Bursty ATM user traffic allowed by a jitter tolerant leaky bucket and its impact on link utilization

In a network based on the asynchronous transfer mode (ATM), quality of service requirements have to be met even in the presence of users who send traffic as bursty as the policing device allows. For peak cell rate policing with a jitter tolerant leaky bucket, a periodic maximally bursty traffic pattern allowed by the leaky bucket is derived. The impact of this kind of bursty user traffic on the cell loss performance of the remaining sources is investigated by introducing, solving and applying the queueing model Geo(n) + P/D/1/K, where P stands for ‘periodic’. Taking bursty user traffic into account, it is shown that the maximal jitter or cell delay variation allocated to the user and tolerated by the leaky bucket is an important parameter for link utilization. The results help to answer the question under which conditions a shaping function is needed in conjunction with the usage parameter control function.     

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。     

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。     

ATM业务监控的最差通过流分析及二级漏桶算法

讨论了一定算法下最差通过流的概念，强调了最差通过流的参数特性是评价一种业务监控算法的重要指标之一。对基本漏桶和缓冲漏桶逄法进行了比较。     

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。     

ATM网络双速漏桶监管算法

本文提出一种ＡＴＭ网络监管新算法———双速漏桶算法。对它的性能进行理论分析和计算机模拟，并探讨其硬件实现的可能性和复杂性。结果表明：在硬件复杂性基本不增加情况下，双速漏桶监管法比单速漏桶算法在监管选择性、信元丢失率及信元等待时间等性能方面有较大改善。     

ATM业务监控的一种模糊逻辑判决算法

本文描述了一种用于ＡＴＭ业务监控的模糊逻辑算法，在本算法中信元的合法性通过提取进入网络的信元流的平均参数和突发性参数，并根据一组模糊规则决定，利用计算机仿真对本算法进行了研究，结果表明本算法对业务流平均到达率的响应和对突发性的响应都优于漏桶算法。     

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.     

A comparative analysis of fuzzy versus conventional policingmechanisms for ATM networks

In ATM networks, usage parameter control is required in order to ensure that each source conforms to its negotiated parameters. To this purpose, several policing methods, such as leaky bucket and window mechanisms, have been introduced in literature. However, traditional methods have proved to be inefficient in coping with the conflicting requirements of ideal policing, that is, a low false alarm probability and high responsiveness. This led us to explore alternative solutions based on artificial intelligence techniques, specifically, in the field of fuzzy systems. We propose a policing mechanism based on fuzzy logic that aims at detecting violations of the parameters negotiated. The main characteristics of the proposed fuzzy policer are simplicity and the capacity to combine a high degree of responsiveness with a selectivity close to that of an ideal policer. Moreover, it can easily be implemented in hardware, thus, enhancing both cost and processing performance. The reported simulation results show that the performance of our fuzzy policer is much better than that of conventional policing mechanisms     

Modeling and performance comparison of policing mechanisms for ATMnetworks

Asynchronous transfer mode (ATM) networks, as proposed by CCITT as the solution for the future broadband ISDN, will provide high flexibility with respect to the varying bandwidth requirements of the different services. They will also support variable bit rates within a connection. The packetized information transfer, without flow control between the user and the network, in combination with the asynchronous multiplexing principle, results in a need to control the individual cell stream during the entire duration of the calls to ensure an acceptable quality of service for all coexisting calls sharing the same network resources. This kind of control will be provided by introducing a policing or usage parameter control function. Basic design objectives and requirements for such a function are described. These requirements serve as a basis for the comparison of some of the mechanisms proposed so far, namely the leaky bucket, the jumping window, the triggered jumping window, the moving window, and the exponentially weighted moving average mechanisms     

ATM突发性业务阻塞控制

在ＡＴＭ网里业务阻塞控制是一个十分重要的问题，本文对一种缓冲漏桶业务阻塞控制算法在突发性业务输入情况下的性能进行了计算机模拟分析，模拟结构表明缓冲漏桶算法是一种适合于突发性业务的阻塞控制算法，文章在模拟结果的基础上给出了缓冲漏桶算法中参量选择的算法。     

ATM网络中优先级业务漏桶算法的研究

本文对优先级业务的漏桶算法进行了分析,得出了各种优先级业务的漏桶性能与输入业务统计特性和漏桶参数之间的关系。文中引入低优先级业务的固定服务速率调节因子,并研究了它对高优先级业务和低优先级业务性能的影响。     

Buffered and Unbuffered Leaky Bucket Policing: Guaranteeing QoS,Design and Admission Control

Traffic shaping and smoothing using buffers or leaky buckets does not necessarily improve Quality of Service (QoS). In fact there is a trade-off between controlling user traffic and guaranteeing QoS to the users. We consider the first two stages (source node and border node before entering a network cloud) of an end-to-end QoS problem and assume that the QoS requirements across each of the two stages are given. We formulate and solve a mathematical programming problem to select optimal leaky bucket parameters that would enable high-speed telecommunication network providers to optimize traffic policing subject to guaranteeing a negotiated Quality of Service requirement across the first stage namely the source end. We address both the buffered and unbuffered leaky bucket cases where using fluid models we characterize the output process from the leaky buckets for general traffic sources. Using the optimal leaky bucket parameters and output characteristics (effective bandwidths in particular), we solve design and connection admission control problems given QoS requirements at the second stage, namely the border node.     

Joint selection of source and channel rate for VBR videotransmission under ATM policing constraints

Variable bit-rate (VBR) transmission of video over ATM networks has long been said to provide substantial benefits, both in terms of network utilization and video quality, when compared with conventional constant bit-rate (CBR) approaches. However, realistic VBR transmission environments will certainly impose constraints on the rate that each source can submit to the network. We formalize the problem of optimizing the quality of the transmitted video by jointly selecting the source rate (number of bits used for a given frame) and the channel rate (number of bits transmitted during a given frame interval). This selection is subject to two sets of constraints, namely, (1) the end-to-end delay has to be constant to allow for real-time video display and (2) the transmission rate has to be consistent with the traffic parameters negotiated by user and network. For a general class of constraints, including such popular ones as the leaky bucket, we introduce an algorithm to find the optimal solution to this problem. This algorithm allows us to compare VBR and CBR under the same end-to-end delay constraints. Our results indicate that variable-rate transmission can increase the quality of the decoded sequences without increases in the end-to-end delay. Finally, we show that for the leaky-bucket channel, the channel constraints can be combined with the buffer constraints, such that the system is identical to CBR transmission with an additional, infrequently imposed constraint. Therefore, video quality with a leaky-bucket channel can achieve the same quality of a CBR channel with larger physical buffers, without adding to the physical delay in the system     

Flow enforcement algorithms for ATM networks

Four measurement algorithms for flow enforcement in asynchronous transfer mode (ATM) networks are presented. The algorithms are the leaky bucket, the rectangular sliding window, the triangular sliding window, and the exponentially weighted moving average. A comparison, based partly on teletraffic theory and partly on signal processing theory, is carried out. It is seen that the time constant involved increases with the increasing burstiness of the connection. It is suggested that the RMS measurement bandwidth be used to dimension linear algorithms for equal flow enforcement characteristics. Implementations are proposed on the block diagram level, and dimensioning examples are carried out when flow enforcing a renewal-type connection using the four algorithms. The corresponding hardware demands are estimated aid compared     

Dynamic bandwidth allocation scheme for multiple real‐time VBR videos over ATM networks

This paper considers VBR transmission of multiple real‐time videos over ATM networks. Multiple real‐time VBR video sources are multiplexed into an ATM switch to transmit cells into the network. Given the ATM switch capacity, the problem is to dynamically allocate the required channel bandwidth for each video source such that the encoder buffer occupancy is maintained at a target level. To solve the problem, we present a mathematical formulation and propose an algorithm for the bandwidth allocation. To allocate a suitable bandwidth at a given control period, QoS demand levels and traffic characteristics of the video sources are considered. The performance of the proposed scheme is examined in terms of the number of encoder rate controls required and the gap between the target and the current buffer occupancy at each control period. Numerical results are analyzed for different QoS environments as well as different levels of target buffer, ATM switch capacity, buffer size and leaky bucket token rate. This revised version was published online in June 2006 with corrections to the Cover Date.     

Lowpass traffic policing mechanism based on the leaky bucket

A traffic throttle can be modelled as a gate with one input and two outputs: pass for accepted calls, and gap for rejected calls. The gate decides whether to pass or to gap an incoming call according to its policing mechanism. The authors show that a small modification to a leaky bucket policing mechanism yields a lowpass filter. The proposed mechanism is a new type of a nonlinear filter     

Performance limitation of the leaky bucket algorithm for ATMnetworks

The performance limitation of the “leaky bucket algorithm” is analyzed for usage parameter control and traffic management in asynchronous transfer mode (ATM) networks. Simulation results show that the conventional statistical bandwidth allocation method, which uses “the worst pattern derived from the cell interarrival time moments” permitted by the leaky bucket algorithm, can not guarantee the quality of service (QOS). As a result, this paper proves that the VC/VP bandwidth allocation method based on the leaky bucket algorithm is unsatisfactory