REVIEW: Globally Distributed Content Delivery

REVIEW: Globally Distributed Content Delivery

The paper discusses the design goals and imlementation challenges of
deploying the Akamai network, a worldwide distributed content distribution
network. The Akamai network aims at solving the "flash crowd" problem at
web sites, based on the observation that serving web content from a single
location can present serius problem for site scalability, reliability and
performance. It is a single point of failure. It is observed that even the
use of clusters with mirroring and multihoming is unsuccessful at fully
addressing these problems.
The Akamai network employs two levels of DNS servers (top and low), edge
servers (caches) as well as entry point servers for streaming media.
Customers of Akamai have their content replicated into the network and
direct clients to Akamai whenever these wish to access this content.
Akamai DNS servers work together to direct the user to its nearest edge
server that is available and likely hosts the content.

The success of Akamai lies in its ability to quickly determine the most
optimal server for each user as well as providing robust solutions to its
customers. Cleverly, their agents make use of the Border Gate Protocol
(BGP) which allows them collect network information from border routers.
They also maintain a distributed monitoring systems that allows for up to
date decisions on where requests should be routed.
A major stregth of Akamai over other caching systems is that by working
with content providers they can provide dynamic content, through the use
of the Edge Side Include (ESI), reducing bandwidth consumption on their
customers by up to 99%.

In the paper it is specified that in resolving a domain query Akamai DNS
servers also make use of the type of service requested (i.e. HTTP, Real
Media streaming, etc) to select a server that provides such service. It is
not clear, however how the service requested is determined since DNS
queries do not carry any service information.

It is worth noting, however, that this is paper written by Akamai
Technologies staff and is thus geared to highlight Akamai's innovative
features.
Received on Thu Oct 06 2005 - 09:41:02 EDT