he television an equipment called "set-top box" that adapts the format of the signal arriving from the network to the television format and allows the user to select via a simple menu system the video he wants to watch. Many set-top boxes also incorporate other features, like a hard disk for video storage and web browsing. However, it is a key point to maintain the set-top box simple to use, due to the fact that it has to be suitable for those who, for different reasons, find the PC too complex. For all these reasons, we will concentrate on the television standards. Telecommunication Networks TABLE 2.1 Bandwidth Occupied by Digital Video with Different Compression Codes Bit Rates per Channel (Mbit/s) Range Typical 1.5-2 15-20 On the coding side, there are several codes available, and the continuous improvement in code compression of video signals is one the keys to the success of broadband video services [22]. The bandwidth occupied on the access line by different video codes is reported in Table 2.1. Let us now consider the most important bundle of services that is offered by almost all carriers to the retail user-the so-called triple play. The triple play is built by putting together one or more phone lines, a package of data services mainly centered on web browsing (even if instant messaging and pair-to-pair are very popular), and one or more contemporary television channels. The need for more than one television channel is related to the fact that frequently more than one television is present in a house and different persons can wish to watch different programs at the same time. The first important observation is that triple play is intrinsically asymmetric. As a mat- ter of fact, video services are delivered from the network to the user at high speed, while the data stream from the user to the network is constituted only by the commands needed to set the options of the service and is low speed. This is the main reason for the success of asymmetric access systems like ADSL and GPON in the retail market that 