Yallcast: A New Paradigm for Content Distribution

Abstract : Disappointing delays in deploying network-layer multicast have triggered recent interest in application-level multicast. Application-level multicast is an attractive and deployable alternative, because it requires no support from the underlying network. Instead, application software automatically creates an overlay distribution tree spanning all the participants of a multicast group. The efficacy of the overlay tree is essential for the usability and performance of an application-level multicast architecture. The Yallcast project has designed and implemented algorithms for overlay tree construction and maintenance. The algorithms are designed for rapid tree repair, and for continual refinement of the distribution tree over time, based on observed loss or latency performance. These algorithms have been evaluated through simulations and experiments within the framework of an application-level multicast architecture called Yoid.