Feature: Transaction satisfaction

Continental Airlines has high-flying plans to expand its e-business infrastructure to Europe and Asia this year, and global load balancers are playing a pivotal role.

In fact, says Andre Gold, director of Internet engineering at Continental, "If the [global] load-balancing technology fails, we fail. Our entire e-business strategy is based on this technology."

Global load balancers use a number of different techniques to direct Web traffic to the most appropriate server farm or data center. Unlike server load balancers, which manage traffic within a company, global load balancers manage traffic between geographically distributed sites.

The Houston airline uses two LinkProof traffic management appliances from Radware to juggle traffic between its two ISPs - WorldCom and Savvis Communications. The ISPs support the airline's busiest Web sites: those that provide frequent flyer information and handle online booking. The global load balancers monitor the performance of both ISPs' networks and shuttle Web traffic from Continental data centers back to the customer through the fastest route.

This improves the efficiency of Continental's e-commerce site, which means customers can obtain information or book a ticket faster than before. Gold estimates that the performance improvements have let Continental shave $20 off the price of a ticket.

This year's e-commerce data center expansion will hinge, in large part, on an upgrade to Radware's Web Server Director-Network Proximity appliances, which will give the airline the ability to redirect customers to the "closest" server using a customizable algorithm.

Global load balancers don't solve all problems

If you need to deliver cacheable data more efficiently and cost-effectively to customers, then a content delivery network (CDN) might be your best bet. A CDN will reduce the amount of traffic hitting a server by moving frequently requested content to the network's edge, says Zeus Kerravala, an analyst with The Yankee Group.

But if you need to handle frequent requests for transaction applications, it's more useful to balance and direct traffic between data centers, because that type of data is not easily cached.

Cendent Mortgage in Mt. Laurel, N.J., has 100 different Web sites across its divisions that are used by individuals seeking mortgage and financial information. Jim New, an advanced technical services specialist at Cendent, says even though the price tag on Cendent's load balancing rollout is about $240,000, the cost is well worth it.

"We can handle about 10% more requests than we otherwise might," New says. "We can also take down servers if necessary to update them without affecting availability."

The company has two global load-balancing appliances from F5 Networks, which both sit outside the firewall. The appliances translate external IP addresses to an F5 Big-IP controller, which routes IP traffic to the best server. Cendent has data centers in Mt. Laurel, Moorestown and Garden City, N.J.

It's not always easy to nail down specific monetary figures to show where global load balancing delivers value. But many corporations are happy knowing they have more control over what's already in their network.

The Web servers at Landstar Systems, a transportation services company, are the most important means of communicating with more than 10,000 employees who work for about 1,000 Landstar agents. These are owners, operators and contractors who log on to Landstar's site each day to conduct business.

The company distributes network traffic to 15 servers in data centers in Jacksonville, Fla., and Rockville, Ill., using two Radware switches -- a WSD-Distributed Solution to ship traffic to either data center, and a WSD NP, to direct traffic to the closest client.

Patrick Wise, vice president of e-commerce at Landstar in Jacksonville, says he has no statistics to prove he is saving money, but by redirecting traffic to an underused Web server, he avoids having to add an extra server.

More important to Landstar is that it can remove a failed server from a cluster without customers ever knowing. Another benefit is it lets Landstar see potential bottlenecks. "We can manage our site better and control our load better," Wise says.

Global load balance bits

Aside from F5 and Radware, other players are Cisco, through its purchase of ArrowPoint Communications; Nortel, through its acquisition of Alteon WebSystems; and Foundry Networks.

Semilof is a freelancer writer living in Watertown, Mass. She can be reached at msemilof@attbi.com.

How global load balancers work

Looking ahead
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