端到端的可用带宽测量方法

目前绝大多数带宽测量方法都是基于网络瓶颈分隔原理的,在此基础上形成了基于包对/包队列的各种容量/可用带宽探测方法.但是,这类方法的测量结果不能超过源节点的最大发送速率,因此无法在高带宽环境中使用.另外,目前的可用带宽测量理论均没有考虑背景流的不同路由对测量方法所产生的影响.全面分析了背景流的路由对可用带宽测量的影响.在此基础上,基于蒙特卡洛(Monte Carlo)随机抽样的思想,提出了一种与现有测量方法截然不同的探测理论.该方法用随机发送单个小探测报文取代了目前的探测理论所依赖的包对/包队列,其测量范围不受源节点最大发送速率的限制.分析及实验表明,该方法不仅可以计算整条路径的可用带宽,也可以计算各段链路的容量和空闲率,进而分析得到各路由节点上的流量变化,以及各链路上对应的不同类型的背景流的分布.     

基于非液体流模型的可用带宽测量精度

现有的可用带宽测量技术大多基于单跳链路和液体流模型,在突发背景流及多跳链路下测量精度较低。因此,分析了更符合网络实际的非液体流模型,提出了一种参数设置方法,减小了探测包长、探测速率、背景流速率及背景流包长等因素对测量精度的影响。在此基础上,改进了探测包对结构,该结构结合生存时间(TTL)值设置减小了探测包对间隔的测量误差,增强了带宽测量算法在多跳链路环境下的健壮性。仿真表明,基于非液体流模型的参数设置方法及改进的包对结构提高了可用带宽测量精度。     

一种自适应的高精度可用带宽测量算法

针对现有可用带宽测量技术在突发背景流及多跳链路下测量精度较低的问题,提出了一种自适应的高精度可用带宽测量算法FPU-ABM(Five-Packet-Unit for Available Bandwidth Measurement);该算法采用五包结构构成探测单元,结合TTL值设置,分别测量瓶颈链路前后的探测包间隔,提高了在多跳链路下带宽测量精度;算法根据反馈包的间隔自适应地调整探测速率,加快了测量速度且减小了探测流对网络的入侵度,增强了算法的适应性;仿真表明,在多跳链路下TFP-ABM算法的测量精度可达到10%以内,相比现有算法,TFP-ABM响应速度快、测量精度高、适应性好。     

基于排队分析的端到端路径可用带宽的测量

端到端路径可用带宽是衡量网络性能的重要指标.目前,大多数对可用带宽测量的研究都集中在自拥塞方法上,但自拥塞方法会严重影响路径上的原有流量,因此,提出了一种基于模型的方法,将Internet视为一个具有单一服务单元且服务两种流量(探测流量和背景流量)的排队系统,通过分析探测流量离开排队系统的过程,在路径的负载与探测流量离去间隔的变异系数之间建立了对应关系,并在此基础上获得可用带宽值.与自拥塞方法相比,不会造成路径拥塞且具有较好的准确性.     

一种速率自调节可用带宽测量算法

可用带宽是网络路由、网络服务质量、流量工程等方面的一个关键参数。目前很多研究方法都基于PGM模型和PRM模型,但这两种方法大都假设背景流量速率为固定比特流,不适用于低带宽的测试。提出一种端值自调节可用带宽测量算法,该算法充分考虑了低链路带宽的情况。通过对排队延时的处理、探测分组列速率端值自适应调节,实现了端到端可用带宽快速准确的测量。实验结果表明,该算法具有良好的测量效果,尤其在低带宽条件下较其它同类算法提高了测量准确性,加快了测量速度并减小了对网络的影响。     

使用自负载降速率探针包列的可用带宽测量方法

可用带宽是一条网络链路或路径的剩余带宽,该指标对网络流量工程以及速率敏感应用具有重要意义。现有的可用带宽测量技术大多基于单跳或者流体背景流量模型,在突发背景流及多跳路径下健壮性不足。现提出一种使用自负载降速率探针包列（SLDRT）技术的可用带宽测量方法。基于NS-2的仿真实验表明,SLDRT在多跳路径并基于非流体流量模型的网络环境下比另一重要测量工具pathChirp具有更高的准确性,并且平均测量时间小于30 ms,证明其可以满足高速、高精度的可用带宽测量需求。     

可用带宽自适应判定算法的研究

在理论分析和实验研究的基础上,提出可用带宽自适应判定算法。该算法采用自适应周期性探测流技术,通过周期性地发送包列,自适应地判断延迟趋势并反馈探测值,以准确快速地实现可用带宽的测量。仿真实验结果表明,该算法可行、有效,是一种对受测网络的影响小、低测量代价的端到端可用带宽测量方法。     

一种改进离群区间计算的PRM带宽测量算法

主动式网络路径可用带宽测量是目前网络路径带宽测量使用的主要方法,与被动式网络路径可用带宽测量相比,具有更高的灵活性且部署方便。为解决主动式网络路径可用带宽测量定义不明确、通用性不强、协议不规范和结果不准确等问题,规范定义了探测通信协议和报文结构,建立了较为完整、统一和规范的主动式网络路径可用带宽测量框架,提出了序列时延增加度和基于序列时延增加度的离群区间计算方法,改进了网络背景流量分析方法,降低了背景流量对网络路径可用带宽测量的干扰,最后使用NS2仿真对比验证了该算法的有效性。     

基于子路径可用带宽测量的紧链路定位方法

针对现有紧链路定位方法存在测量负载较大、测量精度不高等问题,提出一种性能优秀的端到端主动测量方法--PathLoche。该方法通过设计一种新颖的包列Loche,逐步迭代测量子路径的可用带宽,进而得到整条网络路径的可用带宽并确定紧链路的位置。仿真实验表明,PathLoche测量精度高、入侵度低。     

多路径数据传输中的可用带宽测量算法研究

在分布式中转服务器网络辅助的多路径数据传输系统中,为获得最快的数据传输速率,需要使用可用带宽测量技术以获得数据发送端至各中转服务器的可用带宽值列表.然而,传统的可用带宽测量算法难以同时兼顾测量精度与收敛速度,故无法达到实际数据传输系统中准确快速完成维护可用带宽值列表的目的.为解决上述问题,提出了一种可用带宽测量算法.通过收集初始探测流的包对在发送端及接收端的时间间隔关系数据获得可用带宽估测值,再以此值为后续探测流的发送速率初始值,通过自适应方法调整探测流发送速率以逐渐逼近可用带宽真实值.实验结果表明,改进算法能快速获得高精度的测量结果,有效提升可用带宽的测量效率,满足数据传输系统的需求.     

Available bandwidth estimation for the network paths with multiple tight links and bursty traffic

Available bandwidth (ABW) estimation is useful for various applications such as network management, traffic engineering, and rate-based multimedia streaming. Most of the ABW estimation methods are based on the fluid cross-traffic model. Inevitably, their estimation accuracy is limited in the network environments with bursty cross-traffic. In this paper, we apply packet trains (a series of probing packets) and a modified Ping to probe the ABW of a network path. Our proposed probing method can identify several tight links along a path and can infer their individual ABWs. The ABW estimation algorithm developed in this study, GNAPP, is also based on the fluid traffic model, but it can effectively filter out probing noise incurred in networks that carry bursty traffic. The algorithm employs not only the gaps of any two consecutive probing packets but also those of nonadjacent probing packets for ABW estimation. Thus, the number of samples for ABW estimation increases significantly without resorting to sending more probing packets and the estimation efficiency and accuracy are improved. In addition, two-stage filtering and moving averages are used in GNAPP for reducing estimation errors. Numerical results demonstrate that the estimation scheme based on GNAPP can achieve good accuracy even when the traffic is bursty and there are multiple tight links on the path being observed. Thus, it outperforms other well-known ABW estimation tools.     

SLDRT: A measurement technique for available bandwidth on multi-hop path with bursty cross traffic

End-to-end available bandwidth is of great importance as a metric that characterizes the network’s dynamic transmitting capability. Most estimation methodologies infer available bandwidth from the relationship between the input inter-packet gaps and those of the output. This paper analyzes the challenges brought by extending the measurement environment to the multi-hop path with bursty cross-traffic. Based on the analysis, a novel probing technique, self-loading decreasing rate train (SLDRT), is proposed. SLDRT measures the available bandwidth by using a single decreasing rate packet train. The special train can efficiently avoid bias caused by multiple sampling. Performance analysis via NS-2 simulations and PlanetLab experiments verify the effectiveness of our method under multi-hop path with the bursty cross traffic environment, and also show that SLDRT estimates available bandwidth more quickly, accurately, and with less measurement overhead than other existing techniques such as pathload and pathChirp.     

Estimation of the available bandwidth ratio of a remote link or path segments

Available bandwidth is usually sensitive to network anomalies such as physical link failure, congestion, and DDoS attack. Thus, real-time available bandwidth information can be used to detect network anomalies. Many schemes have been proposed to estimate the end-to-end available bandwidth or end-to-end capacity. However, the problem of estimating the available bandwidth for a specific remote link has not been investigated in detail yet. We propose a new scheme to estimate the available bandwidth ratio of a remote link or remote path segments, a group of consecutive links, without deploying our tool at the remote nodes. The scheme would be helpful in accurately pinpointing anomalous links. Two streams of ICMP timestamp packets are sent to both end nodes of a target link according to a Poisson process, and the available bandwidth ratio for the target link is estimated based on the measured packet delay. Since the proposed scheme needs not incur a short-term congestion, unlike conventional end-to-end available bandwidth estimation mechanisms, the intrusiveness is low and the proposed scheme overcomes the limitation of conventional approaches, inability to probe the links beyond the tight link with the minimum available bandwidth. The performance of the proposed scheme is evaluated by ns-2 simulation.     

MANET中基于遗传算法的带宽计算

在MANET中寻找满足带宽约束的QoS路由的前提是确定路径上带宽的大小,在MAC层采用CDMAoverTDMA的网络中,路径上带宽的计算并非单纯地取路径上所有链路的最小带宽,其计算时间复杂度已经被证明是个NP完全问题。该文提出将遗传算法用于带宽计算,并提出了基于空闲时隙链路块的编码方法。仿真结果表明:该算法可以应用于网络规模比较小的带宽计算中,并且可以比其它带宽计算方法获得更大的带宽。     

Virtual network mapping algorithm in the cloud infrastructure

Network virtualization has received considerable attention recently because a Cloud Provider (CP) that is responsible for deploying a substrate network in the cloud infrastructure uses network virtualization to support multiple Virtual Network (VN) requests over the shared substrate network. However, mapping multiple VN requests with constraints on virtual nodes and virtual links into a shared substrate network presents a significant challenge, and is considered an NP-hard problem. In this paper, we propose a heuristic mapping algorithm that handles online VN requests. The node mapping algorithm selects a substrate node for mapping that satisfies both a virtual node's resource requirement and its amount of requested bandwidth. The link mapping algorithm either maps a virtual link to the shortest substrate path that satisfies the requested bandwidth of the virtual link or uses the cut-shortest path approach to map a virtual link to multiple substrate paths that satisfy the requested bandwidth of the virtual link. The path migration algorithm migrates virtual links to different substrate paths to maximize the number of accepted VN requests in a substrate network. Simulation results show that the proposed heuristic mapping algorithm uses resources more efficiently, produces more revenue, and has better performance than existing mapping approaches.     

一种采用不同大小包对测量网络带宽的方法

随着Internet用户数和网络复杂度的激增,人们对网络性能提出了更高的要求。而带宽测量已经成为一种Internet网络性能研究的露要手段,并且越来越广泛地应用于各种网络测量分析平台。依据包对理论,提出一种带宽测量算法,可以解决网络背景流量的干扰问题和首包的排队问题。基于该方法开发的程序已经应用于大型网络性能监测与分析系统——NIPMAs,取得了良好的效果。     

MPLS流量工程最小冲突路径算法

优化网络资源利用是Internet流量工程的重要目标之一.最小冲突路由机制通过利用多协议标记交换(MPLS)网络中的源-目的(SD)节点对信息,在为业务流请求选择标记交换路径(LSP)时,尽可能避免当前请求与将来请求之间的冲突,实现网络资源的合理利用.作者基于最小冲突机制,提出一种新颖的最小冲突路径算法(LIP).LIP通过简单的最短路径算法定位关键链路,并将链路剩余容量、节点对之间的冲突和竞争结合起来定义链路权重,在实现网络资源高效利用的同时,降低了算法的计算复杂度.实验结果进一步验证,相对于以往算法,LIP在请求带宽拒绝率、网络带宽接收量和LSP平均路径长度等方面都比较理想.     

Locating available bandwidth bottlenecks

The spatio-temporal available bandwidth estimator (STAB), a new edge-based probing tool, locates thin links - those links with less available bandwidth than all the links preceding them - on end-to-end network paths. By localizing thin links, STAB facilitates network operations and troubleshooting, provides insight into what causes network congestion, and aids network-aware applications. The tool uses special chirp-probing trains, featuring an exponential flight pattern of packets, which have the advantage of employing few packets while giving an accurate estimate of available bandwidth.     

多逻辑链路最大可用带宽比流量调度算法

针对多逻辑链路间流量调度不平衡问题,分析逻辑链路流量调度模型,给出逻辑链路可用带宽计算方法,提出＂可用带宽比＂指标,以更准确地刻画各链路负载状况,量化特定链路上调度流量的大小。仿真实验证明,该算法有较好的流量调度能力,能有效控制各链路的流量,改善多链路间负载均衡,提高链路利用率。