This post is part two of two, where I’ll cover how you can use network simulation and emulation tools to validate changes, and the limits of each approach. Please read the previous post covering network simulation concepts for further context before reading the rest of this post. Ok, What Can Be Tested? As a reminder, the goal is pre-change network validation. What are examples of things that a network engineer might want to test?

Every few weeks I’m asked about why we1 can’t do pre-change network validation. Most network engineers don’t understand the nuances and details around this topic, and there’s very few words published on this, so it’s time for me to discuss what constitutes network simulation, network emulation, and what the challenges are around trying to validate network changes before they’re put in to production. This is part one of two, where I’ll dive in to defining network simulation and some example tools.