Web Transport Protocol Performance

Joe Touch
USC Information Sciences Institute


Existing Internet transport protocols have been optimized for stability, fairness, and efficiency for long-duration transfers.  These protocols can be particularly inefficient for Web transactions, which have characteristics not found in earlier application streams.  This talk summarizes work in the Large-Scale Active Middleware (LSAM) project to increase the efficiency of web transport.  We describe the characteristics of web transactions, and how they differ from previous transport regimes. These characteristics result in inefficiencies at various levels in the protocol system - at congestion control (e.g., TCP slow-start), protocol state management, and connection management. We present solutions to these problems, including packet pacing, TCP state machine augmentation, and control block sharing. We also present solutions to implementation errors that web analysis only recently revealed. We conclude by presenting a constellation of modifications, called "TCP del Rey", that enable efficient web transactions over TCP, much like the Nagle modifications enable efficient telnet sessions.

Luis Gravano