rk quality parameters (as given in this chapter). Degradation of IAS considering individual OTT applications/services. This case refers to individual applications (Skype, Viber, Facebook, YouTube, etc.), which may expe- rience degradation due to different causes that may be put into the following three main groups: Congestion. This is the situation in IP networks when IP traffic increases to a level at which routers run out of buffer space and are forced to start dropping some IP packets. Congestion appears randomly for various reasons, including not enough capacity in certain parts of the network (e.g. access, core, or interconnection), or it may be the result of temporary network link or segment failures. However, con- gestion affects bitrates, delays, jitter, and losses and with that all OTT Internet applications that are traversing that path. Traffic management. Different approaches applied by ISPs in their own networks may include both limiting measures (e.g. application traffic blocking and/or throt- tling) and enabling measures (e.g. routing and traffic forwarding). 8 Network Neutrality Network security and integrity. This refers to degradations of applications caused by various security attacks (e.g. a denial of service attack on a given website), as well as degradations due to network failures (network integrity in fact includes measures to maintain the quality level during network failures, as well as measures to prevent network failures such as using redundant nodes and links in the network). Certain degradations of OTT services, such as service blocking (e.g. blocking of OTT VoIP services such as Skype, Viber, or WhatsApp), are easier to detect. Meanwhile, throttling of certain services (e.g. torrent traffic throttling by the ISP) is harder to detect and requires measurement (e.g. by the NRA). Congestion management is always required in IP networks; however, the ISPs should not misuse that for degradation of chosen OTT applications, i.e. congestion management should be application agnostic. Network se