动态缓冲区门限漏桶方案的性能分析

本文提出了缓冲区门限随着有漏桶速率变化的动态缓冲区门限漏桶方案,以马尔可夫调制泊松过程（ＭＭＰＰ）作为信源输入人流,用嵌入马尔可夫过程这系统,得到了系统状态在嵌入点和任意时刻的极限分面具人而获得信损失率、信元平均时延及占用的有效带宽性能测度,数值分析表明本方案的信元人率及平均信元时延性能较缓冲区门限漏桶方案有显著提高,而且占用更少的带宽。     

基于统计网络演算的双漏桶模型带宽需求研究北大核心

为满足双漏桶模型的业务流量需求,提出一种基于统计网络演算理论的带宽需求研究方案。该方案利用统计网络演算在分析业务时延性能方面的优势,由时延与带宽的关系建立出双漏桶模型业务流带宽需求的统计模型,对业务带宽需求进行了研究分析。数值分析结果表明了该方案的有效性和优越性,对网络合理分配带宽资源有一定的参考意义。     

模糊逻辑控制方法在ATM网络拥塞控制中的应用

将普通漏桶技术和移动窗口机制相结合，提出了一种基于模糊规则的ＡＴＭ网络拥塞控制方法，并研究了它作为监管机制一些特性，对它的性能进行了计算机仿真，仿真结果表明，该机制对覆行连接接纳控制协议的信元有提供透明传输，对过份违约的信无能快速阻止其进入网络，与普通漏桶技术相比，本文方法具有同时监管信元流峰值速率和平均速率的优点。     

与多媒体信源模型弱相关的ATM复接器监管方案

本文提出一种与信源模型弱相关的复接器监管方案－－采用模糊漏桶控制方法改变令牌产生速率,对多媒体信源接入实施动态带宽分配。用ＭＭＢＰ模型及其合成讨论了该方案的可能性给出了模糊控制方案和规则,计算机仿真表明,在多个不同速率不同特性的语音、图像、数据信源接入时延该方法能很好地满足低时延低丢失的要求,提高带宽利用率,傅诉异步和编者复用特性被有效、充分地利用。     

一种智能监管方法性能的研究

本文提出了改进的模糊漏桶,用于对ＡＴＭ网络业务进行监管,对ＯＮ／ＯＦＦ业务及ＶＢＲ（ＶａｒａｂｌｅＢｉｔＲａｔｅ）视频ＡＲ（一阶ＡｕｔｏＲｅｇｒｅｓｓｉｖｅ模型）业务的仿真结果表明改进模糊漏桶对业务的监管能力要好于漏桶,即监管违约业务响应快,幅度大,并且合法业务对改进模糊漏桶的计资源要求少。     

ATM网络中漏桶算法在突发业务输入时的性能分析

本文首先引入了描述分组图像业务的突发业务模型，分析了漏桶算法在突发业务输入时的性能；研究了各参数对业务服务质量的影响，研究结果表明，增大缓冲器容量可以降低信元丢失率，但会增大时延和时延抖动。     

输入为多媒体信源的ATM业务流警管方案

文章提出了一种输入为多媒体信源的利用模糊控制技术的ＡＴＭ网络业务流警管方案。文章以ＡＴＭ复用器为例，用ＭＭＢＰ模型讨论了了该方案的可能性，给出了模糊控制规则及其调整过程与实现步骤。仿真表明，该方案能满足多个不同语语音，图像，数据信源的分别或同时接入，其信元时延，丢失，抖动等服务质量 优于常规漏桶算法。     

ATM网络中漏桶算法在突发业务输入时的性能分析

本文首先引入了描述分组图像业务的突发业务模型;分析了漏桶算法在突发业务输入时的性能;研究了各参数对业务服务质量的影响。研究结果表明,增大缓冲器容量可以降低信元丢失率,但会增大时延和时延抖动。     

智能网中的SCP过载控制研究

本文首先对Ｃａｌｌａｇｐ、Ｐｅｒｃｅｎｔ和漏梭算法进行了比较,得出了漏桶算法健壮性强适用于ＳＳＰ限制呼叫的结论。通过对过载控制框架的描述,提出了一种基于动态调整的控制算法用于ＳＣＰ过载控制。最后将算法进行扩展,使其满足不同的公平性条件,并适合在多业务环境各执行。模拟结果表明此算法具有较好的有效好性和公平性。     

模糊逻辑在ATM网络实时流量控制中的应用

提出了一种模糊逻辑控制系统，能实时处理ＡＴＭ网络中的流量问题。中使用峰值速率和突发时间长度来描述业务源特性，并据此动态地调节令牌速率。与传统的漏桶算法相比，该系统能透明传输符合流量协议的业务源，并能对业务源的违约行为迅速而有效地作出反应。     

Policing mechanism and cell loss priority control on voice cells in ATM networks using fuzzy logic

The authors present a fuzzy logic-based implementation of the policing mechanism (PM) and cell loss priority control (CLPC) functions on voice cells in asynchronous transfer mode (ATM) networks. Specifically, a redesigned model of fuzzy leaky bucket (FLB) is presented which serves as an alternative PM on the voice sources in an ATM network. As a continuation of the implementation of the FLB in the ATM network, three models of ATM switches with different algorithms are constructed, to perform CLPC on the voice cells, as well as to enhance the network throughput. Simulation results show that FLB is a better PM than the conventional leaky bucket (LB) in terms of cell loss probability and throughput while the mean transfer delay remains unchanged. It is also shown that the model of ATM switch with fuzzy token generator is the most balanced CLPC scheme as compared with the other two models.     

基于分形漏桶整形器的通用处理器共享系统性能分析

为了分析自相似业务流对通用处理器共享（GPS）系统性能的影响,研究了GPS系统性能与业务流自相似参数等因素之间的关系.通过使用分形漏桶的包络曲线对进入GPS系统的自相似业务流进行整形,推导了利用自相似业务流作为输入的GPS系统的队列长度和时延统计上界.数值结果与分析显示,基于分形漏桶的GPS系统性能模型对自相似业务流具有较好的性能.     

An upper bound delay for the virtual-clock service discipline

Proves that a connection composed of virtual-clock servers provides an upper bound on delay for leaky bucket constrained sessions, i.e., sessions conforming to a token bucket filter. This upper bound on delay is calculated, and it is the same upper bound on delay given by PGPS. The authors also prove that leaky bucket constrained sessions are the only type of sessions for which an upper bound on delay can be provided by servers with an upper bound on link capacity     

A generalized processor sharing approach to flow control inintegrated services networks: the multiple node case

Worst-case bounds on delay and backlog are derived for leaky bucket constrained sessions in arbitrary topology networks of generalized processor sharing (GPS) servers. The inherent flexibility of the service discipline is exploited to analyze broad classes of networks. When only a subset of the sessions are leaky bucket constrained, we give succinct per-session bounds that are independent of the behavior of the other sessions and also of the network topology. However, these bounds are only shown to hold for each session that is guaranteed a backlog clearing rate that exceeds the token arrival rate of its leaky bucket. A much broader class of networks, called consistent relative session treatment (CRST) networks is analyzed for the case in which all of the sessions are leaky bucket constrained. First, an algorithm is presented that characterizes the internal traffic in terms of average rate and burstiness, and it is shown that all CRST networks are stable. Next, a method is presented that yields bounds on session delay and backlog given this internal traffic characterization. The links of a route are treated collectively, yielding tighter bounds than those that result from adding the worst-case delays (backlogs) at each of the links in the route. The bounds on delay and backlog for each session are efficiently computed from a universal service curve, and it is shown that these bounds are achieved by “staggered” greedy regimes when an independent sessions relaxation holds. Propagation delay is also incorporated into the model. Finally, the analysis of arbitrary topology GPS networks is related to Packet GPS networks (PGPS). The PGPS scheme was first proposed by Demers, Shenker and Keshav (1991) under the name of weighted fair queueing. For small packet sizes, the behavior of the two schemes is seen to be virtually identical, and the effectiveness of PGPS in guaranteeing worst-case session delay is demonstrated under certain assignments     

Analysis of leaky bucket mechanism based on burstiness characterization

In high-speed networks, a congestion control strategy has to manage bandwidth allocation based on the characteristics of input traffic sources. Accordingly, the definition of traffic characterization becomes significant in all aspects concerning network performance. In this paper, the burstiness characterization of a traffic stream is based on a virtual queue principle. We study the leaky bucket mechanism as a regulator element that controls input traffic before access to a newwork, as well as inside a network. To protect an input traffic stream, we investigate the optimal parameter settings of a leaky bucket. In addition, we analyse the worst case performance, and obtain upper bounds on loss probability and packet delay. We also determine the characteristics of an output stream in the worst case. Such performance bounds reveal the effectiveness of a leaky bucket, and provide enough information for the QOS satisfaction of the network users.     

End-station performance under leaky bucket traffic shaping

The shaping of traffic at its source is a prominent congestion control solution in ATM networks. The “leaky bucket” with a “cell spacer” is a very popular traffic-shaping approach. By sizing the leaky bucket and spacer parameters, an end station shapes its traffic to conform to a “good behaviour” contract with the network. The leaky bucket delays the transmission of a selected number of cells, while the spacer forces a minimum time distance between transmitted cells. When a contracted transmission rate is close to the traffic generation rate of the end station, this traffic stream will utilize most of the bandwidth available on its virtual connection. The high utilization of such a connection leads to large queues of frames and cells at the end station, with high adverse consequences for end-to-end delay and jitter. Based on the negotiated traffic parameters and source traffic characteristics, we study, through simulations, the contribution of the leaky bucket plus cell spacer subsystem to the delay and jitter in an end station. We also study the distribution of the size of the bursts of cells leaving the end station and entering the network. Finally, we derive the theoretical upper bound for the size of bursts of the cells     

Fuzzy neural control of voice cells in ATM networks

This paper presents the design of a fuzzy controller for managing cells generated by voice sources in asynchronous transfer mode (ATM) networks. Typical voice cells, characterized by a high degree of burstiness, complicate any attempt to use classical control theory in the design of an ATM cell rate controller. The fuzzy control approach presented in this paper overcomes this limitation by appealing to the linguistic ability of fuzzy set theory and logic to handle the complexity. Specifically, the cell rate control problem is linguistically stated but treated mathematically via fuzzy set manipulation. In particular, the ATM voice cell controller being proposed is an improved and intelligent implementation of the leaky bucket cell rate control mechanism extensively studied in the literature. This intelligent implementation of the leaky bucket mechanism uses a channel utilization feedback via the QoS parameters to improve its performance. This ATM fuzzy controller takes the form of an organized set of linguistic rules quantitatively expressed and manipulated by means of fuzzy set theory and fuzzy logic. The fuzzy control rules are stored in fuzzy associative memory to permit parallel executions     

GPRS网络中综合业务漏桶算法的研究

GPRS是新一代传输综合业务的网络.本文提出了适用于GPRS网络的一种综合业务漏桶算法.通过对这种算法的分析,得出了实时业务和非实时业务的漏捅性能与输入业务统计参数及漏捅参数之间的关系.并用数值计算结果表明选用合适的漏桶参数可以对GPRS网络进行有效的流量控制.     

Effectiveness of the `leaky bucket' policing mechanism in ATMnetworks

The performance of the leaky bucket, a device for controlling the source traffic parameters of an ATM network is analyzed. The most critical situation, i.e., an on/off bursty source, is assumed. Moreover, the delay jitter introduced by a possible multiplexing of sources inside the customer premises network is not considered. The leaky bucket can be analyzed as a G/D/1/N queue with finite waiting room N and a suitable arrival process. An alternative approach, the fluid flow approximation, in which the bit flow is considered as a continuous variable, is presented. By comparison with the exact model, it is shown that the accuracy of the fluid flow approach is sufficient for practical purposes. An explicit formula for the cell loss probability, in case of exponential distributions for both the burst duration and the inactivity period of the source, is derived. On the basis of that formula, some numerical evaluations are presented with the aim of assessing the effectiveness of the leaky bucket mechanism. It is concluded that while the leaky bucket can easily control the peak rate, difficulties arise in controlling the mean bit rate (because of the long time required) and the burst duration (because of the poor selectivity)