Last time, we pointed out that since a company's CIO as well the company's business and functional managers care more about applications than they do about the WAN, WAN managers need to be able to demonstrate how the WAN enables appropriate application performance. The recommendation that we made was that WAN managers should benchmark any major new application that the company is in the process of deploying.

An IT organization can do the benchmarking themselves or use an outside vendor. The primary purpose of the benchmarking is to determine in advance how the application will perform when run over a production WAN and it endures varying amounts of latency, jitter and packet loss.

For example, before the typical interactive application gets deployed, there is a target for how long a transaction should take. For the sake of example, assume that the target is five seconds and further assume that if there is no WAN latency that the transaction completes in two seconds.

As part of the benchmark exercise, artificial amounts of WAN latency are introduced and the response time of the application is recorded. Typically, as the WAN latency is increased, the application response time also increases. Ideally, the response time increases gradually as WAN latency is increased. However, in some instances application response time can increases dramatically in response to only minor increases in WAN latency.

Staying with our example, assume that when faced with 300 milliseconds of WAN latency the application has a response time of 4 seconds, but if there is a WAN latency of 400 milliseconds, the response time jumps up to 6 seconds.

Armed with this information, the WAN organization can set thresholds throughout the WAN so that the appropriate people are notified when the WAN latency approaches 300 milliseconds. The reason for doing this is so that the WAN organization can know that one of the company's key applications is about to start performing badly and can take steps proactively to ensure that this does not happen.

Future newsletters will come back to the general topic of how WAN managers can better relate the WAN to the company's senior managers.

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Jim Metzler is vice president of Ashton, Metzler & Associates.