Koji Nakamichi

The large capacity ATM backbone switch “FETEX-150 ESP”

The ATM (Asynchronous Transfer Mode) network is regarded as effective for a multimedia telecommunication environment that enables high-speed and broadband communication. This paper reports on the system architecture and design concept of the FETEX-150 ESP (Enhanced Switching Platform) which has been designed as an ATM switch in a public broadband network. To track the latest ATM standards and trends, a simple, scalable, and open architecture was set forth for the FETEX-150 ESP design target at the beginning of the system design. This paper also describes the method for traffic management to support various traffic classes.

Voice quality management for IP networks based on automatic change detection of monitoring data

Recently, quality management of IP networks has become an important issue with the development of real-time applications such as IP-phones, TV-conferencing and video-streaming. Specifically, when voice data is mixed with various application data, there are worries that there will be a critical degradation in voice quality. In current management of voice quality, the general scheme is to monitor the voice quality using a preset threshold for the data. However, its not easy to set a proper threshold for data monitoring in each case, because the characteristics of the monitoring data become more diverse as networks become larger in scale and more complex. We propose an automatic change detection scheme that detects changes in the behavior of the monitoring data with changes in the traffic conditions, without any preset threshold. The essential concept of our scheme is the application of a statistical scheme to sequential data monitoring. We also demonstrate the effectiveness of our proposed scheme when applied to voice quality management.

Analysis of ABR behavior over ATM-based broadband access networks

There has been an enormous growth in the popularity of the Internet. The provisions of access to the Internet will be one of the principal services of the next generation of access networks. In order to provide cost effective Internet access over ATM-based broadband access networks, the introduction of an available bit rate (ABR) service class is a promising solution. This paper describes our analysis of the ABR behavior over ATM based access networks focusing on explicit-rate-based rate controls and their round-trip time effects. We also describe the hardware implementation of the ABR-based rate controls.

Performance evaluation of TCP over ATM using World Wide Web traffic

We propose a new explicit-rate (ER) available bit rate (ABR) algorithm (load-based explicit rate control, or LBERC) that can maintain high link utilization and reduce congestion in asynchronous transfer mode (ATM) networks. In order to evaluate the algorithm, we model World-Wide Web (WWW) traffic using the file transfer distribution of the SPECweb96 benchmark. We simulate Web traffic via a client-server model that consists of Web clients, Web servers, and a finite source function (FSF) to represent client (user) behavior. When network congestion occurs, users access fewer Web pages (and open fewer new transmission control protocol (TCP) sessions). The FSF simulates this user behavior by counting the number of active TCP sessions. We present TCP-over-ABR/LBERC simulation results to verify the compatibility of interactions between TCPs window-based flow control and ABRs rate-based flow control.