VANET (Vehicular Ad-hoc Network) which is a hy- brid network (combination of infrastructure and infra- structure-less networks) is an emergent technology with promising future as well as great challenges especially in security. By the other hand this type of network is very sensible to safety problem. This paper focuses on a new mechanism for DoS (denial of service) attacks on the physical and MAC layers in IEEE standard 802.11p. In this proposed solution, DoS attack is detected and iden- tified by using the values of packet delivery ratio (PDR) metric. Simulation results show the acceptable perfor- mance Manuscript profile