Control In Asynchronous Transfer Mode Networks Research Articles

Submission to CAC

Asynchronous transfer mode (ATM) is the base for future telecommunication network. The greatly variable requirements for different applications, especially in video and data traffic, make high demands on the development of traffic control in ATM networks. Speaking about Quality of Service (QoS), in ATM there is a traffic control mechanism, which ensures the standard requested by a new application or service. In the following paper an introduction to traffic control mechanism in ATM known as a connection admission control (CAC) and appropriate CAC method are presented.

Genetic algorithm-based neural fuzzy decision tree for mixed scheduling in ATM networks

Future broadband integrated services networks based on asynchronous transfer mode (ATM) technology are expected to support multiple types of multimedia information with diverse statistical characteristics and quality of service (QoS) requirements. To meet these requirements, efficient scheduling methods are important for traffic control in ATM networks. Among general scheduling schemes, the rate monotonic algorithm is simple enough to be used in high-speed networks, but does not attain the high system utilization of the deadline driven algorithm. However, the deadline driven scheme is computationally complex and hard to implement in hardware. The mixed scheduling algorithm is a combination of the rate monotonic algorithm and the deadline driven algorithm; thus it can provide most of the benefits of these two algorithms. In this paper, we use the mixed scheduling algorithm to achieve high system utilization under the hardware constraint. Because there is no analytic method for schedulability testing of mixed scheduling, we propose a genetic algorithm-based neural fuzzy decision tree (GANFDT) to realize it in a real-time environment. The GANFDT combines a GA and a neural fuzzy network into a binary classification tree. This approach also exploits the power of the classification tree. Simulation results show that the GANFDT provides an efficient way of carrying out mixed scheduling in ATM networks.

Connection control in ATM networks

This paper describes a new connection management algorithm called parallel connection control (PCC) that allows for fast connection setup in scaleable reliable asynchronous transfer mode (ATM) networks. The two main concepts of PCC are execution of connection setup actions at multiple switches on the route of a connection in parallel, and the separation of the route computation function into servers distinct from switch processors. The associated benefits of these concepts are fast connection setup and increased per-switch call handling capacity relative to the conventional approach of setting up connections sequentially switch-by-switch with switches performing route computation. The PCC solution is designed to work in conjunction with the current ATM Forum signaling and routing standards solutions, offering a means to achieve improved call handling performance. This paper also introduces the concept of application-dependent routing for setting up logical connections, which consist of multiple network-layer connections routed through application-layer resources, such as bridges and converters. In this paper, we propose two models for handling complex communication configurations: an end-host-driven model and a network-value-added model using application-dependent route (ADR) servers.

A performance prediction model for FECN rate-based flow control in ATM networks: a case study

Forward explicit congestion notification (FECN) plays an important role in rate-based flow control for asynchronous transfer mode (ATM) networks. This paper presents a case study in predicting and evaluating the performance of the FECN flow control. Two network models are under investigation; the first model assumes that a target ATM network has no traffic congestion, while the second model assumes that the network has exhibited heavy congestion. For the light-loaded network, we first estimate the number of cells issued by the source during each time interval and then calculate the required number of resource management (RM) cells in the same time interval. A general analytical form to predict allowable cell rate (ACR) at the source can be finally derived. For the heavy-loaded network, RM cells may be delayed and data cells may be discarded due to severe network congestion. Hence, to derive a general form of ACR, we need to estimate the round-trip time (RTT) of RM cells based on the queuing length of the traversed ATM switches. For the purpose of validation, we perform simulation through OPNET. The performance parameters of our interest include the ACR, the RTT of RM cells, the throughput and the cell loss ratio. We have shown that the differences between the analytical and the simulation results are quite small not only in the ACR adjusting rate, but also in the prediction of the system throughput, the CLR, and the RTT of RM cells.

Mobility management and control in intelligent wireless ATM networks

This paper shows how the Asynchronous Transfer Mode (ATM) signaling and the Intelligent Network (IN) concept can be exploited to support mobility in an ATM-based network with wireless access parts and mobile users. The proposed architecture exploits the enhanced service control processing features offered by the IN technology to support location management. The access signaling protocol structure is based on the principles of separation between call and bearer channel control, employed in fixed broadband access networks. The design objective is to minimize the changes required to the wired network signaling, by taking advantage of the well-developed capability sets. This allows the easy introduction of the wireless ATM technology (W-ATM) into the real world. It is shown that the proposed signaling protocol model provides cost-effective implementations without degrading the agreed Quality of Service (QoS) and the system's performance. A comparative signaling performance evaluation is carried-out to demonstrate the impact of the proposed signaling protocol architecture onto various performance measures and to quantify the relative gains. The obtained results can be used for network design purposes in a large-scale private installation supporting many users. The signaling protocol architecture aims for private W-ATM networks, but can be readily extended to fulfill the signaling requirements of public environment broadband wireless systems.

An integrated framework for traffic control in ATM networks based on soft-computing techniques

Abstract In this paper we assess the application of artificial intelligence techniques to the complex problem of traffic control in Asynchronous Transfer Mode (ATM) networks. The paper deals with the close link between Call Admission Control (CAC) and Usage Parameter Control (UPC) and proposes a simulation-based analysis to demonstrate how inefficiency on the part of policing affects bandwidth allocation. To take this into account, the paper proposes a framework for traffic control in which the CAC and policing functions are both based on artificial intelligence techniques, i.e., neural networks and fuzzy logic. A measurement-based CAC mechanism is then proposed and implemented by means of neural networks trained in such a way as to take into account the real behaviour of the policer. As the results obtained show, this allows us to implement traffic management strategies that can improve the exploitation of network resources.

A neural-fuzzy system for congestion control in ATM networks

We propose the use of a neural-fuzzy scheme for rate-based feedback congestion control in asynchronous transfer mode (ATM) networks. Available bit rate (ABR) traffic is not guaranteed quality of service (QoS) in the setup connection, and it can dynamically share the available bandwidth. Therefore, congestion can be controlled by regulating the source rate, to a certain degree, according to the current traffic flow. Traditional methods perform congestion control by monitoring the queue length. The source rate is decreased by a fixed rate when the queue length is greater than a prespecified threshold. However, it is difficult to get a suitable rate according to the degree of traffic congestion. We employ a neural-fuzzy mechanism to control the source rate. Through learning, membership values can be generated and cell loss can be predicted from the status of the queue length. Then, an explicit rate is calculated and the source rate is controlled appropriately. Simulation results have shown that our method is effective compared with traditional methods.

Dynamic bandwidth control in ATM networks

The Asynchronous Transfer Mode (ATM) principle has been recommended by the ITU as the transport vehicle for future Broadband ISDN Networks. One of the most important objectives of ATM-based networks is to support multimedia traffic services. The multimedia traffic is a diverse mixture of several types of traffic (e.g., video, voice, image, data) that have different correlations, burstiness characteristics and quality of services (QoS) requirements form the network. Efficient bandwidth allocation and access control algorithms are required to ensure (and maintain) specific QoS requirements for each type of traffic. In this article, we propose and analyze a dynamic bandwidth allocation and control scheme based upon the virtual path (VP) principle. The scheme exploits the statistical multiplexing gain principle in order to increase the bandwidth utilization per VP. It allocates a certain amount of bandwidth to each VP that is necessary to meet the QoS requirements of the traffic carried by that VP. Each VP carries only homogeneous traffic (i.e., traffic with similar characteristics and QoS requirements are supported by a single VP). To dynamically control the allocated path-bandwidth a Bandwidth Control Period (BCP) rule is proposed to control the scheduling of different types of traffic that are supported by separate VPs. It is shown that with proper choice of the BCP, a path-bandwidth can be allocated to guarantee QoS required by the traffic. The scheme is dynamic in the sense that the bandwidth allocated, per VP, depends upon the number of accepted calls and variations in the traffic characteristics. Further, it is shown that access flow control is essential in order to minimize the cell loss rate and enhance the statistical multiplexing gain per VP.

A novel SVC mechanism for call connection and control in ATM networks

This paper introduces the “train mechanism”, a novel signalling virtual channel (SVC) call control mechanism and protocol for asynchronous transfer mode (ATM) broadband networks. The “train” provides a unifying mechanism, enabling ATM to carry and route user traffic with arbitrary granularity ranging from a single cell, to a datagram, to a permanent virtual circuit. The performance for various length trains is determined.

Fuzzy Inference Based Connection Admission Control in ATM Networks

A connection admission control (CAC) method is proposed for asynchronous transfer mode (ATM) networks by applying the fuzzy inference and learning algorithm of neural networks. In order to guarantee the allowed cell loss ratio (CLR) in CAC, the upper bound of CLR must be used as the criterion for judging whether an incoming call can be accepted or not. For estimating the upper bound of CLR from observed CLR data, fuzzy inference, based on a weighted mean of fuzzy sets, is adopted. This inference method can effectively estimate the possibility distribution of CLR by applying the error back-propagation algorithm with the proposed energy functions in learning and provide the upper bound of CLR efficiently from the distribution. A self-compensation mechanism for estimation errors is also provided, which is simple enough to work in real time by taking advantage of the fuzzy inference method adopted. Fuzzy rules in the area with no observed data are generated by extrapolation from adjacent fuzzy rules in the area with observed data. This increases the multiplex gain, thereby guaranteeing the allowed CLR as much as possible. The simulation results show the feasibility of the proposed CAC method.

A VLSI fuzzy expert system for real-time traffic control in ATM networks

Concerns a fuzzy logic-based system which has been purposely designed to achieve real-time traffic control in high-speed networks using the asynchronous transfer mode (ATM) technique. One of the most critical functions is "policing", which has the task of ensuring that each user source complies with the traffic parameters negotiated in the call setup to avoid network congestion. This function is difficult to implement on account of certain conflicting requirements such as selectivity and responsiveness. This is confirmed by the severe limits affecting the most popular mechanisms proposed so far, based on conventional logic. The capacity to formalize approximate reasoning processes offered by fuzzy logic is exploited to derive rules of behavior for a policer starting from the know-how of an expert. We address two key issues related to the implementation of the fuzzy policer. The first focuses on the possibility of hardware implementation of the mechanism using VLSI technology; we present the design of a VLSI fuzzy processor which exhibits a level of performance of over 3 MFLIPS. The second issue concerns the suitability of applying the fuzzy policer to the policing of several classes of sources to reach high levels of cost effectiveness and scalability.

Routing with admission control in ATM networks

An optimal control parameter, /spl beta/, was developed by optimal control theory for asynchronous transfer mode (ATM) networks. The parameter is related to link utilization, buffer occupancy, system throughput and cell rejection characteristics and is applied to routing and admission control in simulation of a network carrying multiclass traffic. Simulation results show that the parameter produces better performance with respect to the cell rejection rate characteristics compared with the traditional control parameter, utilization, /spl rho/.

Adaptive virtual path capacity control in multimedia ATM networks

AbstractThe Virtual Path concept has several beneficial features to construct an economical and efficient Asynchronous Transfer Mode (ATM) network. The Virtual Path capacity control technique can increase network flexibility and improve transmission efficiency through statistical sharing of facilities.This paper presents an adaptive virtual path capacity control method which maximizes transmission efficiency under the condition of limited processing load. Evaluation shows that the proposed method successfully improves network transmission efficiency with a slight increase in processing load compared to the fixed virtual path capacity scheme.

On congestion control in ATM networks

The origin of congestion control problems in asynchronous transfer mode (ATM) networks is described. The main overall congestion control strategies that have been proposed are summarized. The set of mechanisms that constitute a general framework for congestion control consists of admission control, usage parameter control, relative cell delay/loss priority, and flow/reactive control mechanisms. Depending on their service scenarios, the overall congestion control schemes of different networks may consist of different combinations of these mechanisms. Furthermore, different networks may realize the same mechanism through the use of different algorithms and implementations. The basic techniques that could be used in implementing the overall congestion control of an ATM network are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Congestion control and prevention in ATM networks

Some of the congestion control methods commonly considered suitable for an ATM (asynchronous transfer mode) network are surveyed. Call-level control, which provides preventive control by regulating the admission of new calls into the network, is first discussed. The concept of equivalent bandwidth is defined, and the sharing of network information is discussed. Admission control schemes are described. Methods for cell-level control, which avoids short term congestion, are considered. Included are call admittance, bandwidth policing, and rate control, as well as priority schemes that provide multiple grades of service with ATM.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis of interdeparture processes for bursty traffic in ATM networks

Admission control in asynchronous transfer mode (ATM) networks is considered. An ATM switch is modeled as a discrete-time single-server queue at which the following three different kinds of arrival processes are allowed to join together: arrivals of cells with a general interarrival time distribution; Bernoulli arrivals of cells in batches; and interrupted Poisson processes. An exact analysis is given to derive the waiting-time distributions and interdeparture-time distributions for arriving cells subject to admission control in ATM networks. The model is extended to approximately obtain the end-to-end delay distributions for the designated traffic stream. Such an analysis is important for voice or coded video because they require a playout mechanism at the destination. Since the analysis is approximate, the simulation results needed to assess its accuracy are provided. Numerical examples show how the traffic characteristics of the designated traffic stream are affected by the total traffic load at the switching node, the number of other bursty traffic sources, and the degree of burstiness of the traffic source itself. >

Analysis of a discrete-time single-server queue with bursty inputs for traffic control in ATM networks

The performance of an asynchronous transfer mode (ATM) network subject to admission control and traffic smoothing is analyzed. Basically, an ATM switch is modeled as a discrete-time single-server queuing system in which a new call joins existing calls. Cell arrivals from a new call are assumed to follow a general distribution. It is also assumed that aggregated arrivals of cells from existing calls form batch arrivals with a general batch size distribution and a geometric distribution of the interarrival times between batches. Both finite- and infinite-buffer cases are considered. An exact analysis yields the waiting time distribution and cell loss probability for a new call and for existing calls. Numerical examples are given to show how the network performance depends on the statistics of a new call (burstiness, time that a call stays in an active or inactive state, etc.) and to demonstrate the effectiveness of admission control and traffic smoothing.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>