Rockfall sources are generally well known and the protection is an important issue for the safety of infrastructures such as road in mountain areas. Among the different types of protection 2 different systems of protection come out : netfences used to contain blocs falling with limited energy galleries set up to protect roads particularly exposed. This paper intends to present how modelling can be used for the analysis of the functioning and the performances of both systems and in order to help engineering in the design of efficient devices.