Web Caching and Replication

7.3. Bandwidth Savings

Another major reason for using proxy caching is reduction in bandwidth consumption. Reducing bandwidth consumption not only has the obvious advantage of reducing the overall cost of a network, but it also reduces link- and origin-server utilization and therefore indirectly decreases latency. As a back-of-the-envelope calculation, HTTP constitutes over 60 percent of traffic on the AT&T Worldnet backbone. About 70 percent of traffic due to HTTP was reported on the MCI backbone [Claffy et al. 1998], and a study of cable modem clients found HTTP responsible for close to 90 percent of traffic [Arlitt et al. 1999]. Given the 30 to 40 percent byte hit rate reported for large proxies [Wolman et al. 1999b; Feldmann et al. 1999