Sharif Digital Repository

When implementing some applications in multi-computer systems, broadcast operation is a necessity for efficient communication. Several broadcast algorithms have been proposed in the literature for hypercube networks. In this paper, we evaluate the performance of broadcast routing algorithms for hypercube networks, and propose a new approach by reducing the number of steps required to perform. © 2009 IEEE  

Performance of a data center is a function of three features; bandwidth, latency, and reliability. By adopting optical technology in data center network, bandwidth increment, in addition to reduction of transmission latency and power consumption, is achieved. Unfortunately, fault tolerance of the optical networks has raised less attention so far. So in this paper, we propose a fault-tolerant, scalable, and high-performance optical architecture built upon previously proposed O-TF network, with the goal of redundancy optimization and reducing the minimum number of wavelength channels required for non-blocking functionality of the network. Moreover, reducing network diameter, in O-FTF network... 

On-chip interconnections play an important role in multi/many-processor systems-on-chip (MPSoCs). In order to achieve efficient optimization, each specific application must utilize a specific architecture, and consequently a specific interconnection network. For design space exploration and finding the best NoC solution for each specific application, a fast and flexible NoC simulator is necessary, especially for large design spaces. In this paper, we present an FPGA-based NoC co-simulator, which is able to be configured via software. In our proposed NoC simulator, entitled DuCNoC, we implement a Dual-Clock router micro-architecture, which demonstrates 75x-350x speed-up against BOOKSIM.... 

In this paper, we consider the problem of searching a network for intruders. We propose a strategy for capturing the intruder in the popular interconnection topology, the star network. According to the proposed strategy, a team of collaborative software agents are responsible for capturing a hostile intruder (e.g. a virus). These agents asynchronously move along the network links and the intruder has the capability of escaping arbitrarily fast. © 2009 IEEE  

The star graph, as an interesting network topology, has been extensively studied in the past. In this paper, we address some of the combinatorial properties of the star graph. In particular, we consider the problem of calculating the surface area and volume of the star graph, and thus answering an open problem previously posed in the literature. The surface area of a sphere with radius i in a graph is the number of nodes in the graph whose distance from a given node is exactly i. The volume of a sphere with radius i in a graph is the number of nodes within distance i from the given node. In this paper, we derive explicit expressions to calculate the surface area and volume in the star graph.... 

In massively parallel processing systems that incorporate hundreds and thousands of processing nodes, the problem of placing a limited number of resources (e.g. printers, disks, software copies, etc.) over processing nodes is of great importance. In this paper, we investigate resource placement in the three-dimensional torus network which is the underlying interconnection network in most current multicomputer. We show that there exists an irregular distance-1 placement only for tori of the form 2 × 3 i × 6 j, i, j ∈ N. In addition, we present a new formal proof for the necessary and sufficient conditions for the existence of irregular distance-d placement in 3D tori. © 2009 Elsevier B.V. All... 

The necklace hypercube has recently been introduced as an attractive alternative to the well-known hypercube. Previous research on this network topology has mainly focused on topological properties, VLSI and algorithmic aspects of this network. Several analytical models have been proposed in the literature for different interconnection networks, as the most cost-effective tools to evaluate the performance merits of such systems. This paper proposes an analytical performance model to predict message latency in wormhole-switched necklace hypercube interconnection networks with fully adaptive routing. The analysis focuses on a fully adaptive routing algorithm which has been shown to be the most... 

In this paper, using the chromatic properties of power graphs we propose a new approach for placing resources in symmetric networks. Our novel placement scheme guarantees a perfect placement when such a solution is feasible in the topology, while in general it answers the question of k-resource placement at a distance d where each non-resource node is able to access k resource nodes within at most d hops away. We define a quasi-perfect graph as a graph whose clique number and chromatic number are equal. We derive important properties of quasi-perfect graphs and use them to find a solution for the resource placement problem. We have also applied the proposed method to find a distant resource... 

Data center performance is affected by three main factors; bandwidth, latency, and reliability of intra-data center interconnection network. Bandwidth and latency are definitely improved by adopting optical technology for intra-data center communication, but fault tolerance of the corresponding optical networks has been raised less. Recently, we introduced two Torus-based, all-optical, and non-blocking networks, i.e. O-TF and O-FTF, addressing reliability of optical networks, and now, in this paper, to address the scalability problem, we propose a novel Optical Clos-based architecture which reduces minimum number of required wavelength channels, as well as, the switch size in each node.... 

Optical networks-on-chip are introduced as an alternative for electrical interconnects in many-core systems, due to their low delay and power consumptions, as well as their high bandwidths. Despite these advantages, physical characteristics of the photonic components are highly sensitive to thermal variations, which results in optical data misrouting through the optical networks at the presence of temperature fluctuation. In this paper, we propose a thermally-resilient all-optical communication approach which improves reliability, as well as performance of the optical networks. For this purpose, we take advantages of auxiliary waveguides and a novel wavelength assignment approach to avoid... 

Exponential growth of traffic and bandwidth demands in current data center networks requires low-latency high-throughput interconnection networks, considering power consumption. By considering growth of both multicast and unicast applications, power efficient communication becomes one of the main design challenges in today's data center networks. Addressing these demands, optical networks suggest several benefits as well as circumventing most disadvantages of electrical networks. In this paper, we propose an all-optical scalable architecture, named as OMUX, for communicating intra-data centers. This architecture utilizes passive optical devices and enables optical circuit switching without... 

In this paper, we present a comprehensive analysis of the impact of aging on the interconnection network of field-programmable gate arrays (FPGAs) and propose novel approaches to mitigate the aging effects on the routing network. We first show the insignificant impact of aging on data integrity of FPGAs, i.e., static noise margin and soft error rate of the configuration cells, as well as we show the negligible impact of the mentioned degradations on the FPGA performance. As such, we focus on the performance degradation of datapath transistors. In this regard, we propose a routing accompanied by a placement algorithm that prevents constant stress on transistors by evenly distributing the... 

In this paper, we propose a solution for the problem of capturing an intruder in two popular interconnection topologies namely, the mesh and the torus. A set of agents collaborate to capture a hostile intruder in the network. While the agents can move in the network one hop at a time, the intruder is assumed to be arbitrarily fast i.e. it can traverse any number of nodes contiguously as far as there are no agents in those nodes. Here we consider a new version of the problem where each agent can replicate new agents when needed, i.e. the algorithm starts with a single agent and new agents are created on demand. We define a new class of algorithms for capturing an intruder. In particular, we... 

A routing algorithm defines a route which packet traverses to get to destination. In this research we study some kind of routing algorithms that are used in internal connections networks of multi-processor and multi-computers systems. Then we discuss about some routing algorithms which have been implemented network on chip architecture. First, we present a group of routing algorithms based on various criterions, and review so-called category. Afterwards, we study adaptive and deterministic routing algorithms and express circular model applying in internal connections networks and its governing rules in order to prevent dead lock. Then we survey adaptive algorithms such as Deflection routing,... 

In large systems, economical and efficiency concerns restrict the allocation of each resource to every node in the network. Therefore, it is desirable to distribute copies of resource in order to share them and achieve a certain performance measure. In this paper, we consider the problem of distributing resources in Cube-Connected Cycles. Both adjacency and distant placements are considered in this paper. In adjacency placements, dominating sets and perfect dominating sets are used. The proposed algorithms for distant placements use known placements for basic hypercube graphs. Therefore, in these placements we avoid the additional costs needed for deploying the network. We prove that the... 

In a large system, it is neither economical nor efficient to equip each node with a copy of the resource, and it is desirable to distribute the copies of the resource so that certain performance measure is obtained. In this paper we consider the problem of distributing resources in the edge product of networks. The algorithms presented in this paper make use of the known placements for the basic graphs composing the product graph. Therefore, in these placements we avoid the additional costs needed for deploying and rescaling the network. © 2008 IEEE  

The WK-recursive mesh and WK-pyramid networks are recursively-defined hierarchical interconnection networks with excellent properties which well idealize them as alternatives for mesh and traditional pyramid interconnection topologies. They have received much attention due to their favorable attributes such as small diameter, large connectivity, and high degree of scalability and expandability. In this paper, we deal with packagibility and layout area of these networks. These properties are of great importance in the implementation of interconnection networks on chips. We show that WK-recursive, mesh-pyramid and WK-pyramid networks can be laid out in an area of O(N2) which is the optimal... 

This paper probes the impact of utilizing an IPFC on the reliability indices of interconnected power systems. First, a concise presentation of IPFC and its structure are provided and the reliability model of two unequally-rated parallel transmission lines equipped with IPFC is then extracted. The assumed IPFC is composed from two parallel converting bridges associated with each line. Afterwards, based-on equivalent assisting unit approach, different commonly-used adequacy indices including the loss of load expectation (LOLE), loss of energy expectation (LOEE) and system minutes (SM) are calculated. A set of numerical analyses are conducted to illustrate the sensitivity of these indices with... 

The WK-recursive mesh and WK-pyramid networks are recursively defined hierarchical interconnection networks with excellent properties which well idealize them as alternatives for mesh and traditional pyramid interconnection topologies. They have received much attention due to their favorable attributes such as small diameter, large connectivity, and high degree of scalability and expandability. In this paper, we deal with pancyclicity and surface area of these networks. These properties are of great importance in the implementation of a variety of parallel algorithms in multicomputers. We show that WK-recursive mesh network is 1-partially pancyclic, i.e. any cycle of length 3, 4, 6,..., and... 

This paper proposes an efficient parallel algorithm for computing Lagrange interpolation on k-ary n-cube networks. This is done using the fact that a k-ary n-cube can be decomposed into n link-disjoint Hamiltonian cycles. Using these n link-disjoint cycles, we interpolate Lagrange polynomial using full bandwidth of the employed network. Communication in the main phase of the algorithm is based on an all-to-all broadcast algorithm on the n link-disjoint Hamiltonian cycles exploiting all network channels, and thus, resulting in high-efficiency in using network resources. A performance evaluation of the proposed algorithm reveals an optimum speedup for a typical range of system parameters used...