4.5 Network Management

Summary

• In different QoS investigations, a real-time end-to-end protocol suite was developed and successfully demonstrated using video streams over HIPPI and other networks, and a `broker' approach was developed for end-to-end/network QoS negotiations in conjunction with operating system scheduling for strict real-time constraints
• An evaluation of processing requirements for wide area QoS queuing in ATM switches, using a variation of the WFQ algorithm, found that a factor of 8 increase in processing speed was needed to achieve 622 Mbps port speeds relative to the i960/33MHz processor used for the experiments
• Congestion/flow control simulation modeling was carried out based on testbed application traffic, with the results showing rapid ATM switch congestion variations and high cell loss rates; in other work, a speedup mechanism was developed for lost packet recovery in high delay-bandwidth product networks using TCP's end-to-end packet window protocol
• An end-to-end time window approach using switch monitoring and feedback was developed and evaluated to provide high speed wide area network congestion control, and performed according to simulation-based predictions
• A control and monitoring subsystem was developed for real-time traffic measurement and characterization using carrier-based 622 Mbps ATM equipment, and was used to capture medical application traffic statistics which revealed ATM cell traffic to be more bursty than expected, dictating larger amounts of internal switch buffering than initially thought necessary
• A data generation and capture device for 800 Mbps HIPPI link traffic measurement and characterization was developed and commercialized, and was used for network debugging and traffic analysis; more generally, many network equipment problems were revealed through the use of real application traffic during testbed debugging phases

This section includes testbed work on high speed networking undertaken from a systems viewpoint, and includes investigations in the areas of quality of service (QoS), congestion/flow control, and traffic measurement and characterization. Work in this area was generally constrained by the relatively limited extent of testbed facilities, in particular the existence of only a small number of network switches and hosts, and by the amount of time needed to achieve full operation of the facilities. To deal with these constraints, analytical modeling and simulations were exploited where possible by several of the efforts in the early stages of this work, with testbed experiments successfully carried out for limited contexts later in the project.