The Cloud Computing paradigm involves the delivery of services utilizing a distributed set of assets each connected seamlessly through a high speed communication link over the Internet. This makes the entire solution universally accessible while providing enhanced agility and reduced cost. However, the entire solution uses the Internet as the backbone for data/information exchange and therein lies the Achilles heel of the mantra.

The Internet has, essentially, been at the mercy of the socioeconomic conditions prevailing in any particular region, and while some countries enjoy blazing over the information super highway at Formula One speeds, many countries still have to make do with more sedate access speeds. This may be due to a variety of reasons ranging from the lack of basic infrastructure (Africa and Australia), network congestion (India and South Asia) and socio-political scenario (China and Middle-East). However, one outcome of these constraints has been that the ISP has always been working on a "best-effort" mode rather than any assured delivery model.

Now, while that might be good enough for the general home user or even the traditional enterprise which used the Internet as a communication link only, this does pose a threat to the new-age enterprise relying heavily on the distributed cloud infrastructure. Network latency might not just create performance issues, but also open up the whole systems to potential security and operational risks such as desynchronizing session states and incorrectly replicating database transactions across server locations. Hence, it was only a matter of time that the cloud providers started looking for more reliable backbones for their communication and that's where the concept of Content Delivery Network (CDNs) become so popular.

A content delivery network (CDN) is a collection of web servers distributed across multiple locations to deliver content more efficiently to users. The concept has been around for quite some time now and essentially involves ensuring that the peak demands are serviced efficiently without any blowouts.

A CDN employs several computers, or nodes, networked across the Internet to deliver large content to end users and its components.

The key components of CDN are :

• Content Distribution and Management for ensuring that the right content gets as close to each user as possible
• Content Routing for ensuring the most efficient route to the target user from the closest available content store or content engine.
• Content Delivery for delivering the content quickly frontially other cloud components).
• Content Switching for balancing user requests and making an intelligent decision as to how to distribm the content engine (in this case will be poteute the request across one or multiple sources.
• Intelligent Network Services for boosting the intelligence to the inherent infrastructure components to add more overall value to the infrastructure.

Web Based services such as Youtube and Yahoo have been using them for ages, but these have not found much popularity within the enterprise. All that is going to change.

Load Balancing and High Availability are not new terms at all, and almost every vendor has some flavor of these features built into their products. However, when it comes to the Cloud world, things get challenging because suddenly, we have a network of assets which are essentially communicating over a distributed platform. Hence there is no single owner of the entire platform who can ensure the load balancing of the entire cloud and hence there is no substitute for ensuring that the backbone is very reliable.

The good news of course is that the CDN vendors are now pretty mature in terms of their offerings and the market is competitive thus driving the prices down. The key challenge is to overlay the key principles of Enterprise Architecture on the offerings since the basic nature of the enterprise computing is very different from the commercial services such as video streaming sites.

Security is one of the major concerns and there needs to be a lot of thought provided to the overall solution when it comes to choosing a CDN partner. The federated security model only serves to increase the uneasiness of security architects who see such models as being less secure for systems which contain sensitive information.

The other major concern is TCO of course. This is where there are no clear answers. While the CDN vendors of course claim that outsourcing the network to building it in the cloud, informal surveys have shown that traditional CDNs are anywhere from two to 15 times more expensive than cloud storage and typically often involve one- or two-year contracts and large amounts of data.

While the exact form and shape in which the CDNs will contribute to the cloud is still under the scanner, there is no denying the value that they bring to the table.. err cloud.

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