Institute for Systems Research Technical Reports

Permanent URI for this collectionhttp://hdl.handle.net/1903/4376

This archive contains a collection of reports generated by the faculty and students of the Institute for Systems Research (ISR), a permanent, interdisciplinary research unit in the A. James Clark School of Engineering at the University of Maryland. ISR-based projects are conducted through partnerships with industry and government, bringing together faculty and students from multiple academic departments and colleges across the university.

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Author: search.filters.author.Arora, AnubhavSubject: search.filters.subject.Global Communication Systems

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    Performance Management in ATM Networks
    (2002) Arora, Anubhav; Baras, John S.; ISR; CSHCN
    ATM is representative of the connection-oriented resource provisioning classof protocols. The ATM network is expected to provide end-to-end QoS guaranteesto connections in the form of bounds on delays, errors and/or losses. Performancemanagement involves measurement of QoS parameters, and application of controlmeasures (if required) to improve the QoS provided to connections, or to improvethe resource utilization at switches. QoS provisioning is very important for realtimeconnections in which losses are irrecoverable and delays cause interruptionsin service. QoS of connections on a node is a direct function of the queueing andscheduling on the switch. Most scheduling architectures provide static allocationof resources (scheduling priority, maximum buffer) at connection setup time. Endto-end bounds are obtainable for some schedulers, however these are precluded forheterogeneously composed networks. The resource allocation does not adapt to theQoS provided on connections in real time. In addition, mechanisms to measurethe QoS of a connection in real-time are scarce.In this thesis, a novel framework for performance management is proposed. Itprovides QoS guarantees to real time connections. It comprises of in-service QoSmonitoring mechanisms, a hierarchical scheduling algorithm based on dynamicpriorities that are adaptive to measurements, and methods to tune the schedulers atindividual nodes based on the end-to-end measurements. Also, a novel scheduler isintroduced for scheduling maximum delay sensitive traffic. The worst case analysisfor the leaky bucket constrained traffic arrivals is presented for this scheduler. Thisscheduler is also implemented on a switch and its practical aspects are analyzed.In order to understand the implementability of complex scheduling mechanisms,a comprehensive survey of the state-of-the-art technology used in the industry isperformed. The thesis also introduces a method of measuring the one-way delayand jitter in a connection using in-service monitoring by special cells.
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    On QoS Provisioning in ATM Networks
    (2002) Arora, Anubhav; Baras, John S.; ISR; CSHCN
    ATM is representative of the connection-oriented resource provisioning class of protocols. An ATM network isexpected to provide end-to-end QoS guarantees to connections in the form of bounds on delays, errors and/or losses.Performance management involves measurement of QoS parameters, and application of control measures (if required)to improve the QoS provided to connections, or to improve the resource utilization at switches. QoS provisioning is veryimportant for real-time connections in which losses are irrecoverable and delays cause interruptions in service. Mostscheduling disciplines provide static allocation of resources at connection setup time. End-to-end bounds are obtainablefor some schedulers, however these are precluded for heterogeneously composed networks. The resource allocation doesnot adapt to the QoS provided to connections in real-time. In addition, mechanisms to measure the QoS of a connectionin real-time are scarce.

    A novel framework for QoS management is proposed in this paper to provide QoS guarantees to real-time connections.It comprises of in-service QoS monitoring mechanisms, a hierarchical scheduling algorithm based on dynamicpriorities that are adaptive to measurements, and methods to tune the schedulers at individual nodes based on the endto-end measurements.