Co-operative Proxy Caching Algorithms for Time-Shifted IPTV Services

The increasing popularity of multimedia streaming applications introduces new challenges in content distribution networks. Streaming services such as video on demand (VoD) or digital television over the Internet (IPTV) are very bandwidth-intensive and cannot tolerate the high delays and poor loss properties of today´s Internet. To solve these problems, caching (a sliding segment of popular streams at proxies could be envisaged. This paper presents a novel caching algorithm and architecture for time-shifted television (tsTV) and its implementation using the IETF´s real-time streaming protocol (RTSP). The algorithm uses sliding caching windows with sizes depending on content popularity and/or distance metrics. The caches can work in stand-alone mode as well as in co-operative mode. This paper shows that the network load can already be reduced considerably using small diskless caches, especially when using cooperative caching. A brief overview of the functionality of a prototype proxy implementation is presented as well