Internetworking (Telecommunication)

Peer-to-peer (P2P) networking has been receiving increasing attention from the
research community recently. How to conduct efficient and effective searching in such
networks has been a challenging research topic. This dissertation focuses on unstructured
file-sharing peer-to-peer networks. Three novel searching schemes are proposed,
implemented, and evaluated. In the first scheme named ISRL (Intelligent Search by Reinforcement
Learning), we propose to systematically learn the best route to desired files
through reinforcement learning when topology adaptation is impossible or infeasible. To
discover the best path to desired files, ISRL not only explores new paths by forwarding
queries to randomly chosen neighbors, but also exploits the paths that have been discovered
for reducing the cumulative query cost. Three models of ISRL are put forwarded: a
basic version for finding one desired file, MP-ISRL (MP stands for Multiple-Path ISRL)
for finding at least k files, and C-ISRL (C refers to Clustering) for reducing maintenance
overhead through clustering when there are many queries. ISRL outperforms existing searching approaches in unstructured peer-to-peer networks by achieving similar query
quality with lower cumulative query cost. The experimental results confirm the performance
improvement of ISRL. The second approach, HS-SDBF (Hint-based Searching
by Scope Decay Bloom Filter), addresses the issue of effective and efficient hint propagation.
We design a new data structure called SDBF (Scope Decay Bloom Filter) to
represent and advertise probabilistic hints. Compared to existing proactive schemes, HSSDBF
can answer many more queries successfully at a lower amortized cost considering
both the query traffic and hint propagation traffic. Both the analytic and the experimental
results support the performance improvement of our protocol. The third algorithm, hybrid
search, seeks to combine the benefits of both forwarding and non-forwarding searching
schemes. In this approach, a querying source directly probes its own extended neighbors
and forwards a query to a subset of its extended neighbors and guides these neighbors
to probe their own extended neighbors on its behalf. The hybrid search is able to adapt
query execution to the popularity of desired files without generating too much state maintenance
overhead because of the 1-hop forwarding inherent in the approach. It achieves
a higher query efficiency than the forwarding scheme and a better success rate than the
non-forwarding approach. To the best of our knowledge, this work is the first attempt
to integrate forwarding and non-forwarding schemes. Simulation results demonstrate the
effectiveness of the hybrid search.

The open nature of the wireless medium makes the wireless communication
susceptible to eavesdropping attacks. In addition, fading and shadowing significantly
degrade the performance of the communication system in the wireless networks. A
versatile approach to circumvent the issues of eavesdropping attacks while exploiting the
physical properties of the wireless channel is the so-called physical layer-security. In this
work, we consider a model in which two legitimate users communicate in the presence of
an eavesdropper. We investigate the performance of the wireless network at the physical
layer that is subject to a variety of fading environments that may be modeled by the
Rayleigh, Nakagami-m, and Generalized-K distributions, to mention a few. We use the
secrecy outage probability (SOP) as the standard performance metrics to study the
performance of the wireless networks. We propose two different approaches to compute
the secrecy outage probability, and derive explicit expressions for the secrecy outage probability that allow us to characterize the performance of the wireless networks.
Specifically, we use a direct integration approach as well as a Taylor series base approach
to evaluate the secrecy outage probability. Finally, we use computer simulations, based
on MATLAB, to confirm the analytical results.

This work presents the development of the Context-Aware Hybrid Data Dissemination
protocol for vehicular networks. The importance of developing vehicular networking data
dissemination protocols is exemplified by the recent announcement by the U.S. Department of Transportation (DOT) National Highway Traffic Safety Administration (NHTSA) to enable vehicle-to-vehicle (V2V) communication technology. With emphasis on safety, other useful applications of V2V communication include but are not limited to traffic and routing, weather, construction and road hazard alerts, as well as advertisement and entertainment. The core of V2V communication relies on the efficient dispersion of relevant data through wireless broadcast protocols for these varied applications. The challenges of vehicular networks demand an adaptive broadcast protocol capable of handling diverse applications. This research work illustrates the design of a wireless broadcast protocol that is context-aware and adaptive to vehicular environments taking into consideration vehicle density, road topology, and type of data to be disseminated. The context-aware hybrid data dissemination scheme combines store-and-forward and multi-hop broadcasts, capitalizing on the strengths of both these categories and mitigates the weaknesses to deliver data with maximum efficiency to a widest possible reach. This protocol is designed to work in both urban and highway mobility models. The behavior and performance of the hybrid data dissemination scheme is studied by varying the broadcast zone radius, aggregation ratio, data message size and frequency of the broadcast messages. Optimal parameters are determined and the protocol is then formulated to become adaptive to node density by keeping the field size constant and increasing the number of nodes. Adding message priority levels to propagate safety messages faster and farther than non-safety related messages is the next context we add to our adaptive protocol. We dynamically
set the broadcast region to use multi-hop which has lower latency to propagate
safety-related messages. Extensive simulation results have been obtained using realistic vehicular network scenarios. Results show that Context-Aware Hybrid Data Dissemination Protocol benefits from the low latency characteristics of multi-hop broadcast and low bandwidth consumption of store-and-forward. The protocol is adaptive to both urban and highway mobility models.

With the explosive growth of the Internet and other types of networks, such as cell phones and pager networks, more and more people expect to communicate with each other personally anywhere and at anytime. This thesis studies a new architecture Mobile People Architecture (MPA) proposed by MosquitoNet research group at Stanford University, which is designed to put people, rather than the devices that people use, at the endpoints of communication session. Three usage scenarios in MPA are simulated using SES/Workbench. The Response Time and the Update Cost are used to evaluate the performance of above scenarios. The advantages and disadvantages of different scenarios are also analyzed and discussed in this thesis.

With the advent of cellular technology and portable computers we are on the verge of a new computing paradigm. This computing paradigm is now widely known as "mobile" or "nomadic" computing. Mobile systems frequently change their point of attachment to the network. Mobile computing systems also need to communicate with the existing pool of information and file servers. Mobility defies the very principles that the TCP/IP protocol suite is based on. We study the Internet Engineering Task Force (IETF) Mobile IPv4 protocol and find it to be a highly scale solution. We study some of the other proposed mobile IP solutions. We establish a criterion, call-to-mobility ratio, to compare various mobile IP schemes. Two hypothetical schemes, Static Update and Triangular Routing, are introduced solely for the purpose of comparing the performance of Mobile IPv4. In our simulation we concentrate on calculating the update costs and the routing costs for Triangular Routing, Static update and Mobile IPv4 schemes. The simulation program to simulate Triangular Routing, Static Update and Mobile IPv4 is written in C++. Minetsim, our simulation program is written using object-oriented analysis and design. Minetsim is used to obtain routing and update costs for Triangular Routing, Static Update and Mobile IPv4 schemes. Four different host configurations are simulated for travelling salesman and random motion mobility models.

Innovation has flourished at the edge of the Internet; however, the core has experienced a slower pace of innovation. This lag is impacting the pace of innovation at the edge and threatening quality as ad hoc solutions are implemented to overcome core network barriers to innovation. Active networking technology, which opens up the architecture of routers, is proposed as a standard solution. Researchers draw an analogy to the computer industry where innovation is claimed to be accelerated by modularization. This argument is valid to the extent that the router market is similar to the computer market; however, contemporary innovation theories cast doubt on this likelihood. These theories indicate that for active networking technology to accelerate Internet innovation, extraordinary measures will be required to break the status quo. This paper analyzes this situation and makes recommendations, based on innovation theory, on how active networking can be successful in accelerating Internet innovation.

Current management architectures address portions of the problem of managing high speed distributed networks; however, they do not provide a scalable end-to-end solution that can be applied to both large LAN and WAN high speed distributed networks. A new management architecture, "Web Integrated Network for Distributed Management Including Logic" (WINDMIL), is proposed to address the challenges of managing complex heterogeneous networks. The three primary components of the system are the Network Management Server (NMS), the Network Element Web Server (NEWS), and the Operator's Logic and Processing Platform (OLAPP). The NMS stores the management functions used by both the NEWS and the user. The NEWS is a Web server which collects and processes network element data in order to support management functions. The OLAPP executes the management functions and interfaces with the user.