CSC2231 Review Akamai

Content Delivery Network (CDN) is a solution to deliver contents quickly
by pushing them to the edge servers of Internet. This paper reviews the
architecture, technologies as well as challenges of Akamai, which is one
of biggest CDNs. By using DNS redirection, Akamai directs client requests
to "nearest, available server likely to have the requested content".

The authors claim that Akamai wants to host applications on their global
networks in addition to provide contents. However, security and
maintenance are two hard problems. Although many techniques, for instance
virtual machines, are proposed to provide isolation between applications,
owners of applications still take the risk of losing commercial secrets.
In addition, system maintenance and software updates for applications are
even harder than updating contents in a global network. CDN companies
could not give application administrators full control to their machines.
And thus it may lead to long delay of failure recovery. Moreover, it is
unclear what applications are suitable for running on CDN. Front-ends may
be easier than back-ends since back-end databases usually require strong
consistency, and thus complex consistent protocols are needed between
different data centers. Above reasons explain why most of big companies
prefer to build their own distributed system to run their applications.

For selecting servers, Akamai considers many factors, including server
load, network condition, and client location. Akamai infers network
topology by BGP information. But it is hard to accurately measure network
conditions and predict load variation due to their quick changes. Some
related paper points out that frequent DNS lookup does not generally
result in better server choices. We also wonder whether current server
selection strategies are effective and what metrics are more important. In
addition, we are interested to know the DNS convergence speed in case of
network failure as well as machine failure.

Akamai owns a very large edge server system. In addition to hosting,
Akamai could further provide information based on its resources. For
example, it can monitor and measure current network conditions, and then
sell them to others. In other words, it could become a tool to aid others'
applications.
Received on Thu Oct 06 2005 - 01:08:12 EDT