FUWA Yasushi


Study Summary

My research mainly involves computer networks and can be grouped into the following three areas.

The first is the actual design and construction of our university's campus network. This network is called the ULVAN (S-net) and is a ring type network suited for a campus network layout. The construction of the network began in 1984 and is currrently implemented at three of the Shinshu University campuses with over 400 computer connections in operation.

The main papers related to this work are given below.

  1. A Campus Network of Duplicate Ring Topology -S-net-,IEICE Trans.,Vol.J71-B,No.12, pp.1672-1681(1989)
  2. Utilization of the Shinshu University Campus Network -S-net-, IEICE Trans on Communications, Vol.E74,No.9,pp.2756-2764(1991)

My second area of interest is in the research of protocols suitable for high-speed networks. For this reason, I have analyzed the performance of a number of different protocols for ring type networks. By comparing the results of these analyses under various conditions for high-speed networks, I am able to study the characteristics of each protocol and determine the optimal protocol for a particular network environment.

The papers published in this area are given below.

  1. A Performance Analysis of Slotted Rings Based on the Register Insertion Method , IEICE Trans., Vol.J73-B-I,No.11,pp.813-824(1990)
  2. An Efficient Scheme of Slot Timing in Slotted Rings Based on the Register Insertion Method and Its Performance Analysis, IEICE Trans., Vol.J73-B-I,No.11,pp.813-824(1990)
  3. Register-Insertion Type Slotted Rings: A Performance Analysis, Proc. IEEE INFOCOM, pp.191-201(1991)
  4. A Performance Comparison of High--Speed Ring Networks with nodes having finite buffer capacity,IEICE Trans., Vol.J75-B-I,No.9,pp.575-586(1992)
  5. Performance Analysis of High-Speed Slotted Rings, Proc. IEEE Region 10 Conference, Tencon 92, pp.749-753(1992)
  6. Application of the Equilibrium Point Analysis to Ring Networks -Slotted Rings and Register Insertion Rings -, Proc. International Conference on Communication Technology (ICCT'94),pp.609-614(1994)
  7. A performance analysis of the slotted ring protocol for a voice/data integrated network environment,IEICE Trans.,VolJ78-B-I,No.1(1995)

My third area of interest is in the work of increasing the reliability of ring type networks. For this end, I am pursuing two topics of research. The first is a method for enabling the early detection of abnormal conditions in the individual devices connected to a network and the automatic initiation of self recovery procedures by their CPUs. The second proposal relates to watchdog timers for detecting faults in the CPU element itself and for performing self recovery.

The main publications in this area are given below.

  1. A Statistical Consideration about Validity of Watchdog Timers,IEICE Trans.,Vol.J71-D,No.11, pp.2414-2423(1988)
  2. Diagnosing Hang-Ups and Automatic Restoration for Nodes in Networks of Ring Topology, IEICE Trans.,Vol.J72-B-I,No.9,pp.730-740(1989)
E-mail : fuwa@cs.shinshu-u.ac.jp

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