CDNs taking on enterprise role

Many network professionals may still think of a content delivery network as simply a system of public caching servers that sit at the edge of the Internet. But increasingly, customers are finding Web traffic can be applied to a private WAN.

However, installing an enterprise CDN (eCDN) isn't as easy as putting caches in various locations on your network. It can be expensive, and it can get complicated. But if you determine that an eCDN makes good business sense and then structure it to fit in with your existing architecture, it can be well worth the effort, observers say.

Take Siemens Medical Solutions Health Services. The healthcare IT division of Siemens delivers applications, professional services and outsourcing to more than 5,000 healthcare organizations worldwide. Siemens Health Services wasn't satisfied with the way applications performed over its network. It was tired of having extra servers standing by to handle spikes in traffic while its network still hovered around 90% availability.

So it installed Cisco content-delivery devices to push content out to the edge of its network. With its internal CDN, Siemens Health Services boasts 99.998% network availability and has reduced server costs by more than 80%, says Michael Alban, strategic alliance manager at Siemens Health Services.

"But one can argue that content delivery isn't for everyone," he adds. "It's a question that we had to answer ourselves. You have to look at content delivery and ask if you have an existing network in place that you can take advantage of. And the bottom line is what's the business value you gain by deploying your own content network."

Content considerations

There are a number of things customers must consider before investing in an internal CDN. One of the first things to think about is whether your business has applications that require content-delivery devices, says Dot Powers, advisory network specialist for Siemens Health Services and a Cisco Certified Internetworking Expert.

Analysts say the application that is driving the adoption of internal CDNs is streaming media for online training or companywide CEO addresses. "Streaming media is the killer app for eCDNs," says Greg Howard, principal analyst at HTRC Group.

A recent HTRC study of 200 large companies found that 35% handle streaming today and 42% will in 2002. Of companies doing streaming, more than half will build their own CDNs, the study found.

Other applications may also require an internal CDN. Siemens delivers clinical and financial applications for the healthcare industry. It was delivering a mainframe application with a browser-based interface, but because the application used a 2M-bit Java applet to run the browser, each time an update was needed the applet had to download, putting stress on the network. Because of security concerns, a public CDN wasn't an option, Alban says.

First, Siemens looked at its infrastructure to determine how an eCDN would fit. Powers says network managers should determine whether systems can easily integrate a content-delivery vehicle. If not, it may be more trouble than it is worth. For Siemens Health Services, the integration was easy, she says.

"We have a nice modular-type design in our infrastructure. We have an IP backbone, and we have applications that are very modular," she says. "It was a real easy fit from an architectural perspective."

Application support is key

Application support is an important part of any eCDN, adds Evan Richman, vice president of business development at content networking software provider Digital Pipe. That means making sure the network can support things such as video on demand, live streaming and content management tools. Companies should also determine whether the network architecture can, or will, support applications such as collaboration and database replication.

Another thing to think about is whether the content network architecture is scalable, Richman says. "You're investing in another level of infrastructure, and you want to look at this as a long-term asset that can really grow," he says.

Siemens Health Services is expanding its CDN by adding content switches at the core of its network. Its content networking devices include Cisco content switches, which sit next to Web servers and in front of application and database servers, at the core of the network. A Cisco content engine, which caches content, is then placed in the data center of each healthcare organization accessing applications from Siemens.

Other issues

Powers says it's a good idea to take an inventory of your IT team and determine whether you have the skills to configure application delivery on a CDN.

"Our server team has an in-depth understanding of the rules that they need to configure for the delivery of content. The rules are based on information that is deeper in the packet: Layer 4 and above," she says. "I am a network professional, and it would be difficult for me to come up with a really good set of Layer 4 and above rules for our applications, so I work with our server team."

Alban notes Siemens did not have to add staff to support its eCDN.

"Other enterprises might not have the luxury. So it's an important thing to consider," he says. "Then weigh all the expense against the cost of adding servers and adding potential bandwidth."

Another issue companies should consider when installing internal CDNs is how the content network devices analyze the network and route content. This is a must for eCDNs, Richman says, because most content moving over an eCDN will be targeted for specific users, rather than being open to anyone.

The eCDN architecture should include back-end management that intelligently routes content and integrates with other enterprise systems, and an integrated user interface that lets network managers keep an eye on how content and applications are moving. The bottom line, he says, is that an eCDN should make a network manager's life easier, not more difficult.

"You shouldn't have to have a lot of resources to deploy and manage these things," he says.