Using a Load Generator/Emulator to Test Your Network

By Art Reisman, CTO, APconnections (

One of the most challenging aspects of technology development has always been the process of bridging the gap between theory and application.  What may seem to work on paper, and even in limited trials, was never guaranteed when dealing with real-world scenarios and often unforeseen problems.

Several members of our engineering team just returned from a week of  testing with Candela Technologies’ network load emulator, and once again, we’ve not been dissapointed.  At the touch of a button, we were able to create unbelievably realistic worst-case load scenarios. Candela’s LANforge equipment not only stressed our network elements, but did so with variation, creating an environment that successfully simulated the challenges our technology will face on a regular basis in the field.

Judging by the numerous trials we’ve run, it’s become clear that simply driving a fixed load across a network is not enough to ensure reliability. Instead, you need a simulation with a multitude of elements (different packet sizes, UDP , TCP, broadcast traffic, etc.) and traffic streams, including those that refuse to back down such as with a bad denial of service attack or virus.  Fortunatley, this is exactly the quality of service that Candela Tech offers.

In addition to giving you peace of mind, this type of simulation can also save you and your company time and money.  When implementing a network upgrade, the normal method of operation goes a little like this:

  1. Work late at night and over the weekends
  2. Implement the change
  3. Put staff on standby for the next business day
  4. Have a fallback strategy to revert to a previously proven configuration should things go south

While these steps eventually may do the trick, they’re not without their costs — both financial and otherwise. Aside from the overtime you’ll end up paying your admin, perhaps more importantly, you also run the risk of negatively impacting the service of clients and customers during the hit-and-miss setup process.

Yet, the costs that come with this type of strategy can easily be reduced with a sophisticated load generation device. Network choke points can be stressed and limits determined before unwittingly making  guinea pigs out of your network users.  And, the staff from Candela Tech is more than knowledgeable and eager to help, which has allowed us to be up and running right out of the box on more than one occasion.

Ultimately, using Candela Technologies has been a lot like looking into a crystal ball. After the LANforge simulations, we’re able to identify and address any issues before they affect our customers. What was once a process of bringing our technology to the real world has now become a process of Candela bringing the real world to us.

Note: There are other competitive network load generators on the market, Fluke being the market leader.

Created by APconnections, the NetEqualizer is a plug-and-play bandwidth control and WAN/Internet optimization appliance that is flexible and scalable. When the network is congested, NetEqualizer’s unique “behavior shaping” technology dynamically and automatically gives priority to latency sensitive applications, such as VoIP and email. Click here for a full price list.

NetEqualizer Passes Load Testing with High Marks

Editor’s Note: We just wanted to comment on this recent press release. This is not just industry hype as we really do test our units. To give you an example, several years ago we had a few units locking up in the field (perhaps one out of hundred) after many hours of continuous use. This type of problem is hard to re-create in a lab, but, unless you can recreate it, there’s very little chance of finding and correcting the issue. However, with the help of Candela Technologies and their LanForge equipment, we were able to recreate the problem quite easily. It was just a matter of accelerating time by increasing loads on the NetEqualizer well beyond what was likely in the real world.

Since that first experience with a load-related latent bug, we have always gone back to Candela for validation testing under load and are happy to say we have caught all service-related bugs with new versions prior to release.

With that said, here is the latest press release:

One-Gigabit NetEqualizer Performs Flawlessly Under Independent Load Testing

USA, FERNDALE, Washington (December 03, 2008) – APconnections – a leading supplier of plug-and-play bandwidth shaping products – today announced test results from the independent laboratory of Candela Technologies.

“APconnections has been coming to us for years to put extreme realistic loads on their equipment,” said Ben Greear, lead engineer, Candela Technologies. “We used our LANforge traffic generator to hit the latest NetEqualizer release with over 1.2 million simulated user data streams within a 60 second window. The NetEqualizer shrugged off
the abuse and continued to pass in excess of 800Mbps of bi-directional traffic.  The NetEqualizer successfully ran this torture test for a full 24 hours without a hiccup.”

Eli Riles, vice president of technology at APconnections, was very pleased with the results, noting the importance of the tests to ensuring NetEqualizer’s high level of performance.

“With our higher-end shaping solutions, we cannot afford a problem in the field,” said Riles.

APconnections is extremely grateful to have such a knowledgeable company like Candela Technologies with such impressive simulation capabilities testing its equipment. Their load generator is able to strain equipment well beyond real world situations, ensuring its stability and protecting company and product reputations.

The NetEqualizer is a plug-and-play bandwidth control and WAN/Internet optimization appliance. It is both flexible and scalable. The NetEqualizer’s unique “behavior shaping” technology gives priority to latency-sensitive applications such as VoIP and email. It does it all automatically and so dynamically while improving on other bandwidth shaping technology available.

For more information regarding the New NetEqualizer one-gigabit  carrier class traffic shaping solution, please visit

APconnections is a privately held company founded in 2003 and based in Lafayette, Colorado.

Candela Technologies specializes in emulating network traffic including VoIP and VLANs.

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