 landscape. According to those standards and default traf- fic management principles used on the public Internet, one may distinguish an IETF Internet QoS framework consisting of the following approaches (including accepted scenarios and standardized mechanisms): Best effort. This is the traditional Internet model, without any QoS guarantees. The IP networks simply route packets until they reach their destination. Integrated services (IntServ) [25]. This was the first mechanism standardized by the IETF, based on resource reservation in routers on the path by using signaling. So, routers have to store traffic and QoS information per connection (i.e. per flow). It is an end-to-end QoS mechanism. Differentiated services (DiffServ) [26]. This is the most commonly used method for traffic differentiation, in which all packets are classified into a limited number of classes, SO routers have to store only information per class (not per connection/flow). It is a hop-by-hop QoS mechanism. Multi-protocol label switching (MPLS) [27]. This is the "default" approach for QoS provisioning in transport IP networks, which may be combined with DiffServ as well as other protocols such as BGP, or VPN protocols. Policy-based QoS. This is typically used for QoS provisioning between network providers (e.g. BGP policies are used for routing of packets between interconnected ASs). The ITU has also defined a QoS framework for telecommunication packet-switched networks (where the Internet and Internet networking technologies belong). As usual, 2.7 Integrated Services (IntServ) and Differentiated Services (DiffServ) Admission control QoS routing Resource reservation Control plane Congestion Queuing and avoidance scheduling Buffer Packet Traffic management marking classification Service Traffic policing Traffic shaping Data plane Figure 2.11 QoS architectural framework by the ITU. since the PSTN/ISDN era, the ITU-T QoS architectural framework is organized into three planes [28] (Figure 2.11): Control plane. This includes the admission control