Geostationary satellite networks are currently considered as one of the most promising broadband access network technology for narrowing the digital divide. Though technically attractive and cost effective, the provisioning of end-to-end QoS services in satellite access remains largely undefined for the Next Generation Networks (NGN). In order to bridge this gap, the European SATIP6 project defines a complete QoS architecture involving Application, Session, Network and Link layers over DVB-S/RCS (Digital Video Broadcasting via Satellite/Return Channel via Satellite) systems which is detailed in this paper. First, a review of DVB-RCS standard approaches to QoS in satellite networks is given. Then we focus on the proposed QoS architecture layer by layer: the MAC layer taking benefits from DVB-RCS dynamic allocation schemes, the IP layer implementing differentiated services and finally two separate solutions, at Application/Session layers, for applications to take advantage of the QoS architecture developed on the satellite segment.