Web Traffic Latency: Characteristics and Implications

It is critical to understand WWW latency in order to design better HTTP protocols. In this study we c haracterize Web response time and examine the eeects of proxy caching, network bandwidth, traac load, persistent connections for a page, and periodicity. Based on studies with four workloads, we show that at least a quarter of the total elapsed time is spent on establishing TCP connections with HTTPP1.0. The distributions of connection time and elapsed time can be modeled using Pearson, Weibul, or Log-logistic distributions. Response times display strong daily and weekly patterns. We also characterize the eeect of a user's network bandwidth on response time. Average connection time from a client via a 33.6 K modem is two times longer than that from a client via switched Ethernet. We estimate the elapsed time savings from using persistent connections for a page to vary from about a quarter to a half. This study nds that a proxy caching server is sensitive to traac loads. Contrary to the typical thought about Web proxy caching, this study also nds that a single stand-alone squid proxy cache does not always reduce response time for our workloads. Implications of these results to future versions of the HTTP protocol and to Web application design are discussed.