 the relation between entities that are in different but interlinked value chains. Such common diagonal dimension refers to the relation between the content and application/service providers on one side and broadband ISPs on the other side. Considering the dimensions given above regarding IAS, QoS, and network neutrality, one may note that the vertical dimension denotes the network provider (e.g. the ISP) versus the end-user or service provider. Then, the vertical subdimension between the ISP and the end-user as well as the diagonal dimension (between ISP and OTT ser- vice providers) are the two sub)dimensions to which network neutrality refers on the global scale. That means that network neutrality prohibits QoS differentiation for Inter- net traffic between the ISP network and end-users (as clients) as well as prohibiting business relations (in respect of QoS differentiation of the service providers' Internet traffic) between content and application/service providers and ISPs (which provide IAS 8 Network Neutrality toward end-users, on the client's side). On the horizontal dimension, QoS differentiation due to reasonable traffic management should be allowed and sometimes it is necessary for the purposes of network planning and dimensioning. Network Neutrality Enforcement Network neutrality is essential for innovation in the OTT services space, which gives freedom to end-users to choose content and applications they want to consume, from local (i.e. national) or global (i.e. international) content and application providers (i.e. OTT service providers). Considering the network neutrality ruling in different parts of the world (e.g. Europe, the U.S.), typically non-network-neutral practices refer to blocking, throttling, and pref- erential treatment of certain OTT services (by the ISP, i.e. telecom operators that provide IAS) [17]. Regarding the duties of NRAs, there are three types of actions to monitor and ensure compliance to network neutrality rules: Supervision. It includes network neutrality monitoring by th