ays for residential users) at the customer premises. 3.5 Management of Performance Measurements in NGN TE-to-TE (TE stands for terminal equipment). These services extend to end-user terminals within the given customer premises network. The demarcation points are typically the terminal equipment of the customer. All three services with assured delivery in NGNs have to be supported by a mea- surement model. So, the points in the network in which performance measurements are performed are referred to as demarcation points, which are typically located on the edge nodes in each of the given network segments in the NGN general model for performance management, as shown in Figure 3.11. In the edge-to-edge model, the service delivery is assured between the edge nodes in the access networks to which CPNs are connected. For this model the measure- ments provide performance information for all segments between the egress and ingress demarcation points, including all network segments between them. The transit seg- ment has the demarcation point for the performance measurement at the ingress NGN core network and the egress NGN core network. A given transit segment may include different transit network providers, SO it can span larger geographical areas (cities, coun- tries, regions, as well as globally). However, the choice of the demarcation points for the measurements is done autonomously by the NGN provider. But such choice may be influenced by national legislation on the ICTs, i.e. electronic communications in such a Transit segment Transit network NGN core NGN core network B network A Edge-to-edge NP Demarcation Access points Access network A network B Site-to-site NP CPN A CPN B End-to-end (TE-to-TE) NP ABG - Access border gateway EN - Edge network AN - Access network IBG - Interconnection border gateway CPN - Customer premises network NGN - Next generation network CPNE - Customer premises network edge NP - Network performance TE - Terminal equipment Figure 3.11 Models for performance management in NGN. 3 QoS in NGN and