Distributed Content Distribution?

Traditional content distribution network (CDN) providers have fallen on hard times recently. Confronted with ever-tightening IT budgets, they're struggling to lure customers with new features and cost-effective partnership deals. And if they didn't have troubles enough already, now a new class of CDN company has begun to arrive on the scene. Undaunted by the woes of existing CDNs, these startup players are using peer-to-peer (P2P) technology to take a distributed approach to content delivery.

Classic CDN providers like Akamai and Digital Island bring their clients' data closer to end users by hosting their own caching servers in making data centers around the edge of the network. P2P solutions from companies like CenterSpan approach the problem from a different angle, end-user machines themselves part of the caching network. The result is a dramatically reduced capital investment by the CDN provider and, according to CenterSpan chairman and CEO Frank Hausmann, as much as 90 percent customer savings over traditional CDNs.

P2P content distribution techniques vary. Typically, end users must install a small background application or browser plug-in on their systems to receive CDN-cached content. Some systems, like CenterSpan's C-Star network, cater to content caching, while others, such as Diffuse Network's AllCast, specialize in streaming media. In either case, similar to multicast routing, the goal is to create a one-to-many networking relationship that places fewer burdens on the content provider's infrastructure.

Other products in this space include ChainCast Networks, OpenCola SwarmCast, and Kontiki. Numerous vendors have products that aren't yet ready for market.

Every entry into this burgeoning field faces similar challenges, however. The most important challenge is the question of how to maintain quality of service when end-user machines are doing the actual work. Unlike dedicated servers, the security, reliability, and network connectivity of end-user hardware are beyond the CDN provider's control. CDN providers may also end up butting heads with consumer ISPs, which budget their own network resources under the assumption that their subscribers will be browsing, rather than serving, content. What's more, it remains to be seen whether CDNs will even be able to convince sufficient numbers of end users to participate in such a scheme.

Faced with this daunting set of hurdles, peer-to-peer CDN solutions have some work ahead before they become as trusted and entrenched as the existing, managed CDN providers. If they can overcome even a few of their difficulties, however, it's possible that P2P distribution networks will become an attractive, lower-cost alternative for efficient content delivery.

—Neil McAllister