This paper describes the architecture and functional aspects of the dedicated short-range communications (DSRC) protocol. The DSRC provides a communication link between vehicles and roadside beacons for road transport and traffic telematics (RTTT) applications. The DSRC technology was proposed for standardization in Europe (CEN TC 278) and ENV-standards were developed. An overview of the three DSRC communication layers is given, with a special focus on the functional aspects provided by the application layer. Finally, a presentation of the European Telematics Applications Programme research project VASCO, which deals with the validation of the DSRC ENV-standards, concludes this paper.