Delivering the Goods

Do CDNs Live Up to the Hype?

By Jay Lyman

Content distribution network (CDN) providers promise to make life easier for system administrators. CDNs will cut a company's bottom line by reducing the need for servers and bandwidth, while simultaneously pumping up profits through faster site performance—or at least that's the claim. But some administrators say that using a CDN represents nothing more than the denial of an underlying infrastructure problem—a crutch that will eventually become too expensive to support.

Those who stand by their use of CDN providers say it all depends on the deal you get. Indeed, few administrators seem willing to say they're closing their options when it comes to these networks. Although battered by the downturn, CDN providers like Akamai and Digital Island are working hard to make their offerings more attractive. By changing and consolidating with other managed services, these companies plan to remain prominent players in today's hosting market.

For related information, see the sidebar,

"Distributed Content Distribution?"

Two Speeds: Idle and Fast

In October, Cambridge, MA-based Akamai was being deployed on 1000 different networks, with some 13,000 servers in 63 different countries, according to Director of Product Management Kieran Taylor. Similarly, Tim Wilson, chief marketing officer for San Francisco-based Digital Island, says his company boasts 21 of the top 50 Fortune 500 companies as clients, with more than 2600 servers in 35 countries.

Despite their evolution from the days of deep IT budgets, many services offered by these CDN providers remain essentially the same. However, there's good reason for the ongoing interest in the services they provide.

Content distribution networks move a site away from centralized servers, toward the so-called "edge" of the network—to far-flung caching servers that store content close to end-users. By distributing load and decreasing the number of network hops between each piece of content and its destination, these edge servers are better equipped to handle the sudden Internet traffic spikes that come with big events like the Super Bowl or the September 11 terrorist attacks.

CDNs sell themselves as an alternative to the "unwieldy infrastructure" (as Akamai's Taylor puts it) that most sites rely on to handle sudden heavy loads. "The majority of enterprises have infrastructure that's idle 90 percent of the time," says Taylor. "They have to over-provision hardware and resources to overcome spikes. We're a solution to over-provisioning that enterprises use to achieve scalability, reliability, and performance."

As Digital Island's Wilson points out, a beefed-up data center with added hardware and bandwidth may improve performance somewhat, but not on the other side of the world. "Buying more network pipes doesn't mean your site in the UK is better," he says.

Seconds Count

Although subscribing to a content distribution network can be expensive, to SportsLine.com president of operations and CTO Dan Leichtenschlag, a 15 percent faster load time makes it worth the cost. He adds that what he pays for his site's CDN service isn't far above what he would pay to deliver the content anyway.

"It's going to be fewer hops from the content to the user," Leichtenschlag says bluntly. "The way I look at it, it depends on your deal. What we pay is a reasonable premium over what we pay for bandwidth. Our deal is essentially a wash. If I had to buy all of the equipment I'd need at peak load, I'd have to buy a bunch of machines and rent more space and pay for bandwidth anyway. But as a bonus [of using a CDN], I get speeded up—that's a great tradeoff."

Leichtenschlag, whose NFL.com site sees peak traffic every football Sunday, says his cost analysis was fairly straightforward. For SportsLine.com, going with a CDN provider was a no-brainer. "We have three data centers. They have a lot more," he says. "Why manage the hardware if you're going to pay the same?"

ESPN.com is another sports site that periodically sees heavy bandwidth demand. CDN service is ideal for ESPN because of its "peaky traffic driven by events," according to Vice President of Technology John Zehr. "It's great to leverage their edge content delivery," he says, explaining that ESPN.com takes advantage of both static image and full site delivery. "It puts both the bandwidth and server capacity on their shoulders. Certainly, they've saved us on huge traffic days."

Zehr says it would be impractical to build out the data center for ESPN.com's expected five-fold increase in traffic during peaks, adding that a CDN provides a layer of redundancy that a home-grown infrastructure could not provide. "It just doesn't make sense from an architectural standpoint to scale when you're not going to generate that type of load" on a consistent basis, Zehr adds.