A research study submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Advanced Technologies

Research Studies Project Report (M. Eng.) - Asian Institute of Technology, 1997

In 1988, ITU-T included in its I-series Recommendations provisions on B-ISDN while preserving the concept of one global ISDN. However, not only was B-ISDN a "faster" ISDN but was also a totally different ISDN. It is based on a totally different technology compared to N-ISDN. At this time when both networks have been and will be, for the next couple of decades or so, co-existing, issues regarding the interworking between the two is now being discussed by various players in the communications industry. Not only for the reason of abiding to the concept of "one global ISDN" are these issues considered but most importantly because the end-users consider these as an essential requirement. This paper covers the issues involve in an interworking situation. Even in the advent of B-ISDN users would want to continue using N-ISDN services. The two realization principles, in providing narrowband services to a B-ISDN user, are described in this paper. Another important issue in interworking, is addressing. A numbering/addressing scheme for ISDN was identified by ITU-Tin 1989. However, B-ISDN currently uses three addressing scheme implementations: OSI NSAP, E.164, or both. This issue will be considered in this paper to provide the basis on how the disparate addressing schemes (E.164 and OSI NSAP) is related. This paper identifies the NSAP format E.164, which is what is preferred by the ATM Forum to be used in ATM based networks (B-ISDN). Generally, this work outlines the interworking between N-ISDN and B-ISDN with particular consideration on supporting service interworking and address mapping to support end-to-end communication between entities within the domain of the these ISDN's.