Internetworking Integrated Services Digital Network

www.pragsoft.com Chapter 11: Integrated Services Digital Network 159 1-3 Q.701-Q.708 Message Transfer Part MTP Signaling System 7 4 Q.711-Q.714 Signaling Connection Control Part SCCP 4+ Q.761-Q.766 ISDN User Part IUP 4+ Q.791-Q.795 Operation, Admin and Maintenance OAM 1 X.21 Physical interface Packet Network 2 LAP-B Link access 3 X.25, X.75 Packet interface

11.6. Further Reading

Black 1989 and Freeman 1989 both contain introductory chapters on ISDN. Griffiths 1990, Helgert 1991, Stallings 1992, and Kessler 1993 provid detailed discussions of ISDN architecture, services, and protocols. Dickson and LLoyd 1992 discuss many of ISDN protocols within the context of the OSI model. Deniz 1993 describes the use of ISDN for interconnecting LANs. Lai 1989 provides a useful introduction to frame relay. Deatiled descriptions of frame relay applications and protocols can be found in Chen and Rege 1989, Smith, P. 1993, and Black 1994. www.pragsoft.com Chapter 13: Broadband ISDN and ATM 161

12. Broadband ISDN and ATM

This chapter describes Broadband ISDN B-ISDN and the transfer mode designed for its implementation: Asynchronous Transfer Mode ATM. ATM provides a means for fast switching and transmission at data rates required by B-ISDN services. It relies on the division of information into small fixed-size packets, called cells, and their demand-based transmission over optical fiber – hence the term asynchronous. We will first discribe some of the basic concepts underlying ATM, including its protocol architecture, and then discuss each of its layers in turn. We will also discuss the organization of ATM networks and their potential applications.

12.1. Broadband ISDN

Increasing market demand for data rates substantially greater than those supported by ISDN has lead to the notion of Broadband ISDN B-ISDN. By relying on optical fiber transmission systems, B-ISDN opens the door to a whole range of new applications e.g., high quality digital audio, real-time video, pay TV, video phone, high speed LAN connection with emphasis on interactivity and high speed transfer services. B-ISDN is developed as an evolution of ISDN and hence follows the same principles. This section provides an overview of B-ISDN, its services, and its protocol architecture.

12.1.1. B-ISDN Services

B-ISDN services are clasified into interactive and distribution services. Interactive services involve the bidirectional flow of user information between two subscribers or between a subscriber and a service provider. Interactive services are divided into three subcategories: • Conversational services involve real-time exchange of information such as sound, video, data, or entire documents. Typical examples include: video- telephony, video-conference, and high speed data transfer. Video-telephony is like the normal voice telephony service but also includes video capture, transmission, and display capabilities. Video-conference provides voice and video communication between two conference rooms or between a number of individuals.