Which provides better utility for users, best-effort service or reservation-based service?

Recently, on the Internet, only best-effort service has been provided, in w hich communication quality (QoS) aspects such as throughput and delay are n ot guaranteed. There is an increasing demand, however, for real-time transf er of voice and video data, and reservation-based service is being consider ed in which the communication quality is guaranteed by reserving network re sources. Reservation-based service, however, has problems such as the overh ead of packet processing, as well as scalability. There is an ongoing basic discussion as to whether best-effort service is sufficient or reservation- based service is necessary. This paper defines the communication quality wh ich is obtained when the user uses a network application as the utility for the user. The user utility for the real-time application is derived and co mparatively evaluated for the two service models, that is, best-effort serv ice and reservation-based service. The following results are obtained quant itatively. Best-effort service can provide sufficient utility if a sufficie nt channel capacity is available, for which, however, sufficient channels m ust be provided by adequate network design. If not, reservation-based servi ce is necessary. (C) 2001 Scripta Technica.