Editor's note: More complex networks and more complex applications mean that enterprises need to design WANs capable...
of handling ever-increasing amounts of traffic without sacrificing performance. In the second article of our three-part series on buying the right WAN optimization tools, find out how to benchmark WAN optimization tools before you buy them. Click here to read part one of our WAN optimization overview to help you make the right buying decision.
As soon as LANs became the de facto standard of communication within a building, users saw the benefits of linking LANs across a wide area network (WAN). Unfortunately, LAN applications and protocols -- which ran so well in high-bandwidth LANs -- fared poorly when essentially "squeezed" to fit across low-bandwidth WAN connections. Thus was born the WAN optimization tools business.
Early innovators, like Packeteer, used specialized hardware in pairs of devices on each end of the WAN to work "in line" to scan and optimize traffic flows. At that time, the processing power of a standard, Intel-based PC would have been insufficient for the job required. Today, thanks to vastly more powerful Intel processors, complex tasks like WAN optimization can be performed on standard PC hardware or even prepackaged virtual appliances. As a result, you can have all the benefits of optimization processing without the overhead of deploying standalone hardware.
WAN emulator helps monitor network performance
In cases where your WAN applications evolve significantly over time or involve business-critical systems, you should seriously consider investing in a commercial-grade WAN emulator that will simulate the bandwidth constraints and latency of your WAN. By using an emulator, you can benchmark more complex scenarios leveraging the more sophisticated features of commercial-grade products.
Once you have deployed the emulator, connect your WAN optimization platform (a pair of physical devices or virtual appliances) to the emulator. On one end you'll have your client application, and on the other, the target server -- whether it's a Citrix Xen virtual desktop infrastructure server, file server or whatever app you are benchmarking.
Configuring the WAN emulator is the most critical step. Among the various characteristics you can configure, bandwidth is the most important. Note: You do not need to configure the emulator bandwidth to match your actual bandwidth. The relationship between your application traffic and the available bandwidth is what's important. In order to see how effective your WAN deployment will be, you need to generate traffic that will demand 100% (or more) of the WAN connection.
Since generating sufficient actual traffic could be your greatest benchmarking challenge, it is often better to configure the emulated WAN to a much lower bandwidth level than your actual WAN when testing.
Put another way, if your actual WAN is 20 Mbps, and you configure your WAN emulator to that value, you will need to generate a traffic volume that's greater than 20 Mbps to benchmark your WAN.
Alternatively, if you set the WAN emulator to 2 Mbps, you need only generate 2 Mbps of traffic -- much easier -- to drive the WAN optimization. Since the relative behavior of WAN optimization depends on the ratio between "demand" on the WAN and available bandwidth, configuring to a lower emulated WAN speed will likely still provide you with an accurate assessment of actual WAN optimization while requiring much less work to generate application traffic.
Gauging latency, packet loss other benefits of emulation
The WAN emulator also allows you to enter a desired latency (delay). This is important as WAN optimization products appropriately focus on reducing the effective latency of a connection. A simple "ping" from one station to another on your current WAN can give you an approximate latency value that you can plug into your WAN emulator.
WAN emulators also let you specify packet loss. While this is not a major issue in most of the world, if it is for your environment, be sure to plug in an appropriate value. Excessive packet loss can cause sessions to slow down and even reset. This can have a significant negative effect on user response time.
When reviewing your benchmark results, a WAN optimization platform that provides significant improvements to response time in your lab is most likely to do the same in your production environment (provided that your test environment is a good representation of your production environment.) If, on the other hand, the benchmarked solutions differ only by relatively small amounts (~10% or 20%), your test environment could account for the difference and more analysis or retesting is required before making a product choice.
In the third and last article in this series, we'll cover the steps needed to properly configure your WAN optimization platform to best meet your needs.
Read on to part three in this series: How to use scripting tools to configure your WAN optimizer for your needs.
Before buying, here's what you need to know