Joachim Charzinski

Traffic properties, client side cachability and CDN usage of popular web sites

Web traffic measurement and modeling have contributed to understanding the effect of Web traffic on Internet resources since the 1990s. In the past years, a number of new Web features have gained more and more importance, e.g. content delivery networks (CDNs), increased amount of advertisement, personalization, usage tracking, client scripting and Web 2.0 style “mashups”. This paper uses active Web measurements to assess the efficiency of client side caching for modern Web sites, investigating some Web features in detail. As expected, we see that more than 50 % of the average downstream traffic volume is saved when loading a page using client side caching. More unexpected results comprise the actual distribution of cache effectiveness, varying between extreme and no reduction of traffic, the cachability of “Web bugs” and the variance between sites in cachable image pixels and CDN based files.

Resilient network admission control

Network admission control (NAC) limits the traffic in a network to avoid overload and to assure thereby the quality of service (QoS) for admitted flows. Overload may occur due to exceptional traffic demand, but it is mostly caused by redirected traffic due to link failures. Conventional NAC methods cannot cope with network outages and fail when they are needed most. This paper categorizes existing and new NAC methods and makes them resilient to network failures by a resilient resource management. We compare the efficiency of the NAC methods with and without resilience requirements and show that they have a significant impact on the required backup capacity when resilience is required.

Traffic, Structure and Locality Characteristics of the Web’s Most Popular Services’ Home Pages

Web pages have drastically evolved from single files with some links to very complex structures consisting of a multitude of elements which the user’s Web browser dynamically collects from a widely distributed crowd of servers. Analyzing active traffic measurements of the home pages to the 100 most popular services in the United States, this paper reveals that services nowadays show a large variation in characteristic measures such as the number of elements on a page, the amount of bytes a page consists of, and even the number and logical locations of servers contacted.