Quantitative Network Engineering with Fault Tree Analysis

This is a simple paper outlining how to use some Risk Analysis Techniques with Network Engineering to obtain quantatative results. An attempt to turn network engineering from an artful guessing game into a science.

Modeling the Network as a System

Due to the cheapness of the places I've worked for I've never had the privelige to work with any network modeling packages such as Wandl or OPNET. Hardware was always MUCH more important than software, so very little money was spent on any support software or systems for the networks I worked on. The network management systems consisted of the bare minimum set of commercial software to halfway get the job accomplished in a crippling manner...no open source software at all was allowed unless it was sold by a third party for some reason. So, due to this thrify and stupid nature, network eningeering was approachede more as an art than a science.

Anyway, I'm not sure if any of the network modeling and/or simulation packages out there really approach the network as an entire system. From the marketing pages most of them seem to be based around capacity planning and will show you how your network will (or might) react if nodes and links are removed or added. Not many of them seem to make much of a point of stating how they approach the necessity of the components that make up the network as far as keeping the network uptime up above the sigma levels everyone talks about.

So with no budget, how does one actually start to quantify the components that make up the network and see how much value they contribute to adding as many significant figures to the uptime ratio as possible. One method is to apply some of the risk analysis techniques to network design. One method that seems to work well is Fault Tree Analysis. 




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