30164245
Reliable Multicast based on k-Connected Graph
26449771
Resolving error propagation in distributed systems
This paper investigates the problem of error propagation in distributed systems. To resolve this problem, a state preservation scheme is presented to save process states in main memory. Based on the state preservation, the processes suffering from error propagation can be recovered without involving stable storage. The recovery overhead is significantly reduced. In addition, a well-known single-source-all-destination graph algorithm is also utilized to find the optimal recovery points of the processes suffering from error propagation.
25953242
Restoration from Multiple Faults in WDM Networks without Wavelength Conversion
This paper addresses the problem of achieving full and fast restoration to tolerate as many faults as possible in wavelength-routed wavelength division multiplexing (WDM) networks with no wavelength conversion. We model the problem of finding the maximum number of faults tolerated as a constrained ring cover problem, which is a decomposition problem of exponential complexity. Three heuristic methods which guarantee that at least one fault can be tolerated are proposed. The Ear Decomposition (ED) method can always generate a decomposition to guarantee that only one fault can be tolerated. The Planar Decomposition (PD) method, which takes advantage of the bipartite graph model to generate a decomposition, can tolerate up to f faults, where f is the maximum cardinality between the two bipartite vertex sets. The Maximally Separated Rings (MSR) method uses the greedy method to find a decomposition to tolerate as many faults as possible. The marked-link (ML) method is also proposed to enhance the performance by marking some links, which are originally used for protection, available for normal transmissions. Finally, we also evaluate the number of faults tolerated and the blocking probabilities of these methods in three example networks.
11124619
Effort-index-based software reliability growth models and performance assessment
The authors show that the logistic testing effort function is practically acceptable/helpful for modeling the software reliability growth and providing a reasonable description of resource consumption. Therefore, in addition to the exponential shaped models, we integrate the logistic testing effort function into an S-shaped model for further analysis. The model is designated as the Yamada Delayed S-shaped model. A realistic failure data set is used in the experiments to demonstrate the estimation procedures and results. Furthermore, the analysis of the proposed model under an imperfect debugging environment is investigated. In fact, from these experimental results and discussions, it is apparent that the logistic testing-effort function is very suitable for making estimations of resource consumption during the software development/testing phase.
96190
Optimal resource allocation and reliability analysis for component-based software applications
In this paper we propose an analytical approach for estimating the reliability of a component-based software. This methodology assumes that the software components are heterogeneous and the transfers of control between components follow a discrete time Markov process. Besides, we also formulate and. solve two resource allocation problems. Finally, we demonstrate how these analytical approaches can be employed to measure the reliability of a software system including multiple-input/multiple-output systems and distributed software systems. Experimental results show that the proposed methods can solve the testing-effort allocation problems and improve the quality and reliability of a software system.
17854992
Distributed Fault-Tolerant Ring Embedding and Reconfiguration in Hypercubes
To embed a ring in a hypercube is to find a Hamiltonian cycle through every node of the hypercube. It is obvious that no 2/sup n/-node Hamiltonian cycle exists in an n-dimensional faulty hypercube which has at least one faulty node. However, if a hypercube has faulty links only and the number of faulty links is at most n-2, at least one 2/sup n/-node Hamiltonian cycle can be found. In this paper, we propose a distributed ring-embedding algorithm that can find a Hamiltonian cycle in a fault-free or faulty n-dimensional hypercube (Q,), and the complexity is O(n) parallel steps. The algorithm is based on the recursion property of the hypercube and the free-link dimension concept. In some cases, even when the number of faulty links is larger than n-2, Hamiltonian cycles may still exist. We show that the largest possible number of faulty links that can be tolerated is 2/sup n-1/-1. The performance and the constraints of the fault-tolerant algorithm is also analyzed in detail in this paper. Furthermore, a dynamic reconfiguration algorithm for an embedded ring is proposed and discussed. Due to the distributed nature of the algorithms, they are useful for the simulation of ring-based multiprocessors on MIMD hypercube multiprocessors.
6454250
An Efficient Time-Based Checkpointing Protocol for Mobile Computing Systems over Mobile IP
Time-based coordinated checkpointing protocols are well suited for mobile computing systems because no explicit coordination message is needed while the advantages of coordinated checkpointing are kept. However, without coordination, every process has to take a checkpoint during a checkpointing process. In this paper, an efficient time-based coordinated checkpointing protocol for mobile computing systems over Mobile IP is proposed. The protocol reduces the number of checkpoints per checkpointing process to nearly minimum, so that fewer checkpoints need to be transmitted through the costly wireless link. Our protocol also performs very well in the aspects of minimizing the number and size of messages transmitted in the wireless network. In addition, the protocol is nonblocking because inconsistencies can be avoided by the piggybacked information in every message. Therefore, the protocol brings very little overhead to a mobile host with limited resource. Additionally, by taking advantage of reliable timers in mobile support stations, the time-based checkpointing protocol can adapt to wide area networks.
14504607
Computing system failure frequencies and reliability importance measures using OBDD
The recent literature showed that, in many cases, ordered binary decision diagram (OBDD)-based algorithms are more efficient in reliability evaluation compared to other methods such as the inclusion-exclusion (I-E) method and the sum of disjoint products (SDP) method. We present algorithms based on OBDD to compute system failure frequencies and reliability importance measures. Methods are presented to calculate both steady-state and time-specific frequencies of system-failure as well as system-success. The reliability importance measures include the Birnbaum importance, the criticality importance, and other indices for the risk evaluation of a system. In addition, we propose an efficient approach based on OBDD to evaluate the reliability of a nonrepairable system and the availability of a repairable system with imperfect fault-coverage mechanisms. The powerful capability of OBDD for reliability evaluation is fully exploited. Further, we extend all of the proposed algorithms to analyze systems with imperfect fault-coverage.
46555623
Design and evaluation of fault-tolerant interleaved memory systems
A highly reliable interleaved memory system for uniprocessor and multiprocessor computer architectures is presented. The memory system is divided into groups. Each group consists of several banks and furthermore, each bank has several memory units. Spare memory units as well as spare banks are incorporated in the system to enhance reliability. Reliability figures are derived to evaluate systems with various amounts of redundancy. The result shows that the system reliability can be significantly improved with little hardware overhead. User transparency in memory access is retained.<<ETX>>