The standardization of the broadband integrated services digital network (B-ISDN) is reviewed. The key component of the B-ISDN technology is the asynchronous transfer mode (ATM) of transmission, which is briefly described. The adoption of the ATM as a switching technology for twisted pair wires and other LAN transmission media is carefully explained, and the authors indicate that the transmission medium does not have to be optical, although the use of the synchronous optical network (SONET) was initially advocated for B-ISDN due to the low bit error rates and high bandwidth potential of optical transmission. This information is essential because transmission media that support bandwidths that are inferior to SONET are already implanted in the marketplace.

The thrust of the paper is a discussion of the recent changes in the control, user, and management planes of the B-ISDN protocol reference model. Three figures and two tables are given. The tables list the B-ISDN documents released by the CCITT and ANSI and also the restructuring of ANSI T1.105, and the figures present the bit structures of the ATM cell headers, the configurations for shared medium applications, and the ATM adaptation layer. The physical layer description concentrates on SONET and its modified version, the synchronous digital hierarchy (SDH). The sublayers of the physical layer--the ATM layer and the ATM adaptation layer--are explained in terms of their states of standardization and some of their major open issues. The three releases that explain the signalling needed to establish B-ISDN calls are also mentioned. The paper also addresses the need for accurate synchronization of clocks due to the high data rates and the numerous network nodes. Because the complete set of standards for B-ISDN is not yet available, the discussions are not based on protocol procedures but on rates and formats.