The Use of Session Control in DAVIC to Provide Interactive Multimedia Services
Richard B. Miles, Paul Reece, Laurent Boon · 2001
Chapter 10 introduces DAVIC, its objectives and plans. It then considers the split of the functional model into the three roles; service consumer system, delivery system and service provider system. Once the vertical split of the functional model has been considered, the horizontal split into S1–S4 levels is covered. The chapter expands on the concepts of session and connection control through the use of the S2, S3 and S4 levels in the set-up, transfer and release of a user to network session, and the end-to-end control of the user-to-user session. Finally, the future plans/directions for DAVIC and the adoption of Internet technologies within the DAVIC specifications are considered. As the telecommunications industry evolves, and broadband services start to arrive, customers are increasingly coming to expect the perception of instantaneous access to service providers, together with transparency to network failures. System performance dictates that response times need to be minimised, sufficient redundant capacity be installed in case of failure, and controls be embedded within the design to manage the exceptional situations (such as media stimulated events) that continually threaten network integrity. A vital part of this system is the broadband signalling network, which underpins the dialogue with the customer, and which enables the delivery of the service. Network design based on a ‘top-down’, ‘end-to-end’ methodology plays a fundamental role in delivering solutions that meet customers' performance needs. Simple, approximate performance models at an early stage in this lifecycle are valuable to uncover major performance problems which affect the design of the architecture. Performance issues identified can then be fed back into the design process in an iterative way, to ensure that the design solution will conform to performance requirements.