e colored, recolored, or dropped. So, frames are marked with the appropriate class in the network to which they are being forwarded. Dropping/shaping. Non-conformant Ethernet frames are either marked or dropped. However, the Internet as a network consists of interconnected IP networks, where the main network elements are routers and the packets are being routed based on their IP addresses (i.e. protocol layer 3 IDs), while the layer 2 IDs are LAN (or sometimes MAN) Table 3.3 Ethernet QoS services mapping. Ethernet QoS ITU QoS class service type Traffic parameters Edge rule Bandwidth for IP traffic Premium Constant bit rate and Non-conformant Dedicated Classes 0, 1, 6, committed burst size, no frames are dropped and 7 excess bitrate or bursts Constant bit rate and Excess frames are Delay-sensitive Classes 2, 3, committed burst size, admitted with high statistical and 4 excess bitrate and bursts discard precedence allowed Best-effort No guaranteed bitrate, All frames are admitted, Best-effort Class 5 no guaranteed burst size and the first is dropped at congestion 3.4 QoS Architectures for NGN Service profiles Service stratum Transport stratum Transport profiles Access and core transport Metering Classifier Marker Dropper/ Other shaper networks EVC - Ethernet virtual connections RACF - Resource and admission control functions SCF - Service control function Figure 3.10 Architecture for traffic management of Ethernet-based services in NGN. limited. Each router has its own scheduling and buffer management schemes which are also referred to as nodal behavior. Although theoretically IP networks are based on per hop behaviors (PHBs), that is, each router routes the packets on the next hop (toward the next router) based on certain policies or metrics (e.g. least cost routing), in practice (in telecom operators' networks) that is not really the case in the 2010s. Why? Because each telecom operator does its own network planning and traffic engineering (which influ- ence the capital investments, as well as operational costs f