ork UNI - User to network interface VLAN - Virtual local area network VPN - Virtual private network Provider network (Q-in-Q) Figure 3.9 Reference model for VPN use for end-to-end Ethernet service. 3 QoS in NGN and Future Networks determine further the settings of the CAC values and QoS parameters at E-UNIs and E-NNIs. The edge nodes at these interfaces implement the mechanisms for traffic management of Ethernet QoS-enabled services by specifying the network edge rules, traffic parameters, QoS class mappings between interconnected networks, and other QoS parameters in use. The mapping between Ethernet QoS services and ITU QoS classes is given in Table 3.3. When a telecom operator has implemented the NGN, then Ethernet traffic man- agement functions are based on Ethernet-based NGN services. In such cases SCFs determine the requirements for a given request for Ethernet-based NGN service and then inform the RACF. The RACF then does the policy-based resource control in the transport stratum (for the given request). Further, the transport functions in the access and core networks perform the traffic conditioning (as part of the QoS control) based on the policy rules given by the RACF. The architecture for Ethernet traffic management is shown in Figure 3.10. Based on the policy rules received by the RACE, the transport nodes (e.g. switches), which belong to the NGN transport stratum, are performing the following functions: Metering. This is used to ensure conformance of Ethernet frames at the interfaces (e.g. E-UNI). Classification. For Ethernet services this is based on layer 2 ID information, such as different tags used in Ethernet MAC frames (e.g. VLAN ID, i.e. Q-tag, S-tag, or I-tag, as well as use of higher layer IDs such as IP addresses on protocol layer 3). For flow classification Ethernet tag values (e.g. VLANIDs) are mapped onto labels (used as IDs between layer 2 and layer 3 in the MPLS networks) when the traffic is transported over MPLS transport networks. Marking. Based on the metering Ethernet frames can b