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This paper presents three new results concerning credit-based jlow control for ATIU network:(1) a simple and robust credit up~te pro@col (CUP) suited for relatively inexpensive hardwarei so+are implementation;(2) automatic adaptation of credit bufjer allocation for virtual circuits (VCS) sharing the same bujfer pool;(3) use of credit-based$ow control to improve the effectiveness of statistical multipltning in mim"mizing switch memory. These results hme been substantiated by anulysis, simulation and implementation.

The attempt to provide QoS in IP networks has raised some interesting questions on how a service can be provided to meet the application requirements while obeying the network resource constraints. Previous efforts focussed on a flow-based, connection oriented approach to deliver QoS for IP Networks -Intserv. This approach was quite comprehensive but it has not been widely deployed because of complexity and scalability issues. A recent packet marking based scheme called Differentiated Services (Diffserv) Architecture provides a relatively simple and coarse approach. It is too early to predict the usefulness of this approach. This paper outlines a framework to deliver IP QoS which is based on Intserv. It addresses scalability concerns by removing the need for a connection-oriented reservation setup mechanism and replaces it with a Diffserv-like mechanism to consistently allocate bandwidth end-to-end in a network. A prototype device is discussed that manages bandwidth on a node. An algorithm is presented that allows the device to automatically detect application QoS requirements without the need for application-level signalling. A priority-based scheduling mechanism with a variant of weighted round-robin is described.

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This paper describes a technique for enhancing the effectiveness of RED by dynamically changing the threshold settings as the number of connections (and system load) changes. Using this technique, routers and switches can effectively control packet losses and TCP timeouts while maintaining high link utilization.