Ikuo Tokizawa

Bio: Ikuo Tokizawa is an academic researcher. The author has contributed to research in topics: Asynchronous Transfer Mode & Broadband networks. The author has an hindex of 9, co-authored 16 publications receiving 764 citations.

Broad-band ATM network architecture based on virtual paths

Abstract: Broadband transport techniques and network architectures based on the virtual path concept are examined. ATM (asynchronous transfer mode) techniques, when coupled with recent technological innovations, are expected to pave the way for future universal transport networks. The virtual path concept, which exploits the ATM's capabilities, is proposed to construct an efficient and economic network. The concept matches current and anticipated technological trends well. Characteristics and implementation techniques of virtual paths are discussed. Advantages of the virtual path concept and its impact on the transport network architecture are demonstrated. The virtual path strategy is also shown to provide efficiently for networks with dynamic reconfiguration capability which will enhance network performance. Some basic analytical results on the dynamic control effects of virtual paths are provided. >

Self-healing ATM networks based on virtual path concept

Abstract: This paper proposes self-healing network techniques suitable for ATM networks in order to realize a high-reliablity B-ISDN. First, the characteristics of the virtual paths (VP) and their influence on failure restoration are discussed. A high-speed restoration technique which exploits the benefits of the VP is then proposed and described. The technique simplifies the message transmission processes and reduces the number of generated messages by using preassigned backup virtual paths. Next, the scheme used to design the backup VP routes and spare resource distribution for each link is proposed in order to create a network that applies the proposed restoration scheme. Next, self-reconstruction techniques of backup virtual paths are proposed for the realization of a reversionless restoration cycle. Finally, the feasibility of the distributed control operation is discussed. >

Flexible asynchronous transfer mode networks utilizing virtual paths

Abstract: The effect of virtual paths in ATM (asynchronous transfer mode) networks is investigated. The virtual path concept has been proposed as the key technique in enhancing network performance. The impact of the virtual path scheme on transport network architecture and systems is demonstrated in comparison to the digital path scheme in STM-based networks. One of the outstanding virtual path benefits, increased network flexibility, is highlighted. It is shown that dynamic network reconfiguration capability is effectively provided with the virtual path scheme. Some analytical results on the adaptive virtual path bandwidth control effects for multimedia traffic are provided. >

A new transport network architecture based on asynchronous transfer mode techniques

Abstract: The authors explore an information transport network architecture based on ATM (asynchronous transfer mode) techniques. ATM-based networks, when coupled with recent technological innovations, are expected to open the way to credible solutions to the problem of constructing universal transport networks. Multiplexing and transport aspects of ATM have a great impact on network architectures because of their flexibility and capability to meet virtually any service demand. A philosophy is presented of a future transport network architecture in which the ATM's capabilities will be exploited to construct an efficient and economical network. Important concepts in implementing the network are: introducing service-independent basic transport mechanisms; simplification of the network architecture by implementing the virtual path concept; providing highly distributed functions in a subscriber access network; and developing a universal interface. Based on these considerations, a model network is also proposed. >

A dynamically controllable ATM transport network based on the virtual path concept

Abstract: Studies were carried out on an ATM (asynchronous transfer mode) transport network based on the virtual path concept. An arrangement of node functions in this network is proposed in which the call set-up process is excluded from transit nodes. This leads to a reduction in node processing and simplification of equipment by specialization of transit node functions. Virtual path control is shown to bring benefits in efficiency and flexibility. Among them a transmission efficiency improvement due to bandwidth control, a simple three-value bandwidth control algorithm improves the efficiency considerably with only a slight processing increase. It is concluded that the virtual path concept can provide simple, economical, flexible, and high-performance networks. >

Routing, Flow, And Capacity Design In Communication And Computer Networks

Abstract: In network design, the gap between theory and practice is woefully broad. This book narrows it, comprehensively and critically examining current network design models and methods. You will learn where mathematical modeling and algorithmic optimization have been under-utilized. At the opposite extreme, you will learn where they tend to fail to contribute to the twin goals of network efficiency and cost-savings. Most of all, you will learn precisely how to tailor theoretical models to make them as useful as possible in practice. Throughout, the authors focus on the traffic demands encountered in the real world of network design. Their generic approach, however, allows problem formulations and solutions to be applied across the board to virtually any type of backbone communication or computer network. For beginners, this book is an excellent introduction. For seasoned professionals, it provides immediate solutions and a strong foundation for further advances in the use of mathematical modeling for network design. (Less)

Adaptive coevolutionary networks: a review

Abstract: Adaptive networks appear in many biological applications. They combine topological evolution of the network with dynamics in the network nodes. Recently, the dynamics of adaptive networks has been investigated in a number of parallel studies from different fields, ranging from genomics to game theory. Here we review these recent developments and show that they can be viewed from a unique angle. We demonstrate that all these studies are characterized by common themes, most prominently: complex dynamics and robust topological self-organization based on simple local rules.

Survey of traffic control schemes and protocols in ATM networks

Abstract: The authors survey a number of important research topics in ATM (asynchronous transfer mode) networks. The topics covered include mathematical modeling of various types of traffic sources, congestion-control and error-control schemes for ATM networks, and priority schemes to support multiple classes of traffic. Standard activity for ATM networks and future research problems in ATM are also presented. It is shown that the cell-arrival process for data sources can be modeled by a simple Poisson process. However, voice sources or video sources require more complex processes because of the correlation among cell arrivals. Due to the effects of high-speed channels, preventive control is more effective in ATM networks than reactive control. Due to the use of optical fibers in ATM networks, the channel error rate is very small. The effects of propagation delay and processing time become significant in such high-speed networks. These fundamental changes trigger the necessity to reexamine the error-control schemes used in existing networks. Due to the diversity of service and performance requirements, the notion of multiple traffic classes is required, and separate control mechanisms should be used according to the traffic classes. The priority scheme is shown to be an effective method to support multiple classes of traffic. >

Redundant trees for preplanned recovery in arbitrary vertex-redundant or edge-redundant graphs

Abstract: We present a new algorithm which creates redundant trees on arbitrary node-redundant or link-redundant networks. These trees are such that any node is connected to the common root of the trees by at least one of the trees in case of node or link failure. Our scheme provides rapid preplanned recovery of communications with great flexibility in the topology design. Unlike previous algorithms, our algorithm can establish two redundant trees in the case of a node failing in the network. In the case of failure of a communications link, our algorithm provides a superset of the previously known trees.

Call admission control schemes: a review

Abstract: Over the last few years, a substantial number of call admission control (CAC) schemes have been proposed for ATM networks. We review the salient features of some of these algorithms. Also, we quantitatively compare the performance of three of these schemes.