In "Teletraffic Engineering in a Competitive World" (Editors P. Key and D. Smith), ITC 16. Elsevier, Amsterdam, 1999. 941-952.
We describe how a packet network with a simple pricing mechanism and no connection acceptance control may be used to carry a telephony-like service with low packet loss and some call blocking. The packet network uses packet marking to indicate congestion and end-systems are charged a fixed small amount per mark received. The end-systems are thus provided with the information and the incentive to use the packet network efficiently. We demonstrate that algorithms embedded in the end-systems are able to synthesize a telephony-like service by blocking calls at times when the load in the packet network is high.
Keywords: charging, rate control, Internet, packet network, pricing, measurement-based connection acceptance control, quality of service.
Available as postscript.
We have seen that a gateway may provide a telephony-like service, with low packet loss and some call blocking, from a network providing packet transport. We expect that different gateway strategies will be of some interest, and may be explored in the context of the distributed game described in Key and McAuley (1999). It is important to note that the role of the gateway is informational rather than physical: the aim is to infer expected prices from observations on the network. Thus the gateway itself may be embedded in software and distributed over users.
We have defined Quality of Service, as perceived by users, in terms of call blocking. More general definitions are, of course, possible. For example, the heterogeneous gateways of Section 4 may be differentiated not just by call blocking, but also by the packet rate allocated to an accepted call. Or the strategy of Section 5 mght choose to allocate an accepted call a high or moderate packet rate depending on the proportion of probe packets marked. Quality of Service for a user might then depend on the probability an accepted call has high or moderate speech quality, as well as the probability a call is accepted.
A user may also require a telephony-like service to have a fixed, known charge per unit time for an accepted call. But to provide such a service a gateway need only choose the charge per unit time and the threshold value so that on average the gateway is profitable: the gateway operator would then undertake the various risks associated with predicting traffic conditions. More generally, we think it possible that simple marking and pricing schemes may be sufficient to allow gateways to synthesize Quality of Service, however defined by the user, from an underlying packet network.