nomic ad- vantage in fully integrated voice and data on LAN wiring. And although, not likely, it may be more appropriate to use ATM switch- ing and transport for real-time program content than IP or TDM transport. On the network side, there are similar issues and concerns; how- ever, they must be addressed with carriers or service providers instead of manufacturers of equipment. As a design exercise, net- work access, transport, and switching should logically follow the food chain whereby the network facilities support movement of content within and between the creation, distribution, and delivery sections of the model. For example, moving raw, unedited content from a location to an editing facility, or moving finished program material from the post-production facility to a network opera- tions center. And of course there's the end link, which requires the content to be moved from anywhere else to cable head end, DBS uplink, Internet access facility, or digital television transmitter input. PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS Routing, Switching & Transport Access Access Internet Frame Network Relay Network Interface Interface Device Device POTS & Private FIGURE 3-4 Reference Architecture Figure 3-4 is a network topology diagram showing the details of how the basic elements fit into an overall architecture serving users lo- cated at separate sites, or operating centers. All the various elements must be specified and priced out in detail. CPE is a capital investment. Access and backbone transport is an operating expense and can be provided by third parties, such as Internet service providers (ISPs), ILECs, CLECs, or inter-exchange carriers. Obviously, it is advantageous to deal with a single source for these services. Decisions on the end-to-end solution should only be made after following a due diligence process. Building the simplest of networks is not easy. Scaling start-up or small networks to larger networks becomes geometrically more complex. Churn and change after a network is b