Control of transport dynamics in overlay networks

Transport control is an important factor in the performance of Internet protocols, particularly in the next generation network applications involving computational steering, interactive visualization, instrument control, and transfer of large data sets. The widely deployed Transport Control Protocol is inadequate for these tasks due to its performance drawbacks. The purpose of this dissertation is to conduct a rigorous analytical study on the design and performance of transport protocols, and systematically develop a new class of protocols to overcome the limitations of current methods. Various sources of randomness exist in network performance measurements due to the stochastic nature of network traffic. We propose a new class of transport protocols that explicitly accounts for the randomness based on dynamic stochastic approximation methods. These protocols use congestion window and idle time to dynamically control the source rate to achieve transport objectives. We conduct statistical analyses to determine the main effects of these two control parameters and their interaction effects. The application of stochastic approximation methods enables us to show the analytical stability of the transport protocols and avoid pre-selecting the flow and congestion control parameters. These new protocols are successfully applied to transport control for both goodput stabilization and maximization. The experimental results show the superior performance compared to current methods particularly for Internet applications. To effectively deploy these protocols over the Internet, we develop an overlay network, which resides at the application level to provide data transmission service using User Datagram Protocol. The overlay network, together with the new protocols based on User Datagram Protocol, provides an effective environment for implementing transport control using application-level modules. We also study problems in overlay networks such as path bandwidth estimation and multiple quickest path computation. In wireless networks, most packet losses are caused by physical signal losses and do not necessarily indicate network congestion. Furthermore, the physical link connectivity in ad-hoc networks deployed in unstructured areas is unpredictable. We develop the Connectivity-Through-Time protocols that exploit the node movements to deliver data under dynamic connectivity. We integrate this protocol into overlay networks and present experimental results using network to support a team of mobile robots

PLAN Security System

Active Networks offer the ability to program the network on a per-router, per-user, or even per-packet basis. Unfortunately, this added programmability compromises the security of the system by allowing a wider range of potential attacks. Any feasible Active Network architecture therefore requires strong security guarantees. Of course, we should like these guarantees to come at the lowest possible price to the flexibility, performance, and usability of the system. The PLAN system is a distributed programming framework we have used to build an Active Network, PLANet [4]. In the PLAN system, code implementing distributed programs is broken into two parts: the PLAN level, and the Service Level. All programs in the PLAN level reside in the messages, or packets, that are sent between the nodes of the system. These programs are written in the Programming Language for Active Networks [6] (or simply, PLAN). PLAN programs serve to glue together Service level programs; PLAN may be thought of as a network scripting language. In contrast, Service level programs (or simply, services), reside at each node and are invoked by executing PLAN programs. Services are written in general-purpose languages (in particular, the language that the PLAN interpreter is written in) and may be dynamically loaded. The current Internet (IP and its supporting protocols) allows any user with a network connection to have some basic services. In addition to basic packet delivery provided by IP, basic information services like DNS, finger, and whois, and protocols like HTTP, FTP, TCP, SMTP, and so forth are provided. Similarly, a goal of PLANet is to allow any user of the network to have access to basic services; these services should naturally include some activeness. This goal implies that some functionality, like packet delivery in the current Internet, should not require authentication; in PLANet, we allow pure PLAN programs to run unauthenticated. A PLAN program is considered pure if it only makes calls to services considered safe; for example, determining the name of the current host is a safe operation, while updating the host’s router table is not. Successfully calling unsafe services would require proper authorization. This security policy is stated more formally in the following subsection

Computing infrastructure issues in distributed communications systems : a survey of operating system transport system architectures

The performance of distributed applications (such as file transfer, remote login, tele-conferencing, full-motion video, and scientific visualization) is influenced by several factors that interact in complex ways. In particular, application performance is significantly affected both by communication infrastructure factors and computing infrastructure factors. Several communication infrastructure factors include channel speed, bit-error rate, and congestion at intermediate switching nodes. Computing infrastructure factors include (among other things) both protocol processing activities (such as connection management, flow control, error detection, and retransmission) and general operating system factors (such as memory latency, CPU speed, interrupt and context switching overhead, process architecture, and message buffering). Due to a several orders of magnitude increase in network channel speed and an increase in application diversity, performance bottlenecks are shifting from the network factors to the transport system factors.This paper defines an abstraction called an "Operating System Transport System Architecture" (OSTSA) that is used to classify the major components and services in the computing infrastructure. End-to-end network protocols such as TCP, TP4, VMTP, XTP, and Delta-t typically run on general-purpose computers, where they utilize various operating system resources such as processors, virtual memory, and network controllers. The OSTSA provides services that integrate these resources to support distributed applications running on local and wide area networks.A taxonomy is presented to evaluate OSTSAs in terms of their support for protocol processing activities. We use this taxonomy to compare and contrast five general-purpose commercial and experimental operating systems including System V UNIX, BSD UNIX, the x-kernel, Choices, and Xinu

Network emulation focusing on QoS-Oriented satellite communication

This chapter proposes network emulation basics and a complete case study of QoS-oriented Satellite Communication

A Flexible and Modular Framework for Implementing Infrastructures for Global Computing

We present a Java software framework for building infrastructures to support the development of applications for systems where mobility and network awareness are key issues. The framework is particularly useful to develop run-time support for languages oriented towards global computing. It enables platform designers to customize communication protocols and network architectures and guarantees transparency of name management and code mobility in distributed environments. The key features are illustrated by means of a couple of simple case studies

A novel multi-fold security framework for cognitive radio wireless ad-hoc networks

Cognitive Radio (CR) Technology has emerged as a smart and intelligent technology to address the problem of spectrum scarcity and its under-utilization. CR nodes sense the environment for vacant channels, exchange control information, and agree upon free channels list (FCL) to use for data transmission and conclusion. CR technology is heavily dependent on the control channel to dialogue on the exchanged control information which is usually in the Industrial-Scientific-Medical (ISM) band. As the ISM band is publically available this makes the CR network more prone to security vulnerabilities and flaws. In this paper a novel multi-fold security framework for cognitive radio wireless ad-hoc networks has been proposed. Multiple security levels, such as, encryption of beacon frame and privately exchanging the FCL, and the dynamic and adaptive behaviour of the framework makes the proposed protocol more resilient and secure against the traditional security attacks when compared with existing protocols

The Role of Web Services at Home

The increase in computational power and the networking abilities of home appliances are revolutionizing the way we interact with our homes. This trend is growing stronger and opening a number of technological challenges. From the point of view of distributed systems, there is a need to design architectures for enhancing the comfort and safety of the home, which deal with issues of heterogeneity, scalability and openness. By considering the evolution of domotic research and projects, we advocate a role for web services in the domestic network, and propose an infrastructure based on web services. As a case study, we present an implementation for monitoring the health of an elder adult using multiple sensors and clients

System Support for Bandwidth Management and Content Adaptation in Internet Applications

This paper describes the implementation and evaluation of an operating system module, the Congestion Manager (CM), which provides integrated network flow management and exports a convenient programming interface that allows applications to be notified of, and adapt to, changing network conditions. We describe the API by which applications interface with the CM, and the architectural considerations that factored into the design. To evaluate the architecture and API, we describe our implementations of TCP; a streaming layered audio/video application; and an interactive audio application using the CM, and show that they achieve adaptive behavior without incurring much end-system overhead. All flows including TCP benefit from the sharing of congestion information, and applications are able to incorporate new functionality such as congestion control and adaptive behavior.Comment: 14 pages, appeared in OSDI 200