tratum and the QoS requests are coming from the SCFs (e.g. IMS) in the service stratum via the RACF entity. This way NGN transport network provides the possibility for higher integration with the MPLS (already a legacy transport technol- ogy), which was on the ground even before the NGN appeared, but the MPLS continues to be the main QoS technology for transport networks of telecom operators, combined with Ethernet technologies in local and metropolitan areas. Management of Performance Measurements in NGN Performance measurements in NGNs are important, with the aim of providing QoS support in heterogeneous network environments consisting of many interconnected autonomous domains, as well as heterogeneous services with different QoS require- ments that are provided using the same IP-based transport networks. For that purpose there is a defined general reference network model for performance management in NGNs, which is in line with the basic network model for QoS analysis (see Figure 2.4 in Chapter 2). So, performance measurements in NGNs on the path end-to-end involve two customer premises networks (CPNs), the access networks, and one or multiple core networks, as well as zero or multiple transit networks. In such a model, customer equipment is connected to the access networks, then access networks are connected to core networks, and different core networks are connected via transit networks. In this manner, on the end-to-end path, the networks are partitioned into several network segments and domains, where each of them is responsible for maintaining QoS support in the given segment. Overall, NGNs support three types of QoS-based delivery of services regarding the endpoints: Edge-to-edge. These services extend to the network provider's edge nodes (e.g. gate- ways). The demarcation points for performance measurements are access or core network edge nodes. Site-to-site. These services extend to customer premises (e.g. home, office, public place). The demarcation points are typically the edge nodes (e.g. home gatew