One of the topics we are frequently asked is to explain or clarify the difference between WAN Emulation and WAN Simulation.
WAN Simulation methodology is a set of theoretical algorithms which are usually applied on a trace file. These algorithms aim to predict applications response times with different conditions and then applied to the captured trace file. A typical use case would be varying the conditions, such as available bandwidth and distance (latency), and then predicting the impact on response time. The main challenge with this approach is that those theoretical algorithms are based on assumptions. Assumptions, which are in some cases very wrong and skew the results. Typically, with theoretical WAN Simulation you should expect around 70% accuracy.
On the other hand, when we say Emulation (or WAN Emulation) we mean that the application traffic will traverse in real time through a path that is identical to the path we have in mind. An appliance based WAN Emulator or software based WAN Emulation is usually present to create actual network elements in software, bring into account network impairment characteristics, such as distance (latency), bandwidth and loss. The accuracy of WAN Emulation can exceed 99% depending on the level of configuration. We can expect around 95% accuracy from a straight forward automatic configuration.
Another important difference is time. Theoretical WAN simulation may take days to run, but using WAN Emulation the duration is based on the time it takes the application to run.
The main reason why WAN Emulation triumphs is accuracy.
