Web Transport Protocol Performance
Abstract
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
gravano@cs.columbia.edu