 the following activities: Supervision. This involves monitoring of contract information between the ISPs and customers in the given country, analyzing commercial practices, traffic management practices, and specialized (i.e. managed) services. That is done by means of assess- ment of practices in the market, technical measurements, and gathering of informa- tion from customers. Enforcement. There are different approaches in enforcement which may span from naming and shaming (in countries with a developed telecom market, with enough competition, and applied legislation) to financial penalties (in countries with less developed telecom markets, and significant QoS degradations of IAS or violation of the network neutrality rules). For example, the NRA may require ISPs to deal with degradation of IAS, or to cease or revise specific problematic traffic-management approaches in their networks, to cease providing specialized services (i.e. services with QoS guarantees) in the absence of sufficient capacity for the IAS, and finally imposing fines on ISPs. The main tools of each NRA for QoS enforcement are measurement systems [9]. A reference measurement system to be used by an NRA is shown in Figure 8.4. The concrete implementation is based on connecting the measurement system (through a router which acts as a gateway - with added functionalities regarding QoS measure- ments) to a national IXP where the ISPs are connected within the NRA's jurisdiction. The router/gateway node of such a reference measurement system is responsible for the Other ISPs globally Transit providers router ISP within NRA's jurisdiction router/gateway servers ISP within NRA's ISP within NRA's jurisdiction jurisdiction measurement system ISP - Internet service provider IXP - Internet exchange point NRA - National regulatory agency Figure 8.4 Reference national measurement system for Internet access services. 8 Network Neutrality logical configurations considering that different networks connected to IXP are different autonomous systems, hence it sh