Today's Web interactions are frequently short, with an increasing number of responses carrying only control information and no data. While HTTP uses client-initiated TCP for all Web interactions, TCP is not always well-suited for short interactions. Furthermore, client-initiated TCP handicaps the deployment of interception caches in the network because of the possibility of disrupted connections when some client packets bypass the cache on their way to the server. We propose a new transfer protocol for Web traffic, called dual-transport HTTP (DHTTP), which splits the traffic between UDP and TCP channels. When choosing the TCP channel, it is the server who opens the connection back to the client. Among important aspects of DHTTP are adapting to bottleneck shifts between a server and the network and coping with the unreliable nature of UDP. The comparative performance study of DHTTP and HTTP using trace-driven simulation as well as testing real HTTP and DHTTP servers showed a significant performance advantage of DHTTP when the bottleneck is at the server and comparable performance when the bottleneck is in the network. By using server-initiated TCP, DHTTP also eliminates the possibility of disrupted TCP connections in the presence of interception caches thereby allowing unrestricted caching within backbones.
['Michael Rabinovich', 'Hua Wang']
DHTTP: an efficient and cache-friendly transfer protocol for Web traffic