tatistical multiplexing on the access network works at best and access resources can be shared among many users. Other services of this category are instant messaging, e-mail, pair-to-pair file sharing, access to network databases (like online file repository), and a plethora of other services that do not require real-time data transmission. Multimedia services are, on the contrary, based on real-time data exchange and are dominated by video streaming (either broadcast or on demand) and IP phone (e.g., either audio or video as the service provided by Skype). It is clear that even if IP-based audio telephone imposes on the network severe require- ments in terms of quality of service (QoS), the required bandwidth is not very high, being in general lower than kbit/s, which is needed for traditional telephones. Thus, the class of services requiring a higher bandwidth is constituted by video services. The bandwidth occupied on the access line by video streaming depends both on the video resolution and on the line code used for video coding. Under the video resolution point of view, there are a great number of possibilities related to the different possible resolutions of the screen of a PC, but two cases are par- ticularly important. These are the resolutions compatible with the television standards: standard television (SDTV) [21] and high-definition television (HDTV) [21]. As a matter of fact, a television is present in almost all houses in rich countries, and it spreads rapidly in all emerging countries. Moreover, many video services (e.g., streaming film or television online) are conceived to be used by more than one person at the same time, and this is difficult using a PC, while the television is naturally designed to be watched by more than one person. For these reasons, many carriers also offer PC-less video services to the retail market, directed to people who do not want to use a PC but are of course skilled in using television. In this case, the service is delivered by connecting to the access line and to t