Broadband Integrated Service Digital Network (B-ISDN) is expected to support diverse applications ranging from low bit rate communications between terminals and host computers, to the broadcasting high resolution TV signals. One of the most promising approaches for the B-ISDN is the Asynchronous Transfer Mode (ATM) where all information (such as voice, data, image and video) is divided into fixed length data format, called cells, and these cells are asynchronously transmitted through the network. Because of the large number of bursty traffic sources that an ATM network is expected to support, a controlling network traffic becomes essential in providing a desirable level of network performance to its users. The reason why the ATM is considered to be the most promising technique for B-ISDN is reviewed in this paper. The congestion control methods that have been proposed so far are briefly surveyed and problems which must be solved for the implementation of the ATM network are cleared.

This paper reviews various switch architectures for Asynchronous Transfer Mode, which have been proposed and developed so far in Japan. The switch fabrics can be classified, owing to the arrangement of switch matrices and buffer memories, into four categories, input buffer switch, output buffer switch, shared buffer switch and crosspoint buffer switch. Those switches have their own advantages and disadvantages, which require additional effort to implement the switches for the practical network. This paper introduces examples of each category switch fabric and additional technical modifications to make it practical. Other general issues to construct ATM switch fabrics, such as non-blocking characteristics and path assignment within a multi-stage switch network, are also addressed. Furthermore, future directions in the ATM switch fabric is discussed.

This paper surveys and discusses traffic control in ATM networks. Traffic control can be classified into path level control, call level control and cell level control. The effectiveness and the remaining problems are clarified for each level of control. The emphasis is on research activities in this field in Japan.

ATM's bandwidth flexibility and high switching speed advantages have made it the preeminent solution to the B-ISDN. However, networks based on ATM suffer from phenomena not encountered in the STM network, e.g., cell loss, and cell jitter. For ATM to support varied media, problems arising from these phenomena must be resolved. This paper discusses techniques which enable ATM to support CBR, VBR voice, VBR video, and connectionless services. We determine the problems to be resolved for each service and discuss solutions. We focus on dejittering and clock recovery for CBR service, on talk-spurt synchronization for VBR voice, and on video frame synchronization and lost-cell compensation for VBR video service. We show experimental results for a prototype HDTV codec and terminal adapter. For connectionless service, we show that connectionless service should be supplied by the B-ISDN itself using message handlers which support message routing and addressing, i.e., connectionless service functions (CLSF), as described by the CCITT. We propose a network topology of message handlers, which reduces the routing database and avoids transit message handler overload. We show an example of system configuration for connectionless service.

Enhancing the ISDN (Integrated Services Digital Network) capability to cover broadband capacity will change the telecommunication world greatly. This paper discusses the way where telecommunication networks should be evolved, the main features of the ATM (Asynchronous Transfer Mode) based B-ISDN, and its basic structure principles with the close relationship to customers' demands. ATM will play a key role in technology toward the B-ISDN. This paper proposes a concept of "ATMization" as the next technical revolution step coming after "digitalization". Firstly, various customers' views are summarized as four evaluation factors, and the scheme of the B-ISDN to reflect these customers demands are discussed. Then, by clearing the role of B-ISDN as the transport infrastructure, it is proposed that service control and OAM information be transferred by the ATM infrastructure. Based on these considerations, basic structure of B-ISDN and four scenario elements toward the ATMized B-ISDN era are further proposed.