At the same time, budgeting for intra-university ATM network systems for universities through-out the country and for a new ATM switching system for connecting these intra-university ATM network systems to NACSIS was authorized by the first revised budget. As a result, the Science Information Network will operate at even higher speeds and its functions will be even more sophisticated than before.
In view of these conditions, the improvements and additions to be made to the Science Information Network during the course of the current year will be as described below.
Changes in domestic network circuit configuration
As shown in Fig. 1, the physical and theoretical circuit con-figuration resulting from the improvements and additions to the circuits will consist of three loops: central Japan loop (NACSIS, University of Tokyo, Nagoya University, Osaka University, Kyoto University, and University of Tsukuba), northern Japan loop (Hokkaido University, Tohoku University, Niigata University and Kanazawa University), and western Japan loop (Kobe University, Hiroshima University, Kyushu University, Kumamoto University and Ehime University). Other node universities will be arranged in a star-shaped configuration around the node universities in the loops.
The theoretical virtual path between SINET routers will employ an ATM full mesh for the central Japan loop, and frame relay full meshes for the northern and western Japan loops. It will enable communication to be controlled more flexibly than with the existing loop configuration while reducing overheads for relays and vulnerability to trouble and node stoppages.
Introduction of ATM switching system and upgrading of SINET routers
In order to support the ultra-high-speed operation of the Science Information Network and connect the intra-university ATM network systems, plans call for the introduction of new ATM switching systems at both the 28 node institutions nationwide and at NACSIS, and preparations are now underway to procure these systems. This will serve to construct an ATM switching network by integrating the internet backbone (SINET) com-munication network with the packet switching network.
Furthermore, in order to increase the subscriber institutions and support the ultra-high-speed circuits, high-speed SINET routers featuring high-grade functions and incorporating silicon processors and FDDI interfaces will be additionally provided in 7 node institutions (University of Electro-Communications, Chiba University, Yokohama National University, Niigata University, Kobe University, Ehime University and Kumamoto University).
Furthermore, silicon processors and FDDI interfaces will be added to the existing SINET routers both at the 9 main node institutions (Hokkaido University, Tohoku University, University of Tsukuba, University of Tokyo, Nagoya University, Kyoto University, Osaka University, Hiroshima University and Kyushu University) and at NACSIS. This will make it possible to connect the intra-university LANs using the FDDI interfaces.
The SINET router upgrading is scheduled for December 1995. Reference should be made to Fig. 2 for details on the configuration of the node equipment.
International leased circuits
The international leased circuits between Japan and the United States were upgraded from 2 Mbps to 6 Mbps in July. Starting in September, a new international leased circuit will be installed between Japan and Thailand.
