length, which is expressed as a number of AS hops (not router hops), is stable [21]. This implies that ASs are more richly connected than in the past. In 2017, the entire Internet consisted of approximately 60 000 active ASs, with the average path length (end-to-end) span across 3-5 ASs. Regarding end-to-end QoS, more ASs on the path of the IP packets (i.e. the traffic) add more delay and a higher probability of bottlenecks somewhere on the path between the endpoints of a commu- nication call/session. This shows that the Internet has good scalability, that is, with its increase in size, the number of ASs that the traffic passes end-to-end remains almost the same, which directly influences the end-to-end QoS (fewer ASs on the path is better). The different types of ASs lead to different types of business relationships between them, which in turn translate to different policies for exchanging and selecting routes. Overall, there are two main types of exchange of traffic between ASs at inter-As inter- connections [22]: 2.3 Internet Traffic Characterization Transit. In this case one ISP provides access to most or all destinations in its routing tables. Transit is typically based on financial settlement for an inter-AS relationship where the provider ISP charges its customers (other ISPs or companies which have their own ASs) for forwarding/routing their IP packets on behalf of customers to des- tinations (and vice versa). Peering. In this case two ASs (which are typically ISPs) provide mutual access to a subset of each other's routing tables. Similar to the transit, the peering is also a busi- ness deal; however, it may be set up without particular financial settlement. There are also cases for paid peering in some parts of the world, though in most of those cases it is based on reciprocal agreements. That is acceptable from a business point of view in cases where the traffic ratio between the concerned ASs is not highly asymmetric (e.g. a ratio of 1:4 may be considered as some boundary [22]). Large network operators