Suresh Muknahallipatna

Fibre Channel Switch Modeling at Fibre Channel-2 Level for Large Fabric Storage Area Network Simulations using OMNeT++: Preliminary Results

Black hole attacks are a serious threat to communication in tactical MANETs. In this work we present TOGBAD a new centralised approach, using topology graphs to identify nodes attempting to create a black hole. We use well-established techniques to gain knowledge about the network topology and use this knowledge to perform plausibility checks of the routing information propagated by the nodes in the network. We consider a node generating fake routing information as malicious. Therefore, we trigger an alarm if the plausibility check fails. Furthermore, we present promising first simulation results. With our new approach, it is possible to already detect the attempt to create a black hole before the actual impact occurs.Abstract—Typically, in the current enterprise data centers dedicated fabrics or networks are implemented to meet their LAN, Inter-Processor communication and storage traffic requirements. The storage traffic requirements of a group of servers are met through multiple storage area networks based on fibre channel, which has become the standard connection type. Typically, this fibre channel storage area networks are small (maximum of 32 switches/directors in a single fabric) and do not experience any scaling, stability and other performance issues. The advent of I/O consolidation in enterprise data centers for multiple traffic types to converge on to a single fabric or network (typically Ethernet platform) to reduce hardware, energy and management costs has also the potential to allow implementation of large storage area networks based on the fibre channel standards. Large storage area networks are being planned with more than two hundred switches/directors in a single fabric or network in addition to servers and storages connected to the fabric on Ethernet platforms. Even though these large storage area networks are envisioned to operate on Ethernet platform, they still have to satisfy the stringent operating and performance requirement set forth by the fibre channel standards. The two important issues of concern with large storage area networks are scaling and stability. The scaling and stability issues are dependent on the interactions and performance capabilities of various fabric servers located on each switch/director in the fabric in order to provide fabric services. In order to determine the extent of scaling and stability issues of a large fabric first the detailed models of the switch/director addressing the operations of the individual fabric servers are required. Next, the interactions of the switches/directors using the detailed models are to be simulated to study the scaling and stability issues. In this paper, the detailed modeling of the fibre channel switch and the fabric servers using the OMNeT++ discrete event simulator is presented first. Detailed models are developed addressing the behavior of the switch at the level-2 of the fibre channel protocol since this layer addresses the requirements and operations of various mandatory fabric services like fabric build, directory, login, nameserver, management, etc. Next, using the OMNET++ discrete event simulator large fabrics are simulated. The results from the simulation are compared against the test bed traffic and the accuracy is demonstrated. Also, results and analysis of multiple simulations with increasing fabric size are presented.

Optimal trajectory determination of a single moving beacon for efficient localization in a mobile ad-hoc network

An ad hoc network of small robots (sensor nodes) adjusting their positions to establish network connectivity would be able to provide a communication infrastructure in an urban battlefield environment. A sensor node would be capable of moving to a particular position to establish network connectivity, provided it knows its current position, positions of other sensor nodes and the radio propagation characteristics of the sensor area. In this paper, we present a pseudo formation control based trajectory algorithm to determine the optimal trajectory of a moving beacon used in localization of the sensor nodes in real-time. The trajectory and the frequency of transmission of the GPS based position information of the moving beacon influences the accuracy of localization and the power consumed by the beacon to localize. Localization accuracy and reduction in the number of position information messages can be achieved, in real-time, by determining the optimal position from where the beacon should transmit its next position information. This will decrease the time required to localize, and power consumed by the beacon in comparison to random or predetermined trajectories. We first show that optimal position determination is a pseudo formation control problem. Next, we show the pseudo formation control problem formulated as an unconstrained optimization problem under the free space propagation model. We further present the modeling of the beacon incorporating the trajectory algorithm based on the pseudo formation control in a discrete event simulator. Simulation results, comparing the performance of localization with pseudo formation control based trajectory against random waypoint and predetermined trajectories for the beacon are presented. The simulation results show that the localization accuracy is significantly improved along with reduction in the number of position information messages transmitted when the beacon traverses along the pseudo formation control based trajectory.

Fibre Channel based Storage Area Network Modeling using OPNET for Large Fabric Simulations: Preliminary Work

Fibre channel based storage area networks have been a common implementation for data storage in enterprise data centers. As the size of the storage area network tends to grow along with geographical distribution leading to distributed storage area network, also known as large fabric, the network seems to exhibit scaling and stability issues. The scaling and stability issues seem to stem from the construction, route discovery, and management process of the network which are fibre channel-2 level traffic more than the actual I/O data transmission process. To determine the scaling and stability issues of a large fabric, an adequate tool is required. The tool is usually a discrete event simulator since an analytical or hardware simulator tool would not be able to handle the large size of the storage area network and model in detail. In this paper, the preliminary work on modeling and simulations of a fibre channel based storage area network using OPNET as a discrete event simulator are presented. As a preliminary step, the fibre channel host bus adapter and its interactions with the fabric login server of a fibre channel switch during the fabric login process is modeled at the fibre channel-2 level and preliminary simulations are performed.

Power system transient stability analysis software tool for an undergraduate curriculum

This paper describes, a technique of the transient stability assessment, known as the Extended Equal Area Criterion (EEAC) as applied to a multimachine power system. The EEAC is implemented using the MATLAB program to provide a software tool with GUI. The software tool of the EEAC is developed to incorporate the transient stability analysis, into an undergraduate curriculum in power engineering. Another criterion for developing this software is to reduce the effort normally associated with the instruction of the complex theory of the transient stability and the use of the software in an undergraduate classroom environment. The results obtained from the MATLAB software on two multimachine power systems are compared with the traditional time domain analysis technique for verification purposes.

DETERMINATION, BY KOHONEN NETWORK, OF THE GENERATOR COHERENCY IN DYNAMIC STUDIES

ABSTRACT For on-line security assessment, mere is a need for a tool which, during a disturbance, will quickly recognize impacted system components. A Kohonen artificial neural network is described which can be used for coherency identification among generators. Additional information provided by this method makes it better than the conventional approach used to identify coherency for dynamic equivalencing. The method is tested on two representative power systems.

Use of radio propagation maps in a single moving beacon assisted localization in MANETs

A mobile ad-hoc network (MANET) of small robots (sensor nodes) adjusting their positions to establish network connectivity would be able to provide a communication infrastructure in an urban battlefield environment. A sensor node would be capable of moving to a particular position to establish network connectivity, provided it knows its current position, positions of other sensor nodes and the radio propagation characteristics of the sensor area. Typically, the nodes in the MANET determine their positions using a localization algorithm. Most localization algorithms use either the free space or the “two ray” radio propagation models, which are only accurate in communication environments where there are no hills or buildings. In an urban environment, direct transmission through buildings is limited and most communications rely on reflections and refractions around buildings. The presence of the buildings, therefore, greatly influences radio propagation. Consequently, free space or two-ray propagation models are inaccurate in outdoor urban areas. This paper, presents a single moving beacon assisted localization algorithm that incorporates an urban radio propagation map to localize sensor nodes in a MANET. First, the paper describes using a convex hull to represent irregular radio propagation shapes in terms of regular geometric shapes. Next, an algorithm to determine intersection (localized area) of multiple convex hulls is discussed. Simulation results, comparing the performance of localization using an urban radio propagation map against the free space model are presented. The simulation results show the effect of the radio propagation map on localization accuracy and demonstrate the free space model inaccuracy.

Performance analysis of a fibre channel switch supporting node port identifier virtualization: Preliminary results

The server virtualization architecture, encompassing the sharing of data storage subsystems among the virtual servers or operating systems on a single host server using I/O channel sharing capabilities in fibre channel fabrics, was pioneered by IBM through their System z9 mainframe and its predecessors. The implementations of I/O channel sharing capabilities were based on the fibre connectivity channel standard. With the advent of sharing small computer system interface devices among host servers in storage area networks using the fibre channel protocol, certain problems arose in sharing the I/O channels between virtual servers on a host. To implement server virtualization with this new environment, IBM invented the N-Port identifier virtualization architecture, which is now part of the fibre channel standards. This paper examines the performance of a Fibre channel switch supporting N-Port identifier virtualization. In particular, the switch latency for discover fabric services command during the process of granting multiple virtual N-Port identifiers to single and multiple hosts, hosting a large number of virtual servers is examined.

A method to improve signal quality in wireless ad-hoc networks with limited mobility

A wireless ad-hoc network is a collection of nodes that are dynamically and arbitrarily located in such a manner that the interconnections between each node are capable of changing on a continual basis. In this paper, we provide a novel way to improve node interconnects without changing the overall network topology by allowing nodes to have limited mobility. Received signal strength (RSS) measurements are recorded from neighboring nodes as the node makes small changes in position. This allows the node to move out of fades due to multi-path or shadowing, and is a form of selection diversity that requires only a single antenna. This algorithm is tested using a full 3-D ray tracing propagation model as well as physical measurements in an indoor scenario.

Antenna array geometry for mobile ad-hoc networks

Small antenna arrays are advantageous for ad-hoc networks. Typically antenna array geometry is designed using simplified objective measures to make analysis tractable or maximize search efficiency. This paper investigates array design using fitness functions more tightly related to network performance. Particle swarm optimization (PSO) is used to design planar antenna arrays with minimum mean-square error or noise-to-signal ratio. Fitness functions are averaged across look angle to include effects of random signal and interference directions, resulting in a better measure of performance in real-world conditions. We found that irregular “T” or “diamond” geometries can outperform more common arrays such as Y or square arrays.

Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. Experiments involving methane conversion reactions were conducted with a preliminary pulsed corona discharge reactor design in order to test and improve the reactor and membrane designs using a non-toxic reactant. This report details the direct methane conversion experiments to produce hydrogen, acetylene, and higher hydrocarbons utilizing a co-axial cylinder (CAC) corona discharge reactor, pulsed with a thyratron switch. The reactor was designed to accommodate relatively high flow rates (655 x 10{sup -6} m{sup 3}/s) representing a pilot scale easily converted to commercial scale. Parameters expected to influence methane conversion including pulse frequency, charge voltage, capacitance, residence time, and electrode material were investigated. Conversion, selectivity and energy consumption were measured or estimated. C{sub 2} and C{sub 3} hydrocarbon products were analyzed with a residual gas analyzer (RGA). In order to obtain quantitative results, the complex sample spectra were de-convoluted via a linear least squares method. Methane conversion as high as 51% was achieved. The products are typically 50%-60% acetylene, 20% propane, 10% ethane and ethylene, and 5% propylene. First Law thermodynamic energy efficiencies for the system (electrical and reactor) were estimated to range from 38% to 6%, with the highest efficiencies occurring at short residence time and low power input (low specific energy) where conversion is the lowest (less than 5%). The highest methane conversion of 51% occurred at a residence time of 18.8 s with a flow rate of 39.4 x 10{sup -6} m{sup 3}/s (5 ft{sup 3}/h) and a specific energy of 13,000 J/l using niobium and platinum coated stainless steel tubes as cathodes. Under these conditions, the First Law efficiency for the system was 8%. Under similar reaction conditions, methane conversions were {approx}50% higher with niobium and platinum coated stainless steel cathodes than with a stainless steel cathode.