 (such as national telecom operators) typically exchange traf- fic with other comparably large network operators through private peering arrange- ments, which are based on direct connections between the operators. Such peering agreements are usually subject to contracts and to certain nondisclosure commitments. In terms of the amount of Internet traffic carried through peering interconnections, they are very important because most of the Internet traffic travels across them. In the 2010s it is becoming common for interconnection between IP networks of large network operators to be realized via Internet Protocol eXchange (IPX) points on a national or international level, which are typically used by operators in a given country or region. 2.3 Internet Traffic Characterization There are different applications/services present on the public Internet. Also, there are different requirements for telecom-provided services over managed IP networks, with certain guaranteed QoS and based on signed agreements with customers (e.g. fixed or mobile telephony and TV, business services). All Internet packets on a given network interface (e.g. on a host, on a router), or in a given network or a network segment, are referred to as IP traffic. The traffic notion comes from legacy telecommunication net- works, where it was used to denote mainly voice traffic (in PSTNs). There are different traffic classifications. Although there are many different applica- tions for traffic nowadays (e.g. millions of applications are available in different ecosys- tems of global OTT service providers), they all can be grouped into three main types: audio, video, and data. The first two, audio and videos, are based upon the human senses and their "design" for hearing (audio) and viewing (video), while the data traffic type includes everything else. Each of these traffic types has specific traffic characteristics which influence network performances and QoS solutions. So, typically we have the following types of traffic on the Internet: Voice traffic. 