17596019
Performance Analysis of FFT Algorithms on Multiprocessor Systems
A decimation-in-time radix-2 fast Fourier transform (FFT) algorithm is considered here for implementation in multiprocessors with shared bus, multistage interconnection network (MIN), and in mesh connected computers. Results are derived for data allocation, interprocessor communication, approximate computation time, and speedup of an N point FFT on any P available processing elements (PE's). Further generalization is obtained for a radix-r FFT algorithm. An N X N point two-dimensional discrete Fourier transform (DFT) implementation is also considered when one or more rows of the input data matrix are allocated to each PE.
40094538
A Generic Design Methodology for Deadlock-Free Routing in Multicomputer Networks
This paper introduces a generic methodology for defining deadlock-free wormhole routing schemes in any arbitrary network. The basic strategy is to partition a graph into subdigraphs with no cyclic dependencies and selectively assign virtual channels. The usefulness of our scheme is shown for the n-dimensional hypercube, the n-dimensional mesh, and the k-ary n-cube torus by identifying subdigraph characteristics that ensure acyclic routing. Further generalization which allows partial cyclic dependencies without deadlock is achieved by our extended generic methodology. We also illustrate how to identify shortest fixed path and nonminimal adaptive routing schemes using minimum required channels.
15237323
Testing and Fault Tolerance of Multistage Interconnection Networks
Test length is independent of network size in this simple, straightforward methodology for testing MINs (multistage interconnection networks). It requires only four test sequences for single-fault diagnosis. 26 references.
22890668
Arithmetic Algorithms in a Negative Base
Algorithms are described for the basic arithmetic operations in a negative base. These algorithms are simpler, faster, and more general than those proposed by Sankar et al.
26743853
Design and Analysis of a Class of Highly Scalable Hierarchical Networks: PdBCube
Abstract A class of hierarchical networks called the dBCube, that provides cost-effective and high-performance communication in large multicomputer systems, has recently been introduced. Such a compound graph of a hypercube and a de Bruijn (dB) graph utilizes every node of the hypercube as a gateway for intercluster communication. This paper presents a partially connected dBCube subclass (PdBCube), wherein the use of fewer nodes as gateways makes the PdBCube highly scalable in terms of both the hypercube and the dB size. This enhancement in scalability can be achieved by two different approaches to assigning gateways. Performance degradation of the proposed PdBCube is illustrated in terms of diameter and average distance. Improvement in track efficiency and reduction in cost are observed to be directly related to a decrease in the number of remote links.
43408451
Network Intrusion Detection System Using Random Projection Technique
13652126
Using certes to infer client response time at the web server
As businesses continue to grow their World Wide Web presence, it is becoming increasingly vital for them to have quantitative measures of the mean client perceived response times of their web services. We present Certes (CliEnt Response Time Estimated by the Server), an online server-based mechanism that allows web servers to estimate mean client perceived response time, as if measured at the client. Certes is based on a model of TCP that quantifies the effect that connection drops have on mean client perceived response time by using three simple server-side measurements: connection drop rate, connection accept rate and connection completion rate. The mechanism does not require modifications to HTTP servers or web pages, does not rely on probing or third party sampling, and does not require client-side modifications or scripting. Certes can be used to estimate response times for any web content, not just HTML. We have implemented Certes and compared its response time estimates with those obtained with detailed client instrumentation. Our results demonstrate that Certes provides accurate server-based estimates of mean client response times in HTTP 1.0/1.1 environments, even with rapidly changing workloads. Certes runs online in constant time with very low overhead. It can be used at websites and server farms to verify compliance with service level objectives.
7357174
On the design and quantification of privacy preserving data mining algorithms
The increasing ability to track and collect large amounts of data with the use of current hardware technology has lead to an interest in the development of data mining algorithms which preserve user privacy. A recently proposed technique addresses the issue of privacy preservation by perturbing the data and reconstructing distributions at an aggregate level in order to perform the mining. This method is able to retain privacy while accessing the information implicit in the original attributes. The distribution reconstruction process naturally leads to some loss of information which is acceptable in many practical situations. This paper discusses an Expectation Maximization (EM) algorithm for distribution reconstruction which is more effective than the currently available method in terms of the level of information loss. Specifically, we prove that the EM algorithm converges to the maximum likelihood estimate of the original distribution based on the perturbed data. We show that when a large amount of data is available, the EM algorithm provides robust estimates of the original distribution. We propose metrics for quantification and measurement of privacy-preserving data mining algorithms. Thus, this paper provides the foundations for measurement of the effectiveness of privacy preserving data mining algorithms. Our privacy metrics illustrate some interesting results on the relative effectiveness of different perturbing distributions.
202287
Wire speed packet classification without tcams: a few more registers (and a bit of logic) are enough
Packet classification is the foundation of many Internet functions such as QoS and security. A long thread of research has proposed efficient software-based solutions to this problem. Such software solutions are attractive because they require cheap memory systems for implementation, thus bringing down the overall cost of the system. In contrast, hardware-based solutions use more expensive memory systems, e.g., TCAMs, but are often preferred by router vendors for their faster classification speeds. The goal of this paper is to find a "best-of-both-worlds" solution -- a solution that incurs the cost of a software-based system and has the speed of a hardware-based one. Our proposed solution, called smart rule cache achieves this goal by using minimal hardware -- a few additional registers -- to cache evolving rules which preserve classification semantics, and additional logic to match incoming packets to these rules. Using real traffic traces and real rule sets from a tier-1 ISP, we show such a setup is sufficient to achieve very high hit ratios for fast classification in hardware. Cache miss ratios are 2 ∼ 4 orders of magnitude lower than flow cache schemes. Given its low cost and good performance, we believe our solution may create significant impact on current industry practice.
15003245
Probabilistic treatment of MIXes to hamper traffic analysis
The goal of anonymity providing techniques is to preserve the privacy of users, who has communicated with whom, for how long, and from which location, by hiding traffic information. This is accomplished by organizing additional traffic to conceal particular communication relationships and by embedding the sender and receiver of a message in their respective anonymity sets. If the number of overall participants is greater than the size of the anonymity set and if the anonymity set changes with time due to unsynchronized participants, then the anonymity technique becomes prone to traffic analysis attacks. We are interested in the statistical properties of the disclosure attack, a newly suggested traffic analysis attack on the MIXes. Our goal is to provide analytical estimates of the number of observations required by the disclosure attack and to identify fundamental (but avoidable) 'weak operational modes' of the MIXes and thus to protect users against a traffic analysis by the disclosure attack.
11059176
Policy-based validation of SAN configuration
Historically, storage has been directly connected to servers for fast local access and easy configuration. In recent years, storage area networks (SANs) have defined an alternative storage paradigm that allows storage to be shared among servers using fast interconnects. One of the key challenges of SAN management is the large number of configuration problems that are encountered in a typical SAN deployment. These configuration problems can be addressed by SAN management software. However, hard-coding the SAN configuration rules into the management software is not a viable option since it is not possible to easily modify or replace old configuration rules and specify new policies and guidelines. In this paper, we propose a novel policy-based SAN configuration validation system that can be used to specify, store, and evaluate configuration policies for SANs. We also introduce five new operators for collection policies that are useful for evaluating a wide variety of practical SAN configuration policies found in practice. The policy-based SAN configuration checking approach proposed in this paper is discussed within the context of device interoperability constraints. However, this approach is extensible as it can also be used to enforce performance, reliability, and security-related configuration constraints.