A Dag Based Wormhole Routing Strategy

The wormhole routing (WR) technique is replacing the hitherto popular storeand- forward routing in message passing multicomputers. This is because the latter has speed and node size constraints. The wormhole routing is, on the other hand, susceptible to deadlock. A few WR schemes suggested recently in the literature, concentrate on avoiding deadlock. This thesis presents a Directed Acyclic Graph (DAG) based WR technique. At low traffic levels the proposed method follows a minimal path. But the routing is adaptive at higher traffic levels. We prove that the algorithm is deadlock-free. This method is compared for its performance with a deterministic algorithm which is a de facto standard. We also compare its implementation costs with other adaptive routing algorithms and the relative merits and demerits are highlighted in the text

Optimizing QOS in Mobile Ad Hoc Networks Through Advanced Routing Protocols Under Wormhole Attack Scenarios

 A Mobile Ad hoc Network (MANET) is a wireless network that may autonomously reconfigure itself without relying on a centralised structure. This type of network does not have a fixed quantity and arrangement, but rather, it self-organizes and enables the automatic connection of diverse nodes. Due to its adaptive and strong character, this network is very susceptible to attacks, which may be easily rectified. Consequently, the attacker would then function as a transmitter or recipient for forged packets. The wormhole attack is considered one of the most perilous attacks on this network. A wormhole attack involves the unauthorised movement of data packets from one node to another, which may be a harmful node located either within or outside the network. In this study, we want to investigate the impact of a wormhole attack on two specific routing protocols: Ad hoc On-Demand Distance Vector (AODV) and Dynamic Source Routing (DSR). The comparison will be conducted based on two primary network performance metrics: throughput and end-to-end delay. The simulation tests in this work will be conducted using Network Simulator-2 (NS-2) to calculate the impacts. This paper provides an alternative contribution to the realm of network attacks. The proposed Worm Hole Attack Model (WHAM) serves as an alternative for MANET routing in NS-2. WHAM has utilised the aforementioned tests to assess their resilience and durability when subjected to an attack

New Fault Tolerant Multicast Routing Techniques to Enhance Distributed-Memory Systems Performance

Distributed-memory systems are a key to achieve high performance computing and the most favorable architectures used in advanced research problems. Mesh connected multicomputer are one of the most popular architectures that have been implemented in many distributed-memory systems. These systems must support communication operations efficiently to achieve good performance. The wormhole switching technique has been widely used in design of distributed-memory systems in which the packet is divided into small flits. Also, the multicast communication has been widely used in distributed-memory systems which is one source node sends the same message to several destination nodes. Fault tolerance refers to the ability of the system to operate correctly in the presence of faults. Development of fault tolerant multicast routing algorithms in 2D mesh networks is an important issue. This dissertation presents, new fault tolerant multicast routing algorithms for distributed-memory systems performance using wormhole routed 2D mesh. These algorithms are described for fault tolerant routing in 2D mesh networks, but it can also be extended to other topologies. These algorithms are a combination of a unicast-based multicast algorithm and tree-based multicast algorithms. These algorithms works effectively for the most commonly encountered faults in mesh networks, f-rings, f-chains and concave fault regions. It is shown that the proposed routing algorithms are effective even in the presence of a large number of fault regions and large size of fault region. These algorithms are proved to be deadlock-free. Also, the problem of fault regions overlap is solved. Four essential performance metrics in mesh networks will be considered and calculated; also these algorithms are a limited-global-information-based multicasting which is a compromise of local-information-based approach and global-information-based approach. Data mining is used to validate the results and to enlarge the sample. The proposed new multicast routing techniques are used to enhance the performance of distributed-memory systems. Simulation results are presented to demonstrate the efficiency of the proposed algorithms

The Effect Of Hot Spots On The Performance Of Mesh--Based Networks

Direct network performance is affected by different design parameters which include number of virtual channels, number of ports, routing algorithm, switching technique, deadlock handling technique, packet size, and buffer size. Another factor that affects network performance is the traffic pattern. In this thesis, we study the effect of hotspot traffic on system performance. Specifically, we study the effect of hotspot factor, hotspot number, and hot spot location on the performance of mesh-based networks. Simulations are run on two network topologies, both the mesh and torus. We pay more attention to meshes because they are widely used in commercial machines. Comparisons between oblivious wormhole switching and chaotic packet switching are reported. Overall packet switching proved to be more efficient in terms of throughput when compared to wormhole switching. In the case of uniform random traffic, it is shown that the differences between chaotic and oblivious routing are indistinguishable. Networks with low number of hotspots show better performance. As the number of hotspots increases network latency tends to increase. It is shown that when the hotspot factor increases, performance of packet switching is better than that of wormhole switching. It is also shown that the location of hotspots affects network performance particularly with the oblivious routers since their achieved latencies proved to be more vulnerable to changes in the hotspot location. It is also shown that the smaller the size of the network the earlier network saturation occurs. Further, it is shown that the chaos router’s adaptivity is useful in this case. Finally, for tori, performance is not greatly affected by hotspot presence. This is mostly due to the symmetric nature of tori

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

Secure Routing in Wireless Mesh Networks

Wireless mesh networks (WMNs) have emerged as a promising concept to meet the challenges in next-generation networks such as providing flexible, adaptive, and reconfigurable architecture while offering cost-effective solutions to the service providers. Unlike traditional Wi-Fi networks, with each access point (AP) connected to the wired network, in WMNs only a subset of the APs are required to be connected to the wired network. The APs that are connected to the wired network are called the Internet gateways (IGWs), while the APs that do not have wired connections are called the mesh routers (MRs). The MRs are connected to the IGWs using multi-hop communication. The IGWs provide access to conventional clients and interconnect ad hoc, sensor, cellular, and other networks to the Internet. However, most of the existing routing protocols for WMNs are extensions of protocols originally designed for mobile ad hoc networks (MANETs) and thus they perform sub-optimally. Moreover, most routing protocols for WMNs are designed without security issues in mind, where the nodes are all assumed to be honest. In practical deployment scenarios, this assumption does not hold. This chapter provides a comprehensive overview of security issues in WMNs and then particularly focuses on secure routing in these networks. First, it identifies security vulnerabilities in the medium access control (MAC) and the network layers. Various possibilities of compromising data confidentiality, data integrity, replay attacks and offline cryptanalysis are also discussed. Then various types of attacks in the MAC and the network layers are discussed. After enumerating the various types of attacks on the MAC and the network layer, the chapter briefly discusses on some of the preventive mechanisms for these attacks.Comment: 44 pages, 17 figures, 5 table

Path-Based partitioning methods for 3D Networks-on-Chip with minimal adaptive routing

© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Combining the benefits of 3D ICs and Networks-on-Chip (NoCs) schemes provides a significant performance gain in Chip Multiprocessors (CMPs) architectures. As multicast communication is commonly used in cache coherence protocols for CMPs and in various parallel applications, the performance of these systems can be significantly improved if multicast operations are supported at the hardware level. In this paper, we present several partitioning methods for the path-based multicast approach in 3D mesh-based NoCs, each with different levels of efficiency. In addition, we develop novel analytical models for unicast and multicast traffic to explore the efficiency of each approach. In order to distribute the unicast and multicast traffic more efficiently over the network, we propose the Minimal and Adaptive Routing (MAR) algorithm for the presented partitioning methods. The analytical and experimental results show that an advantageous method named Recursive Partitioning (RP) outperforms the other approaches. RP recursively partitions the network until all partitions contain a comparable number of switches and thus the multicast traffic is equally distributed among several subsets and the network latency is considerably decreased. The simulation results reveal that the RP method can achieve performance improvement across all workloads while performance can be further improved by utilizing the MAR algorithm. Nineteen percent average and 42 percent maximum latency reduction are obtained on SPLASH-2 and PARSEC benchmarks running on a 64-core CMP.Ebrahimi, M.; Daneshtalab, M.; Liljeberg, P.; Plosila, J.; Flich Cardo, J.; Tenhunen, H. (2014). Path-Based partitioning methods for 3D Networks-on-Chip with minimal adaptive routing. IEEE Transactions on Computers. 63(3):718-733. doi:10.1109/TC.2012.255S71873363

A Packet Traversal Time per Hop based Adaptive Wormhole Detection Algorithm for MANETs

Routing security challenges significantly impact the wide-scale adoption of mobile ad hoc networks (MANET), with wormholes constituting an especially severe threat. Wormhole detection algorithms like traversal time and hop count analysis (TTHCA) and modified transmission time-based mechanism (M-TTM) combine effective detection with low traffic overheads. TTHCA measures packet traversal time (PTT) per route hop count (HC), while M-TTM compares an expected round trip time (RTT) with a measured RTT. However, using only fixed thresholds for the permissible PTT/HC and measured RTT deviations respectively, both algorithms are compromised so participation mode (PM), out-of-band (O-B) wormholes are inadequately detected in MANETs with large radio range fluctuations. This paper presents an extended variant of the TTHCA algorithm called traversal time per hop analysis (TTpHA) that dynamically adapts the PTT per hop threshold to prevailing MANET conditions and nodes’ radio coverage. Experimental results confirm TTpHA provides superior PM O-B detection performance compared to TTHCA and M-TTM, with commensurately low false positive rates and traffic overheads