Translating scalable video streams from wide‐area to access networks
Campus-Wide Information Systems
Transmitting video over UDP has been considered advantageous because it allows for discarding of packets in favor of retransmissions, and sender-controlled timing. Using UDP has been criticized because it allows video streams to consume more than their fair share of bandwidth, which is typically associated with the back-off behavior of TCP. TCP-friendly algorithms are meant as a middle path. However, UDP delivery to end systems may still be prevented by firewalls or for other reasons, and TCP
... st be used. This in turn suffers from bandwidth fluctuations. Therefore, we investigate an architecture that separates the transfer of a video stream over long distances in a TCP-friendly transmission in the backbone and TCP transmission in access networks. In this paper, we consider a proxy server to translate the traffic and two straight-forward approaches for the translation of a layered video stream transmission from the TCP-friendly transport protocol to TCP. In the first approach, we look at two strictly decoupled transfers with unlimited buffers at the proxy. In the second approach, we consider a single-threaded proxy implementation that uses blocking TCP sockets and experiences backpressure for forwarding the data. We do not expect that one of these two approaches is by itself suited for the task, but investigating them will provide with insights in their basic functions and help in discovering appropriate modifications. For the investigation, we use an experimental approach where network behavior and content are emulated.