检索结果-内蒙古大学图书馆

IEEE Conference and Exhibition on Global Telecommunications (GLOBECOM)

作者： H. Wang K.G. Shin Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

Random early detection (RED) was proposed as an active gateway queue-management mechanism. This paper proposes to alter the RED design guideline that unconditionally allows transient congestion, and evaluates its impacts. This unconditional allowance of transient congestion is shown to be harmful when the queue is near full, because it causes buffer overflow at a gateway. Buffer overflow at a gateway leads to the global synchronization and oscillation of traffic load on the network. To effectively prevent buffer overflow at a gateway, the RED framework is refined in such a way that the gateway can detect a transient congestion in a timely manner and take actions to quench it when the queue is near full. Based on our simulation results, two enhancements are made in estimating average queue size. Equipped with these enhancements, the refined RED can strike a good balance between the allowance of transient bursty traffic and the avoidance of buffer overflow. Using extensive simulations, the refined RED is comparatively evaluated against and is shown to be superior to the original RED.

关键词： Traffic control Internet Bandwidth Buffer overflow Laboratories Guidelines Telecommunication traffic Explosives Transport protocols Aggregates

来源：评论

学校读者我要写书评

暂无评论

Experiments on six commercial TCP implementations using a software fault injection tool†

引用

Software: Practice and Experience 1999年第12期27卷

作者： Scott Dawson Farnam Jahanian Todd Mitton Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109-2122 USA

TCP, the de facto standard transport protocol in today's operating systems, is a very robust protocol that adapts to various network characteristics, packet loss, link congestion, and even significant differences in vendor implementations. This paper describes a set of experiments performed on six different vendor TCP implementations using ORCHESTRA, a tool for testing and fault injection of communication protocols. These experiments uncovered violations of the TCP protocol specification, and illustrated differences in the philosophies of various vendors in their implementations of TCP. The paper summarizes several lessons learned about the TCP implementations through these experiments. © 1997 John Wiley & Sons, Ltd.

关键词： TCP distributed systems communication protocols fault injection tool protocol testing

来源：评论

学校读者我要写书评

暂无评论

Comparison of connection admission-control schemes in the presence of hand-offs in cellular networks 98

Comparison of connection admission-control schemes in the pr...

引用

4th Annual ACM/IEEE International Conference on Mobile computing and Networking, MobiCom 1998

作者： Choi, Sunghyun Shin, Kang G. Real-Time Computing Laboratory Department Of Electrical Engineering And Computer Science The University Of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)9781581130355

In this paper, we compare four distributed connection admission control schemes in cellular networks where the first two schemes are to keep the hand-off dropping probability below a target value, the third scheme is to guarantee no hand-off drops through a per-connection bandwidth reservation, and the fourth scheme uses another type of per-connection bandwidth reservation. The first scheme predicts the bandwidth required to handle hand-offs by estimating possible hand-offs from adjacent cells, then performs the admission control for each newly-requested connection. On the other hand, the second scheme predicts the total required bandwidth in the current cell by estimating both incoming and outgoing hand-offs at each cell. The third scheme requires the set of cells which the mobile with a newly-requested connection will traverse, and reserves bandwidth for each connection in each of those cells. The fourth scheme reserves bandwidth for each connection in the predicted next cell of a mobile. We adopt the history-based mobility estimation for the first two schemes. Using extensive simulations, the four schemes are compared quantitatively in terms of (1) important performance measures such as the hand-off dropping probability, connection-blocking probability, and bandwidth utilization, (2) dependency on the de-sign parameters, (3) dependency on the mobility estimation accuracy, and (4) complexity. The simulation results indicate that the first scheme is the most desirable in the sense that it achieves reasonably good performance while requiring much less memory and computation than the other three schemes. © Copyright ACM 1998.

关键词： Bandwidth

来源：评论

学校读者我要写书评

暂无评论

Predictive and adaptive bandwidth reservation for hand-offs in QoS-sensitive cellular networks 98

Predictive and adaptive bandwidth reservation for hand-offs ...

引用

Proceedings of the ACM SIGCOMM '98 conference on Applications, technologies, architectures, and protocols for computer communication

作者： Sunghyun Choi Kang G. Shin Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann Arbor Michigan

ISBN: (纸本)9781581130034

How to control hand-off drops is a very important Quality-of-Service (QoS) issue in cellular networks. In order to keep the hand-off dropping probability below a pre-specified target value (thus providing a probabilistic QoS guarantee), we design and evaluate predictive and adaptive schemes for the bandwidth reservation for the existing connections' handoffs and the admission control of new *** first develop a method to estimate user mobility based on an aggregate history of hand-offs observed in each cell. This method is then used to predict (probabilistically) mobiles' directions and hand-off times in a cell. For each cell, the bandwidth to be reserved for hand-offs is calculated by estimating the total sum of fractional bandwidths of the expected hand-offs within a mobility-estimation time window. We also develop an algorithm that controls this window for efficient use of bandwidth and effective response to (1) time-varying traffic/mobility and (2) inaccuracy of mobility estimation. Three different admission-control schemes for new connection requests using this bandwidth reservation are proposed. Finally, we evaluate the performance of the proposed schemes to show that they meet our design goal and outperform the static reservation scheme under various scenarios.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Optimization of a real-time primary-backup replication service

Optimization of a real-time primary-backup replication servi...

引用

Reliable Distributed Systems

作者： Hengming Zou F. Jahanian Real-time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

The primary-backup replication model is one of the commonly adopted approaches to providing fault tolerant data services. Its extension to the real time environment, however, imposes the additional constraint of timing predictability, which requires a bounded overhead for managing redundancy. The paper discusses the trade-off between reducing system overhead and increasing (temporal) consistency between the primary and backup, and explores ways to optimize such a system to minimize either the inconsistency or the system overhead while maintaining the temporal consistency guarantees of the system. An implementation built on top of the existing RTPB model (H. Zou and F. Jahanian, 1998) was developed within the x-kernel architecture on the Mach OSF platform running MK 7.2. Results of an experimental evaluation of the proposed optimization techniques are discussed.

关键词： Fault tolerance Timing Redundancy Fault tolerant systems Real time systems Laboratories Environmental management Buildings Protocols Application software

来源：评论

学校读者我要写书评

暂无评论

End-host architecture for QoS-adaptive communication

End-host architecture for QoS-adaptive communication

引用

Real-time Technology and Applications Symposium

作者： T. Abdelzaher K.G. Shin Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

Proliferation of communication-intensive real-time applications with "elastic" timeliness constraints such as streaming stored video, requires a new design for end-host communication subsystems. The design should (i) provide per-flow or per-service-class guarantees, (ii) maximize the aggregate utility of the communication service across all clients, (iii) gracefully adapt to transient overload, and (iv) avoid, if possible, starving lower-priority service classes during the period of sustained overload. The authors propose a QoS-optimization algorithm and communication subsystem architecture that satisfy the above requirements. It provides each client its contracted QoS, while adapting gracefully to transient overload and resource shortage. A new concept of flexible QoS contract is introduced, specifying multiple acceptable levels of service (or QoS levels for short) and their corresponding rewards for each client. Allowing clients to specify multiple QoS levels permits the server to perform QoS-optimization and degrade client's QoS under transient overload predictable, as specified in the QoS contract. Clients receive a money-back guarantee if the contracted QoS is violated by the server. The proposed resource-management mechanism maximizes server's total reward under resource constraints. They implemented and evaluated the architecture on a Pentium-based PC platform running under The Open Group (TOG) MK7.2 kernel, demonstrating the capability of the communication subsystem in meeting its design goals.

关键词： Contracts Degradation Aggregates computer architecture Resource management Laboratories Application software Streaming media Kernel Monitoring

来源：评论

学校读者我要写书评

暂无评论

Efficient all-to-all personalized exchange in multidimensional torus networks

Efficient all-to-all personalized exchange in multidimension...

引用

International Conference on Parallel Processing (ICPP)

作者： Young-Joo Suh K.G. Shin Department of Computer Science and Engineering Pohang University of Science and Technology Pohang South Korea Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

This paper presents new algorithms for all-to-all personalized exchange in multidimensional torus-connected multiprocessors. Unlike existing message-combining algorithms in which the number of nodes in each dimension should be power-of-two and square, the proposed algorithms accommodate non-power-of-two tori where the number of nodes in each dimension need not be power-of-two. In addition, destinations remain fixed over a larger number of steps in the proposed algorithms, thus making them amenable to optimizations. Finally, the data structures used are simple, hence making substantial saving of message-rearrangement time.

关键词： Intelligent networks Multidimensional systems Samarium computer science Propagation delay Scattering computer networks Laboratories Communication switching Data structures

来源：评论

学校读者我要写书评

暂无评论

Statistical real-time channels on multiaccess bus networks

引用

IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 1997年第8期8卷 769-780页

作者： Chou, CC Shin, KG the Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science The University of Michigan

Real-time communication with performance guarantees is expected to become an important and necessary feature of future computer networks. In this paper, we present a scheme which can provide real-time communication services with both absolute and statistical performance guarantees on multiaccess bus networks for given input traffic characteristics and performance requirements. The proposed scheme reserves network bandwidth for real-time connections according to their needs. It also allows for independent addition and deletion of real-time connections while preserving existing guarantees. Our extensive simulation results for motion video communication have shown the proposed scheme to outperform the other well-known schemes.

关键词： real-time communication real-time connection/channel multimedia systems FieldBus (SP50) multiaccess networks digital video transmission

来源：评论

学校读者我要写书评

暂无评论

A fast algorithm for the minimax flow problem with 0/1 weights

引用

APPLIED MATHEMATICS LETTERS 1997年第1期10卷 11-16页

作者： Han, CC Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann Arbor MI 48109-2122 U.S.A.

In this paper, we define the minimax flow problem and design an O(k . M(n, m)) time optimal algorithm for a special case of the problem in which the weights on arcs are either O or 1, where n is the number of vertices, m is the number of arcs, k (where 1 less than or equal to k less than or equal to m) is the number of arcs with nonzero weights, and M(n;m) is the best time bound for finding a maximum flow in a network.

关键词： design and analysis of algorithms f-saturated critical arcs maximum flow minimax flow residual network

来源：评论

学校读者我要写书评

暂无评论

QoS negotiation in real-time systems and its application to automated flight control

QoS negotiation in real-time systems and its application to ...

引用

3rd IEEE Real-time Technology and Applications Symposium

作者： Abdelzaher, TF Atkins, EM Shin, KG Real- Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109-2122 United States

ISBN: (纸本)0818680164

We propose a model for quality-of-service (QoS) negotiation in building real-time services to meet both predictability and graceful degradation requirements. QoS negotiation is shown to (i) outperform conventional ''binary'' admission control schemes (either guaranteeing the required QoS or rejecting the service request), and (ii) achieve higher application-perceived system utility. We incorporated the proposed QoS-negotiation model into an example realtime middleware service, called RTPOOL, which manages a distributed pool of shared computing resources (processors) to guarantee timeliness QoS for real-time applications. The efficacy and power of QoS negotiation are demonstrated for an automated flight control system implemented on a network of PCs running RTPOOL. This system is used to fly an F-16 fighter aircraft modeled using the Aerial Combat (ACM) F-16 Flight Simulator. Experimental results indicate that QoS negotiation, while maintaining real-time guarantees, enables graceful QoS degradation under conditions in which traditional schedulability analysis and admission control schemes fail.

关键词： Real time systems

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：