Because of different resource requirements, network efficiency can be increased if the different types of traffic are treated differently---giving a delay guarantee to, say, a real-time video session but not to routine e-mail or file transfer. But in order to do this, the user must truthfully indicate what type of traffic he or she is sending. If real-time video bit streams get the highest quality service, why not claim that all of your bit streams are real-time video?
[Cocchi et al. 1992] point out that it is useful to look at network pricing as a mechanism design problem. The user can indicate the ``type'' of his transmission, and the workstation in turn reports this type to the network. In order to ensure truthful revelation of preferences, the reporting and billing mechanism must be incentive compatible. The field of mechanism design has been criticized for ignoring bounded rationality of human subjects. However, in this context, the workstation is doing most of the computation, so that quite complex mechanisms may be feasible.