time services (e.g. VoIP, video streaming) which use UDP/IP. That may result in lower bit rates at cell edges in mobile networks, SO mobile networks are tran- siting to micro and pico cell environment to improve the QoS by lowering both the packet loss and the packet delay in the radio access networks (due to shorter distances between the mobile terminal and the serving base station, which gives less attenuation of radio signals and lower delay due to shorter path). 7 Broadband QoS Parameters, KPIs, and Measurements 7.5.2 KPIs for VPN Services The VPNs are typically used in core and transport networks. The most common use of VPN is in MPLS-based core and transport networks. Also, VPNs can be used in Car- rier Ethernet, which is becoming widely spread also in metro, wide area networks, as well as on the regional and global levels. There are layer 2 and layer 3 VPNs, depending on whether the tunneling is done on the layer 2 Ethernet frame (the Ethernet, includ- ing WiFi as its wireless "extension," has become the unified LAN technology, which is spreading its use to larger and global networks) or the layer 3 IP packet (all packet networks nowadays are IP-based, hence on the network layer, i.e. layer 3, is always the Internet Protocol). When Ethernet is LAN technology (as it is in most of scenarios) then QoS manage- ment is based on class-of-service (CoS) use. The CoS provides layer 2 differentiation between different types of services such as best effort IAS, business services, voice ser- vices (i.e. VoIP with QoS support), video services with QoS support (e.g. IPTV, VoD with QoS). Each of the service types typically uses separate VPNs for its transfer in core and transport networks. One should note that 3GPP mobile networks use GTP (GPRS Tunneling Protocol), which is standardized by 3GPP (unlike other tunneling protocols, such as IP-in-IP, which are standardized by the IETF) [12]. There are mainly two models (Figure 7.6) for provision of VPN services regarding QoS [13]: VPN pipe model. In this case the VPN service