To those familiar with network modeling and its advantages across different phases of system development, the thought of generating test cases based on informal specifications would sound unreal. However, manual test generation is still a current practice in industry. Given that the use of models provides many distinct advantages, why is it not more widespread in the validation phase? This paper presents a case study of a network protocol validation. We present a process for formalizing system specifications and applying a model-based approach for test generation, and consider how AGATHA, a tool developed by an academic community, can encourage industrial interest in efficient practices such as model-based testing (MBT). The drawbacks and advantages observed during our experiments are discussed. © 2012 Alcatel-Lucent.