在ATM网络中业务流分布的自适应路由优化控制

根据ＡＴＭ网络中所有信道上业务流的分布情况，采用业务流自适应的优化算法，动态地调整各节点的路由，达到防止拥塞，保证服务质量的目的。     

基于反馈机制的自愈算法

提出了一种网络自愈算法,当网络中的节点发生故障或链路出现拥塞时,该算法利用Q学习的反馈机制、多QoS约束的评价函数和基于Boltzmann-Gibbs分布的路径选择策略,自适应地选择恢复路径,降低了选择发生故障和拥塞路径的概率,从而实现了自愈。仿真结果表明,该算法在恢复率、区分业务能力和网络资源优化等方面,表现出了良好的性能。     

ATM宽带网络流量与拥塞控制研究

文章阐明对ＡＴＭ网络进行流量与拥塞控制不仅是由ＡＴＭ网络的分组交换本质所决定，也是实现Ｂ－ＩＳＤＮ的基本要求，文章还对目前ＡＴＭ网络的ＡＢＲ流量与拥塞控制机制进行了评述，提出了ＡＢＲ流量控制尚待解决的一些问题。     

在ATM网络中利用神经网络计算进行路由优化和流量管理

近年来,ＡＴＭ网络中路由发现和拥塞控拆的资源优化分配方法正在得到广泛的关注。本提供的解决方案是基于神经网络策略的。中描述的方案采用多变量约束优化算法来处理ＡＴＭ网络中ＵＮＩ／ＮＮＩ（用户网络接口／网络网络接口）的业务需求,从而找到近似最佳的ＰＶＣ／ＳＶＣ（永久虚电路／交换虚电路）路由。自动回归反向传播网络的预知流量规定、、用户定义的业务参数以及网络负荷条件等都限制了优化的程度。利用计算机仿真神     

防止ATM通信网拥塞的方法

本文用综合法定义和计算了ＡＴＭ一种业务源（ＯＮ－ＯＦＦ）的有效带宽。用有效带宽作为判断ＡＴＭ网是否接收新连接的标准，不仅提高了ＡＴＭ网络资源的利用率，而且避免了网络拥塞。最后还介绍了一些其他防止拥塞的方法。     

多目标的Internet路由优化控制算法

研究通过优化链路权值以控制网络路由来实施流量工程.以网络拥塞最小化和时延最小化为流量工程目标,建立了多目标的全局路由优化数学模型.求解该问题是NP困难的,提出一种混沌群搜索优化算法进行求解.算法采用群局部搜索,利用混沌变量产生一组分布好的初始解,并在邻域搜索进程中应用扩展贪心思想,提高了算法的全局搜索能力.仿真结果表明所提算法能够有效减少由于流量分布不平衡造成的网络拥塞,同时限制长路径,提高了网络性能.     

MPLS自适应流量工程的随机队列网络模型

负载均衡是改进Internet性能和可扩展性的关键技术,本文采用自适应流量工程方法优化网络资源利用率、最小化网络拥塞。假定Internet流量模型具有平稳随机过程特性,其统计变量具有长时间尺度下的恒定不变性,据此提出了一种基于流的多径负载均衡随机队列网络模型。基于M/Pareto/1队列模型的优化公式对减小网络拥塞、改善网络性能具有统计意义上的指导作用。     

最小化路径代价和流量均衡模型及算法

流量均衡是流量工程中为避免网络拥塞经常采用的路由优化目标,如何选择路径以使流量达到均衡分布是流量路由的研究热点和难点.为了最小化网络拥塞,该文在指出网络拥塞决定于流量路由时所选路径的拥塞特征后,建立了流量分布的最小化路径代价和模型.在流量路由选择路径时,提出基于瓶颈链路的最小代价路径路由算法.在实际的网络拓扑和流量矩阵数据基础上对所提模型及算法进行了实验验证,结果显示:在网络负载较大时最大链路利用率相对于已有模型可降低近20%.     

自适应流量评估方法在IDC网络的应用

为了确保IDC网络的服务质量,往往需要了解IDC网络中各出口、各链路的网络拥塞、大规模网络攻击等流量信息并进行及时全量的数据监测和分析.本文提出了一种自适应流量评估方法,通过测量精度和存储资源两方面的调控,来优化现有的流量测量技术.     

ATM网络中ABR业务的开环控制机制

ＡＴＭ网络中ＡＢＲ业务的流量控制是ＡＴＭ论坛的流量管理规范（ＴＭ４．０）中没有完全解决的问题,ＡＢＲ基于速率的闭环控制方案在最大－最小准则下获得了一定进展。但在拥塞发生在信源外或对突发性业务进行控制的情况下,添加开环控制的ＡＢＲ拥塞控制可以获得比闭环控制更佳的作用。研究了ＡＢＲ的开环控制方案,早期的ＵＩＬＩ机制本身存在在一定的问题,在交换机处采用基于计数的ＵＩＬＩ机制能够取得较好的效果。     

Development of a Real-Time Dynamic Weighting Method in Routing for Congestion Control: Application and Analysis

Congestion control issues have received consistent attention from several telecommunication researchers and practitioners for many years because network congestion often causes significant packet loss and delay problems. Although many suggested methods for these issues and problems can be available in telecommunication literature, there is room for improvement. This paper's primary objective is to propose a dynamic weighting method in routing to reduce congestion during peak hours by predicting incoming traffics and optimizing weights in the adjacency matrix of the routing table online. While changing weight values in the routing table, this method implicitly changes the routing path of many nodes through the congested node. As a result, the packet losses and delays can be decreased in used nodes. The main steps of this proposed framework are fourfold. First, the candidate weighing list is calculated based on the routing table of the congested node. Second, a proposed auto-adaptive framework (AAF) is used to predict congestion levels and apply the weighing list in the network node. Third, the evaluation of network congestion is then performed by the probability of packet losses due to overflowing buffers. Finally, the case study results demonstrate that the proposed AAF framework can significantly reduce network congestion.

     

一种环境感知的无线Mesh网络自适应QoS路径选择算法

本文针对如何改善无线多跳Mesh网络的服务质量,满足无线多媒体业务对数据传输的带宽、时延、抖动的要求等问题,研究了一种基于无线信道状态和链路质量统计的MAC层最大重传次数的自适应调整算法。该算法通过对无线Mesh网络的无线信道环境的动态感知,利用分层判断法区分无线分组丢失的主要原因是无线差错还是网络拥塞导致,实时调整MAC层的最佳重传次数,降低无线网络中的分组冲突概率。基于链路状态信息的统计和最大重传策略,提出了一种启发式的基于环境感知的QoS路由优化机制HEAOR。该算法通过动态感知底层链路状态信息,利用灰色关联分析法自适应选择最优路径,在不增加系统复杂度的基础上,减少链路误判概率,提高传输效率。NS2仿真结果表明,HEAOR算法能有效减少重路由次数,降低链路失效概率,提高网络的平均吞吐率。本文提出的方法不仅能够优化MAC层的重传,而且通过发现跨层设计的优化参数实现对路径的优化选择。      

一种基于OBGP协议的光网络域间路由的新型机制

本文提出一种采用光边界网关协议(OBGP)实现WDM光格状网的域间路由的新型机制;该机制基于最小跳选择策略建立最优化路径的思想,同时引进"迂回路由"策略和"并行信令"方式,实现了动态、分布式的光通道确立过程.在OPNet平台上针对两种网络拓扑进行仿真实验,结果表明:该机制能够在网络繁忙时期降低阻塞率,提高网络性能;同时发现:网络规模、单信道波长数以及网络负载等网络参数对于网络性能具有一定的影响.     

基于进化规划的ATM网络优化路由算法

根据ATM网络承载业务的特性，提出了以最小化全网平均信元丢失率为目标函数，以途经交换节点数目为约束的优化路由准则，并应用进化规划方法求解此优化问题。     

Dynamic burst discarding scheme for deflection routing in optical burst switching networks

This paper proposes a dynamic burst discarding scheme for deflection routing in optical burst switching networks. In general, deflection routing is effective in lightly loaded situations, whereas it has a contrary effect in congested networks because deflected bursts accelerate network congestion. Thus deflection routing should be employed in lightly loaded networks. Incoming traffic, however, varies in time and location, so that temporal and/or local congestion cannot be avoided. Our proposed scheme resolves this problem in the following way. Each node autonomously detects congestion with local information, and bursts to be deflected are discarded in a probabilistic manner, based on the degree of detected congestion and the numbers of elapsed and remaining hops of those bursts. Simulation experiments show that when congestion happens temporarily, the proposed scheme reduces the burst loss probability, and it utilizes network resources efficiently when local congestion happens.     

ATM网络中突发业务的漏桶算法分析

统计复用可以使突发业务获得较高的频带利用率，但必须对输入的业务量进行恰当的控制，否则会造成严重的网络拥塞，漏桶法是ＡＴＭ网络基于速率调节进行业务量控制的一种重要的方法，本文对突发业务的漏桶算法进行了分析，得出了突发业务的漏桶性能与输入业务统计参数和漏桶参数之间关系的解析式，计算机模拟结果表明它与理论分析的一致性。     

Modeling and call admission control algorithm of variable bit ratevideo in ATM networks

The authors propose a new method for the modeling and call admission control (CAC) of variable bit rate video source, which come to the front of ATM networks as hot issues nowadays. First, the modeling of video source is accomplished using the three-state Markov chains including the effects of scene change at which the bit rate of video source is abruptly increased. Also, using two AR models, they improve the defects which an AR model has in modeling a video source. In addition, they represent the analytical model of a video source so that a network manager can acquire the information which is very important in managing the entire networks. CAC is accomplished using the previously defined analytical model. A routing manager calculates the cell loss probability of a chosen VP where a new call is connected so that the routing manager decides whether this new call is accepted or not. This calculation is accomplished through the GB/D/1-S queuing system. Using BIA (bandwidth increasing algorithm), they check whether the calls rejected by the routing manager could be accepted if possible. Finally, the applicable procedures to suitable allocate bandwidth to each VP on a link are presented in detail     

Asymptotic optimality of shortest path routing algorithms

Many communication networks use adaptive shortest path routing. By this we mean that each network link is periodically assigned a length that depends on its congestion level during the preceding period, and all traffic generated between length updates is routed along a shortest path corresponding to the latest link lengths. We show that in certain situations, typical of networks involving a large number of small users and utilizing virtual circuits, this routing method performs optimally in an asymptotic sense. In other cases, shortest path routing can be far from optimal.     

基于分解协调的SWCC-OBS网络路由选择研究

针对稀疏分布有限波长转换能力的光突发交换(SWCC-OBS)网络容易出现的高丢包率和负载不均 衡问题,建立了稀疏分布OBS全网丢包率的数学模型。为了克服模型求解过程中多 变量带来的非 线性问题,对影响全网突发丢包率的参变量进行分解预估和反馈更新,求得全网对应业务流 模型下的优化 路由路径,获得了全网突发数据的近似最低丢包率。仿真实验表明,在SWCC-OBS网络中, 本文提出的路由 选择模型及分解协调的路由选择算法,不仅能有效地避免突发数据包间的相互冲突、降低了 全网丢包率,而 且能很好地适应突发数据业务的动态变化,保证了网络的负载均衡和较低的丢包率。