Asynchronous Transfer Mode Networks Research Articles

Design and simulation of an efficient real-time traffic scheduler with jitter and delay guarantees

In this paper, we propose a framework for real-time multimedia transmission in asynchronous transfer mode (ATM) networks using an efficient traffic scheduling scheme called multilayer gated frame queueing (MGFQ). MGFQ employs only one set of FIFO queues to provide a wide range of QoS for real-time applications. We also propose special cell formats for real-time multimedia transport and a hybrid design to allow MGFQ to combine its scheduling scheme with Age Priority Packet Discarding scheme. For this hybrid design, the cell level performance as well as the packet level QoS can be improved at the same time, Simulation results show that this hybrid design will be useful for packetized voice and progressive layer-compressed video transmission across the backbone networks. With the presented framework and the MGFQ algorithm, real-time multimedia traffic streams can be much better supported in terms of cell/packet delay and jitter.

Smith's principle for congestion control in high-speed data networks

In high-speed communication networks, large propagation delays could have an adverse impact on the stability of feedback control algorithms. In this paper, the classical control theory and Smith's principle are exploited to design an algorithm for controlling "best effort" traffic in high-speed asynchronous transfer mode (ATM) networks. The designed algorithm guarantees the stability of network queues, along with the fair and full utilization of network links, in a realistic traffic scenario in which multiple available bit rate connections, with different propagation delays, share the network with high priority traffic.

Development of a System to Provide Full, Real-time Remote Control of a Scanning Electron Microscope across the Second Generation Internet: The Teaching SEM

Abstract The development and makeup of a real-time full remote control system for the University of Michigan, Department of Materials Science and Engineering Teaching SEM is described. The instrument was initially controlled via the campus local area Ethernet network and cable TV network. The latest implementation employs Fast Ethernet, Asynchronous Transfer Mode (ATM) networks, and moving picture experts group (MPEG) video encoding to effect the remote control via the computer network alone. Remote control demonstrations from Washington, DC, Dearborn, MI, and Emerson School, Ann Arbor, MI are described.

Performance analysis of fuzzy thresholding-based buffer management for a large-scale cell-switching network

This paper addresses three key issues in buffer management in cell switching networks including asynchronous transfer mode (ATM) networks. First, it develops a model of fuzzy thresholding-based buffer management for a 50-switch representative cell-switching network, to study its performance under realistic conditions. Second, it presents an approach to re-route to their final destinations, the fraction of the selectively blocked cells that correspond to the difference of cell loss due to buffer overflow between the fixed and fuzzy schemes. Third, it reports on the influence of the buffer management scheme on the end-to-end delay performance of a representative cell switching network. The model is simulated on a testbed consisting of a network of 25+ Pentium workstations under Linux, configured as a loosely coupled parallel processor. Simulation results obtained are discussed.

The departure process of discrete-time queueing systems with Markovian type inputs

This paper proposes a unified matrix-analytic approach to characterize the output processes of general discrete-time lossless/lossy queueing systems in which time is synchronized/slotted into fixed length intervals called slots. The arrival process can be continuous- or discrete-time Markovian processes. It can be either renewal or non-renewal. The service of a customer commences at the beginning of a slot, consumes a random number of slots, and completes at the end of a later slot. The service times are independent and follow a common and general distribution. Systems with and without server vacations are both treated in this paper. These queueing systems have potential applications in asynchronous transfer mode (ATM) networks, packet radio networks, etc. Since the output process of a node in a queueing network becomes an input process to some node at the next stage, the results of this paper can be used to facilitate end-to-end performance analysis which has attracted more and more attention in the literature.

A Distributed Fair Queueing (DFQ) Architecture for Wireless ATM Local Access Networks

The application of Asynchronous Transfer Mode (ATM) to a Wireless Local Area Network (WLAN) environment is an undertaking that poses many problems not encountered in either wireline ATM or data-only WLAN. Wireline ATM networks do not have to transmit over multiple-access, unreliable transmission media while data-only WLANs do not have to satisfy heterogeneous Quality of Service (QoS) contracts for multimedia services. To address this issue, we propose in this paper a DFQ-based WLAN architecture, designed as a centrally controlled network where a complex base station polls simpler mobile terminals for channel access.

Optimizing a Single-Hop Virtual Path System Using a Genetic Algorithm

The virtual paths (VPs) system has been proposed as a key technique in order to utilize the asynchronous transfer mode (ATM)-based transport network. This article addresses the problem of how to assign the VPs system-based ATM network. This problem can be classified as a combinatorial and NP-hard complete optimization problem in which we want to minimize the designed VPs system assignment objective subject to the network constraints. A genetic algorithm (GA) is introduced as a new approach to solve this problem. Using the ON-OFF source and the fluid flow concepts, the equivalent bandwidth is formulated as the effective transmission rate of each heterogeneous traffic VP which guarantees both quality of service (QoS) in the cell level and the grade of service (GoS) in the connection level. The multi-objective function which comprises the average blocking rates (ABR) and the average packet delay (APD) is regarded as our designed VPs system assignment objective. A new coding technique in which each chromosome represents one of the VP system configurations and is also created associating with the designing delay bound of each VP is proposed. The concept of past solution is modified to suit the dynamic VPs system control technique that requires fast calculation speed. Numerical results show that by using our proposed method, it gives a good solution. Faster calculation speed than offered in previous literature, can be obtained by using our new coding technique. Moreover, comparative studies between this Genetic Algorithm (GA) application and conventional exhaustive search method which has been used as a reference algorithm to evaluate the quality of solution for global optimum provides very similar results.

Optimization of spare capacity in self-healing multicast ATM network using genetic algorithm

The objective of this paper is to optimize the amount of spare capacity reserved for the backup virtual paths (BVPs) in multicast asynchronous transfer mode networks. In this paper, we study the capacity and routing assignment problem arising in the design of self-healing networks using the VP concept. A major contribution of this work is to apply a genetic algorithm (GA) to the backup path search process instead of the trivial exhaustive search method. Experimental results indicate that both approaches have very comparable results in finding the multicast backup paths. Further, it also indicated that using a GA approach has a number of advantages over the exhaustive search approach, such as the computational requirement for a GA in finding good BVPs is small when compared to the exhaustive search method. A major drawback of our approach is that we cannot guarantee the finding of global optimum in real time.

Design and Configuration of Reconfigurable ATM Networks with Unreliable Links

This paper considers a problem of configuring both physical backbone and logical virtual path (VP) networks in a reconfigurable asynchronous transfer mode (ATM) network where links are subject to failures. The objective is to determine jointly the VP assignment, the capacity assignment of physical links and the bandwidth allocation of VPs, and the routing assignment of traffic demand at least cost. The network cost includes backbone link capacity expansion cost and penalty cost for not satisfying the maximum throughput of the traffic due to link failures or insufficient link capacities. The problem is formulated as a zero-one non-linear mixed integer programming problem, for which an effective solution procedure is developed by using a Lagrangean relaxation technique for finding a lower bound and a heuristic method exploited for improving the upper bound of any intermediate solution. The solution procedure is tested for its effectiveness with various numerical examples.

Traffic control through in-service monitoring for QoS improvement in ATM networks

Asynchronous transfer mode (ATM) networks are expected to support multimedia communications with diverse traffic characteristics, these traffic are statistically multiplexed to efficiently utilize the network bandwidth. However, the high bandwidth utilization may deteriorate traffic-dependent quality of service (QoS). To accommodate QoS requirements while still maintaining high bandwidth utilization, it is necessary to prioritize user's service requirements through effective resource management. This article presents a traffic control approach through in-service monitoring, which employs dynamic buffer allocation to allow complete buffer sharing by all service classes as well as improves QoS of delay-sensitive traffic using the so-called Earliest Expected Due-time First scheduling. The simulation results demonstrate that diverse multimedia traffic achieves satisfactory performance using our scheme. A feasible implementation architecture is also addressed.

On the optimality and the asymptotic optimality of the smallest weighted available buffer policy

A major design challenge of Asynchronous Transfer Mode (ATM) networks is to efficiently provide the quality of service (QOS) specified by users with different demands. We classify sources so that sources in one class join the same buffer and have the same requirement for the ATM cell loss ratio. It is important to search for the service discipline that minimizes the accumulated cell loss under the constraint that the cell loss ratios of the sources are proportional to their QOS requirements. In this paper we consider a model that has N finite buffers and a single server. Buffer i, of size B i , is assigned a positive number w i . The server serves from one of the non-empty buffers whose indices are equal to argmin w i (B i -Q i ), where Q i is the queue length of buffer i. This scheduling policy is called the smallest weighted available buffer policy (SWAB). We show that in a completely symmetric setting, the SWAB policy minimizes the discounted expected loss of cells under some technical conditions. For asymmetric models, we show that the accumulated loss of cells of the SWAB service discipline is asymptotically optimal under heavy traffic conditions in the diffusion limit. Finally, we obtain the expression of w i so that the cell loss ratios of the sources in the diffusion limit are proportional to their QOS requirements.

On the optimality and the asymptotic optimality of the smallest weighted available buffer policy

A major design challenge of Asynchronous Transfer Mode (ATM) networks is to efficiently provide the quality of service (QOS) specified by users with different demands. We classify sources so that sources in one class join the same buffer and have the same requirement for the ATM cell loss ratio. It is important to search for the service discipline that minimizes the accumulated cell loss under the constraint that the cell loss ratios of the sources are proportional to their QOS requirements. In this paper we consider a model that hasNfinite buffers and a single server. Bufferi, of sizeBi, is assigned a positive numberwi. The server serves from one of the non-empty buffers whose indices are equal to argminwi(Bi-Qi), whereQiis the queue length of bufferi. This scheduling policy is called the smallest weighted available buffer policy (SWAB). We show that in a completely symmetric setting, the SWAB policy minimizes the discounted expected loss of cells under some technical conditions. For asymmetric models, we show that the accumulated loss of cells of the SWAB service discipline is asymptotically optimal under heavy traffic conditions in the diffusion limit. Finally, we obtain the expression ofwiso that the cell loss ratios of the sources in the diffusion limit are proportional to their QOS requirements.

A cell-numbering plan for seamless handoff in a wireless ATM network

This paper proposes a cell-numbering plan for mobile stations to handoff seamlessly to the cells in a wireless Asynchronous Transfer Mode (ATM) network. It also proposes a minimum-hop rerouting (MHR) method to perform the rerouting of user connections during the handoff. The cell-numbering plan assigns each cell an integer from 1 to 5, ensuring that neighboring cells will have different numbers. Any mobile station that performs a handoff beween any two cells can easily calculate if a reroute is needed. Furthermore, by using the MHR, the path between the originating and terminating mobile stations will be the shortest whenever either of them moves. The signaling bandwidth used for this kind of rerouting is believed to be the smallest among the methods reported to date.

A study using a RISC core for ATM network interfaces design

The use of a general purpose processing core in the design of high-speed network interfaces can be very useful in providing some important features to these interfaces, such as simplicity, shorter developing cycle time, low development cost, and flexibility. However, it is not clear whether such a core can efficiently provide the processing power required by these high-speed interfaces without significantly increasing the clock rate of the processing core. Such an increase will make the cost of the core very high and not practical to be used with Asynchronous Transfer Mode (ATM) interfaces. In this paper, we have demonstrated that a general purpose processing core, such as an 80 MHz Reduced Instruction Set Computer (RISC), can be used in ATM network interfaces for a wide range of transmission line speeds, up to 1.2 Gb/s. Also, we have discussed some of the design issues related to the RISC core based network interfaces.

Efficient simulation of QoS in ATM switches using connection traffic descriptors

High speed networks using asynchronous transfer mode (ATM) will be able to carry a broad range of traffic classes and will be required to provide QoS measures, such as the cell loss and cell delay probabilities, to many of these traffic classes. The design and testing of ATM networks and the algorithms that perform connection admission control is difficult due to the rare event nature associated with QoS measures, and the unwieldiness of matching statistical models of the broad range of traffic classes entering the network to the connection traffic descriptors used by the connection admission control algorithms. In this paper, as an alternative to using statistical traffic models, we describe the traffic entering the network by the connection traffic descriptors standardized by the ATM Forum and used by the connection admission control algorithms. We present a Monte Carlo simulation model for estimating the cell loss and cell delay probabilities using a multinomial formulation to remove the correlation associated with estimating bursty events. We develop importance sampling techniques to increase the efficiency of the simulation for ATM networks with heterogeneous input traffic classes, namely constant bit rate and variable bit rate traffic. For the experimental examples considered here, the improvement in simulation efficiency compared to conventional Monte Carlo simulation is inversely proportional to the probability estimate. The efficient simulation methods developed here are suitable for the design and testing of the switches and connection admission control algorithms planned for use in ATM networks.

A NEW CALL ADMISSION CONTROL METHOD BASED ON THE ESTIMATION OF THE LOST CELL

Due to the capability to serve a large number and various types of user traffic, ATM (Asynchronous Transfer Mode) networks are going to be the leading role in telecommunications in the immediate future. To guarantee high quality communications for a lot of customers and efficient use of network resources, the ATM network management has to contain appropriate Call Admission Control (CAC) algorithms. Choosing suitable network and user models, the CAC problem can be traced back to statistical inequalities. This paper introduces a CAC technique based on the Mean Value of the Lost Cells (MVLC) instead of using Cell Loss Probability that follows Gaussian approach. Two methods are presented which are able to estimate efficiently the MVLC. These methods are based on special transformation of the Chernoff bound.

A fault-tolerant architecture for ATM networks

The asynchronous transfer mode (ATM) is the transfer mode recommended for the broad integrated service digital network (B-ISDN) by ITU-T. In this paper, we propose a self-routing fault-tolerant switching architecture for ATM networks. The proposed architecture uses subswitches and extra links to provide alternative paths; hence, can tolerate multiple faults. Analytical results show that the total number of redundant paths increases exponentially as the size of the network increases. A simulation model is developed. Simulation results indicate that the proposed architecture is much more fault-tolerant and cost-effective than those architectures found in the literature. Simulation results also illustrate that the proposed architecture still maintains a high throughput with an acceptable cell delay time, even when the number of faulty elements increases.

A congestion control mechanism for enterprise network traffic over asynchronous transfer mode networks

Available bit rate (ABR) is an emerging asynchronous transfer mode (ATM)-based telecommunication service, which dynamically allocates bandwidth to the users according to the available bandwidth in the network. However, research shows that ABR-based connections suffer from congestion at LAN–ATM gateway when ATM network abruptly reduces the bandwidth available to the gateway. Gateway congestion may result in high packet loss. This paper proposes a gateway congestion control mechanism, which controls the rate of outgoing enterprise traffic according to the available bandwidth at the gateway. Our analysis shows how to achieve a stable system and keep the packet loss below a desired threshold. Analytical results are validated by simulation.

Analysis of neural-network-based congestion control algorithms for ATM networks

Congestion control provides a challenge in the design of Asynchronous Transfer Mode (ATM) networks. Several algorithms have been proposed in the literature for alleviating or reducing congestion. In this paper the Jumping Window (JW), Triggered Jumping Window (TJW) and the Exponentially Weighted Moving Average (EWMA) window algorithms are analyzed, based on a closed-loop predictive feedback mechanism using a neural network. Single- and multiple-source models with real-world and simulated data are used to test the performance of the proposed mechanisms. The consequences of delayed feedback messages is also considered. Results indicate that neural controllers are effective in reducing the cell loss rate, while introducing minimal additional delays.

NASA/DARPA Advanced Communications Technology Satellite Project for Evaluation of Telemedicine Outreach Using Next-Generation Communications Satellite Technology: Mayo Foundation Participation

To describe the development of telemedicine capabilities-application of remote consultation and diagnostic techniques-and to evaluate the feasibility and practicality of such clinical outreach to rural and underserved communities with limited telecommunications infrastructures. In 1992, Mayo Foundation (Rochester, Minn, Jacksonville, Fla, and Scottsdale, Ariz), the National Aeronautics and Space Administration, and the Defense Advanced Research Projects Agency collaborated to create a complex network of fiberoptic landlines, video recording systems, satellite terminals, and specially developed data translators linking Mayo sites with other locations in the continental United States on an on-demand basis. The purpose was to transmit data via the asynchronous transfer mode (ATM) digital communications protocol over the Advanced Communications Technology Satellite. The links were intended to provide a conduit for transmission of data for patient-specific consultations between physicians, evaluation of medical imagery, and medical education for clinical staffs at remote sites. Low-data-rate (LDR) experiments went live late in 1993. Mayo Clinic Rochester successfully provided medical consultation and services to 2 small regional medical facilities. High-data-rate (HDR) experiments included studies of remote digital echocardiography, store-and-forward telemedicine, cardiac catheterization, and teleconsultation for congenital heart disease. These studies combined landline data transmission with use of the satellite. The complexity of the routing paths and network components, immaturity of available software, and inexperience with existing telecommunications caused significant study delays. These experiments demonstrated that next-generation satellite technology can provide batch and real-time imagery for telemedicine. The first-generation of the ATM and satellite network technology used in these experiments created several technical problems and inconveniences that should be overcome as the network infrastructure matures.