Replication Strategies for Streaming Media

Large-scale, real-time multimedia distribution over the Internet has been the subject of research for a substantial amount of time. A large number of mechanisms, policies, methods and schemes have been proposed for media coding, scheduling and distribution. Internet Protocol (IP) multicast was expected to be the primary transport mechanism for this, though it was never deployed to the expected extent. Recent developments in overlay networks has reactualized the research on multicast, with the consequence that many of the previous mechanisms and schemes are being re-evaluated. This report provides a brief overview of several important techniques for media broadcasting and stream merging, as well as a discussion of traditional IP multicast and overlay multicast. Additionally, we present a proposal for a new distribution system, based on the broadcast and stream merging algorithms in the BitTorrent distribution and replication system. Rapporten ger en översikt över ett flertal mekanismer för multicast-distribution av strömmande media i IP-nät. Mekanismer för strömsammanslagning, schemaläggning och buffring presenteras. En diskussion kring s.k. overlay-nät och deras applikation till mediadistribution ges även. Vidare presenteras utökningar av BitTorrent-protokollet för mjuka QoS-garantier samt modifikationer av huvudalgoritmerna för att tillhandahålla strömmande tjänster.