B-ISDN (Broadband Integrated Services Digital Network)

The subject of B-ISDN came into being in the late 1980s, together with the concept of Asynchronous Transfer Mode (ATM). ATM is closely tied to high-speed packet switching by means of specialized switches implemented in hardware. Due to its high speed and packet structure, ATM technology was considered attractive to unify voice, data, and video services. A unification of these services over the telephone infrastructure was attempted earlier by a standards offering known as Integrated Services Digital Network (ISDN). Consequently, this new service unification was termed Broadband ISDN (B-ISDN). Although due to its origins, B-ISDN is sometimes closely tied to ATM technology, the term independently represents the vision of packet-based high-speed integration of voice, data, and video services. It is important that in this process, guarantees to satisfy different Quality-of-Service (QoS) needs (in terms of delay, loss, etc) required by voice, data, and video services are provided. In this vision, what is important is the unification, or integration of services; and the underlying technology is of secondary importance. As of the early 2000s, the technology to be employed in realizing this vision seems to have shifted from its origins of ATM. In this article, our emphasis is on B-ISDN as a service integration vision. Nevertheless, we will describe its original emphasis as the service offering of ATM as well as the path the industry seems to be taking in implementing this vision.