e more frequently using applications that are increasingly bandwidth-intensive and sensitive to delay, such The number of backbones involved depends on whether service is being provided under a peering or a transit arrangement. Under peering arrangements, backbones only exchange traffic that originates from the customer of one backbone and terminates with the customers of the other peered backbone. In that case, the maximum number of backbones involved is two. Under transit arrangements, backbones serve as intermediaries for traffic that neither originates from nor terminates with their customers or the customers of their peering partners. In this case, the number of backbones involved may exceed two (Kende 2000). In addition to congestion in backbone and middle-mile services, cable modem customers share bandwidth both between the end users' premises and the fiber node and between the fiber node and the cable headend. As a result, both segments are subject to congestion. DSL systems have historically used dedicated circuits that were less subject to congestion. Telephone companies are increasingly deploying remote terminals that aggregate traffic and convey it via fiber to their central office facilities in a manner quite similar to the hybrid fiber-coaxial architecture of most cable modem systems. To the extent that they employ remote terminals, telephone networks may be subject to congestion effects between the remote terminal and the central office that are similar to those suffered by cable modem systems between the fiber node and the headend. The connection between the end users' premises and the remote terminal continues to be through dedicated wires that are not subject to congestion. Networks in Telecommunications as streaming media and virtual worlds. Thus, guaranteed throughput rates have become increasingly important at the precise time that increases in the volume of traffic are making quality of service harder to maintain. Indeed, some technologists have come to regard the thirty-year-old suite of pr