 access. Successful attempt Stop: First Web content is received. Unsuccessful attempt Stop trigger point not reached. the public Internet) with certain QoS support. So, although the Web has appeared in the public Internet (which is served in a best-effort manner), nowadays it is used in both the public Internet and managed IP networks (depending upon the ToS in which it is used). As with email there are standardized QoS parameters for HTTP services (i.e. Web services, such as Web browsing) [17], which are listed in Table 6.6. For example, QoS parameter HTTP Service Non-Accessibility [%] is defined with the following abstract equation (the trigger points for this HTTP QoS parameter are given in Table 6.7): unsuccessful_HTTP_attempts HTTP_service_non - accessibility = (6.3) all.HTTP_attempts Besides email and HTTP, similar QoS parameters are defined for other Internet ser- vices, such as FTP (File Transfer Protocol). However, FTP is almost completely replaced by HTTP for uploads and downloads of files as well as for testing purposes such as QoS measurements. 6 Services in Fixed and Mobile Ultra-Broadband 6.5 QoS for Business Users (VPN Services) Business services have been present in telecommunication networks since the second part of the twentieth century. Since digitalization in the 1970s and the 1980s, business services have been provided over TDM telecommunication networks (created primar- ily for digital telephony), typically to provide site-to-site connections with predefined bitrates and guaranteed QoS. This was referred to as "leased lines," which were in the range of Nx64 Kbit/s up to PDH (plesiochronous digital hierarchy) reserved bitrates (e.g. multiples of 2, 34, and 140 Mbit/s in Europe, or multiples of 1.5, 6, and 140 Mbit/s in the Americas) and SDH bitrates whose brut values are N X 155.52 Mbit/s. With the transition from digital to all-IP networks, the leased lines continued to be provided by telecom operators to business users by virtual private networks. However, the VPN by itself does not contain