The MAGNeT Toolkit: Design,Implementation and Evaluation

The current trend in constructing high-performance computing systems is to connect a large number of machines via a fast interconnect or a large-scale network such as the Internet. This approach relies on the performance of the interconnect (or Internet) to enable fast, large-scale distributed computing. A detailed understanding of the communication traffic is required in order to optimize the operation of the entire system.Network researchers traditionally monitor traffic in the network to gain the insight necessary to optimize network operations. Recent work suggests additional insight can be obtained by also monitoring traffic at the application level.The Monitor for Application-Generated Network Traffic toolkit (MAGNeT) we describe here monitors application traffic patterns in production systems, thus enabling more highly optimized networks and interconnects for the next generation of high-performance computing systems.     

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。     

数据中心网络路由研究进展

随着云计算的迅速发展,运营商对数据中心的需求与日俱增.作为数据中心网络的关键技术,路由负责在数据中心内部以及数据中心之间为流量选路,为不同服务质量要求的流量提供差异化的路由转发服务.当数据中心规模比较大时,由于应用不可预估的通信流量以及数据中心网络的拓扑特点,传统因特网路由方法不能提供令人满意的高吞吐率和资源利用率,网...     

适用于大规模无线传感器网的流量优化系统设计

针对大规模无线传感器网络(WSN)流量随访问者数量增加而上升的问题,设计并实现了一种适用于构建大型WSN并降低系统流量的应用系统框架。系统采用IPv6和低功耗无线个域网的IPv6技术(6LoWPAN)搭建大规模WSN,使用消息队列遥测传输(MQTT)协议和针对WSN设计的消息队列遥测传输(MQTT-SN)协议在应用层搭建了连接WSN和传统互联网的发布/订阅结构。实验结果显示,当系统中存在5个传感器节点时,与受限应用协议(CoAP)构建的WSN应用系统相比,提出的系统框架的数据流量仅为前者的18%左右。这表明该系统框架可有效地控制访问者增加对WSN流量造成的影响。     

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...     

中国北车集团计算机网络安全系统的设计与实现

中国北车集团计算机网络系统既有局域网也有广域网，网络覆盖规模大，体系结构复杂，且高速广域网采用虚拟专网（VPN）技术以国际互连网（Internet）作为载体。Internet网络病毒的泛滥、内外部用户的恶意攻击、关键应用系统的数据安全等已成为影响集团网络系统安全稳定运行的主要因素。为了保证集团网络系统安全可靠运行，集团逐步建立了计算机网络安全系统．重点解决网络用户行为管理、网络病毒的防杀、网络系统管理和关键应用系统的数据备份．     

绿色网络理论与技术研究

互联网的飞速发展,也使网络能耗急剧增长.但目前网络设备能效低下,未实现能耗比例计算的理念.而网络却为峰值负载而设计,在众多时间处于低负载,存在巨大的节能契机.首先介绍网络设备的能耗模型,继而从两方面阐述网络能耗优化的理论与技术:一方面,在假设网络总流量无法改变的前提下,为网络设备增加能源和性能状态,并优化本地控制策略,从而使单个网络设备实现能耗比例计算,或者在不提高现有网络设备能效的前提下,通过网络范围的协同和流量工程,使网络整体实现能耗比例计算的理念;另一方面,为网络提供缓存能力可以降低或缓解网络流量,从而减少网络的传输能耗或缓解其增长速度,智能的缓存部署、内容存储和请求路由能够进一步优化网络的能耗.在上述基础上,比较了各种技术的优劣,并分析了未来的研究方向.     

Communication Requirements and Interconnect Optimization for High-End Scientific Applications

The path toward realizing next-generation petascale and exascale computing is increasingly dependent on building supercomputers with unprecedented numbers of processors. To prevent the interconnect from dominating the overall cost of these ultrascale systems, there is a critical need for scalable interconnects that capture the communication requirements of ultrascale applications. It is, therefore, essential to understand high-end application communication characteristics across a broad spectrum of computational methods, and utilize that insight to tailor interconnect designs to the specific requirements of the underlying codes. This work makes several unique contributions toward attaining that goal. First, we conduct one of the broadest studies to date of high-end application communication requirements, whose computational methods include: finite difference, lattice Boltzmann, particle-in-cell, sparse linear algebra, particle-mesh ewald, and FFT-based solvers. Using derived communication characteristics, we next present the fit-tree approach for designing network infrastructure that is tailored to application requirements. The fit-tree minimizes the component count of an interconnect without impacting application performance compared to a fully connected network. Finally, we propose a methodology for reconfigurable networks to implement fit-tree solutions. Our Hybrid Flexibly Assignable Switch Topology (HFAST) infrastructure, uses both passive (circuit) and active (packet) commodity switch components to dynamically reconfigure interconnects to suit the topological requirements of scientific applications. Overall, our exploration points to several promising directions for practically addressing the interconnect requirements of future ultrascale systems.     

Design challenges for high-performance network interfaces

A network interface is a device that allows a computer to communicate with a network. Network interface design has a crucial impact on communication efficiency. It determines the cost of communication actions, moving data, and providing application isolation across communicating domains. With the advent of distributed computing and the Internet, and with dramatically faster processor clock rates and complete systems on chips, computing is increasingly concerned with the efficient movement of data-across the interconnects within a machine, the system area network within a machine room, and the local area or wide area network. The authors discuss network interface design issues     

Traffic measurement and analysis in an ATM-based internet backbone

This paper reports our measurements and analysis of traffic characteristics in an Internet backbone ATM network. In order to utilize network resource efficiently while satisfying the quality of service requirement, it is important to understand the traffic characteristics. We therefore monitored the traffic from the flow or application level to the cell level on a link between NTT's Open Computer Network (OCN) and the Science Information Network (SINET), which are two of the largest Internet backbone ATM-based networks in Japan. Using the monitored traffic, we also evaluated the performance of the aggregate traffic by real-time simulation. Results show that the performance (cell loss ratio) greatly depended not only on link utilization but also on the number of flows, flow size, and traffic composition in terms of applications. We also found that the degree of self-similarity in the Internet backbone was not large. In addition, we clarified that more statistical multiplexing gain could be obtained in the Internet backbone when more flows were multiplexed onto a link.     

高性能计算环境下对校园网络安全体系的设计与优化

目前高校也建立起了高性能计算环境体系，主要被用于从事大规模科学计算和复杂问题求解，拥有很高的计算能力和海量的存储资源，时常遭受来自互联网的入侵或攻击。由于单一的安全技术无法满足高性能计算环境复杂的安全防护需求，进一步恶化了高性能计算环境的安全状况。因此建立一套安全防御体系对高性能计算环境的正常运行有着非常重要的意义。     

Modeling external network behavior by using internal measurements

Network behavior is the set of observations or measurements that can be made about a network over time. The growth of network-based computing and the Internet have ensured that networks can no longer be considered in isolation, as events external to a particular network increasingly impact its behavior. Network management requires that information be known about these events, a task that is not always possible. We present a modeling strategy that takes partial information about a network and uses it to predict the behavior in unmonitored areas. This implementation is based on a meta-heuristic (genetic algorithm), and uses IP-packet information as well as a limited understanding of the external topology. This is then used to model the full topology, routing tables and traffic for the entire network at periodic intervals. The system was tested using the ns-2 network simulator and a Java implementation on a series of cases. The results showed a reasonable level of accuracy in predicting traffic and topology. Performance increased under system load, and at no point did the system generate any additional network traffic. This provides an efficient and effective strategy for network management.     

Interconnection of CAN segments through IEEE 802.16 wireless MAN

The Controller Area Network (CAN) is a high-performance and highly reliable advanced serial communication protocol, which efficiently supports distributed real-time control. CAN-based distributed control systems have generally two main problems that are the size of distributed area and the need for communication with other LANs and with remote CAN segments. A straightforward solution is to use internetworking devices with wireless support to extend CAN segments. In this paper, a new solution to interconnect CAN segments is proposed, which uses a wireless MAN based on the IEEE 802.16 standard as a backbone system. Also, the solution describing a model for internetworking unit integrates the traffic generated by CAN segments into IEEE 802.16 wireless MAN using encapsulation technique.     

A reconfigurable,regular-topology cluster/datacenter network using commodity optical switches

Hybrid optical/electrical interconnects using commercial optical circuit switches have been previously proposed as an attractive alternative to fully-connected electronically-switched networks. Among other advantages, such a design offers increased port density, bandwidth/port, cabling and energy efficiency, compared to conventional packet-switched counterparts. Recent proposals for such system designs have looked at small and/or medium scale networks employing hybrid interconnects. In our previous work, we presented a hybrid optical/electrical interconnect architecture targeting large-scale deployments in high-performance computing and datacenter environments. To reduce complexity, our architecture employs a regular shuffle network topology that allows for simple management and cabling. Thanks to using a single-stage core interconnect and multiple optical planes, our design can be both incrementally scaled up (in capacity) and scaled out (in the number of racks) without requiring major re-cabling and network re-configuration. In this paper, we extend the fundamentals of our existing work towards quantifying and understanding the performance of these type of systems against more diverse workload communication patterns and system design parameters. In this context, we evaluate–among other characteristics–the overhead of the reconfiguration (decomposition and routing) scheme proposed and extend our simulations to highly adversarial flow generation rate/duration values that challenge the reconfiguration latency of the system.     

Automatically composed workflows for grid environments

Once the realm of high-performance computing for scientific applications, grid computing is rising as a key enabling infrastructure for resource sharing and coordinated problem solving in dynamic multiinstitutional virtual organizations. Grids build over networking technology to provide middleware support such as locating files over a network of computers, scheduling the distributed execution of jobs, and managing resource sharing and access policies.2 The need of scientific communities to interconnect applications, data, expertise, and computing resources is shared by other application areas, such as business, government, medical care, and education.     

Analysis and modelling of traffic produced by adaptive HTTP-based video

The increase of HTTP-based video popularity causes that broadband and Internet service providers’ links transmit mainly multimedia content. Network planning, traffic engineering or congestion control requires an understanding of the statistical properties of network traffic; therefore, it is desirable to investigate the characteristic of traffic traces generated by systems which employ adaptive bit-rate streaming. Our first contribution is an investigation of traffic originating from 120 client-server pairs, situated in an emulated content distribution network, and multiplexed onto a single network link. We show that the structure of the traffic is distinct from the structure generated by the first and second generation of HTTP video systems, and furthermore, not similar to the structure of general Internet traffic. The obtained traffic exhibits negative and positive correlations, anti-persistence, and its distribution function is skewed to the right. Our second contribution is an approximation of the traffic by ARIMA/FARIMA processes blue and artificial neural networks. As we show, the obtained traffic models are able to enhance the performance of an adaptive streaming algorithm.     

A fast network partition method for large-scale urban traffic networks

In order to control the large-scale urban traffic network through hierarchical or decentralized methods, it is necessary to exploit a network partition method, which should be both effective in extracting subnetworks and fast to compute. In this paper, a new approach to calculate the correlation degree, which determines the desire for interconnection between two adjacent intersections, is first proposed. It is used as a weight of a link in an urban traffic network, which considers both the physical characteristics and the dynamic traffic information of the link. Then, a fast network division approach by optimizing the modularity, which is a criterion to distinguish the quality of the partition results, is applied to identify the subnetworks for large-scale urban traffic networks. Finally, an application to a specified urban traffic network is investigated using the proposed algorithm. The results show that it is an effective and efficient method for partitioning urban traffic networks automatically in real world.     

基于覆盖网的协同式网络安全防护与分析系统

互联网安全形势依然严峻,网络安全事件层出不穷,虽然网络安全系统一直在不断的发展,但是传统安全系统间缺少协同机制,难以实施统一的安全策略,无法发挥整体优势。文章提出了一种基于覆盖网的协同式网络安全防护与分析系统,通过覆盖网架构,将原本孤立的网络安全设备互连起来,协同工作,分布式感知与控制管理网络流量,集中分析与处理安全事件,形成全程全网的网络安全事件管理与解决方案。该方案充分利用了覆盖网技术、P2P通讯技术、可信网络连接技术、高速流量记录查询技术和云计算技术等现有的技术来架构一个实用的协同网络安全防护与分析系统。     

Compiling network traffic into rules using soft computing methods for the detection of flooding attacks

The ability to dynamically collect and analyze network traffic and to accurately report the current network status is critical in the face of large-scale intrusions, and enables networks to continually function despite of traffic fluctuations. The paper presents a network traffic model that represents a specific network pattern and a methodology that compiles the network traffic into a set of rules using soft computing methods. This methodology based upon the network traffic model can be used to detect large-scale flooding attacks, for example, a distributed denial-of-service (DDoS) attack. We report experimental results that demonstrate the distinctive and predictive patterns of flooding attacks in simulated network settings, and show the potential of soft computing methods for the successful detection of large-scale flooding attacks.     

A mobile-agent-based approach to software coordination in the HOOPE system

Software coordination is central to the construction of large-scale high-performance distributed applications with software services scattered over the decentralized Internet. In this paper, a new mobile-agent-based architecture is proposed for the utilization and coordination of geographically distributed computing resources. Under this architecture, a user application is built with a set of software agents that can travel across the network autonomously. These agents utilize the distributed resources and coordinate with each other to complete their task. This approach' s advantages include the natural expression and flexible deployment of the coordination logic, the dynamic adaptation to the network environment and the potential of better application performance. This coordination architecture, together with an object-oriented hierarchical parallel application framework and a graphical application construction tool, is implemented in the HOOPE environment, which provides a systematic support for the de