/ Behcet Sarikaya / Professor
/ Senro Saito / Associate Professor
The Computer Communications Laboratory is involved with education and research on all aspects of computer communications. Ongoing projects in education include an SCCP project on Social Hyper-networking and two topdown courseware design projects one on High-speed Network Courseware Design for Synthetic Worlds and another on authoring system AuthCAL for topdown courseware development environments.
The social hyper-networking project aims at providing communication facilities such as electronic mail, voice mail, electronic conference, bulletin board, real time talk and facsimile. The AuthCAL project has the goal of providing an object oriented graphical user interface and programming tools to make some teaching materials. The high-speed network courseware project aims at designing graduate and undergarduate level courses to teach the basics of high-speed networking.
In research, all aspects of computer networking are being investigated. However, present interest areas are concentrated on:
We are doing collaborative research with several Japanese and foreign universities and research centers. In Japan, our partner researchers work in Shizuoka, Tohoku and Osaka Universities and the Advanced Institute of Communications in Sendai. Overseas, we collaborate with Protocol Test Center in Montreal, Canada; Sherbrooke University in Sherbrooke, Canada; Northern Telecom in Istanbul, Turkey; and Magdeburg University in Magdeburg, Germany.
The Computer Communications Laboratory presently has the following equipment and software systems:
Refereed Journal Papers
Syntax Notation-One(ASN.1) is a standard external data representation language used to define messages of application layer protocols. Its encoding rules, the Basic Encoding Rules (BER), are also international standards that define the encoding/decoding of data values into/from a transfer syntax. Various approaches to automating BER encoding/decoding are examined; in particular, two widely used software packages (ISODE and CASN1) are studied. A hardware BER encoder/decoder called VASN is presented. Performance of software and hardware approaches are evaluated on real instances of file transfer using a standard FTAM protocol. Benchmarks obtained from running CASN1 on one of the fastest workstations and from running VHDL simulations of VASN1 indicate the superiority of the hardware approach.
Verification of a test case for testing the conformance of protocol implementations against the formal description of the protocol involves verifying three aspects of the test case: expected input/output test behaviour, test verdicts, and the test purpose. We model the safety and liveness properties of a test case using branching temporal logic. There are four types of safety properties: transmission safety, reception safety, synchronization safety, and verdict safety. We model a test purpose as a liveness property and give a set of notations to formally specify a test purpose. All these properties expressed as temporal formulas are verified using model checking on an extended state machine graph representing the composed behaviour of a test case and protocol specification. This methodology is shown to be effective in finding errorss in manually developed conformance test suites.
Refereed Proceeding Papers
OSI conformance test design based on SDL-88 is introduced. Several steps in the design process are identified and shortly explained. Next, the method is extended to SDL-92. The technique used is to transform SDL-92 specifications into SDL-88 specifications. The transformations are applied to the access control system and the ODP trader specifications.
Doctoral Dissertations Advised
Thesis Advisor: S. Saito.
Grant for Scientific Research by the Ministry of Education, Science and Culture. No. 05302065.
Investigation report of improvment in the information and communication network of the gaverment office quarter, editing by Public Building Association, June, 1993.