Network Fault Tolerance System

The world of computers experienced an explosive period of growth toward the end of the 20th century with the widespread availability of the Internet and the development of the World Wide Web. As people began using computer networks for everything from research and communication to banking and commerce, network failures became a greater concern because of the potential to interrupt critical applications. Fault tolerance systems were developed to detect and correct network failures within minutes and eventually within seconds of the failure, but time-critical applications such as military communications, video conferencing, and Web-based sales require better response time than any previous systems could provide. The goal of this thesis was the development and implementation of a Network Fault Tolerance (NFT) system that can detect and recover from failures of network interface cards, network cables, switches, and routers in much less than one second from the time of failure. The problem was divided into two parts: fault tolerance within a single local area network (LAN), and fault tolerance across many local area networks. The first part involves the network interface cards, network cables, and switches within a LAN, which the second part involves the routers that connect LANs into larger internetworks. Both parts of the NFT solution were implemented on Windows NT 4.0 PC\u27s connected by a switched Fast Ethernet network. The NFT system was found to correct system failures within 300 milliseconds of the failure

Mobile IP: state of the art report

Due to roaming, a mobile device may change its network attachment each time it moves to a new link. This might cause a disruption for the Internet data packets that have to reach the mobile node. Mobile IP is a protocol, developed by the Mobile IP Internet Engineering Task Force (IETF) working group, that is able to inform the network about this change in network attachment such that the Internet data packets will be delivered in a seamless way to the new point of attachment. This document presents current developments and research activities in the Mobile IP area

Rationale, Scenarios, and Profiles for the Application of the Internet Protocol Suite (IPS) in Space Operations

This greenbook captures some of the current, planned and possible future uses of the Internet Protocol (IP) as part of Space Operations. It attempts to describe how the Internet Protocol is used in specific scenarios. Of primary focus is low-earth-orbit space operations, which is referred to here as the design reference mission (DRM). This is because most of the program experience drawn upon derives from this type of mission. Application profiles are provided. This includes parameter settings programs have proposed for sending IP datagrams over CCSDS links, the minimal subsets and features of the IP protocol suite and applications expected for interoperability between projects, and the configuration, operations and maintenance of these IP functions. Of special interest is capturing the lessons learned from the Constellation Program in this area, since that program included a fairly ambitious use of the Internet Protocol

Internet connectivity for mobile Ad Hoc networks

Ad hoc networking allows portable devices to establish communication independent of a central infrastructure. However, the fact that there is no central infrastructure and that the devices can move randomly gives rise to various kind of problems, such as routing and security. In this thesis the problem of routing is considered. There are several ad hoc routing protocols, such as AODV, DSR, OLSR and ZRP, that propose solutions for routing within a mobile ad hoc network. However, since there is an interest in communication between not only mobile devices in an ad hoc network, but also between a mobile device in an ad hoc network and a fixed device in a fixed network (e.g. the Internet), the ad hoc routing protocols need to be modified. In this thesis the ad hoc routing protocol AODV is used and modified to examine the interconnection between a mobile adhoc network and the Internet. For this purpose Network Simulator 2, ns2, has been used. Moreover, three proposed approaches for gateway discovery are implemented and investigated. The goal of the thesis project is twofold: • To modify the source code of AODV in accordance with the Internet draft\Global connectivity for IPv6 Mobile Ad Hoc Networks " which presents a solution where AODV is used to provide Internet access to mobile nodes. • To implement and compare di®erent approaches for gateway discovery. In this thesis, three di®erent type of gateway discovery have been taken: • The proactive gateway discovery is initiated by the gateway itself. The gateway periodically broadcasts a gateway advertisement message which is transmitted after expiration of the gateways timer. The time between two consecutive advertisements must be chosen with care so that the network is not °ooded unnecessarily. All mobile devices residing in the gateways transmission range receive the advertisement and update information about gateway. After receiving advertisement, a mobile device just forward it broadcast it again. This process goes on within entire MANET. • In reactive gateway discovery a mobile device of MANET connects by gateway only when it is needed. For that the mobile device broadcasts request message to the ALL MANET GW MULTICAST address (the IP address for the group of all gateways in a mobile ad hoc network). Thus, only the gateways are addressed by this message and only they process it. Intermediate mobile nodes that receive the message just forward it by broadcasting it again up to gateway. • To minimize the disadvantages of proactive and reactive gateway discovery, the two approaches can be combined. This results is a hybrid gateway discovery. For mobile devices in a certain range around a gateway, proactive gateway discovery is used. Mobile devices residing outside this range use reactive gateway discovery to obtain information about the gateway. In comparing theses di®erent gateway discovery, three matrices are used. These are packet delivery ratio,average end-to-end delay and overhead. In case of proactive gateway discovery and hybrid gateway discovery, value of packet delivery ratio is larger than reactive gateway discovery. In case of proactive gateway discovery and hybrid gateway discovery, value of end to end delay is less than reactive gateway discovery. The overhead of proactive gateway discovery is greater than other two gateway discovery As for the average end-to-end delay, the proactive and hybrid methods perform slightly better than the reactive method. Concerning the routing overhead, when the advertisement interval is short the reactive method generates much less overhead than the proactive method, which in turn generates much less overhead than the hybrid method

Scalability of broadcast performance in wireless network-on-chip

Networks-on-Chip (NoCs) are currently the paradigm of choice to interconnect the cores of a chip multiprocessor. However, conventional NoCs may not suffice to fulfill the on-chip communication requirements of processors with hundreds or thousands of cores. The main reason is that the performance of such networks drops as the number of cores grows, especially in the presence of multicast and broadcast traffic. This not only limits the scalability of current multiprocessor architectures, but also sets a performance wall that prevents the development of architectures that generate moderate-to-high levels of multicast. In this paper, a Wireless Network-on-Chip (WNoC) where all cores share a single broadband channel is presented. Such design is conceived to provide low latency and ordered delivery for multicast/broadcast traffic, in an attempt to complement a wireline NoC that will transport the rest of communication flows. To assess the feasibility of this approach, the network performance of WNoC is analyzed as a function of the system size and the channel capacity, and then compared to that of wireline NoCs with embedded multicast support. Based on this evaluation, preliminary results on the potential performance of the proposed hybrid scheme are provided, together with guidelines for the design of MAC protocols for WNoC.Peer ReviewedPostprint (published version

Security and Privacy Issues in Wireless Mesh Networks: A Survey

This book chapter identifies various security threats in wireless mesh network (WMN). Keeping in mind the critical requirement of security and user privacy in WMNs, this chapter provides a comprehensive overview of various possible attacks on different layers of the communication protocol stack for WMNs and their corresponding defense mechanisms. First, it identifies the security vulnerabilities in the physical, link, network, transport, application layers. Furthermore, various possible attacks on the key management protocols, user authentication and access control protocols, and user privacy preservation protocols are presented. After enumerating various possible attacks, the chapter provides a detailed discussion on various existing security mechanisms and protocols to defend against and wherever possible prevent the possible attacks. Comparative analyses are also presented on the security schemes with regards to the cryptographic schemes used, key management strategies deployed, use of any trusted third party, computation and communication overhead involved etc. The chapter then presents a brief discussion on various trust management approaches for WMNs since trust and reputation-based schemes are increasingly becoming popular for enforcing security in wireless networks. A number of open problems in security and privacy issues for WMNs are subsequently discussed before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the author's previous submission in arXiv submission: arXiv:1102.1226. There are some text overlaps with the previous submissio

HoPP: Robust and Resilient Publish-Subscribe for an Information-Centric Internet of Things

This paper revisits NDN deployment in the IoT with a special focus on the interaction of sensors and actuators. Such scenarios require high responsiveness and limited control state at the constrained nodes. We argue that the NDN request-response pattern which prevents data push is vital for IoT networks. We contribute HoP-and-Pull (HoPP), a robust publish-subscribe scheme for typical IoT scenarios that targets IoT networks consisting of hundreds of resource constrained devices at intermittent connectivity. Our approach limits the FIB tables to a minimum and naturally supports mobility, temporary network partitioning, data aggregation and near real-time reactivity. We experimentally evaluate the protocol in a real-world deployment using the IoT-Lab testbed with varying numbers of constrained devices, each wirelessly interconnected via IEEE 802.15.4 LowPANs. Implementations are built on CCN-lite with RIOT and support experiments using various single- and multi-hop scenarios