A systems approach to network security in private ISDN

The point of departure was the use of commercially available ISDN terminals and switching equipment and applying network security measures as add-on units. This approach could be used meaningfully by any network operator or user, as determined by individual security requirements, for implementing (or migrating) to a transparent secure network, with ease of use and maximum availability of features. This paper emphasises the system issues, rather than the implementation details. The layered ISDN model is discussed, with the considerations for placement of security services. End-to-end and link-oriented security measures are compared. Security in the terminal, switch and transmission systems is discussed. Key distribution and network management implications are referred to