This talk is about temporal verification in real-time communication systems. Early in the design cycle, the two main approaches for verifying timing constraints and dimensioning the networks are worst-case schedulability analysis and simulation. The aim of the talk is to demonstrate that both provide complementary results and that, most often, none of them alone is sufficient. In particular, it will be shown that response time distributions that can be derived from simulations cannot replace worst-case analysis. This will be done on automotive case-studies using analysis and simulation software tools.