Evaluation of the availability, quality, performance and possible applications on narrowband-ISDN

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The ISDN (Integrated Services Digital Network) is becoming increasingly important for both data and non-data communications. For the evaluation of ISDN functionality and services in the area of ESA's communications requirements the ESA Computer and Network operations Department has built an ISDN testbed at ESTEC. This report describes results of testing and evaluation of availability and quality of national and international ISDN bearer channels. ISDN channels seem an efficient and flexible alternative for leased lines. A cost-comparison between ISDN and dedicated leased lines is also presented. Secondly, several applications using the ISDN network have been evaluated. The digital ISDN lines offer a bigger capacity than existing analog telephone lines and therefore several new applications can be used. Typical applications are the interconnection of LANs and desktop applications like filetransfer, fax and videoconferencing. Measured performance of LAN-to-LAN connections has been compared to theoretical values that have been calculated.