一种基于CICQ的动态重路由交换机制

多径路由交换机制能够通过改变到达网络交换节点的流量分布缓解交换系统的端口争用.本文深入探讨了多下一跳交换机制在核心交换网实施的可能性,提出了一种支持动态重路由的交换结构MHRS和支持多下一跳流量均衡的转发表管理结构HMFT.MHRS算法根据交换系统当前拥塞度实施交换系统内部的动态重路由,实现网络流量的实时动态均衡.HMFT对多下一跳交换节点进行QoS度量和区分,从而为不同业务需求提供不同转发路径.理论分析和仿真结果表明:以MHRS和HMFT算法为构件的网络交换系统能够获得良好的时延和吞吐量保障.     

交换结构到达分组可选输出端口个数的研究*

针对目前单一路径路由交换机制的问题,引出多下一跳路由交换机制,并在路由交换协同设计的基础上分析讨论了到达分组可选输出端口个数k的取值,基本思路是路由层面分析路由表转发表对k,取值要求特点,交换层面基于Mp-iSLIP匹配算法对比不同k取值下时延丢包率的仿真结果,综合两方面结果得出当k=3时,路由实现难度与交换性能提高得到较好的折中。     

网络天地

D-Link推出新款路由器 DES-9000是D-Link公司推出的模块化线速高密度城域网核心路由器,它采用基于ASIC(专用集成芯片)的分组处理器,每端口都可实现2～4层的线速交换,并能提供极高的端口密度以及线速路由和交换功能:背板容量高达170Gbps,交换容量达240Gbps,最高可实现90Mpps的全线速包转发率。它全面支持     

路由交换原型系统关键技术的研究和实现

探讨了基于多QoS约束的路由交换原型系统及其关键技术的设计和实现。通过分析传统路由交换体系中路由协议和交换机制的局限性,提出支持多QoS约束的QOSPF路由协议,并在此基础上结合多协议标记交换技术,实现了基于多QoS约束的路由交换原型系统,它能为数据流建立满足多QoS约束的标记交换路径,不仅满足了数据流的多QoS需求,并能提高分组交换效率。最后通过实验验证了原型系统的有效性和可行性。     

一步到三级——联想推出三层骨干网交换机

6月9日获悉,联想集团推出了一款具有三层路由交换功能,用于骨干级设备上的iSpirit6808交换机。该交換机是联想全模块、高密度端口的骨干交换机,符合NEBS三级标准,主要应用于大型网络核心层和汇聚层网络平台     

基于OPNET的BGP4重分布的仿真

边界网关协议BGP4是用于自治系统之间交换路由信息的动态分布式路由协议。作为BGP4路由策略之一的路由重分布是自治系统之间信息交互时控制流量的重要环节。文中首先简单介绍了BGP4路由协议及相关内容,然后以BGP4路由重分布为主要讨论对象,利用OPNET仿真软件建立网络仿真模型,通过具体实例详细探讨了BGP4路由重分布在网络设计过程中存在的问题及相应的解决方法,深入理解BGP4路由重分布的机理,从而为网络规划设计更好地提供客观、可靠的定量依据。     

交换机提升备战——北电网络推动融合网络发展

以太网的发展历程基本上是端口速率在不断提升、端口密度不断加大的过程,而这些都要求交换机的交换性能相应增强并为未来发展作好准备。早在2000年,北电就推出了Passport8600路由交换机,该产品重新定义了高性能以太网交换机的标准——线速的路由交换和数据分类,高端口密度。2004年5月,北电为Passport8600路由交换机推出了新的交换引擎Passport8692,在提高产品性能方面不遗余力的努力,使得用户可以只升级CPU交换矩阵就可将单台Passport8600路由交换机的交换能力提高到以往的4倍。据了解,升级以后的该产品所具有的512Gbps的交换能力、380M…     

网络天地

2002年10月,清华比威公司推出了模块化核心路由器 BitEngine 7500,它既可作为企业网的核心路由器,又可用于运营商网络的汇聚层。 BitEngine 7500为模块化机箱式结构,共提供8个模块插槽,其中1个为路由交换单元(RP)插槽,另外7个为通用接口单元(VP)插槽。该产品可选配路由交换模块、10/100Mbps 模块、1000Base-SX/LX 模块、OC-3 ATM模块、OC-3 POS模块、2端口高速同步串口模块以及4端口CE1模块等。     

匿名通信中短距离优先分组重路由方法的研究

重路由技术是匿名通信系统中采用的主要技术手段之一.目前典型的匿名系统中大多采用随机重路由的策略,即在所有中转代理中随机选择一个进行转发的策略,随机转发策略要求每个中转代理知道系统中所有其他代理.随着系统的扩大,一方面中转代理数增加使得系统维护代价增加,另一方面由于部分中转代理之间距离很远,重路由带来的延迟增加.提出了一种新的重路由策略--距离优先分组重路由,实现了短距离优先转发的策略,重路由时在近距离分组中进行随机转发.分别将距离优先分组策略应用在随机概率转发和有限路长限制的重路由算法中,数学分析和模拟测试结果表明,新的重路由策略在一定分组成员数情况下能保持与非分组重路由算法相当的匿名性能,同时明显地降低了服务延迟.新的策略中每个中转代理只需知道就近分组中的代理,这为匿名系统的扩展性研究提供了一定的基础.     

基于动态消息路由的ESB框架的研究与应用

企业服务总线(ESB)是一个具有高分布性、事件驱动服务的SOA架构,是当前企业集成的主流框架。论文通过分析传统的ESB软件只能支持由静态配置文件配置的路由的缺陷,提出了一个将预测路由机制和反馈型过滤机制相结合的基于内容的动态消息路由机制,并在此基础上设计了一个基于动态路由的ESB框架(DMR-ESB)。该框架包含三层：业务处理层、ESB层和服务层。实验与实际运行系统表明,DMR-ESB框架在系统服务复杂多变的情况下,具有灵活、高效的特性。     

Achieve load balancing with a dynamic re-routing CICQ switching scheme

Multi-path based routing and switching can achieve network-wide load balancing and reduce the port conflicts of switching devices.Motivated by this novel idea,in this paper,through analyzing the feasibility of implementing multi-next-hops in core switching networks comprehensively,we advance a switching scheme called MHRS(multi-next-hop re-routing switch)and a forwarding table management scheme called HMFT(hierarchical multi-stage forwarding table)to support multi-next-hop dynamical re-routing.MHRS implements dynamical re-routing in the switches according its congestion status to achieve real-time load balancing,while HMFT can provide traffic with different forwarding paths based on their QoS requirements.Theoretical analysis and simulation results show that switches equipped with HMFT and MHRS can provide good delay and throughput performance.Besides,they can reduce port conflicts significantly.     

Optimal Routing Designs in Self-healing Communications Networks

Self-healing communication networks that allow re-routing of demands through switching processes at designated nodes are studied. It is shown how network utilization, demand throughput and reliability of such networks can be studied simultaneously to achieve an optimal design for all three. This is done through a max–min–max multi-commodity network flow formulation of the routing problem in which it is ensured that maximum network throughput is achieved with minimum loss of demands that are blocked due to single switching node failures. It is shown that a node-path linear programming approximation to the multi-commodity network flow formulation solves the problem for medium and large network sizes in moderate computational times.     

Performance Quality of Re-Routing Networks: Influence of Equipment Failure

An algorithm is designed for computing throughput service quality characteristics of circuit-switched re-routing networks with regard for the influence of undetected failures in commutation devices if crankbacking is used for switching. Experimental results are presented.     

A very large-scale switching system by using nested ring-based architecture

In recent years, network applications and hardware technology have been developed in impressive speed. That is, a large-scale network switching system is needed to satisfy all demand among network service providers and population, such as data, voice, image, video on demand, videoconferencing, telecommunications, remote control and teaching, etc. A general large-scale network switching system cannot fulfill various application needs, such as the correctness of data transmission and the capacity of extension for input/output port of switching system. In this paper, we propose a nested ring-based architecture to build a very large-scale network switching system. In order to satisfy the various network application needs, a nested ring-based architecture is designed as a switching element. It can make input data exchange fast to the destined output port, and input/output port of switching system can easily be extended up to 100 ports or 1000 ports to construct a very large-scale network switching system. The simulation results show that a better performance can be achieved in data transmission, delay, throughput and extensibility for the proposed system.     

Decision support for flight re-routing in Europe

Congestion has plagued air traffic in the US and in Europe for the last 20 years. To protect air traffic control from overloads, air traffic flow management tries to anticipate and prevent overloads and to limit resulting delays. This paper focuses on understanding the requirements for developing re-routing decision support systems (DSS). It identifies participants in re-routing decisions and investigates the concept of, and need for, a re-routing decision support system. A re-routing demonstrator is discussed as a first step in the development of a DSS and a demonstrator for pre-tactical and tactical re-routings is described. User feedback is presented and issues of automation and complexity of re-routing DSS are discussed. Finally, the integration of re-routing DSS in future air traffic management systems is addressed.     

具有服务质量保障的片上网络路由仲裁控制

片上网络(Network on Chip,NoC)通过仲裁机制控制各个端口间的数据交换。经典的RR(Round-Robin)算法保障了各端口间的公平性,但却难以为时延敏感业务提供具有低数据交换等待时延的QoS保障。为此,提出一种区分优先级并行调度RR(PP-RR)算法,其根据端口数据负载提供区分优先级服务,高优先级端口数据享有更多仲裁成功机会。采用并行调度两级轮控制模型实现了对PP-RR仲裁算法的数学建模,获得了时延性能的数学解析。     

基于SNMP的IPMAC绑定系统的研究与设计

针对当前网络中IP地址管理混乱的状况,根据网络管理需求,设计并实现了IP-MAC-PORT绑定系统。通过简单网络管理协议(SNMP)定期对路由及交换设备进行数据采集和分析,对网络进行实时监控,追踪并定位出IP地址异常主机的具体位置,然后利用交换机支持端口管理的特性,实现对IP盗用者的有效网络隔离。     

The Forcer Concept and Express Route Planning in Mesh-Survivable Networks

To date, mesh network design theory has beendeveloped for the case where working and protectioncapacity is terminated at every node. It is recognizedthat express routes, which bypass some nodes en-route, would decrease the total DCS port costs but ithas been unclear how to incorporate bypass planning inthe optimal spare capacity design for a mesh-restorablenetwork. An important issue is whether the introduction of nodal bypass will increase the total sparecapacity needed for restorability, due to a reduction ofrestoration re-routing flexibility. To address thesequestions, we introduce the forcer concept for analysis of the relationship between workingand spare capacity in a mesh-restorable network. Weapply the forcer concept to show theoretically whybypass in fact need never require an increase in sparing and may actually permit a decrease in somecases. In tests to validate and exploit these findings,an average reduction of 12% in total spare capacity and16% in DCS port count totals were obtainedsimultaneously with an Integer Programming optimization. Thesesavings are relative to an already optimized fullyterminated network design. The work thus contributes togreater theoretical understanding and designcost-effectiveness for mesh-based restorable networks.     

一种USB OHCI主机控制器的根集线器设计

USB OHCI根集线器的基本功能是根集线器设计的基础.由根集线器的基本功能需求确定其具体实现中采用的结构并对这种特定的实现方法加以验证是USB主机控制器根集线器设计的关键.根据USB规范和OHCI规范,根集线器在功能上划分为寄存器模块、端口状态机模块、端口接收模块、端口恢复模块以及端口多路复用器模块.下行端口在根集线器中具有核心作用,而下行端口状态机是下行端口设计中的难点,其运行机制通过状态图做了详细介绍.设计分别在虚拟仿真环境和FPGA验证平台上得到了验证,验证结果论证了设计的正确性.