scalable per-class-type virtual networks in an intra-AS domain network is one of the key traffic grooming functions in QoS-guaranteed DiffServ provisioning. The MPLS TE-LSP establishment in an AS domain network may be eas- ily provided by the proprietary MPLS signaling that is supported by the IP/MPLS routers. The NNI signaling for inter-AS TE-LSP establishment is not well standardized yet, and transport MPLS (T-MPLS) is under develop- ment as a joint working effort between ITU-T and IETF [2]. As a intermediate solution for the inter-AS TE-LSP establishment, as shown in Figure 15.11, the network management system (NMS) in each AS domain network may config- ure multiple virtual overlay networks for each DiffServ class-type considering the QoS parameters [10]. In a per-class-type virtual overlay network, multiple QoS-guaranteed TE- LSPs are established among provider edge (PE) routers to configure con- nectivity of full mesh topology. The DiffServ-over-MPLS AS domain network provides the network-view information of IP/MPLS routers, data links among routers, and constraint-based shortest path first (CSPF) routing function. For open service provisioning, the QoS-guaranteed per-class-type virtual over- lay networking function must be provided as the connectivity management application programming interface (API) of Parlay/Open Service Architec- ture (OSA) standard. In order to provide QoS-guaranteed service while maintaining the network in optimal resource utilization level, we need to configure the IP/MPLS tran- sit network to provide multiple per-class-type virtual overlay networks with different operation modes. In order to provide QoS-guaranteed differentiated services, we use the concept of multiple virtual overlay network on an MPLS network, where virtual networks for network control traffic (NCT), expedited forwarding (EF), and assured forwarding (AF) class-types are configured and managed separately [10]. In the performance analysis of end-to-end QoS-provisioning across the IP/ MPLS transit network, we used on