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1.
何民  程一帆 《福建电脑》2009,25(8):42-43
电力通信业务正由以语音业务为主导向以数据业务为主导转移,并进一步向IP化方向发展,它驱动电力通信光传送网由基于TDM的光传送网向基于分组的光传送网演进。本文分析了电力通信业务IP化的发展趋势及其对现有电力光传送网产生的新挑战,并简述了T-MPLS分组传送技术及发展的基本原则。  相似文献   

2.
波分复用光传输网中波长路由算法的研究进展   总被引:4,自引:0,他引:4  
许胤龙  陈国良  万颖瑜 《计算机学报》2003,26(11):1409-1423
光纤正迅速成为主干通信网的标准传介媒质.随着光学器件的发展,使得信号在传输过程中,除了在源、汇节点需要光电转换外,中间节点可保持光传输,这种通信网络叫光传送网.光传送网中的波分复用技术是将整个光纤的带宽分成多个信道,不同的信道可使用不同的波长来同时进行信息传输,从而增加了整个网络的带宽.在光传送网中,实现一个通信请求需要建立一条通信路径,并为该通信路径所经过的每条链上分配一个波长,即所谓波长路由.该文详细介绍了波分复用光传送网中波长路由算法的研究进展,内容包括波长分配算法、网络的信元阻塞率分析、容错和QoS波长路由、多播波长路由、最小化ADM数路由以及基于光或光电连接的并行机模型等.  相似文献   

3.
王勐  朱培栋  尚韬 《计算机工程》2003,29(22):34-35,47
可用性是衡量计算机系统性能的重要指标。作为计算机网络关键设备的核心路由器必须具有高可用性。该文介绍了计算网络设备可用度的方法;并详细分析了动态冗余技术实现的关键。结合核心路由器的特点,此技术成功地运用到银河风云核心路由器的设计与开发中。  相似文献   

4.
普适计算模式追求随时随地的计算境界,对可用性管理提出了很高的要求。该文基于定量分析的角度,提出了一种基于马尔科夫重生过程(MRGP)的普适计算系统可用性度量方法,以解决关联用户的普适计算系统可用性度量问题。建立了具有双扩展特点的用户模型,分析了用户行为特征;构建了普适计算系统可用性的MRGP模型,对可用性进行了随机过程分析,并给出了对应瞬态和稳态行为的度量方法;结合普适计算模式的特点,定义了普适计算系统请求可用性度量。进行了数值分析,评价了用户和系统参数等因素对普适计算系统可用性度量的影响。  相似文献   

5.
OTN(光传送网,OpticalTransportNetwork).是通过G.872、G.709、G.798等一系列ITU—T建议所规范的新一代“数字传送体系“和“光传送体系”。OTN是以波分复用技术为基础、是在光层组织网络的传送网.是下一代的骨干传送网。光传送网面向IP业务、适配IP业务的传送需求.已经成为光通信下一步发展的一个重要议题。  相似文献   

6.
唐俊勇  田鹏辉  王辉 《计算机应用》2018,38(12):3518-3523
针对网络可用性在不同网络业务中的服务质量(QoS)存在差异,且与性能花费相互制约的问题,引入了马尔可夫链理论,在定义了基于业务开销最小的服务能力匹配度的基础上构建了基于马尔可夫链和QoS指标的网络可用性(MCQNA)评价模型。首先,从最能反映网络可用特征的QoS指标出发,兼顾性能开销,同时定义了代价函数,并且给出了状态转移矩阵;然后,通过平稳状态与网络可用性关系的分析,求解出平稳分布并作为QoS运行开销的动态权重,实现了以业务运行代价最小为特点的网络可用性评判。仿真结果表明,所提模型构建的遍历性转移矩阵存在平稳分布,对网络可用性评判是可行的。该模型能针对不同业务的QoS标准,且有效针对具体业务衡量网络的可用性。  相似文献   

7.
一个基于事件驱动的网络故障管理系统的设计与实现   总被引:2,自引:0,他引:2  
故障管理是保证网络可靠性和可用性的重要功能,高效的网络事件服务是大规模网络故障管理的难点。借鉴CORBA事件服务的方式,该文提出了一个轻量级的事件通道服务模型,旨在克服标准CORBA事件服务的低效性,同时实现海量网络事件的缓冲、过滤和分发能力。事件通道负责调度整个系统的各个功能模块,它以守护进程的形式工作,接受来自各方的事件,然后通过预定的管理策略,决定是调用某个功能模块,还是向其它守护进程发送消息,从而触发相应的操作。文中描述了一个基于该模型的网络故障管理系统结构。  相似文献   

8.
基于NS的光突发交换仿真平台设计   总被引:1,自引:0,他引:1  
张奭  于挺进  张冰 《计算机仿真》2006,23(1):128-132
光突发交换(OBS)是一种可行的构建下一代光网络的交换技术,它可以在现有光交换技术基础上较好地支持网络中的突发性业务。由于业务的突发性强,所以路由和波长分配的设计是OBS网络需要解决的一个关键问题。仿真是设计网络协议和验证算法的重要手段之一,但对于OBS,目前还缺乏一种通用仿真模型。该文在NS-2网络仿真软件的基础上,实现了一个光突发交换的仿真平台OBSns。仿真数据表明,OBSns得到的仿真结果和理论分析结果相符,可以用来设计并验证光突发交换网络中的波长和路由分配算法。  相似文献   

9.
基于数据挖掘的实时检测系统的改进方案   总被引:2,自引:0,他引:2  
为了更好地应用和推广基于实时数据挖掘的入侵检测系统,就要提高基于数据挖掘入侵检测模型的准确性,高效性和可用性。该文针对这三个方面分别提出了各种解决方法和改进方案,并在最后提出一个改进的检测模型结构,这种结构综合了该文提出的各种解决方法,可以大大提高实时IDSs的效率和可伸缩性。  相似文献   

10.
《信息网络》2006,(10):57-57
上海贝尔阿尔卡特1850全业务交换传送平台(TSS),采用独具特色的设计体系提供业务完全的扩展能力,克服了传统传送设备的缺陷。这是一款全新的多业务传送平台,是业内第一款业务交换传送设备。它不仅继承了阿尔卡特原有光多业务节点(OMSN)的灵活性和可扩展性,还支持所承载的业务在百分之百传统TDM业务到百分之百的分组数据业务间灵活改变。  相似文献   

11.
Optical/wireless convergence has become of particular interest recently because a combined radio wireless and optical wired network has the potential to provide both mobility and high bandwidth in an efficient way. Recent developments of new radio access technologies such as the Long Term Evolution (LTE) and introduction of femtocell base stations open new perspectives in providing broadband services and applications to everyone and everywhere, but the instantaneous quality of radio channel varies in time, space and frequency and radio communication is inherently energy inefficient and susceptible to reflections and interference. On the other hand, optical fiber-based networks do not provide mobility, but they are robust, energy efficient, and able to provide both an almost unlimited bandwidth and high availability.In this paper, we analyze the energy efficiency of combined wireless/optical access networks, in which LTE technology provides ubiquitous broadband Internet access, while optical fiber-based technologies serve as wireless backhaul and offer high-bandwidth wired Internet access to business and residential customers. In this contest, we pay a particular attention to femtocell deployment for increasing both access data rates and area coverage. The paper presents a novel model for evaluating the energy efficiency of combined optical/wireless networks that takes into account the main architectural and implementational aspects of both RF wireless and optical parts of the access network. Several hypothetical network deployment scenarios are defined and used to study effects of femtocell deployment and power saving techniques on network’s energy efficiency in urban, suburban and rural areas and for different traffic conditions.  相似文献   

12.
The Internet is the primary means for multimedia content sharing, playing a central role in the lifestyle of users. As a consequence, in the past few years, the traffic demand for access and edge networks has increased (video stream downloading, videoconferencing or even the broadcasting of video streams through the Internet), since multimedia applications have strict requirements, including high bandwidth, small amount of loss and low delay. To address this scenario, the edge as a service (EaaS) paradigm arises as a suitable approach to increasing the quality of Internet access. The EaaS uses network virtualization and software-defined networks to improve the resource utilization and manageability. Within this context, this article proposes a framework to manage the virtual network resource (VNR) according to the multimedia application characteristics, and not only the network requirements. Additionally, a study about the relationship between quality of experience (QoE) and VNR availability was performed to be used as a basis for a proposed resource allocation adjustment mechanism. Experiments using real multimedia traffic under distinct scenarios demonstrate the effectiveness of the proposed framework to ensure the QoE of users through the management of the VNR.  相似文献   

13.
In this paper, we propose a feasibility analysis of periodic hard real-time traffic in packet-switched networks using first come first served (FCFS) queuing but no traffic shapers. Our work constitutes a framework that can be adopted for real-time analysis of switched low-cost networks like Ethernet without modification of the standard network components. Our analysis is based on a flexible network and traffic model, e.g., variable-sized frames, arbitrary deadlines and multiple switches. The correctness of our real-time analysis and the tightness of it for network components in single-switch networks are given by theoretical proofs. The performance of the end-to-end real-time analysis is evaluated by simulations. Moreover, our conceptual and experimental comparison studies between our analysis and the commonly used Network Calculus (NC) shows that our analysis can achieve better performance than NC in many cases.  相似文献   

14.
《Computer Networks》2008,52(6):1281-1290
With the migration of real-time and high-priority traffic in IP networks, dynamic admission control mechanisms are very important in high-capacity networks where IP and optical technologies have converged with a GMPLS-based control-plane. In this paper proposes, we propose an integrated multilayer traffic engineering framework that considers both physical and logical (optical layer) topologies for dynamically admitting new label switched paths (LSPs) in GMPLS networks. The dynamic admission control mechanism is based on an optimal resolution of an integer linear programming model that takes into account both lightpaths availability, wavelength continuity and routing constraints. In order to minimize LSPs set up delays, this mechanism first considers the logical topology (set of lightpaths) that is already in place before setting up a new lightpath for the incoming LSP, resulting in an additional set up signaling delay. When tested by simulations, results confirm that the proposed formulation effectively improves the network performance by reducing the connection blocking rate, while guaranteeing strict delay and noise constraints.  相似文献   

15.
EPON(Ethernet passive optical network)是解决宽带接入中瓶颈问题的关键技术.为了实现EPON中共享上行带宽的公平和有效分配,以及不同分类业务的QoS保证,提出了基于门限的动态带宽分配算法.该算法根据ONU(optical network unit)的带宽请求和门限值授权分配带宽,实现了3种基于反馈控制理论的自适应调整门限方法并分析了其优缺点.模拟实验结果表明,与其他算法相比,该算法能够减少平均包时延,提高网络吞吐量.  相似文献   

16.
17.
提出了一个典型的模型,该模型考虑到包延时的相关性和串联队列的相关性,这对端到端的抖动有重要影响。针对一个单队列的Poisson流量分布的抖动,给出了一个非常易于计算的公式,然后推广到基于串联队列的标记流的端到端抖动。通过模拟实验可以发现,模型的分析值和模拟值基本吻合,在大流量背景下更为精确,更重要的是对于抖动而言该值是可信的,这样就可以用于网络设计过程中。  相似文献   

18.
To obtain accurately end-to-end network traffic is a significantly difficult and challenging problem for network operators, although it is one of the most important input parameters for network traffic engineering. With the development of current network, the characteristics of networks have changed a lot. In this paper, we exploit the characteristics of origin-destination flows and thus grasp the properties of end-to-end network traffic. An important and amazing find of our work is that the sizes of origin-destination flows obey the power laws. Taking advantage of this characteristic, we propose a novel approach to select partial origin-destination flows which are to be measured directly. In terms of the known traffic information, we reconstruct all origin-destination flows via compressive sensing method. In detail, here, we combine the power laws and the constraints of compressive sensing (namely restricted isometry property) together to build measurement matrix and pick up the partial origin-destination flows. Furthermore, we build a reconstruction model from the known information corresponding to compressive sensing reconstruction algorithms. Finally, we reconstruct all origin-destination flows from the observed results by solving the reconstruction model. And we provide numerical simulation results to validate the performance of our method using real backbone network traffic data. It illustrates that our method can recover the end-to-end network traffic more accurately than previous methods.  相似文献   

19.
Network processor technology has advanced to the point where high-precision time-based store-and-forward logic is readily incorporated into packet switches and routers. With appropriate scheduling, packets from multiple flows can be serviced without contending for link resources. Accordingly, packet flows traversing a network of switching elements can have both path and time determinacy attributes which support ideal end-to-end QoS (zero jitter, zero loss, acceptable end-to-end latency) for real-time UDP packet flows and guaranteed goodput for TCP flows. One approach to packing a network with a relatively large number of such deterministic flows, i.e. achieving high availability of the ideal QoS service in a network, uses precise buffering of packets at each switch, which introduces latency. This paper describes analysis methods for quantifying how much buffering may be necessary to achieve high (99.999%) availability. For typical network topologies the analysis shows that buffering latency requirements are very small compared to transport delays, even when the network is highly utilized with heterogeneous (e.g. voice, video, circuit emulation, and data) traffic. Actual physical implementations have empirically validated the analysis results as well as the scalability of the end-to-end, time-based forwarding approach and the end-to-end availability of ideal QoS services in IP packet networks.  相似文献   

20.
SpaceWire is a standard for on-board satellite networks chosen by the ESA as the basis for multiplexing payload and control traffic on future data-handling architectures. However, network designers need tools to ensure that the network is able to deliver critical messages on time. Current research fails to address this needs for SpaceWire networks. On one hand, many papers only seek to determine probabilistic results for end-to-end delays on Wormhole networks like SpaceWire. This does not provide sufficient guarantee for critical traffic. On the other hand, a few papers give methods to determine maximum latencies on wormhole networks that, unlike SpaceWire, have dedicated real-time mechanisms built-in. Thus, in this paper, we propose an appropriate method to compute an upper-bound on the worst-case end-to-end delay of a packet in a SpaceWire network.  相似文献   

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