Sites of intermediate size may also be served economically with coaxial cable runs in some network segments. Each classroom should have a minimum of three network drops. These drops can accommodate three devices, including classroom telephones as needed. Rooms requiring more devices can use fan-out hardware to accommodate as many devices as might be desired. The choice of three drops is a compromise between convenience and cost and is based upon experiences with this wiring architecture in Pittsburgh and elsewhere.
Some redundancy is desirable for ease of expansion, flexibility and added network integrity.
Neither the precise needs in terms of bandwidth nor the precise solutions in terms of services can be specified at the present time with any great degree of confidence, but graphical applications require a minimal bandwidth on the order of 56 kilobits per second. The layering concept allows one to mix these technologies at different sites in a network so as to obtain the required performance at the most economical cost. Unless one single technology can be obtained at a cost significantly lower than any competing technologies, one should plan to accommodate a mix of technologies at the physical layer of a MAN, with the choice at each site matched to that site's needs and accessibility. Graphical and video applications will eventually require higher bandwidth for many school sites. If one technology proves much cheaper than the others, it could provide a suitable choice for districtwide adoption.