Special Focus: Testing & Monitoring

Scale smart to balance traffic

In recent years, McLean, Va.-based Cvent has seen a 40 percent to 60 percent annual growth in traffic to its hosted, Web-based applications. Providing the infrastructure to handle this rapid growth-before customers feel any impact-is a top priority for Dwayne Sye, vice president of technology. "Whether or not the end-users notice anything is the measure of how well my team does its job," he explains. "Our customers are paying us a subscription fee to use the service, so there is an expectation that the service be available whenever they need it."

As one of the largest event-planning software companies in the United States, Cvent assists marketing professionals with more than 100,000 events each year. Using a software-as-a-service model, Cvent provides on-demand strategic meetings management, online registration, Web surveys and e-marketing tools to corporations, associations, nonprofits, educational institutions and other organizations. Its customers include Microsoft, Verizon, Goodwill and the U.S. Postal Service.

In early 2007, the growing traffic began to tax the F5 BIG-IP version 4.x devices that Cvent had installed in 2000. "The legacy controllers served us well for nearly seven years, but with our tremendous growth, they suffered from over-utilization," Sye says. "It was clear that an upgrade was needed to support projected growth."

Sye also wanted to implement an application-delivery infrastructure that would help enhance the performance and availability of the company's services. "We needed a solution that would provide geographic site redundancy and load balancing in order to deliver a higher level of service to our customers," he says.

In his search for a solution, Sye focused on five primary factors: functionality, performance, reliability, ease of management and total cost of ownership. After a thorough evaluation of more than 12 other products, Cvent once again chose the BIG-IP product line from F5.

The ability to minimize the impact on customers during maintenance windows was a critical differentiator, Sye explains. Cvent uses the BIG-IP system to direct customers to different servers during these windows. "We can control how the site functions when we do a code deployment or application release," Sye explains, "and not all vendors were able to offer that same kind of seamless user experience."

Another key deciding factor was the potential impact on available resources. "Some of the solutions we looked at definitely would have required full-time network engineering resources dedicated to managing just those devices, versus doing something else that might be more beneficial to our customers," Sye reports.

In the first half of 2007, Cvent initiated a major network infrastructure migration, during which it replaced the old F5 devices with new BIG-IP solutions. Compatibility testing performed prior to deploying the BIG-IP devices, and implementation guidance from F5, "ensured that the migration was smooth and trouble-free," Sye says. "The F5 engineer convinced me we could do the job ourselves, and we did."

In June, the team deployed the application-delivery networking solution they had selected: three F5 BIG-IP Local Traffic Manager (LTM) 3400s and two F5 BIG-IP Global Traffic Manager (GTM) devices.

Sye estimates that the migration process took eight to 10 weeks of preparation. "By doing all the planning up front, we were able to do the migration seamlessly and with virtually no impact to the customer. We kept the window of intermittent access down to less than 15 minutes," he says.

The BIG-IP GTMs-one located at each data center-optimize and route Cvent traffic to the appropriate data center, based on traffic type and volume. The BIG-IP LTM 3400s sit in front of the company's 12 Web and application servers, the edge of the Cvent application infrastructure, intelligently managing and delivering Web and e-mail traffic.

These application-delivery networking devices also provide secure sockets layer (SSL) acceleration to improve the performance of the application servers. BIG-IP SSL acceleration offloads CPU-intensive SSL encryption and decryption from Cvent servers, migrating it to the high-performance BIG-IP devices, which are designed to handle SSL transactions more efficiently.

The devices run on F5's TMOS application-delivery platform, which includes an intuitive graphical user interface and remote-management capabilities that simplify management and administration tasks for Sye and his team.

Cvent also uses F5 iRules technology-customizable commands that offer granular control over application traffic-to aid in the collection of customer Web statistics using a hosted, third-party model.

Cvent's former method, which required tagging each Web page with a script that referenced a data collector maintained by the hosted vendor, was problematic in security-conscious corporate environments.

"Customers often blocked access to our hosted statistics vendor, resulting in some fraction of usage not being logged, and, in some instances, the security restrictions interfered with site functionality," Sye explains.

To remedy this problem, Sye implemented an iRule to redirect traffic directly to the statistics vendor host. He notes this resulted in "more accurate Web traffic statistics for us, and better application compatibility for our customers. The iRule also saves us the hassle and cost of deploying and managing a complex, installed Web application statistics collection and reporting infrastructure."

"When we first deployed the devices, our requirements were probably not all that sophisticated," Sye adds. "But now, as we run into new issues or want to add more functionality, one of the first things we ask ourselves is, 'Can we solve that problem with an iRule or other BIG-IP capability?'"

For Cvent, the gain in network scalability remains the most important benefit of deploying the devices. "If we were still on the old controllers, by now we would be getting complaints from end-users about slow performance or dropped connections," Sye says. "In contrast to that, we've been on the new devices for almost a year and the CPU utilization barely registers.

For more information from F5 Networks (click here)

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Virtual servers create challenges

by Bill Allen

IT organizations are under constant pressure to roll out more applications, support more users, deliver higher levels of service and handle more intense processing workloads-with budgets that rarely increase proportionally to these escalating demands. As a result, they are exploring the virtualization waters in varying degrees. Even the most enthusiastic adopters, however, are only applying virtualization to some of their new production machines.

Virtual server technology can introduce new management complexities and challenges. Some of these challenges arise because virtual servers are managed in conjunction with servers in the data center that are not virtualized.

For many applications-especially high input/output ones like e-mail-virtualization is neither practical nor advisable. Therefore, IT organizations may always have to deal with a mix of physical and virtual server resources. IT organizations are still figuring out how and when to implement virtualization, and adoption rates can depend on many non-technical factors, such as competition for IT budget and whether the department can deliver the appropriate support for virtualization.

Challenges that arise from virtual server technology include:

Giving specific IT staff appropriate privileges for specific virtual machines. When multiple virtual servers are running on individual physical machines, the administration of these rights becomes even more complex.

Maintaining management assignments as virtual servers move from one physical machine to another. To avoid giving systems administrators and application specialists access to virtual centers (because of potential inappropriate control over the data center's virtual infrastructure), IT organizations often use a manual approach for the distribution of IP addresses and/or management URLs to the specific virtual machines for which each IT employee is responsible.

Accessing multiple virtual servers connected to different virtual centers. At this time, IT staff cannot unify views of multiple virtual servers residing on different physical machines if the service consoles of those different physical machines are connected to different virtual centers.

Protecting many virtual servers from component failure in a single physical server. Physical servers have a one-to-one relationship between component failure and application outage. When multiple applications are running on that same server, the stakes go up. IT organizations implementing virtualization have to be sensitive about the vulnerabilities created by multiplexing large numbers of virtual servers onto a single physical machine, and should be sure they have the out-of-band access to those physical machines necessary to address BIOS- and hardware-level issues.

Exclusive use of Microsoft Active Directory. This can be problematic for IT organizations that need to drive management access using technologies such as RADIUS and single sign-on in order to support their broader infrastructure-management architecture.

While understanding how virtualization will impact management operations before they are implemented can be difficult, solutions that deliver integrated management functionality across both physical and virtual server platforms are available.

Bill Allen is director of product management, Avocent Corp., Huntsville, Ala.

For more information (click here)