Enabling Live Internet Broadcasting Using an Application Endpoint Architecture

摘要

It has been a long-standing challenge to make Internet audio/video broadcasting a commodity service. This means that anyone with a commodity Internet connection and computer equipment can broadcast high-quality video to a large group of receivers in real time. The key challenge is the bandwidth cost in distributing the video streams. To distribute 300 Kbps video stream to 100 receivers directly, a publisher must provision 30 Mbps bandwidth to the Internet. This is too expensive for most individuals to afford. The conventional wisdom is to add functionality in the underlying network infrastructure (i.e., at the IP layer). With IP Multicast, the publisher sends just one copy of the video stream to the IP network, and the network intelligently replicates the video streams to all the receivers. By shifting the task of data replication to the IP routers, IP Multicast greatly reduces the bandwidth requirements for the publishers and receivers. However, 15 years after its initial proposal, IP Multicast is still plagued with concerns pertaining to scalability, network management, deployment, and support for higher level functionality. This dissertation takes a different architecture approach to meet the challenge in broadcasting high quality video over the Internet. The author's thesis is that it is feasible today to provide video broadcasting as a commodity service, without changing the underlying IP infrastructure. He proposes a new architecture called End System Multicast. In End System Multicast, data replication is performed not by the routers, but by the receivers in the broadcast, which are end systems on the Internet. Thus, the publisher only needs to send the video stream to a few receivers, and these receivers iteratively forward the video streams to other receivers. This avoids costly bandwidth provisioning for the publisher and requires no changes to the IP infrastructure.