C. R. DESPRES AdministrationFrancaise de PTT Rennes, France and J. WEDLAKE UnitedKingdom Post Office London, England

ABSTRACT manufacturers of data processing and terminal equipment and common carriers. Public packet switching networks are at various stages of development around the world, notably in the U.S., Canada, France, the United Kingdom and Japan. The INTRODUCTION success of these networks is highly dependent on the use of an agreed-upon standard device-independent Telenet has been commercially available in the U. S. interface between the packet networks and the user de- since August 1975; Datapac will start commercial vices operating in the packet-mode. This interface operation in Canada next month; the French experi- consists of far more than the data link control pro- mental RCP network started operation in 1975 and cedure (i.e., HDLC), which administers the physical Transpac development has been contracted out and transmission medium between the data terminal equip- will start providing service in France in 1978; the of the ment (DTE) and the network. The specification of the Experimental Packet Switching Service United into the stage; packet-mode interface defines a Bet of conventions Kingdom Post Office is well evaluation public are being planned and governing the manner which DTEs establish, main- and other data networks in developed in Japan Nordic countries. tain and clear calls, format control information and both and the technology used in all of these net- data into packets manage the datafor many The fundamental and flow of works is packet switching. In packet switching, all calls over a single and from the packet net- circuit to user data is formed into discrete units called packets. work. In to the data to be transferred (typically Packet-Mode addition This paper describes the International part of a message), each packet includes a header Interface, developed jointly by Telenet Communica- specifying control functions and the destination to tions Corp., the Trans-Canada Telephone System which the data is to be delivered. Packets are routed (TCTS), the United Kingdom Post Office and the through the network on a store and forward basis and French PTT. This interface has been designed to en- travel very rapidly and accurately through the net- able DTEs such as computers, programmable termi- work, experiencing only a fraction of a second delay nal controllers and intelligent terminals to gain access from source to destination. Additionally, the network to public packet networks throughout the world. The performs buffering functions so that the speed and present status of international standardization of this format of the data sent into the network can be dif- interface within the CCITT is also covered. ferent from those of the data received at the destina- Standardization of the International Packet-Mode tion. Interface is to the advantage of teleprocessing users, The packet switching technology described briefly

477 V 478 National Computer Conference, 1976 in the preceding paragraph is actually of little direct terminals that require device-dependentinterfaces and concern here, since the sophisticated routing, monitor- because of the large incompatibilities that presently ing and error correction techniques internal to packet exist among these terminals, a large number of inter- networks are invisible to users of the networks. face specifications are required. On the other hand, (Readers are referred to a book edited by Chu 1 for a only a single specification of a device-independent discussion of packet network design considerations). interface is necessary. Rather, the user's primary interests are the character- The International Telephone and Telegraph Con- istics of the service provided by a network and of the sultative Committee (CCITT) in Geneva has recog- interface between him and the network. nized the need for these two types of interfaces and The public data networks listed above are supporting has put priority on the development of a recommenda- packet-mode services based on the virtual circuit con- tion for the second type of interface; that is, a device- cept. A virtual circuit is a bi-directional association independent interface between what it calls a packet- between a pair of DTEs over which all data transfer terminal and the packet switching network. A similar takes the form of packets. Transmission facilities are conclusion has been drawn by an Ad Hoc Group of only assigned when data or control packets are ac- U. S. ANSI Task Group X3537 (Public Data Net- tually being transferred. The virtual circuit concept works). 2 a DTE equipment) permits (data terminal to establish Likewise, TCTS, the French PTT, Telenet, the paths many DTEs concurrent communications to other Japanese NTT, and the United Kingdom Post Office over a single physical access (Figure 1). circuit The have put high priority on the development and stan- high degree sharing possible by use of made the of of Inter- savings to be dardization the International Packet-Mode virtual circuits enables communication specification passed on to The virtual circuit concept mini- face. The of the International Packet- the user. Mode submitted draft Recommenda- mizes the impact of new packet switching services on Interface was as tion X.25: to the CCITT Secretariat for consideration existing user systems. ' Two types of interfaces may exist on any packet by the Study GroupVII Plenary. switching network. The first type may be called a The purpose of specifying the International Packet- device-dependent interface such as would be required Mode Interface is to provide an efficient means by at present for most hard-wired terminals (e.g., point- which a large set of characteristically different tele- of-sale terminals, teletype machines) . The second type processing systems can gain access to the services and may be called a device-independent interface which is related technical and economic benefits of packet applicable to most programmable devices (e.g., com- switching networks. puters, programmable controllers, concentrators, intelligent terminals). Because of the large number of GENERAL DESCRIPTION

Interface requirements

The basic requirements imposed upon the architecture of the interface are introduced below : 1. The interface shall provide a full duplex transmission path between the DTE and the network. 2. It shall ensure the integrity and accuracy of the data transmitted between the DTE and the network. 3. It shall provide the DTE with switched and permanent virtual circuits. 4. It shall be capable of efficiently supporting concurrent communication between a packet mode DTE and numerous other DTEs over a single physical circuit to the network. 5. It shall allow both DTE and network to control the flow of data over the access circuit so that one does not overload the other. 6. It shall provide supervisory and control functions to administercalls satisfactorily. 7. It shall do all of above using existing standards Figure I—Use1—Useof virtual circuits wherever possible. "

International Packet-Mode Interface 479

Interface characteristics of a data link control procedure which is compatible with the High-Level Data Link Control (HDLC) pro- The International Packet-Mode Interface consists of cedures being standardized by ISO and with the Ad- three distinct levels of control procedures as illustrated vanced Data Communications Control Procedure in Figure 2 : (ADCCP) being standardized by U. S. ANSI. The the principles 1. the Physical Interface Frame Level Interface uses of a new ISO Class of Procedure for a point-to-point balanced 2. the Frame Level Logical Interface 3. the Packet Level Logical Interface system, whereby the DTE and the network node each have a primary and a secondary function. The Frame Each of these levels functions independently of the Level Interface is defined in terms of primary and other levels, with the exception that failures at a level secondary responsibilities, and may be thought of as may affect the operation ofhigher levels. two independent but complementary transmission The Physical Interface specifies the use of a duplex, paths superimposed on a single physical circuit. The point-to-point synchronous circuit, thus providing a use of this data link control procedure ensures that physical transmission path between the DTE and the packets provided by the packet level and contained Network. It also specifies the use of an existing physi- in HDLC information frames are accurately exchanged cal interface (i.e., EIA RS-232-C standard) between between the DTE and the Network. The functions per- the DTE and a data set or modem. Therefore, no formed by the Frame Level Interface are : changes to the interface hardware of the DTE are of an timely fash- required. 1. transfer data in efficient and ion; The Frame Level Logical specifies the use Interface 2. synchronizing the link to ensure that the receiver is in step with the transmitter ; 3. detecting transmission errors and taking steps to recover from such errors ; 4. identifying and reporting procedural errors to higher levels for recovery. The major significance of the Frame Level Interface is that it provides the Packet Level Logical Interface with an error-free, variable delay link between the DTE and the Network. The Packet Level Logical Interface is the highest level of the International Packet-Mode Interface and specifies the manner in which control information and user data are structured into packets. The control information including addressing information is contained in the packet header field and allows the network to identify the DTE for which the packet is destined. It also allows a single physical circuitto support a number of virtual circuits to numerous other DTEs concurrently. The Packet Level Logical Interface is further de- scribedin the next section.

THE PACKET LEVEL LOGICAL INTERFACE

I Multiplexing at thepacket level DTE DTE/DCE DCB (caalaajar aida of INTERFACE (natwark aida of The Packet Level Logical Interface accommodates talartaeaj DTE/DCE hatarfaca) DTE/DCE both permanent and switched virtual circuits. A permanent virtual circuit is a permanent association exist- ■lata. Wal.aat la maip.iaa.lla aracaaa-ta-aaacaae i ■ ulcatlaa. ing between two DTEs which is analogous to a point- to-point private line. Thus, it requires no call set up or call clearing action by the DTE. A switched virtual

DCS Data Clrcall TaindalHaa, »aala»aal circuit is a temporary association between two DTEs - - sending request (a.«. data aet) and is initiated by a DTE a call packet to the network. Call establishment and clearing is de- Figure 2—lnternationalpacket-mode interface architecture scribed in the nextsection. '

480 National Computer Conference, 1976

In order to allow a DTE to establish concurrent BIT virtual circuits with a number of DTEs over a single 0 1 2 3 4 5*7 physical access circuit, the Packet Level Logical In- terface employs packet-interleaved Statistical Multi- OCTET 1 Logieol plexing. This multiplexing technique is used to exploit ° ° ° ' the fact that a typical virtual circuit to a remote DTE 2 I Chonnal Numbar may actually be carrying data for only a small per- logical Typa Raquast centage of the time. Each packet contains a 3 - Coll the packet with a x channel number which identifies Calling 4 DTE or permanent virtual circuit for both direc- Langth U switched I Addrait o tions of transmission. A packet that contains user data a. identifying it as for example has a three octet header 5 I DTE Addrass a data packet and specifying its logical channel num- I Fiald ber as illustrated in Figure 3.

Call establishment and clearing A signalling method is provided to allow a DTE to establish switched virtual circuits to other DTEs using numbers at end to locally desig- I logical channel each I nate these switched virtual circuits. i a call by sending a call request i I A DTE initiates I 4, the The call request packet, Figure to Network. i Ui»r Data logical number chosen by (0-16 octatt) i packet includes the channel i i the DTE to be used to identify all packets associated i with that call. It also includes the network address of the called DTE. A facility field is present only when an optional facility 7 it the DTE wishes to request user Bit. of on octal ora numbarad 0 to 7, whara bit (i.e., network feature) requiring some indication at tha low ordar bit ond ll tronsmittod first. Octal, ef consoeutivaly Hotting from call up. Reverse charging is an example of such a 0 pockat ora numbarad set 1 and ora tronsmittod in thi, ordar. facility. User data may follow the facility field and may contain any number of bits up to a maximum of Evary poeltat haodar has a 4-bit (laid which is 12-bitlogieol 16octets. allactivaly rasarvad for lutura usa. o chonnal numbarand on 8 -bit fiald u.ad for pocbat calling will a response indicating lottar fiald is The DTE receive typa informotion and control. This whether or not the called DTE accepts the call. When intantionolly .apt vary similarto tha control fiald a switched virtual circuit cannot be established, the of HDLC. network will transfer clearing call progress signals

Figure 4—Call request packet format BIT 1 2 3 4 5 6 7 to the DTE indicating the reason why the call was not established; call progress signals are listed in Table I. OCTET 1 Either DTE may clear an established call with this 2 information being conveyed to the opposite DTE. 3 Figure 5 is an illustration of call establishment, clearing. I datatransfer and call I j Data Fiald I on a virtual circuit Usar I Data transfer I I Data packets, illustrated in Figure 2, can only be transferred on a virtual circuit after the virtual cir- and flow control constraints 0 Data Quollfior cuit has been established " The third octet of the data packet M ' Mora Data Indicator are not violated. header is identical to the control byte of HDLC information frames except that the poll/final bit is replaced by More Data bit discussed later. Figure 3—Data packet format the w*

International Packet-Mode Interface 481

tearing 'rogress lignal CALLING OTE/DCC CALLED DCE/DTE INTERFACE INTEAF error. — — — — remote procedure I I I fot obtainable The called number is not assigned or is no longer assigned. I " CLEAN INDICATION lut of Order The called number is out of order. PACKET CLEAR REQUEST PACKET a -*" include OISCONMECTION Possible reasons *~ C...CLEAR tLtCLEAR — ONNCCTION (1) functioning; CONFIRMATION" PACKET au»«F DTE not PHASE CONFIRMATION PACKET **»« (2) Subscriber link not functioning; (3) Frame level not in operation. T " T

P(S) is the packet send sequence number of the Figure s—lllustration5 Illustration of call establishment, data transfer and packet. (Only data packets are numbered, modulo 8). — call clearing The maximum number of sequentially numbered data packets that the DTE may be authorized to transmit, without further authorization from the network, may being 16, 32, 64, 255, 256, 512 and 1024. The governing never exceed seven. The actual maximum value, called principle is that a virtual circuit is used for the trans- the window size W, is set for the virtual circuit either fer of streams of user bits, where packet size may be at subscription time or at call set up. chosen in such a way as to locally optimize : access line Each data packet also carries a packet receive se- performance, cost, errorrates, queuingdelays, through- quence number P(R) which authorizes the transmis- put, etc. sion of W data packets on this virtual circuit starting In order to facilitate the segmentation and grouping with a send sequence number equal to the value of of the user's data stream into data packets, the user P(R). If the DTE or the network wishes to authorize may indicate in a full data packet whether there is a the transmission of one or more data packets across logical continuation of his data inthe next data packet the interface, but there is no data flow on a given vir- on a particular virtual circuit. This he does with the tual circuit inthe reverse direction on which to piggy- More Data bit (M) indicated in Figure 3. Only a full back this information, it can transmit a Receive Ready data packet requires a More Data indication since a (RR) packet. Flow control based on the conveyance partially full packet is treated as if it had the M bit of P(R) numbers on a virtual circuit basis ensures off. The use ofthe Mbit ensures that two communicat- that a sending DTE does not transmit data at an aver- ing DTEs can each operate at their locally selected age rate which isgreaterthan that at which the receiv- packet sizes. ing DTE can accept that data. Two independentmechanisms are provided to trans- The datafield of a data packet to be transmitted on fer control information between a pair of DTEs out- a virtual circuit may be any number of bits long up to side the normal flow of data. The first mechanism some maximum value. The latter may be established transfers control data within the normal flow control independently at each end of a virtual circuit. Every and sequencing procedures on a virtual circuit. This network will support a maximum value of 128 octets. is called the data qualifier procedure. The format used It may optionally support other values, possible values in this procedure is identicalto the normal data trans- "* "-. 482 National Computer Conference, 1976

the restarting procedure will fer packet except that the "Q" bit is set (see Figure 3) . virtual circuits. Thus, state it was The data transmitted is then interpreted by the re- bring the user/network interface to the ceiving DTE. An example of the use of the data quali- in when service was initiated. fier is to transfer device control information such as echoing or packet forwarding rules and transmission CONCLUSIONS control parameters for device-dependent interfaces on the packet network. This paper has presented a description of a new com- The second mechanism bypasses the normal data protocol for accessing packet switching non-sequenced munications packet transmission sequence providing networks. The International Packet-Mode Interface a short interrupt packets. Interrupt packets consist of has been developed by a number of administrations a header identifying the logical channel number and and common carriers in cooperation with standards one octet data field. Interrupt packets will be trans- organizations, users and manufacturers. We strongly mitted by the network without waiting for all other believe that it is to the advantage of teleprocessing packets to be delivered and will be delivered to a DTE users, manufacturers of data processing equipment and even when it is not accepting data packets. They con- common carriers that standards and recommendations tain neither send nor receive sequence numbers. In continue in this area. The benefits to accrue are sim- this way, interrupt conditions, such as would be gen- plified design and use of equipment, lower cost, higher erated by the depression of a break key on a keyboard transmission efficiency, interconnectivity and en- terminal, can be signalled between DTEs without be- hanced performance. ing subject to the flow control imposed on data packets. The International Packet-Mode Interface has already been implemented in a number of installations Datapac experi- Error recovery to give access to the Telenet, and mental RCP networks. It has been specified for use and for the The reset procedure is used to reinitialize the flow on the French PTT's Transpac network being developed by a control procedure on a given virtual circuit to the Euronet international network state it was in when the virtual circuit was established large number of European administrations. (i.e., all sequence numbers equal to zero and no data in transit) . To reach this state, all data and interrupt REFERENCES packets which may be in transit atthe time of resetting are discarded. Reset packets are used in the reset pro- 1. Chu, W. W., Advances in Computer Communications, cedure. Artech House Inc., Dedham, Massachusetts, 1974. by the 2. Cotton, I. W. and J. W. Benoit, "Prospects for the Stan- The restart procedure is primarily used DTE Fourth Data from major dardization of Packet-Switched Networks," and provides a mechanism to recover Communications Symposium, Quebec City, Canada, October failures. The issuance of a restart request packet is 7-9 1975 equivalent to sending a clear request on all switched 3. CCITT Study Group VII Contribution No. 262, December virtual circuits and a reset request on all permanent 1978. Submitted by the French PTT and U.K. Post Office. litOigfe IMaM WtMrDtG ..aretechnological, financial, and organizational. Telenet Communications then Director for Informa- spent more than three public services are pro- Corporation is an affiliate of tion Processing Tech- years planning, engineer- vided pursuant to a tariff the U. S. pioneer in packet- mques at the Advanced ing, implementing, and filed with the Federal switched data commumca- Research Projects Agency, testing this new data Communications Com tions — Bolt Beranek and U. S. Department of communications network. mission, as required unde r Newman Inc. A publicly- Defense. the Communications Act heldcorporation (AMEX), Telenet inaugurated serv- of 1 934. The tariff, con- BBN is the founder of and Since 1973, Dr. Roberts, ice in August 1975 and taining Telenet rates and a major stockholder in widelyknown as the archi- immediately began serving regulations, may be Telenet. Beginning in 1968, tect of packet-switching customers from switching changed only with FCC BBN designed, built, technology, has served as centers in major cities coast consent. andput into operationthe President and Chief Execu to coast. Additional centers world-famous ARPA Com- tive Officer of Telenet have been put into opera- puterNetwork, ARPANET, Communications Corpora- tion on a regular basis, and under the direction of Dr. tion. the projected 60-city network is well on its way to completion.

Telenet is a government- regulated communications common carrier. This means that all of Telenet's

George A. Fish Telenet District Manager cttdJ Communications -JJ V= Corporation ngton Telenet =U IL Communications Corporation 271 0 Sand Hill Rd. Menlo Park, CA 94025 41 5/854-5845