PhD, University of Cincinnati, 2008, Engineering : Computer Science and Engineering

Currently, Peer-to-Peer overlays can be classified into two main categories: unstructured and structured ones. Unstructured overlays are simple, robust, and powerful in keyword search. Structured ones can scale to very large systems in terms of node number and geography, and guarantee to locate an object within O(Log N) hops. However, both of them face difficulties in efficiency and security of overlays. For unstructured ones, the efficiency problem presented is poor scalability. For structured ones, it is long routing latency and enormous overhead on handling system churn. Moreover, both of them are vulnerable to malicious attacks. Peer-to-Peer overlays belong to application-level network. To a great extension, overlay network designs ignore physical characteristics. As the result, their structures are far from underlying physical network or the distribution pattern of overlay peers. These inconsistencies induce system common operations costly, such as routing and lookup. On the other hand, most peers are assumed to have uniform resources and similar behaviors. Thus, Peer-to-Peer protocols were designed to be symmetric. However, in the realistic environment, peers' resources and behaviors are highly skewed. Symmetric protocols actually compromise system performance. Frequently joining and leaving of peers generates enormous traffic. The significant fraction of peers with high latency/low bandwidth links increase lookup latency. Moreover, under the environment without mutual trust, Peer-to-Peer systems are very vulnerable for varied attacks because they lack a practical authentication mechanism. From a different perspective, this dissertation proposes to construct a highly efficient and secure Peer-to-Peer overlay based on the physical network structure of the Internet and network locality of overlay peers. By naturally integrating different network-aware techniques into the Peer-to-Peer overlay, a novel SNSA (Scalable Network Structure Aware) technique has been dev (open full item for complete abstract)

Committee: Dr. Yiming Hu (Advisor) Subjects: Computer Science

Master of Sciences, Case Western Reserve University, 2017, EECS - Computer and Information Sciences

Multipath TCP (MPTCP) is an extension to TCP which allows hosts to establish connections consisting of multiple TCP “subflows” that travel across different Internet paths. MPTCP it is based on the assumption that at least one communicating host is multi-homed. Meanwhile, the Internet contains considerable path diversity, and research has shown that routes chosen by the Internet's routing infrastructure are not always the most efficient. Although mechanisms have been proposed which are designed to take advantage of detour routing, none can be applied to unmodified applications. In this thesis, we leverage MPTCP to allow unmodified applications on single-homed devices to use detour routes. We find that this mechanism is capable of significant bandwidth aggregation under appropriate network conditions.

Committee: Michael Rabinovich (Advisor); Mark Allman (Committee Member); Vincenzo Liberatore (Committee Member) Subjects: Computer Science

Master of Science (MS), Ohio University, 2005, Electrical Engineering & Computer Science (Engineering and Technology)

The goal of resource management in a distributed system is to appropriate the available resources in such a way as to meet the requirements of the individual applications and system as a whole. In addition to commonly managed resources such as CPU cycles or memory usage, network resources are a critical part of this goal. Current attempts at network resource management do not provide direct control of the route to the resource manager. The solution that we propose is an overlay network of relays. Traffic may be redirected among these relays in order to provide a network resource manager the means to control routing. Two types of relays are presented. The first operates in kernel-space, providing a more efficient relay but requiring higher system privileges. The second operates in user-space, allowing for deployment on systems without administrative access. This user-space relay, however, has a greater impact on performance. We discuss the design, implementation, and performance analysis of the system, as well as the costs associated with using it.

Committee: Shawn Ostermann (Advisor) Subjects: Computer Science