Several pricing models which address the problem of Internet congestion have been studied. Internet users are usually charged on a flat-fee basis, regardless of the network load they introduce to the network. Different Quality of Service (QoS) models have been proposed, however, such as the price-controlled best-effort model, which introduces the general idea of usage-sensitive or variable pricing. Other possible models include per-packet or per-volume flat rate pricing, and flat rate pricing dependent on the QoS class. In practically all proposed models, a price is established for each network connection (sometimes also for data buffers on network nodes, i.e., routers).
One of the issues for the proposed pricing mechanisms is the calculation of the total cost of data transfer, which is basically the sum of the costs incurred along the network path, or in other words, the summed costs for data transfer over each node-to-node connection. A GoldSim model was built in which the traffic in the communication network is represented as the flow of data between network nodes in order to evaluate alternative pricing mechanisms.