Cloud computing and CDNs
Normally, cloud computing services and applications are delivered to
users through an Internet connection. This is one of the pillars of
cloud computing, making it distributed, accessible and affordable from
wherever and, increasingly, via various wireless devices. But what about
organizations that want something more than a “best effort” service
delivery through the Internet?
Well, obviously there are several alternatives, including managed networks, e.g. MPLS, ATM and, in the future, many other types of virtual networks that run across multiple physical networks or substrates.
But then there is the possibility of Content Delivery Network or CDNs like Akamai and Limelight Networks, which promise a better than best effort service or content delivery. Although the CDNs use in fact the Internet as the mechanism for carrying traffic, they strategically distribute replication servers (sometimes called Surrogates) in the network that replicated content stored on a origin server or servers farms. Users accessing content from a particular server are directed to the most appropriate “surrogate” based on multiple criteria, including distance, network congestion, etc., determined by a load balancer in the network that calculates the most efficient delivery route. CDN providers use a combination of technologies to provide better than best effort service delivery, including the distributed surrogates, or caching servers, mention, but also by using different proprietary protocols/algorithms than the native Internet uses for inter-network communications, i.e. the Border Gateway Protocol, and by reducing drag caused by TCP multiple round trips to set up and tear down connections.
It is interesting to note that already some cloud providers have started to integrate CDNs into their products offering. This includes for example Rackspace that offers a storage solution called CloudFiles that is integrated with the Limelight CDN. Through the CDN, content can be distributed, cached and shared in edge locations throughout the world – so that users gain access to content from a nearby surrogate.
It will be interesting to follow this trend as see if and how more and more cloud service providers will integrate CDNs to their service offerings.
Well, obviously there are several alternatives, including managed networks, e.g. MPLS, ATM and, in the future, many other types of virtual networks that run across multiple physical networks or substrates.
But then there is the possibility of Content Delivery Network or CDNs like Akamai and Limelight Networks, which promise a better than best effort service or content delivery. Although the CDNs use in fact the Internet as the mechanism for carrying traffic, they strategically distribute replication servers (sometimes called Surrogates) in the network that replicated content stored on a origin server or servers farms. Users accessing content from a particular server are directed to the most appropriate “surrogate” based on multiple criteria, including distance, network congestion, etc., determined by a load balancer in the network that calculates the most efficient delivery route. CDN providers use a combination of technologies to provide better than best effort service delivery, including the distributed surrogates, or caching servers, mention, but also by using different proprietary protocols/algorithms than the native Internet uses for inter-network communications, i.e. the Border Gateway Protocol, and by reducing drag caused by TCP multiple round trips to set up and tear down connections.
It is interesting to note that already some cloud providers have started to integrate CDNs into their products offering. This includes for example Rackspace that offers a storage solution called CloudFiles that is integrated with the Limelight CDN. Through the CDN, content can be distributed, cached and shared in edge locations throughout the world – so that users gain access to content from a nearby surrogate.
It will be interesting to follow this trend as see if and how more and more cloud service providers will integrate CDNs to their service offerings.
Categories:
CLOUD COMPUTING
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