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published_or_final_version / Computer Science / Doctoral / Doctor of Philosophy

published_or_final_version / Electrical Engineering / Master / Master of Philosophy

published_or_final_version / abstract / Computer Science / Doctoral / Doctor of Philosophy

published_or_final_version / Business Administration / Master / Master of Business Administration

Providing robust congestion control is essential prior to Internet-wide deployment of long-lived multicast flows. This thesis therefore reviews currently proposed techniques, and identifies key issues. It then proposes a new framework that enables the network to police and enforce correct congestion behaviour. Receiver-driven layer multicast congestion control is especially vulnerable to misbehaving receivers. Countering these problems demands a new paradigm to enforce correct receiver behaviour. A framework based on Explicit Congestion Notification (ECN)-nonce is proposed, which preserves the ability to work with system/network heterogeneity in the multicast tree, mandates layered multicast receivers to feedback nonce-reports in an arrayed form. Appropriate behaviour may be enforced in the new framework by introducing selected border routers in the multicast tree, known as <i>enforcers</i>. This also avoids practical limitations requiring an upgrade to all edge routers, and allows local service providers to protect their own network. The approach uses re-active policing. This can not prevent receivers joining under congestion, but reacts by preventing forwarding of specific groups within a reasonable delay. This approach eliminates the need for secure transfer of information from the sender to the enforcing routers and avoids a need to upgrade the IGMP and PIM protocols. The method is compatible with using ECN when Active Queue Management (AQM), which has benefit when using Forward Error Correction (FEC) based reliability. This framework was analysed using simulation. The thesis also analyses some important related performance issues for congestion-controlled multicast transport protocols, considering issues such as excessive overshoot and poor congestion response in delay-diversified networks using the IETF NACK-Oriented Reliable Multicast (NORM) framework and an unnecessary congestion response with heterogeneous receivers in Asynchronous Layered Coding (ALC) framework.

Approved for public release, distribution unlimited / Policy based network management has an increasing importance depending on the increasing importance of distributed large networks and the growing number of services that run on them. Policy languages, which enable users define policies in a formal language, are one of the main tools of policy management. Even though there are policy languages like PFDL or RPSL, none of them has the capability of a robust conflict detection and resolution focused on policy. A new Policy Language, Path-based Policy Language (PPL), has been developed recently. It encompasses as many of the features addressed in the other policy languages as possible, as well as providing means for testing policies for consistency and defining both static and dynamic policies. The most important, PPL provides the ability to detect and resolve conflicts between by translating policy rules into formal logic statement and checking them with a Prolog program. Even though in theory PPL seems to be a very high performance policy language, its current compiler has a performance bottleneck. In some cases the PPL compiler can not finish compilation and runs forever without returning any conflict results. This thesis focuses on the PPL compiler's performance bottleneck and introduces solutions speeding up the PPL compiler. The new PPL compiler achieves a reasonable compilation time for any configuration file for a network with 100 nodes while maintaining its ability to detect and resolve policy conflicts. / Lieutenant Junior Grade, Turkish Navy

M.Sc. (Computer Science) / Please refer to full text to view abstract

"The purpose of this paper is to make an analysis of the acceptability of electronic data processing system information to the independent auditor as a basis for reliance thereon in expressing an opinion regarding the financial statements under examination"--Introduction. / Typescript. / "August, 1958." / "Submitted to the Graduate Council of Florida State University in partial fulfillment of the requirements for the degree of Master of Science." / Advisor: Finley E. Belcher, Professor Directing Paper. / Includes bibliographical references (leaves 40-42).

by Choi Che Shing. / Bibliography: leaves 70-71 / Thesis (M.B.A.)--Chinese University of Hong Kong, 1986