Currently, the most promising digital video delivery network technologies are the Internet and ATM-based3.1 networks. In the recent years, the Internet has emerged as one of the most important candidate platforms for the delivery of multimedia information. Its global presence and exponentially increasing user base, has driven the proliferation of both applications and content provision in it. Furthermore, it has attracted attention from worldwide research and evolves rapidly to a multi-capable network, accommodating information types that were not in its initial scope. ATM, on the other hand, as a later design, provides flexibility for the efficient delivery of information with differing requirements. Internet and ATM technologies are not mutually exclusive, as it is possible to implement the former over the latter.
In this chapter, the network services will be discussed and assessed from the user's point of view, i.e. the QoS will be the main criterion. The focus will be on the Internet technologies, however, the ATM capabilities will also be discussed for comparison. Although not strictly required, a familiarity of the reader with the principles of computer networks, such as the OSI seven-layer stack, would make the chapter more apprehensible.
The outline of the chapter follows. After a taxonomy of digital video communications applications, their requirements as far as it concerns the network service are presented. Last, the current and emerging network technologies are described and assessed with respect to the offered QoS.