This paper presents the "Allocated Capacity" framework for providing different levels of best-effort service in times of network congestion. The "Allocated Capacity" framework - extensions to the Internet protocols and algorithms - can allocate bandwidth to different users in a controlled and predictable way during network congestion. The framework sup ports two complimentary ways of controlling the bandwidth allocation: sender-based and receiver-based. In today's heterogeneous and commercial Internet, the framework can serve as a basis for charging for usage, an more efficiently utilizing the network resources.