Dynamically configurable message flow control for fault-tolerantrouting

Fault-tolerant routing protocols in modern interconnection networks rely heavily on the network flow control mechanisms used. Optimistic flow control mechanisms, such as wormhole switching (WS), realize very good performance, but are prone to deadlock in the presence of faults. Conservative flow control mechanisms, such as pipelined circuit switching (PCS), ensure the existence of a path to the destination prior to message transmission, achieving reliable transmission at the expense of performance. This paper proposes a general class of flow control mechanisms that can be dynamically configured to trade-off reliability and performance. Routing protocols can then be designed such that, in the vicinity of faults, protocols use a more conservative flow control mechanism, while the majority of messages that traverse fault-free portions of the network utilize a WS like flow control to maximize performance. We refer to such protocols as two-phase protocols. This ability provides new avenues for optimizing message passing performance in the presence of faults. A fully adaptive two-phase protocol is proposed, and compared via simulation to those based on WS and PCS. The architecture of a network router supporting configurable flow control is also described     

一种改进的高性能远程内存直接访问(RDMA)的实现

Infiniband体系架构(IBA)是一种新兴的互联技术,它主要用于处理节点和输入输出节点之间的互联,从而形成一个系统级的网络.为了改进通信子系统的性能,IBA提供了很多特性,其中之一就是远程直接内存访问(Romote Direct Memory Access,RDMA).但是在标准的IBA实现中,对于控制报文和小报文使用发送接收操作来进行.本文提出了一种改进的RDMA实现,使得RDMA能够应用于控制报文和小报文,从而使得传输小报文和控制报文的延迟平均降低24%.     

面向HPC和DC的可重构光互连网络体系结构综述

互连网络是高性能计算系统和数据中心的核心组件之一,也是决定其系统整体性能的全局性基础设施。随着高性能计算、云计算和大数据技术的迅速发展,传统的电互连网络在性能、能耗和成本等方面无法满足高性能计算应用和数据中心业务的大规模可扩展通信需求,面临着严峻的挑战。为此,近年来相关研究者提出了多种面向高性能计算和数据中心的可重构的光互连网络结构。首先阐明了光互连网络相对于电互连网络的优势;然后介绍了几种典型的可重构光互连网络体系结构,并对其特点进行了分析比较;最后探讨了可重构光互连网络的发展趋势。     

Message latency in hypercubic computer networks with the bursty traffic pattern

An interconnection network is a crucial component of parallel computers because the overall system performance is very sensitive to the latency of messages delivered by the network to communicate among collaborating processors. This paper presents an analytical performance model to calculate message latency in circuit-switched hypercubic networks in the presence of bursty traffic pattern, which is a typical scenario for multimedia applications. A message in circuit switching may need a number of connection attempts before successfully setting up a path from source to destination. The proposed model uses the approach of superposing infinite bursty traffic streams to capture the effective traffic entering the network from a source node, which includes the traffic generated by the source and those due to many connection attempts. Results obtained from simulation experiments confirm that the proposed model exhibits a good degree of accuracy for various network sizes and under different operating conditions.     

声纳湿端数据远传DWDM光电交换模块设计

声纳的应用极其广泛,海洋渔业以及军事应用使得声纳技术得到了大力发展;声纳湿端数据传输的可靠性、实时性是声纳系统性能得到保障的前提;设计一用于声纳湿端数据远传的DWDM光电交换模块;在该模块中,使用以太网交换芯片和两个DWDM光模块对数据进行多路转发并实现光通路的冗余备份,提升了系统可靠性的同时使网络拓扑更为灵活;由于DWDM光模块可将电信号转换为波长可选定的光信号,故通过若干该模块协同使用,可实现多路光信号复用即同时传输多条声纳水下阵缆的数据;经实际开发与测试,该模块以太网业务性能指标符合设计需求,且该模块已在某声纳工程项目中得到了应用,并可为其他领域数据远传工程应用提供设计参考。     

基于OMNet++的大规模InfiniBand互连网络模拟系统

随着多核处理器的发展和计算需求的不断增长,高性能计算系统规模不断增大.使用模拟器对高性能计算系统进行模拟,对系统设计及优化有着重要的作用,互连网络模拟则是其中不可或缺的一部分.设计实现了一种基于OM Net++的大规模InfiniBand互连网络模拟系统,该系统通过记录的并行程序M PI消息来驱动网络仿真过程,可以模拟...     

片上光网络:一种新型片上互连网络

随着单个芯片上集成的处理器的个数越来越多,传统的电互连网络已经无法满足对互连网络性能的需求,需要一种新的互连方式,因此光互连网络技术应运而生.目前,电互连的片上网络在功耗、性能、带宽、延迟等方面遇到了瓶颈,而光互连作为一种新的互连方式引用到片上网络具有低损耗、高吞吐率、低延迟等无可比拟的优势.本文主要探讨了片上光网络的...     

具有高效确认机制的双层卫星网络多径路由协议

针对资源受限的LEO卫星网络中传统单路径路由协议数据传输速率较低的问题,基于GEO/LEO双层卫星网络模型提出一种基于网络编码（NC）的双层卫星网络多径路由协议（N-NCMR）。首先,通过GEO卫星为LEO卫星网络计算路由减轻LEO卫星的负担,结合NC技术动态地沿着多个不相交路径传输数据流的不同部分;其次,设计了一种高效的延迟确认机制加速数据传输,源节点在接收到前一组的确认（ACK）消息之前可以连续发送后续的组。仿真结果表明,该路由协议显著提高了LEO卫星网络的吞吐量和数据传输效率。     

一种新的处理器间光互连网络

随着计算机系统对互连网络性能需求的提高,传统的电互连技术出现了许多无法克服的问题,光互连技术应运而生。本文设计了一种新的基于高速光开关的处理器间光互连结构——PIBOS,并在此基础上提出了单级PIBOS和多级PIBOS中的链路仲裁和路由算法。模拟结果表明,采用PIBOS互连结构,减少了数据传输过程中的光电转换操作,提高了网络的吞吐率,降低了系统延时,并很好地实现了互连系统的扩展。     

基于无线能量采集的多跳网络安全传输中的路径选择

针对具有无线能量采集技术的多跳传输网络,提出了全双工中继网络在有多个窃听者和多个功率节点场景下进行多跳多路径传输时的路径选择问题。首先,所提系统模型在有多个窃听者和功率节点的场景下进行信息传输,将源发射端和接收端之间的最佳路径作为数据传输路径。然后,为了增强系统性能,中继节点对功率节点发出的射频信号进行能量采集并利用所获能量来进行下一跳的数据传输。最后,推导出了所提路径选择方法在瑞利衰落信道下端到端中断概率的精确表达式,蒙特卡洛仿真和理论分析曲线拟合较好,说明了理论推导的正确性,以及所提方法具有性能上的优越性。     

神威E级原型机互连网络和消息机制

本文描述了神威E级原型机的互连网络和消息机制.神威E级原型机是继神威蓝光、神威?太湖之光之后神威家族的第三代计算机.该计算机作为一台E级计算机的原型机,峰值性能3.13PFlops,其最大的特色之一就是采用28Gbps传输技术,设计开发了新一代的神威高阶路由器和神威高性能网络接口两款芯片,在传统胖树的基础上,设计了双轨...     

高性能FTP服务系统的研究与实现

基于FTP协议中控制流和数据流逻辑分离的特点，提出了一种新型的高性能FTP服务系统。该系统在实验室原有研究成果的基础上，通过增加存储子系统(磁盘阵列)与网络客户之间的网络通道，使所有网络服务请求由服务器统一管理，而数据则由磁盘阵列本身直接从网上接收和发送。这种命令与数据的分离免除了数据流在服务器与磁盘阵列之间的往返传送和存储转发，极大地提高了系统的平均响应速度。     

The Data Vortex, an All Optical Path Multicomputer Interconnection Network

All optical path interconnection networks employing dense wavelength division multiplexing can provide vast improvements in supercomputer performance. However, the lack of efficient optical buffering requires investigation of new topologies and routing techniques. This paper introduces and evaluates the data vortex optical switching architecture which uses cylindrical routing paths as a packet buffering alternative. In addition, the impact of the number of angles on the overall network performance is studied through simulation. Using optimal topology configurations, the data vortex is compared to two existing switching architectures-butterfly and omega networks. The three networks are compared in terms of throughput, accepted traffic ratio, and average packet latency. The data vortex is shown to exhibit comparable latency and a higher acceptance rate (2times at 50 percent load) than the butterfly and omega topologies     

Modelling and analysis of pipelined circuit switching in interconnection networks with bursty traffic and hot-spot destinations

Pipelined circuit switching (PCS) that combines the advantages of both circuit switching and wormhole switching is an efficient method for passing messages in interconnection networks. Analytical modelling is a cost-effective tool and plays an important role in achieving a clear understanding of the network performance. However, most of the existing models for PCS are unable to capture the realistic nature of message behaviours generated by real-world applications, which have a significant impact on the design and performance of communication networks. This paper presents a new analytical model for PCS in interconnection networks in the presence of bursty and correlated message arrivals coupled with hot-spot destinations, which can capture the bursty message arrival process and non-uniform distribution of message destinations. Such a traffic pattern has been found in many practical communication environments. The accuracy of the proposed analytical model is validated through extensive simulation experiments. The model is then applied to investigate the effects of the bursty message arrivals and hot-spot destinations on the performance of interconnection networks with PCS.     

长链型无线传感器网络QoS路由优化的研究*

针对输电线路监测系统对无线传感器网络实时性和可靠性要求较高的特点,在抽象出的长链型传感器网络QoS路由模型中把网络带宽、时延、跳数、收包率作为链路约束,寻求网络中的最优数据传输路径。考虑到基本蚁群算法存在收敛速度慢、易陷入局部最优等缺陷,提出一种用自适应蚁群算法求解最优路径的方法。仿真结果表明,改进的算法通过自适应地调整信息素挥发因子,能够快速地找到满足约束的最优路径,网络规模越大其优势越明显,保证了用于输电线路监测的无线传感器网络数据传输的服务质量。     

FC-AE-1553网络的建模仿真研究

研究了FC-AE-1553（Fibre Channel-Avionics Environment-1553,光纤通道-航空电子环境-1553）网络的计算机仿真问题。从FC-AE-1553网络的基本原理出发,提出了网络结构模型和数据传输控制方法;在OPNET Modeler中创建了FC-AE-1553网络节点模型和FC交换机模型;采用数据传输控制方法控制整个FC-AE-1553网络的数据传输,对航空电子典型拓扑网络进行仿真。通过仿真实验与结果分析证明了FC-AE-1553网络具有良好的实时性能,采用提出的数据传输控制方法比MIL-STD-1553B的数据控制方法有更高的网络吞吐能力和更强的适应性。     

基于协议解析的工控网络安全仿真平台设计

工业控制网络的安全防护通常采用防火墙技术和多种复杂的应用层协议协同完成,但是未涉及应用层协议的深入分析。为了更好地保障工控网络数据访问的安全,结合工控网络报文定制性的特点,详细分析了基于应用层协议解析的安全防护策略。该方案在工业防火墙的基础上,通过对工控网络通信协议的报文深入解析,直接在报文层面解析过滤,从而拦截与功能实现无关的报文,并发现隐藏较深的威胁。以OPC协议为例,搭建了基于应用层协议深度解析的工控网络安全仿真测试平台,并利用石化企业现场设备的通信数据对该平台进行了验证。所提出的安防策略为工控网络安全设备的设计和制造提供了一种基于应用层协议解析的方案,具备较高级别的安全性能。     

Real-Time Virtual Channel Flow Control

Real-time communication system support for large scale parallel multicomputers becomes an important issue as the number of real-time applications developed on these systems increases. Flow control is a key component that affects the performance of the communication subsystem. We develop a range of new real-time virtual channel flow control schemes for wormhole networks. The flow control schemes differ in their priority mapping strategies, priority adjustment methods, and arbitration functions. The priority mapping strategy and priority adjustment method of a flow control scheme determine the priority of a message. The priority of a message is used for the virtual channel assignment and the physical channel arbitration. We discuss the trade-off between the performance and the hardware cost of each flow control scheme. A simulator is implemented for studying the performance of the schemes, and simulation experiments are designed to compare the importance of priority mapping, priority adjustment and arbitration toward the system performance. As wormhole networks scale to larger sizes, the average distance between source and destination nodes increases. The flits of messages in wormhole networks, which are buffered in nodes along the path from the source to the destination, consume network resources in these nodes. Therefore, increased scaling may lead to increased resource consumption, congestion, and late messages. In real-time systems, messages lose their value when they miss their deadlines. In order to reduce congestion, we provide a scheme for dropping messages that miss their deadlines.     

基于工业无线网络性能评价的规划路径算法

针对路由节点查找消息路径的局限性,提出了一种网关设备规划消息路径的算法。该算法结合工业无线网络通信数据的规律性,在考虑时延、能耗、可靠传输和负载均衡方面的性能综合评价之后,找出一种路径组合,避免消息拥塞和干扰,提高通信性能。然后,设计了仿真实验来对比规划路径与AODV查找路径两种情况下的通信性能。实验结果证明,规划的消息路径下的通信性能更好。     

An analytical model for torus networks in the presence of batch message arrivals with hot-spot destinations

Interconnection networks are hardware fabrics supporting communications between individual processors in multi- computers. The low-dimensional k-ary n-cubes （or torus） with adaptive wormhole switching have attracted significant research efforts to construct high-performance interconnection networks in contemporary multi-computers. The arrival process and destination distribution of messages have great effects on network performance. With the aim of capturing the characteristics of the realistic traffic pattern and obtaining a deep understanding of the performance behaviour of interconneetion networks, this paper presents an analytical model to investigate the message latency in adaptive-routed wormhole-switched torus networks where there exists hot-spot nodes and the message arrivals follow a batch arrival process. Each generated message has a given probability to be directed to the hot-spot node. The average degree of virtual channel multiplexing is computed by the GE/G/1/V queueing system with finite buffer capacity. We compare analytical results of message latency with those obtained through the simulation experiments in order to validate the accuracy of the derived model.