OCTOBER 1981 LIDS-R-1158 COMMUNICATION, DATA BASES & DECISION SUPPORT Edited By Michael Athans Wilbur B. Davenport, Jr. Elizabeth R. Ducot Robert R. Tenney Proceedings of the Fourth MIT/ONR Workshop on Distributed Information and Decision Systems Motivated by Command-Control-Communications (C3) Problems Volume ilI June 15 - June 26, 1981 San Diego, California ONR Contract No. N00014-77-C-0532 Room 14-0551 MIT Document Services 77 Massachusetts Avenue Cambridge, MA 02139 ph: 617/253-5668 1fx: 617/253-1690 email: docs @ mit.edu http://libraries.mit.edu/docs DISCLAIMER OF QUALITY Due to the condition of the original material, there are unavoidable flaws in this reproduction. We have made every effort to provide you with the best copy available. If you are dissatisfied with this product and find it unusable, please contact Document Services as soon as possible. Thank you. PREFACE This volume is one of a series of four reports containing contri- butions from the speakers at the fourth MIT/ONR Workshop on Distributed Information and Decision Systems Motivated by Command-Control-Communication (C3 ) Problems. Held from June 15 through June 26, 1981 in San Diego, California, the Workshop was supported by the Office of Naval Research under contract ONR/N00014-77-C-0532 with MIT. The purpose of this annual Workshop is to encourage informal inter- actions between university, government, and industry researchers on basic issues in future military command and control problems. It is felt that the inherent complexity of the C 3 system requires novel and imaginative thinking, theoretical advances and the development of new basic methodol- ogies in order to arrive at realistic, reliable and cost-effective de- signs for future C3 systems. Toward these objectives, the speakers, in presenting current and future needs and work in progress, addressed the following broad topics: 1) Surveillance and Target Tracking 2) Systems Architecture and Evaluation 3) Communication, Data Bases & Decision Support 4) C 3 Theory In addition to the Workshop speakers and participants, we would like to thank Dr. Stuart Brodsky of the Office of Naval Research, and Ms. Barbara Peacock-Coady and Ms. Lisa Babine of the MIT Laboratory for Information and Decision Systems for their help in making the Workshop a success. Cambridge, Massachusetts MichaeZ Athans October 1981 Wilbur B. Davenport, Jr. Elizabeth R. Ducot Robert R. Tenney III COMMUNICATION, DATA BASES & DECISION SUPPORT FOREWORD ............................................... iv RELIABLE BROADCAST ALGORITHMS IN COMMUNICATIONS NETWORK Professor Adrian SegallZZ ..................................... 1 THE HF INTRA TASK FORCE COMMUNICATION NETWORK DESIGN STUDY Drs. Dennis Baker, Jeffrey E. Wieselthier, and Anthony Ephremides .................................... 7 FAIRNESS IN FLOW CONTROLLED NETWORKS Professors Mario Gerla and Mark Staskaukas ................ 31 PERFORMANCE MODELS OF DISTRIBUTED DATABASE Professor Victor O.-K. Li ................................. 37 ISSUES IN DATABASE MANAGEMENT SYSTEM COMMUNICATION Mr. Kuan-Tsae Huang and Professor Wilbur B. Davenport, Jr. .. 47 MEASUREMENT OF INTER-NODAL DATA BASE COMMONALITY Dr. David E. Corman ........................................ 73 MULTITERMINAL RELIABILITY ANALYSIS OF DISTRIBUTED PROCESSING SYSTEMS Professors Aksenti Grnarov and Mario GerZa ................. 93 FAULT TOLERANCE IMPLEMENTATION ISSUES USING CONTEMPORARY TECHNOLOGY Professor David Rennels ........................... 123 APPLICATION OF CURRENT AI TECHNOLOGIES TO C2 Dr. Robert BechtaZ ....................................... 143 ~~~ -^---------~~~~~~~~~~~~~~~~14311 A PROTOCOL LEARNING SYSTEM FOR CAPTURING DECISION-MAKER LOGIC Dr. Robert BechtaZ .................................... ..... 151 ON USING THE AVAILABLE GENERAL-PURPOSE EXPERT-SYSTEMS PROGRAMS Dr. CarroZZ K. Johnson ...................... 155 --1e1- e COMMUNICATION, DATA BASES AND DECISION SUPPORT FOREWORD As in the companion volumes, the papers included in this volume are not in the order of their presentation at the Workshop, but rather are grouped according to theme. The corresponding talks were, in fact, scattered over five different days of the ten day Workshop. The first three papers in this volume concentrate on C communica- tion issues: SegaZZ's paper first reviews the present status of broad- cast routing algorithms for communication networks from the standpoint of reliability and efficiency, and thenpresents an adaptive tree broad- cast algorithm designed to be both reliable and efficient. The next paper by Baker, et. al., first describes the requirements for, and design constraints placed upon, the HF Intra-Task Force Communication Network, and then gives a distributed algorithm that is designed to allow Task Force nodes to organize themselves into an efficient network structure. Finally, a paper by Gerla and Staskanskas addresses the issue of fair- ness in routing and flow control algorithms. The next five papers concern database and distributed processing issues in C2 systems: Li's paper discusses a five-step approach to the modeling of the performance of concurrency control algorithms used in distributed databases. Next, the Huang and Davenport paper discusses the communication problems associated with nonintegrated, heterogeneous and distributed database management systems. Corman's paper presents the results of an analysis designed to establish the general requirements for internodal database commonality so as to obtain effective coordi- nation of Over-the-Horizon Targeting tactical operations. The Grnarov and GerZa paper presents a novel multiterminal reliability measure that reflects the connections between subsets of resources in a system composed of distributed processors, a distributed database and communications. Finally, RenneZs paper discusses fault-tolerance problems concerning systems using contemporary LSI & VLSI technology; both from the view- point of fault-detection, recovery and redundancy within component -iv- computers and from the viewpoint of the protection of sets of computers against faults. The last three papers in this volume relate to decision support systems: First, BechteZ reviews the application of current artificial intelligence technologies to C2 systems and then, in his second paper, discusses the early stages of work directed towards the development of a protocol learning system that attempts to capture the logic used by human decision makers. Lastly, Johnson's paper gives a comparison and evaluation of the various presently available general-purpose expert- systems programs. _v_ RELIABLE BROADCAST ALGORITHMS IN COMMUNICATION NETWORKS BY Adrian Segall Department of Electrical Engineering Technion, Israel Institute of Technology Haifa, IsraeZ This work was conducted on a consulting agreement with the Laboratory for Information and Decision Systems at MIT with support provided by the Office of Naval Research Under Contract ONR/NOOOZ4-77-C-0532. 1. Introduction Broadcast multipoint communication is the delivery of copies of a message to all nodes of a communication network. C3 - oriented communication network, as well as civilian networks, often require broadcasts of messages and the purpose of this paper is to first survey the existing broadcast algorithms and second to introduce a new algorithm that has the advantage of combining reliability and efficiency, properties that are of major importance to C3 - systems. Many subscribers of a C3 - communication network, whether they are ships, aircraft, Marine Corps units, etc., are mobile, and their location and connectivity to the network may change frequently. Whenever such a change occurs and the user needs to connect to a new network node, this information must be broadcast to all nodes, so that the corresponding directory list entry can be updated. Broadcast messages are used in many other situations, like locating subscribers or services whose current location is unknown (possibly because of security reasons), updating distributed data bases, transmitting battle information and commands to all units connected to the communication network, and in fact in all cases when certain information must reach all network nodes. There are certain basic properties that a good broadcast algorithm must have and the most important, especially for C3 - systems, are: a) reliability, b) low communication cost, c) low delay, d) low memory requirements. Reliability means that every message must indeed reach each node, duplicates, if they arrive at a node, should be recognizable and only one copy accepted, and messages should arrive in the same order as transmitted. The reliability requirement is important in both civilian and military networks, but in the latter type it is much more difficult to satisfy, since changes in network topology are more likely to occur because of enemy actions and mobility of network nodes. Communication cost is the amount of communication necessary to achieve the broadcast and consists of, first, the number of messages carried by the network per broadcast message, second, the number of control messages necessary to establish the broadcast paths and, third, the overload carried by each message. Low delay and memory are basic requirements for any communication algorithm, and broadcasts are no exception. 2 2. Broadcast algorithms - a brief survey A detailed survey of the existing broadcast algorithms appears in [1]; we shall give here a brief description of the most important ones and of their main properties. (i) Separately addressed