In order to fully support computer resource sharing reliably and responsively on a nationwide basis, the communications network must be approximately the size and cost of the current ARPANET (34 nodes and $2M/yr). Based on recent measurements the network traffic generated by a fully loaded, moderate size, time-shared computer is 720,000 packets per day. A minimal network such as the current ARPANET has a basic capacity of 10M packets per day. Therefore, to fully utilize the basic capacity of the ARPANET would require 14 moderate size computers to be fully accessed through the network. Additional capacity can easily be added beyond this point with no great economy of scale. Figure 2 shows this effect for generalized national networks of ARPANET technology. By utilizing the above measurement of network traffic produced by a host and estimating its rental at $720,000 per year, total network traffic can be related to the total computer resource value accessed via the network (each computer dollar produces 365 packets of traffic). Thus the relative cost of network communication can be related to overall the annual computer value used. Since there are some fixed costs associated with adding each additional node, the cost-effectiveness depends partially on the number of nodes, but the main effect is produced by the dollar volume of usage. This means that at least 10-20 million dollars of computer time usage must be expected before a nationwide network becomes optimally cost-effective. Once the activity level is reached the main benefit from increased usage is improved reliability and increased peak throughput capability. ARPANET OPERATIONAL NETWORK NODES *Aberdeen-U.S. Army Material Command, Aberdeen R & D Center, Maryland AFGWC-Air Force Global Weather Central, Omaha, Nebraska Ames-Ames Research Center, NASA, Mountain View, California *ARPA-Advanced Research Projects Agency, Arlington, Virginia *Belvoir-Mobility Equipment R & D Command, Ft. Belvoir, Virginia BBN-Bolt Beranek & Newman Inc., Cambridge, Massachusetts Case Case Western Reserve University, Cleveland, Ohio *CCA-Computer Corporation of America, Cambridge, Massachusetts CHI-Culler-Harrison Inc., Goleta, California CMU-Carnegie-Mellon University, Pittsburgh, Pennsylvania *DOCB-Department of Commerce, Boulder, Coloradio ETAC-Air Force Environmental Technical Applications Center **FNWC-Fleet Numerical Weather Central, Monterey, California Harvard-Harvard University, Cambridge, Massachusetts **Hawaii-University of Hawaii, Honolulu, Hawaii Illinois University of Illinois, Champaign-Urbana ISI-Information Sciences Institute, Marina del Rey, California **LBL-Lawrence Berkeley Laboratory, Berkeley, California Lincoln-Lincoln Laboratory, MIT, Bedford, Massachusetts **LLL-Lawrence Livermore Laboratory, Livermore, California *London-University of London, London, England Michigan-University of Michigan, Ann Arbor, Michigan MIT-Massachusetts Institute of Technology, Cambridge, Massachusetts **Moffett-Moffett Field, Mountain View, California NBS-National Bureau of Standards, Gaithersburg, Maryland Rand-The Rand Corporation, Santa Monica, California RML-Range Measurements Laboratory, Patrick AFB, Florida Rutgers-Rutgers University, New Brunswick, New Jersey SCRL-Speech Communications Research Lab, Santa Barbara, California *SDAC-Seismic Data Analysis Center, Alexandria, Virginia SDC-System Development Corporation, Santa Monica, California SRI-Stanford Research Institute, Menlo Park, California SU-Stanford University, Palo Alto, California UCLA University of California at Los Angeles UCSB-University of California at Santa Barbara *UCSD-University of California at San Diego UNIVAC-UNIVAC, St. Paul, Minnesota USC-University of Southern California, Los Angeles Utah-University of Utah, Salt Lake City **X-PARC-Palo Alto Research Center, Xerox Corporation, Palo Alto, Calif. *Operations commence May-August 1973. **Óperations commence September-December 1973. FULL COSTS FOR "INCREMENTAL" ADDITIONS TO THE ARPA NETWORK OF Initial Costs: GOVERNMENT-SPONSORED USERS (1) 316 IMP: $54K (including first year's maintenance and one local Host, standard interface). (2) TIP: $98K (including first year's maintenance and one local Host, standard interface). (3) Specialized Host-IMP interface hardware (cost depends upon charteristics of the Host machine): typically $10K to $15K. (4) Modification of the Host's executive software (again, cost depends upon the particular Host; typically, 4 to 12 man-months of system programming required). Recurring Costs: (1) Maintenance: $5K per year for 316 IMP; $7K per year for TIP. (2) Use of communications subnetwork: $16.5K per year plus 30 cents per Kilopacket of internodal traffic in excess of 4500 Kp in a single month. |