d delivering content, the food chain model provides a way to characterize each phase with a quality metric. Establishing a quality classification allows practical sizing and selection of network bandwidth and cost. The second model is a Network Interface Device (NID). The NID functions as a standardized interface between broadcast and network facilities. Another way to view the NID is to see it as the enabler network based content transport between production, distribution, and delivery phases of the program content food chain. Figure 2 is a block functional block diagram of the concept of a network interface device. Realization of a practical network interface is likely to require use of more than one commercial off the shelf product. In today's environ- ment where constant churn and change are a fact of life, multiple products and a constant insistence on compliance with formal, rec- ognized standards provide the ability to migrate from one generation to the next as an alternative to wholesale replacement of single items of equipment and software. The main message in the NID concept is standardization, where Broadcast Standards are invoked on one side; Internet and Telecom Standards on the other. SMPTE 259 L4 (ATM VBR nrt, TCP, UDP) SMPTE 292 Compression & Decompression L3 (ATM VBR rt, IP) AES-EBU Audio L2 (ATM CBR, Ethernet, ISDN) DVB-ASI Wired Direct Mapping & L1 Channel Interface (PDH, E1/T1 Adaptation SONET, SDH) Wireless E3/DS3 Internet Broadcast Interface Telecom Interface RS 232 10/100BT FIGURE 2 Network Interface Device Block Diagram INTRODUCTION The third model we want to use is an End-to-End Service Model. The notion behind such a model is to recognize another fact of life in networking and that is the basic connection or movement of infor- mation through a transmission facility. Even though we think of broadcasting and multicasting, audiences and their source of revenue are made up of individual viewers. As far as the viewer is concerned, there is only one path and that's between their set and where 