Programmable Active Networking supporting Next Generation Multimedia Services in Satellite Networks

Programmable Active Networking is one approach to providing open service engineering for telecommunications and networked services. The overall objective is to provide a platform which may be tailored to provide all the functionality required for many applications. Through the years a number of approaches have been developed, some of which have found substantial success, others are still in the research arena. The vision of Programmable Active Networking is to increase the systems flexibility and to allow components and services to evolve and develop, without vendors or operators needing to completely re-build their systems. From this aspect especially the space segment of satellite networks could take benefit. The first commercial regenerative satellite systems are now available, providing mainly switching services on the link layer; in future also IP routing functionality will become available. However, from the design of these satellite systems throughout their long time of operation the continuous development of multimedia services progresses significantly, coupled with rapidly and dynamically changing requirements to the underlying networks. As all these requirements cannot be foreseen during the design phase of satellite systems, Programmable Active Networking provides a mean for a dynamic adaptation of satellite networks to these newly arising requirements. During the installation of satellite networks Programmable Active Networking functionality is added to the various involved components, to satellite hubs, to satellite receiver equipment, or also to the space segment itself. This functionality will allow throughout the lifetime of operation of satellite components the remote uploading of new code and its execution in a specific environment. This new code could serve different purposes; for example it could add a new functionality, such as a newly available transcoder to be used for adapting multimedia streams to the characteristics of different satellite beams, or it could also transmit just a new policy for configuring an existing transcoding service. To optimally exploit its benefits, a careful design of Programmable Active Networking functionality for satellite networks is required and needs to especially consider aspects of security, performance and network operation. For example the distribution of active components could be abused for performing network attacks; consequently appropriate security functionality has to be included, like the authentication and integrity protection of the distributed code. To avoid the execution of malfunctioning code on sensitive components like the space segment, one should perform plausibility checks and run the code in protected environments like a Java sandbox. As processing power and memory are expensive especially in the space segment, resource intensive functionality needs to be executed in the ground segment whenever possible. To make the introduction of Programmable Active Networking as economically as possible, its design should be applicable to a broad variety of multimedia services.