One man's quest for a load-balancing product

By Eric Blue
Network World, 05/01/00

Recently, I led a team charged with selecting a load-balancing product for my company, a major player in the business-to-business e-commerce world.

Our network consisted of more than 500 Web servers, mostly Sun Solaris boxes and a few Windows NT machines as well. Our team spent nearly eight months on the project. This is our story.

Our first step was to make a list of required features. This is the most important step in picking a product, as this list will determine which products to consider and which to eliminate. Our list was fairly demanding, but we wanted to get the biggest bang for our buck. These were our requirements:

Features list

Robust load-balancing algorithms.
Global load-balancing capabilities.
High availability.
Reporting and notification features.
Load balancing of HTTP and FTP connections.
Reliability.
Multiple protocol support.
300-plus virtual servers supported.
Dynamic routing capabilities.
Network address translation capabilities.
SNMP support.
Minimal installation disruptions.
Easy administration.
Security features.

We searched the Internet, browsed through newsgroups and came up with seven products. Using our list of features, we immediately narrowed our list to three: F5 Networks' BigIP, Radware's WSD Pro and Resonate's Central Dispatch/Global Dispatch.

Our next step was to invite each of the three vendors in house for a technical meeting. We scheduled one vendor per week so we would have time to digest the information between meetings. This gave us an opportunity to meet each vendor face to face and provided an impression of the companies' professionalism and technical capabilities.

We asked each vendor to describe its product in detail against each item on our features list. We were particularly interested in their responses to our setup and implementation criteria.

Most load-balancing products require that you renumber the IP addresses of all servers to map the advertised IP address to the virtual IP address of the Web server. In a 24-7 production environment, it's important to minimize server downtime and, thereby, business interruption.

From these meetings, we eliminated Resonate from our list because some of the functionality we needed wasn't there.

The next step was to contact users of the two remaining products. We asked them to reference the following:

How long have you used this product?
What other products did you consider?
Describe the implementation.
How reliable has the product proven to be?
How helpful has the vendor been with problems, questions and concerns?
Have you experienced any surprises? Are there any bugs or shortcomings?
Would you recommend this product?
How long does the product stay online without failing?
What level of administration is required?
How much traffic does the product handle?
Our two finalists offered different ways of accomplishing their goals.

At the time we reviewed it, BigIP ran on a BSDi box. The product had many features we liked, but we were disappointed that it depended on a hard drive and the Unix operating system.

We believed a router-like product would probably be more stable in the long run. We called several end users of both products. Reports of uptimes confirmed our position.

Radware's offering has an architecture similar to a router, which was appealing. We also liked the multiple interfaces that allowed different implementations on our network and the robust load-balancing features. It was the only product that met all our criteria.

At that point, we brought a pair of boxes in on a trial basis. We built a replica of our network to serve as a test environment. We included the key elements of our production environment, firewalls, switches, routers and several Web servers.

The initial setup was very straightforward, taking only about 20 minutes. Web farms were easy to set up and administer. We liked the smooth failover.

We discovered a few problems in our testing period, but they were fixed with the help of Radware. The first issue we encountered was with source addressing from Sun's Quad Fast Ethernet cards. This problem was more of a Sun issue and was easily solved.

Overall, our final choice has proved to be stable, and we are happy with our decision.

One thing to keep in mind is that your network has to be completely stable before implementing any load-balancing product. Network, Domain Name System and Web server problems will only be magnified with a load-balancing product in place.

The entire process from start to finish took almost eight months. In the end, we picked a product that fit our needs and performed well. The key to picking the right product is defining your needs, researching and testing, testing, testing.

Related links

Blue is a network engineer. He can be reached at bluez@mindspring.com.

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