This paper proposes a general, parameterized modelfor analyzing protocol control overhead in mobile ad-hoc networks. A probabilistic model for the network topology and thedata traffic is proposed in order to estimate overhead due to control packets of routing protocols.Our analytical model is validated by comparisons with simulations, both taken from literature and made specifically for this pa-per. For example, our model predicts linearity of control overhead with regard to mobility as observed in existing simulations results.We identify the model parameters for protocols like AODV, DSR and OLSR.Our model then allows accurate predictions of which protocol will yield the lowest overhead depending on the node mobility andtraffic activity pattern.