Microsoft's CDN Analysis: Akamai vs. Limelight

Could an additional five data center locations level the playing field between content delivery network (CDN) market leader Akamai Technologies and its leading rival, Limelight Networks? That's the intriguing question raised by researchers at Microsoft, who have published a detailed analysis of the two companies' delivery networks (link via Dan Rayburn).

Microsoft found small performance differences between the two CDN providers in North America, but a "big gap in performance" in Europe and Asia, where Akamai has more data centers than Limelight. The researchers identified 27,000 content servers in Akamai's global network, compared to just 4,100 for Limelight. But the Microsoft researchers suggested that the gap between the two isn't nearly as vast as those numbers might suggest.

"By learning from Akamai’s existing deployment, a few more data centers can dramatically reduce the delay and make Limelight on par with Akamai," they wrote. "For instance, 5 more data centers can reduce the delay to about 10% of Akamai and 9 more is enough to match Akamai."

Chicago would be the best location for Limeight to place additional data center infrastructure, the researchers conclude, followed by Tokyo, Frankfurt, San Jose, Washington, D.C. and Singapore.

The paper, titled "Measuring and Evaluating Large-Scale CDNs," compared the "radically different" design philosophies of Akamai (AKAM) and Limelight (LLNW) in building their networks. The Microsoft researchers charted the location of both companies' content caching and DNS servers, and tracked their performance over a two-month period. The document is quite detailed, and includes many caveats about its methodology and conclusions, which are bound to be discussed in the industry in coming days.

The analysis will be of special interest to users of content delivery networks, as well as the many companies seeking to challenge Akamai and Limelight. "Our measurement techniques can be adopted by CDN customers to independently evaluate the performance of CDN vendors," the paper notes. "It can also be used by a new CDN entrant to choose an appropriate CDN design and to locate its servers."

Microsoft has more than an academic interest in the optimal design for global content delivery, as it is building its own CDN, with Limelight providing software and engineering support.