Access control AAA infrastructures are traditionally used by the service providers so as to charge their subscribers. Given the easiness and the cheapness of MANET deployment and provided that charging is possible, service providers are likely to offer their services over MANET. In previous works [1] and [2], we presented a distributed AAA framework for MANET. We propose to evaluate the overhead of this framework authentication protocol by modeling and simulating typical cases that are fairly representative of the reality and can easily be extended. Results show that when routes are already established, the authentication overhead is about three times smaller than the overhead due to routing. Hence the overhead doesn't appear to be an impediment to distributed AAA infrastructures implementation