新品发布

万兆以太网交换机网捷网络美国网捷网络公司(FoundryNetworks)日前宣布为其EdgeIron第2层以太网交换机系列增加了一款结构紧凑的8端口万兆以太网交换机。凭借无阻塞的160Gbps以太网交换机设计和每一个端口上的线速万兆转发性能,这款EdgeIron 8X10G交换机是小型企业骨干、高性能集群和网格计算网络互联的理想解决方案。在结构紧凑的1U机箱内,EdgeIron 8X10G交换机的8个万兆端口均支持线速交换。这款交换机使用了卓越的万兆小型可插拔(XFP)光纤收发器,与其它收发器相比,这种收发器能够提供成本更低、功率效率更高的解决方案。凭借每秒…     

诱偏暨导航一体化平台位置误差补偿算法

分布式转发平台的位置误差,是诱偏暨导航一体化系统中导航误差的重要因素。在分别推导了由转发平台位置误差和信号时延造成的系统定位误差的基础上,提出了转发平台的位置误差补偿算法。该算法是通过将转发平台的位置误差等效到所转发信号的时延上,在接收机解算中对时延信息进行补偿,从而提高系统的导航定位精度。通过理论推导和仿真验证了此算法的有效性。     

新品方案

网捷网络推出8端口第2层万兆以太网交换机网捷网络公司日前宣布为其EdgeIron第2层以太网交换机系列增加一款结构紧凑的8端口万兆以太网交换机。凭借无阻塞的以太网交换机设计和每一个端口上的线速万兆转发性能,这款EdgeIron 8X10G交换机成为小型企业骨干、高性能集群和网格计算网络互联的理想解决方案。每秒将近1.2亿数据包(MPPS)的性能,令EdgeIron 8X10G交换机有望成为同类产品中最高性能的无阻塞万兆交换机。ECOM推出一系列新产品新产品主要有EN-2204RW路由器、EN-2924SGM+千兆网管型交换机、EN-2309SGM千兆网管型交换机和E…     

基于lP交换技术的以太网交换机的设计与实现

文章分析了基于三层的交换技术,给出了一种三层以太网交换机的硬件设计方案和基于分层的交换网络软件平台设计方案,对交换机的主要性能进行了测试并对测试结果作了分析。     

一种基于OFDM信号周期平稳特性的系统时延和频偏的盲估计算法

该文首先提出一种基于信号周期平稳特性的OFDM系统时延和频偏的盲估计算法,然后分析算法,获得一种可以估计非整数倍样点周期的时延和扩大频偏估计范围,实现整个OFDM系统带宽范围内的频偏估计的方法,并指出本算法可以在信道未知的情况下获得好的估计性能,最后给出相应的仿真结果。理论分析和仿真结果表明,本算法有很好的抗噪特性、强的变化信道适应性,与同类方法比较,具有更高的估计精度、估计非整数倍样点周期时延和扩大频偏估计范围的能力。     

领跑云数据中心新华三高性能核心交换机出炉

近日,新华三委托全球权威测试机构Network Test针对数据中心核心交换机S12500X-AF进行了测试.在测试中,S12500X-AF实现了单框768个100G端口的线速转发,成为目前业内惟一一款达到这一性能的数据中心核心交换机设备.     

大唐微电子智能卡芯片跃居世界前列

美国网捷网络公司日前宣布，为其Edge Iron第2层以太网交换机系列增加了一款结构紧凑的8端口万兆以太网交换机。凭借无阻塞的160Gbit／s以太网交换机设计和每一个端口上的线速万兆转发性能，这款EdgeIron8X10G交换机是小型企业骨干、高性能集群和网格计算网络互联的理想解决方案。与现有的Edgelron第2层交换机系列相同，Edgekon 8X10G交换机具有一套先进的标准第2层交换功能和服务、冗余电源和业界标准的CLI。     

移动无线传感网能量时延约束的自适应路由及性能评估

 针对间歇性连通的移动无线传感网提出一种能量时延约束的自适应路由协议(EDCA),EDCA由初始化阶段、转发决策阶段、转发阶段和等待阶段组成,传感器节点根据目标时延实时判断是否转发副本,并选择剩余能量多的节点进行副本转发.EDCA对平均时延和网络负载具有控制力,对网络环境变化具有自适应能力,能够有效延长网络生命周期.     

低成本VLSI时延测试策略的探讨

本文针对VLSI的时延测试进行了研究和讨论.介绍了几种实现时延测试的方法,并提出了一种低成本实现时延测试的策略.在实际应用中取得了良好效果.     

软件定义网络中基于时延和负载的多控制器部署策略研究

多控制器体系结构的出现,解决了经典软件定义网络(SDN)架构控制层以单一集中控制器为主,在大规模网络环境中的可扩展性问题.在多控制器体系结构中,由于生成转发规则并将其填充到交换机的任务被委托给了控制器,网络的性能在很大程度上取决于控制器的放置.该文以降低总时延和均衡控制器间负载为目标,提出了一种基于子网划分的多控制器部...     

利用微引擎技术实现IP快速交换

微引擎是一种可以实现网络数据高速转发的技术。简单介绍了微引擎的特点和内部结构,并说明了如何利用微引擎技术实现3层以太网交换机中IP包快速转发的方法。     

基于交换式以太网的列车通信网络建模与性能分析

为了满足未来大容量、高速率、硬实时性的信息传输需求,将交换式以太网技术引入列车通信网络（TCN, train communication network）。针对不同优先级消息,根据其通信调度方式对传输过程建立了TCN的确定与随机Petri网(DSPN, determined and stochastic Petri nets)模型,比较了交换机不同调度算法对时延的影响,并分析了消息数目和产生周期,以及消息数目和吞吐量的关系。实验结果表明,采用优先级调度算法能在牺牲非实时数据时延的条件下降低实时数据的时延,验证了采用交换式以太网的TCN吞吐量远超过现有的TCN,并且能够为今后的设计和优化提供理论依据。     

面向大规模确定性网络的全局循环排队与转发机制

时延抖动敏感的工业控制和远程驾驶应用驱动网络由尽力而为服务向确定性转发服务转变。为满足确定性应用时延抖动的有界需求,工业界和学术界在逐流过滤整形和队列转发控制方面进行了大量研究,实现了小规模以太网环境下轻载稳定流的微秒级时延和亚微秒级抖动保障。多数研究因较少考虑长距离网络拓扑变化、传输时延波动和短时突发流量过载等影响,难以满足大规模骨干网场景下的确定性要求。在循环排队转发（cyclic queuing and forwarding,CQF）基础上,考虑了源目的路径特性和确定性流量强度因素,提出了全局循环排队转发三队列（global cyclic queuing and forwarding 3-queue,GCQF-3）,并在基于OMNeT++搭建的确定性网络仿真系统中,比较了CQF、CQF-3和GCQF-3的转发控制机制,实验表明GCQF-3能根据确定性流量状态及时调整门控时机和排队优先级,在时延、抖动和网络利用率等方面都达到最佳。     

基于位交换的电子配线技术

传统结构化布线的跳线由工程师在现场手工完成,效率较低。文中提出一种电子配线技术ePatch,用户可以在管理终端上远程完成电子配线动作。以太网交换机进行帧交换时建立了临时虚拟链路,文中提出利用端口对应表让交换机进行＂位交换＂,实现了永久虚拟链路,永久虚链路可以替代传统的跳线,从而达到电子配线的目的。     

Scalable multi-QoS IP+ATM switch router architecture

This article proposes a scalable multi-QoS IP+ATM switch router architecture. The proposed switch router is based on a core ATM switching system with multi-QoS capability. Forwarding engines and a routing engine are attached in front of the line cards of the ATM switching system. The FEs and RE are interconnected with each other via internal VCs. A novel longest matching algorithm is employed at the FE to achieve packet forwarding at wire-speed of OC-12c rate (622.08 Mb/s). Wire-speed unicast and multicast packet forwarding are performed using point-to-point and point-to-multipoint VCs in a unified way. Because FEs and RE are decoupled from the base ATM switching system, the full spectrum of ATM QoS capability is nicely applied for IP QoS control with a packet classification at the edge of the network. The core switching fabric is scalable from 40 to 160 Gb/s capacity (371 MPPS in terms of packet forwarding throughput). Feedback rate control is employed at each line card to eliminate congestion in the high-speed core switching fabric even with a small amount of buffer.     

多模车载视频监控系统中负载均衡算法设计

为了提高车载视频监控系统的视频传输质量,本文基于排队论,利用多链路捆绑技术,设计了基于TD-SCDMA,WCDMA和CDMA2000的多模车载视频监控的负载均衡算法.该负载均衡算法以各个网卡在数据传输时的传输时延、信号强度、运营商因子和丢包率加权作为均衡因子,依次作为负载均衡时数据转发的依据.经实验测试,本算法能够充分利用增加用户卡来增加传输速率,并通过捆绑不同运营商的用户卡来提高数据传输的稳定性,并且该算法较常用的轮询算法的数据传输速率有了较大提高.     

Linear regression‐based delay‐bounded routing protocols for VANETs

Routing protocols for vehicular ad hoc networks (VANETs) have attracted a lot of attention recently. Most of the researches emphasize on minimizing the end‐to‐end delay without paying attention to reducing the usage of radio. This paper focuses on delay‐bounded routing, whose goal is to deliver messages to the destination within user‐defined delay and to minimize the usage of radio because radio spectrum is a limited resource. The messages can be delivered to the destination by the hybrid of data muling (carried by the vehicle) and forwarding (transmitted through radio). In the existing protocol, a vehicle may only switch the delivery strategy (muling or forwarding) at an intersection according to the available time of the next road segment, which is between the current intersection and the next intersection. To improve previous works, our protocol uses linear regression to predict the available time and the traveling distance, and thus, the vehicle can switch to a proper delivery strategy at a proper moment and can reduce the number of relays by radio. Our protocol contains two schemes: the greedy and centralized schemes. The greedy scheme uses only the current sampling data to predict the available time and decide when to switch the delivery strategy, whereas the centralized scheme uses the global statistical information to choose a minimum‐cost path. Simulation results justify the efficiency of the proposed protocol. Copyright © 2011 John Wiley & Sons, Ltd.     

2D Mesh片上网络中交换机服务性能影响 的研究及其拓扑改进

 本文研究了交换机服务性能对2D Mesh片上网络的缓冲区资源和端到端延时的影响,发现在较低的丢包率的情况下,即使交换机能够提供很高的服务性能,却难以节省其所使用的缓冲区资源的现象.针对该现象,提出了一种基于星型子网的网状拓扑结构SSBM(Star-Subnet-Based-Mesh),在同样的网络规模以及丢包率的情况下,该种结构与2D Mesh结构相比具有更少的端到端通信延时,并且能够以较少的交换机服务性能为代价来节省较多的缓冲区资源,在较大程度上优化了2D Mesh片上网络的面积.     

Using cut-through forwarding to retain the real-time properties of Profibus over hybrid wired/wireless architectures

The benefits of wireless extensions in industrial networks are well recognized as long as the integration of the wireless and fieldbus domains will be capable of retaining the real-time and dependability quality of the current wired industrial networking solutions. In this paper, the architecture and the operation of a cut-through forwarding device are described, to be used in broadcasting, hybrid wired/wireless Profibus systems. Analytical models of the delay overhead introduced due to frame forwarding are presented. It is shown that the usage of cut-through forwarding devices relaxes the bit-rate requirements in the radio segments, while it drastically improves the inherent advantages and reduces the drawbacks of hybrid transmission media architectures, which are based on a single Medium Access Control domain.     

Multipath Security Aware Routing Protocol for MANET Based on Trust Enhanced Cluster Mechanism for Lossless Multimedia Data Transfer

The dynamic nature of mobile nodes of ad hoc network is mostly affected by security problems which reduce data forwarding rate in multimedia sources. Due to the rapid growth of wireless applications, the different multitalented routing protocols are proposed in recent years. But the recent protocols are not efficient for multimedia applications, till now, specific security aware routing protocols are not proposed for multimedia data transfers. In this paper, we proposed trust enhanced cluster based multipath routing (TECM) algorithm. We use energy efficient PSO algorithm used to create cluster formation and cluster head, super cluster head are selected from trust values, which compute form proposed TECM algorithm. The multi trust factors are used for trust computation, such as frame/packet loss ratio, frame/packet forward energy, frame/packet receiving energy, routing overhead, received signal strength, frame/packet forward rate, average forward delay and protocol deviation flag. We then combine proposed TECM algorithm with standard multipath OLSR protocol (TECM-OLSR) to analyze the performance of proposed algorithm. The simulated results show that proposed TECM-OLSR protocol is very effective in terms of loss and delivery rate, delay, routing overhead and network lifetime compare to FPNT-OLSR.