Routing in MANET is a challenging task due to the dynamic nature of the participating nodes in MANET. This challenge has led to the development of many different routing protocols, with each originator claiming that his or her proposed protocol was more effective than its predecessors were. Nonetheless, the effectiveness of these protocols relies on the prevailing network scenarios, which differ in terms of node density and traffic. Against this challenging backdrop, the authors provide an overview of the different MANET protocols, such as OLSR, AODV, DSR, DSDV, ZRP and TORA, which are broadly classified based on three categories, namely Proactive (table-driven), Reactive (on-demand) and Hybrid routing protocol. The authors then provide a comparative analysis of the different protocols based on qualitative metrics. This paper concludes by highlighting the expected performance of each protocol for a particular network environment, which is deemed suitable based on the specific characteristics of the protocol.
Ad hoc on-demand distance vector (AODV) is one of the commonly used reactive routing protocols in mobile ad hoc network (MANET) as it can achieve relatively better communication performance. However, AODV can lead to heavy routing overhead and additional delay due to the flooding broadcast of route request (RREQ) packets during the route discovery cycle. Additionally, the multiple route reply (RREP) packets in response to a single RREQ can also contribute to overhead and additional delay. Thus, a new algorithm called Less Flooding-AODV (LF-AODV) was proposed to reduce the broadcasted RREQ and the transmitted RREP during the route discovery cycle by decreasing the number of nodes involved in the route establishment phase. A simulation test was carried out to compare the difference in performance between LF-AODV and AODV algorithms. The simulation test revealed that the steps of the route discovery process in LF-AODV were significantly reduced, thus improving its performance in terms of packet delivery fraction, end-to-end delay and routing overhead compared to the traditional algorithm. Clearly, these results reinforce the theoretical principles used in formulating the new algorithm of LF-AODV.
This paper reports the measurements of MPI communication benchmarking on Khaldun cluster which ran on Linux-based IBM Blade HS21 Servers with Intel Xeon dual quad-core processor and Gigabit Ethernet interconnect. The measurements were done by using SKaMPI and IMB benchmark programs. Significantly, these were the first results produced by using SKaMPI and IMB to analyze the performance of Open MPI implementation on Khaldun cluster. The comparison and analysis of the results of point to point and collective communication from these two benchmark programs were then provided. It showed that different MPI benchmark programs rendered different results since they used different measurement techniques. The results were then compared to the experiment's results that were done on cluster with Opteron dual quad-core processor and Gigabit Ethernet interconnect. The analysis indicated that the architecture of machines used also affected the results.
The performance of MPI implementation operations still presents critical issues for high performance computing systems, particularly for more advanced processor technology. Consequently, this study concentrates on benchmarking MPI implementation on multi-core architecture by measuring the performance of Open MPI collective communication on Intel Xeon dual quad-core Gigabit Ethernet and InfiniBand clusters using SKaMPI. It focuses on well known collective communication routines such as MPI-Bcast, MPI-AlltoAll, MPI-Scatter and MPI-Gather. From the collection of results, MPI collective communication on InfiniBand clusters had distinctly better performance in terms of latency and throughput. The analysis indicates that the algorithm used for collective communication performed very well for all message sizes except for MPI-Bcast and MPI-Alltoall operation of inter-node communication. However, InfiniBand provides the lowest latency for all operations since it provides applications with an easy to use messaging service, compared to Gigabit Ethernet, which still requests the operating system for access to one of the server communication resources with the complex dance between an application and a network.
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