用稳定CPC噪声合成网络业务量

该文提出了一种新的网络业务量合成方法稳定CPC噪声。该方法用于近似业务量的无穷可分层叠模型。实验证实,该方法生成的序列能很好仿真实际网络业务量。而排队简析也说明合成的业务量序列大大优于fBm自相似业务量模型,适合网络性能的研究。     

自相似业务量的流量控制研究

由于自相似性是宽带网络中业务量的一个普遍特性,因此在进行宽带网络管理和流量控制时必须考虑它所带来的影响。目前,有关基于自相似业务量的流控机制的研究已经引起了人们广泛地注意。一些研究表明自相似业务量表现出了与传统模型不同的排队特征。本文围绕业务质量保证和流量控制机制。具体研究和分析了业务量的自相似性质对业务量成形、用法参数控制和呼收接纳控制等流量控制机制的影响,并得到了一些重要结论。     

基于GLV模型的异构网络联合无线资源管理

为使不同的无线接入网络协同工作,实现异构无线网络的接纳控制,基于生态学种群竞争与异构无线网络资源管理的映射关系,提出了一种分布式联合无线资源管理(JRRM)算法。建立了基于Gause-Lotka-Volterra(GLV)的异构网络业务量预测模型,根据预测的业务量是否达到共存状态来调整网络参数,以使各网络的业务量达到稳定平衡状态。性能分析与仿真结果表明,该算法可以均衡各个网络的业务量,减少竞争对于网络的影响,使不同网络运营商均获得了一定收益。     

自相似业务量的流量控制研究

由于自相似性是宽带网络中业务量的一个普遍特性,因此在进行宽带网络管理和流量控制时必须考虑它所带来的影响。目前,有关基于自相似业务量的流控机制的研究已经引起了人们广泛地注意。一些研究表明自相似业务量表现出了与传统模型不同的排队特征。本文围绕业务质量保证和流量控制机制,具体研究和分析了业务量的自相似性质对业务量成形、用法参数控制和呼叫接纳控制等流量控制机制的影响,并得到了一些重要结论。     

网络带宽需求分析

文章以智能光网络中的信令网带宽需求分析为例,给出了一种网络带宽需求分析方法。提出采用排队论方法来分析智能光网络中的信令网带宽需求,以排队时延作为性能参量,对比分析了重尾分布业务量与轻尾分布业务量的排队性能差异。给出了有关的仿真模型和数学解析模型以及分析结果。该分析模型对于智能光网络信令网设计具有重要的理论指导意义,并可推广应用到其他带宽需求分析场合。     

多业务量矩阵下流量工程算法性能研究

传统域内流量工程TE(traffic engineering)算法中,基于OSPF/IS-IS的TE思想是通过调整链路权重使得全网的负载最均衡.由于Internet的急速发展以及用户业务需求的动态性导致业务量矩阵的不确定性,多业务量下的TE算法研究显得很有必要,而对于多业务量矩阵采取这种算法来最优化网络的研究很少见.本文提出了一种新的启发式基于OSPF/IS-IS链路权重调整的TE算法来解决多业务量矩阵,通过大量仿真实验分析了影响该算法性能的因子,从而为网络规划提供了很好的参考价值.     

一种智能化小区业务量指标预测方法研究

通信网络的业务量指标对指导网络运维工作非常重要。如果能够提前预知业务量指标的变化，则有助于网络中资源调度和节能减排工作的成功实施。当前，对大规模小区的海量业务量指标实现快速、精准预测是一个不小的挑战。本文研究了一种智能化大规模小区业务量指标预测的方法。首先，通过构造鲁棒的特征，对小区的高低负荷情况进行描述；之后，运用聚类算法，对小区进行基于业务量情况的场景划分；最后，对于不同业务场景下的小区，通过集成学习算法进行预测模型的建模与训练。经实验验证，该模型预测性能良好，成功实现了对大规模小区业务量指标的精准预测。     

ATM网络的业务量工程初探

对ATM网络的有关业务量工程方面的问题进行了探讨,对建立业务量模型、性能测量、性能评估和网络规划四个方面可能涉及到的问题进行了概括性描述。     

基于业务量和速率的分组调度算法研究

文中基于无线通信系统中用户的公平性和系统的吞吐量,结合几种传统的分组调度算法在性能衡量指标上的差异,提出一种按照业务量大小的测量数据和分组业务的QoS属性相结合的方法。该算法将平均业务量的测量数据对应不同的业务量级别,对分组用户的数据速率也进行相应的划分,然后建立起分组数据业务量等级与分配的速率级别之间的映射关系,并给出了系统的分析,以此来实时分配分组用户的数据速率,从而达到动态的无线资源高效管理的目的。该算法充分考虑了系统吞吐量和用户公平性之间的平衡,并且简单易实现。     

高负荷下TD网络性能的优化

高负荷业务量对网络的影响较大,而且对后3G时代网络建设和规划都有明显的影响,也对网优工作提出了挑战。     

Experimental queueing analysis with long-range dependent packettraffic

Traffic measurement studies from a wide range of working packet networks have convincingly established the presence of significant statistical features that are characteristic of fractal traffic processes, in the sense that these features span many time scales. Of particular interest in packet traffic modeling is a property called long-range dependence (LRD), which is marked by the presence of correlations that can extend over many time scales. We demonstrate empirically that, beyond its statistical significance in traffic measurements, long-range dependence has considerable impact on queueing performance, and is a dominant characteristic for a number of packet traffic engineering problems. In addition, we give conditions under which the use of compact and simple traffic models that incorporate long-range dependence in a parsimonious manner (e.g., fractional Brownian motion) is justified and can lead to new insights into the traffic management of high speed networks     

Multiplicative multifractal modelling of long‐range‐dependent network traffic

We present a multiplicative multifractal process to model traffic which exhibits long‐range dependence. Using traffic trace data captured by Bellcore from operations across local and wide area networks, we examine the interarrival time series and the packet length sequences. We also model the frame size sequences of VBR video traffic process. We prove a number of properties of multiplicative multifractal processes that are most relevant to their use as traffic models. In particular, we show these processes to characterize effectively the long‐range dependence properties of the measured processes. Furthermore, we consider a single server queueing system which is loaded, on one hand, by the measured processes, and, on the other hand, by our multifractal processes (the latter forming a MF_e/MF_g/1 queueing system model). In comparing the performance of both systems, we demonstrate our models to effectively track the behaviour exhibited by the system driven by the actual traffic processes. We show the multiplicative multifractal process to be easy to construct. Through parametric dependence on one or two parameters, this model can be calibrated to fit the measured data. We also show that in simulating the packet loss probability, our multifractal traffic model provides a better fit than that obtained by using a fractional Brownian motion model. Copyright © 2001 John Wiley & Sons, Ltd.     

Towards the formation of comprehensive SLAs between heterogeneous wireless DiffServ domains

Traffic patterns generated by multimedia services are different from traditional Poisson traffic. It has been shown in numerous studies that multimedia network traffic exhibits self-similarity and burstiness over a large range of time-scales. The area of wireless IP traffic modeling for the purpose of providing assured QoS to the end-user is still immature and the majority of existing work is based on characterization of wireless IP traffic without any coupling of the behaviour of queueing systems under such traffic conditions. Work in this area has either been limited to simplified models of FIFO queueing systems which do not accurately reflect likely queueing system implementations or the results have been limited to simplified numerical analysis studies. In this paper, we advance the knowledge of queueing systems by example of traffic engineering of different UMTS service classes. Specifically, we examine QoS mapping using three common queueing disciplines; Priority Queuing (PQ), Low Latency Queuing (LLQ) and Custom Queueing (CQ), which are likely to be used in future all-IP based packet transport networks. The present study is based on a long-range dependent traffic model, which is second order self-similar. We consider three different classes of self-similar traffic fed into a G/M/1 queueing system and construct analytical models on the basis of non-preemptive priority, low-latency queueing and custom queueing respectively. In each case, expressions are derived for the expected waiting times and packet loss rates of different traffic classes. We have developed a comprehensive discrete-event simulator for a G/M/1 queueing system in order to understand and evaluate the QoS behaviour of self-similar traffic and carried out performance evaluations of multiple classes of input traffic in terms of expected queue length, packet delay and packet loss rate. Furthermore, we have developed a traffic generator based on the self-similar traffic model and fed the generated traffic through a CISCO router-based test bed. The results obtained from the three different queueing schemes (PQ, CQ and LLQ) are then compared with the simulation results in order to validate our analytical models.     

基于分形点过程自相似流的队列性能分析

通过对交换机排队系统进行仿真,分析了以分形点过程( FPP )自相似业务流为输入的排队系统的性能.仿真结果显示,自相似业务流量模型下队列的性能与传统指数流量模型下的队列性能大不相同.文中所获得的仿真结果可用于网络流量模型、网络设计、网络拥塞控制和流量工程等.     

Delay Analysis of All-Optical Packet-Switching Ring and Bus Communications Networks

We study the delay performance of all-optical packet communication networks configured as ring and bus topologies employing cross-connect switches (or wavelength routers). Under a cross-connect network implementation, a packet experiences no (or minimal) internal queueing delays. Thus, the network can be implemented by high speed all-optical components. We further assume a packet-switched network operation, such as that using a slotted ring or bus access methods. In this case, a packet's delay is known before it is fed into the network. This can be used to determine if a packet must be dropped (when its end-to-end delay requirement is not met) at the time it accesses the network. It also leads to better utilization of network capacity resources. We also derive the delay performance for networks under a store-and-forward network operation. We show these implementations to yield very close average end-to-end packet queueing delay performance. We note that a cross-connect network operation can yield a somewhat higher queueing delay variance levels. However, the mean queueing delay for all traffic flows are the same for a cross-connect network operation (under equal nodal traffic loading), while that in a store-and-forward network increases as the path length increases. For a ring network loaded by a uniform traffic matrix, the queueing delay incurred by 90% of the packets in a cross-connect network may be lower than that experienced in a store-and-forward network. We also study a store-and-forward network operation under a nodal round robin (fair queueing) scheduling policy. We show the variance performance of the packet queueing delay for such a network to be close to that exhibited by a cross-connect (all-optical) network.     

Queueing study of a 3-priority policy with distinct servicestrategies

A discrete-time, single server, 3-queue system is presented and analyzed. A distinct service strategy, namely the consistent-gated (c-G), 1-limited (L) and head-of-line (HoL), is applied to each of the queues (c-G/L/HoL policy). It is shown that this queueing system provides for an accurate analytical model for a DQDB station, as well as a means for an approximate evaluation of the correlation associated with key traffic processes in that network. In addition, the developed queueing system could be useful for the modeling of the queueing behavior of an ATM link shared by high-priority, low priority and control traffic. Through an asymptotic analysis under heavy low-priority traffic, the worst case performance for the high priority traffic is determined. Furthermore, it is illustrated that the asymptotic analysis provides for a potentially tight delay bounding technique. Finally, the delay performance of the developed queueing system is compared to that of a similar system in which one of the queues receives 1-limited service and the other two exhaustive (HoL^-/L/HoL⁺ policy)     

Design and performance of Multinet switch: a multistage ATM switcharchitecture with partially shared buffers

A new ATM switch architecture is presented. Our proposed Multinet switch is a self-routing multistage switch with partially shared internal buffers capable of achieving 100% throughput under uniform traffic. Although it provides incoming ATM cells with multiple paths, the cell sequence is maintained throughout the switch fabric thus eliminating the out-of-order cell sequence problem. Cells contending for the same output addresses are buffered internally according to a partially shared queueing discipline. In a partially shared queueing scheme, buffers are partially shared to accommodate bursty traffic and to limit the performance degradation that may occur in a completely shared system where a small number of calls may hog the entire buffer space unfairly. Although the hardware complexity in terms of number of crosspoints is similar to that of input queueing switches, the Multinet switch has throughput and delay performance similar to output queueing switches     

Contradictory relationship between Hurst parameter and queueing performance (extended version)

Long Range Dependent (LRD) network traffic does not behave like the traffic generated by the Poisson model or other Markovian models. From the network performance point of view, the main difference is that LRD traffic increases queueing delays due to its burstiness over many time scales. LRD behavior has been observed in different types and sizes of networks, for different applications (e.g., WWW) and different traffic aggregations. Since LRD behaviour is not rare nor isolated, accurate characterization of LRD traffic is very important in order to predict performance and to allocate network resources. The Hurst parameter is commonly used to quantify the degree of LRD and the burstiness of the traffic. In this paper we investigate the validity and effectiveness of the Hurst parameter. To this end, we analyze the UCLA Computer Science Department network traffic traces and compute their Hurst parameters. Queueing simulation is used to study the impact of LRD and to determine if the Hurst parameter accurately describes such LRD. Our results show that the Hurst parameter is not by itself an accurate predictor of the queueing performance for a given LRD traffic trace.     

The Tera project: a hybrid queueing ATM switch architecture for LAN

The Tera ATM LAN project at Carnegie Mellon University addresses the interconnection of hundreds of workstations in the Electrical and Computer Engineering Department via an ATM-based network. The Tera network architecture consists of switched Ethernet clusters that are interconnected using an ATM network. This paper presents the Tera network architecture, including an Ethernet/ATM network interface, the Tera ATM switch, and its performance analysis. The Tera switch architecture for asynchronous transfer mode (ATM) local area networks (LAN's) incorporates a scalable nonblocking switching element with hybrid queueing discipline. The hybrid queueing strategy includes a global first-in first-out (FIFO) queue that is shared by all switch inputs and dedicated output queues with small speedup. Due to hybrid queueing, switch performance is comparable to output queueing switches. The shared input queue design is scalable since it is based on a Banyan network and N FIFO memories. The Tera switch incorporates an optimal throughput multicast stage that is also based on a Banyan network. Switch performance is evaluated using queueing analysis and simulation under various traffic patterns