An open (in the sense of extensible and programmable) architecture for IP telecommunications must be based on a comprehensive strategy for managing feature interaction. We describe our experience with BoxOS, an IP telecommunication platform that implements the DFC technology for feature composition. We present solutions to problems, common to all efforts in IP telecommunications, of feature distribution, interoperability, and media management. We also explain how BoxOS addresses many deficiencies in SIP, including how BoxOS can be used as a SIP application server.

We propose a new objective for network research: to build a fundamentally different sort of network that can assemble itself given high level instructions, reassemble itself as requirements change, automatically discover when something goes wrong, and automatically fix a detected problem or explain why it cannot do so.We further argue that to achieve this goal, it is not sufficient to improve incrementally on the techniques and algorithms we know today. Instead, we propose a new construct, the Knowledge Plane, a pervasive system within the network that builds and maintains high-level models of what the network is supposed to do, in order to provide services and advice to other elements of the network. The knowledge plane is novel in its reliance on the tools of AI and cognitive systems. We argue that cognitive techniques, rather than traditional algorithmic approaches, are best suited to meeting the uncertainties and complexity of our objective.

Testing commercial software is expensive and time consuming.Automated testing methods promise to save a great deal of time and money throughout the software industry.One approach that is well-suited for the reactive systems found in telephone switching systems is specification-based testing.We have built a set of tools to automatically test software applications for violations of safety properties expressed in temporal logic.Our testing system automatically constructs finite state machine oracles corresponding to safety properties, builds test harnesses, and integrates them with the application.The test harness then generates inputs automatically to test the application.We describe a study examining the feasibility of this approach for testing industrial applications.To conduct this study we formally modeled an Automatic Protection Switching system (APS), which is an application common to many telephony systems.We then asked a number of computer science graduate students to develop several versions of the APS and use our tools to test them.We found that the tools are very effective, save significant amounts of human effort (at the expense of machine resources), and are easy to use.We also dis-

A* is an experimental language designed to facilitate the creation of language-processing tools. It is analogous either to an interpreted yacc with Awk as its statement language, or to a version of Awk which processes programs rather than records. A* offers two principal advantages over the combination of lex, yacc, and C: a high-level interpreted base language and built-in parse tree construction. A* programmers are thus able to accomplish many useful tasks with little code. This paper describes the motivation for A*, its design, and its evolution. Experience with A* is described, and then the paper concludes with an analysis of that experience.>