ommunication management, Performance management (PM), Performance measurements Universal terrestrial radio access network (UTRAN) TS 32.410: Telecommunication management, key performance indicators (KPI) for UMTS and GSM Fundamentals of EMS, NMS and OSS/BSS Core network Node B Packet network Node B UTRAN Figure 9.4 UMTS network simplified architecture. 9.6 MPLS Network MPLS (multi protocol label switching) was developed with the intent of having a unified network for circuit and packet based clients. It can be used for transmission of a variety of traffic including ATM, SONET, and IP. It is called label switching because each packet in an MPLS has an MPLS header that is used for routing. The routing is based on label look up, which is very fast and efficient. Connectionless packet based network fails to provide the quality of service offered by circuit based networks that are connection oriented. MPLS connection oriented service is intro- duced in IP based networks. MPLS can be used to manage traffic flows of various granularities across different hardware and applications. It is independent of layer 2 and 3 protocols and is sometimes referred to as operating on "Layer 2.5." There are two main kinds of routers in an MPLS network (see Figure 9.5): Label edge routers (LER): The entry and exist point for packets into an MPLS network is through edge routers. Incoming packets have a label inserted into them by these routers and the label is removed when they leave the MPLS network by the routers. Based on the functionality performed on the packets, these routers are classified in to Incoming (Edge) Router or Ingress router, and Outgoing (Edge) Router or Egress router. Label switch routers (LSR): Inside the MPLS network, packet transfer is per- formed using LSR based on the label. An additional functionality of the LSR is to exchange label information to identify the paths in the network. Another terminology for routers is in MPLS based VPN network. Here the MPLS label is attached with a packet at the ingress router an