John Heidemann

Modelling the Performance of HTTP Over Several Transport Protocols

TitleModelling the Performance of HTTP Over Several Transport Protocols
Publication TypeUnpublished
Year of Publication1996
AuthorsJ. Heidemann, K. Obraczka, and J. Touch
Date Publishednov

This paper considers the interaction of HTTP with several transport protocols, including TCP, Transaction TCP, a UDP-based request–response protocol, and HTTP with persistent TCP connections. We present an analytic model for each of these protocols and use that model to evaluate network overhead carrying HTTP traffic across a variety of network characteristics. This model includes a analysis of the transient affects of TCP slow-start. We validate this model by comparing it to network packet traces measured with two protocols (HTTP and persistent HTTP) over local and wide-area networks. We show that the model is accurate within 5% of measured performance for wide-area networks, but can underestimate latency when the bandwidth is high and delay is low. We use the model to compare the connection-setup costs of these protocols, bounding the possible performance improvement. We evaluate these costs for a range of network characteristics, finding that setup optimizations are relatively unimportant for current modem, ISDN, and LAN users but can provide moderate to substantial performance improvement over high-speed WANs. We also use the model to predict performance over future network characteristics.