THE ANALYSIS OF CELL LOSS RATES IN AN ATM MUX WITH LOSS PRIORITIES

The analysis of cell loss rates in an ATM Mux with loss priorities is an important problem in the-study of traffic control in ATM networks. In this paper, the loss rates of the cells with different priorities in an ATM Mux are analyzed by approximating the actual input process with two-state MMDP and fluid flow technique, and the analytical expressions of the relation between the loss rates and the buffer size are obtained. Simulation shows that the approach is sulliciently accurate for applications.     

Estimation of the cell loss ratio in ATM networks with a fuzzysystem and application to measurement-based call admission control

An important parameter in asynchronous transfer model (ATM)-based network design and management is the cell loss ratio (CLR) in ATM multiplexers. It is a key parameter to many vital functions in the network such as call admission control (CAC), bandwidth allocation, etc. However, the CLR depends usually on many unknown and unpredictable traffic parameters such as input traffic correlations. In this paper, we propose a simple and robust fuzzy-based algorithm to predict the CLR in large-sized systems based on both a small amount of information from small-sized systems, and the asymptotic behavior for very large systems. Unlike the model-based approaches, our approximation avoids the problem of assuming any traffic parameters or arrival process. This algorithm is used with real-time traffic measurement to propose an effective measurement-based call admission control framework for ATM networks     

Efficient estimation of cell blocking probability for ATM systems

The assessment of the cell loss performance of networks using asynchronous transfer mode (ATM) via Monte Carlo simulation incurs an enormous computational burden due to the need to estimate an event that has a very small probability of occurrence. Although importance sampling (IS) techniques have been proven useful in simulations of rate events related to bit error rate in digital communications and false alarm rate in radar systems, its application to ATM queuing problems with correlated input traffic has yet to be demonstrated. It is established that significant computational savings can be obtained using IS for correlated traffic by using regenerative properties of the underlying system and biasing the conditional arrival process. The results show that IS can reduce the computational burden by more than three orders of magnitude. Extensions of the methodology to more complex arrival processes are discussed. The foundation for applying IS to ATM systems given can be used to study congestion control as well as networks of ATM queues in the future     

ATM network design and optimization: a multirate loss networkframework

Asynchronous transfer mode (ATM) network design and optimization at the call-level may be formulated in the framework of multirate, circuit-switched, loss networks with effective bandwidth encapsulating cell-level behavior. Each service supported on the (wide area, broadband) ATM network is characterized by a rate or bandwidth requirement. Future networks will be characterized by links with very large capacities in circuits and by many rates. Various asymptotic results are given to reduce the attendant complexity of numerical calculations. A central element is a uniform asymptotic approximation (UAA) for link analyses. Moreover, a unified hybrid approach is given which allows asymptotic and nonasymptotic methods of calculations to be used cooperatively. Network loss probabilities are obtained by solving fixed-point equations. A canonical problem of route and logical network design is considered. An optimization procedure is proposed, which is guided by gradients obtained by solving a system of equations for implied costs. A novel application of the EM algorithm gives an efficient technique for calculating implied costs with changing traffic conditions. Finally, we report numerical results obtained by the software package TALISMAN, which incorporates the theoretical results. The network considered has eight nodes, 20 links, six services, and as many as 160 routes     

LAN emulation on an ATM network

The authors evaluate architecture alternatives relating to the provision of a LAN emulation service over a connection-oriented ATM network, and present the LAN emulation architecture as actually adopted by the ATM Forum LANE SWG. The role of servers is discussed as is the provision of broadcast/multicast services     

Neural network based cell scheduling in ATM node

This letter deals with the queueing discipline for the superposition of arrival processes in the asynchronous transfer mode (ATM) case, particularly for the bursty traffic. A competitive algorithm, based on neural networks, for the cell scheduling is suggested. Computer simulations demonstrate that the new algorithm may be very useful in the bursty traffic case: the cell loss rate is at least one order of magnitude lower than in case of the classical round-robin discipline     

Connection management for an ATM network

The facilities required to control and manage multiservice applications in asynchronous transfer mode (ATM) networks are discussed. An overview of the hardware aspects of ATM networks is presented. Requirements and architectural models for multiservice applications and an architecture for connection management are described. The requirements at each layer of the connection management architecture are discussed, and the services and protocols are outlined     

Reducing cell loss in banyan based ATM switching fabrics

In this paper, we propose a new technique for reducing cell loss in multi‐banyan‐based ATM switching fabrics. We propose a switch architecture that uses incremental path reservation based on previously established connections. Path reservation is carried out sequentially within each banyan but multiple banyan planes can be concurrently reserved. We use a conflict resolution approach according to which banyans make concurrent reservation offers of conflict‐free paths to head of the line cells waiting in input buffers. A reservation offer from a given banyan is allocated to the cell whose source‐to‐destination path uses the largest number of partially allocated switching elements which are shared with previously reserved paths. Paths are incrementally clustered within each banyan. This approach leaves the largest number of free switching elements for subsequent reservations which has the effect of reducing the potential of future conflicts and improves throughput. We present a pipelined switch architecture based on the above concept of path‐clustering which we call path‐clustering banyan switching fabric (PCBSF). An efficient hardware that implements PCBSF is presented together with its theoretical basis. The performance and robustness of PCBSF are evaluated under simulated uniform traffic and ATM traffic. We also compare the cell loss rate of PCBSF to that of other pipelined banyan switches by varying the switch size, input buffer size, and traffic pattern. Copyright © 2001 John Wiley & Sons, Ltd.     

Modeling and simulation of an ATM backbone network

We present a simulation model to analyze the performance of a Mesh ATM backbone network: using the proposed model, we study the performance of a fully connected network topology. Then we assess the impact of different routing schemes on network performance. Copyright © 2000 John Wiley & Sons, Ltd.     

Improved loss calculations at an ATM multiplexer

In this paper we develop a simple and accurate analytical technique to determine the loss probability at an access node to an asynchronous transfer mode (ATM) network. This is an important problem from the point of view of admission control and network design. The arrival processes we analyze are the Markov-modulated Poisson process (MMPP) and the Markov-modulated fluid (MMF) process. These arrival processes have been shown to model various traffic types, such as voice, video, and still images, that are expected to be transmitted by ATM networks. Our hybrid analytical technique combines results from large buffer theories and quasi-stationary approaches to analyze the loss probability of a finite-buffer queue being fed by Markov-modulated sources such as the MMPP and MMF. Our technique is shown to be valid for both heterogeneous and homogeneous sources. We also show that capacity allocation based on the popular effective-bandwidth scheme can lead to considerable under-utilization of the network and that allocating bandwidth based on our model can improve the utilization significantly. We provide numerical results for different types of traffic and validate our model via simulations     

New call blocking versus handoff blocking in cellular networks

In cellular networks, blocking occurs when a base station has no free channel to allocate to a mobile user. One distinguishes between two kinds of blocking, the first is called new call blocking and refers to blocking of new calls, the second is called handoff blocking and refers to blocking of ongoing calls due to the mobility of the users. In this paper, we first provide explicit analytic expressions for the two kinds of blocking probabilities in two asymptotic regimes, i.e., for very slow mobile users and for very fast mobile users, and show the fundamental differences between these blocking probabilities. Next, an approximation is introduced in order to capture the system behavior for moderate mobility. The approximation is based on the idea of isolating a set of cells and having a simplifying assumption regarding the handoff traffic into this set of cells, while keeping the exact behavior of the traffic between cells in the set. It is shown that a group of 3 cells is enough to capture the difference between the blocking probabilities of handoff call attempts and new call attempts. This revised version was published online in July 2006 with corrections to the Cover Date.     

Distributed restoration in an ATM test bed network

Network resilience is a crucial area of concern for telecommunications network operators who aim to provide high availability services supported by a broadband platform based on ATM technology. This paper describes the development of an ATM test bed network which incorporates resilience by executing distributed restoration in the event of failures. Since the work originated from collaborative research between BT Laboratories and Alcatel Telecom of Belgium, the paper highlights challenges faced in developing a restorable network, both by a network operator, and a switch manufacturer.     

Sizing exit buffers in ATM networks: an intriguing coexistence ofinstability and tiny cell loss rates

This paper deals with the sizing of end buffers in ATM networks for sessions subject to constant bit rate (CBR) traffic. Our objective is to predict the cell-loss rate at the end buffer as a function of the system parameters. We introduce the D+G/D/1 queue as a generic model to represent exit buffers in telecommunications networks under constant rate traffic, and use it to model the end buffer. This is a queue whose arrival rate is equal to its service rate and whose arrivals are generated at regular intervals and materialize after a generally distributed random amount of time. We reveal that under the infinite buffer assumption, the system possesses rather intriguing properties: on the one hand, the system is unstable in the sense that the buffer content is monotonically nondecreasing as a function of time. On the other hand, the likelihood that the buffer contents will exceed certain level B by time t diminishes with B. Improper simulation of such systems may therefore lead to false results. We turn to analyze this system under finite buffer assumption and derive bounds on the cell-loss rates. The bounds are expressed in terms of simple formulae of the system parameters. We carry out the analysis for two major types of networks: (1) datagram networks, where the packets (cells) traverse the network via independent paths and (2) virtual circuit networks, where all cells of a connection traverse the same path. Numerical, examination of ATM-like examples show that the bounds are very good for practical prediction of cell loss and the selection of buffer size     

Dynamic call admission control in ATM networks

The authors present dynamic call admission control using the distribution of the number of cells arriving during the fixed interval. This distribution is estimated from the measured number of cells arriving at the output buffer during the fixed interval and traffic parameters specified by users. Call acceptance is decided on the basis of online evaluation of the upper bound of cell loss probability, derived from the estimated distribution of the number of calls arriving. QOS (quality of service) standards can be guaranteed using this control when there is no estimation error. The control mechanism is effective when the number of call classes is large. It tolerates loose bandwidth enforcement and loose policing control, and dispenses with modeling of the arrival processes. Numerical examples demonstrate the effectiveness of this control, and implementation is also discussed     

Implementation of multipoint connections in an ATM switching network

This paper presents the problems in the implementation of multipoint connections at switching level using the example of an ATM switching network. By choosing the proper routeing mechanism and the appropriate architecture of the switching element, a switching network can gradually be adapted to an increasing share of multipoint traffic. The first section describes the problems with the handling of multipoint connections within a multiple stage connection oriented switching network. In particular this refers to the routeing of the cells through the switching network. Several alternatives on this issue are discussed. Both, the selected approach based on a differentiated self-routeing mechanism and the corresponding cell format are introduced. In the second part of this article several switch architectures are compared in respect of their multipoint capability. It is demonstrated that at present the most promising solution are switching elements based on the principle of central buffering. A single chip solution using this concept is employed in the presented switching network.     

Satellite ATM network architectures: an overview

A satellite ATM network has been envisioned as the next information super-skyway. There has been a migration from traditional bent pipe satellites to onboard processing ATM satellites. The current congestion in the Internet has motivated the use of alternate paths-using satellites to support global Internet transport and access. This article presents the various system and protocol layer architectures of SATM networks     

Parallel host interface for an ATM network

The design of a parallel protocol processing system for a host system connected to an asynchronous transfer mode (ATM) network is described. Interesting aspects of the design are that the AAL5 adaptation layer is realized in hardware directly on the network adapter, and that the network adapter semetric interfaces to a multiprocessor using the processor's memory bus. Support also exists for implementing parallel protocols up to and including the application layer. Parallel implementations of TCP/IP, ISO Session, and presentation protocols are outlined     

A cell loss recovery method using FEC in ATM networks

A cell loss recovery method to be applied to the virtual paths (VPs) of asynchronous transfer mode (ATM) networks is introduced. The method uses forward error correction (FEC). Its advantages over conventional methods on virtual circuits (VCs) include reduced coding/decoding delays and facility sharing. In addition to consecutive cell loss compensation, another feature of this method is that cell loss compensation facilities are only required at VP terminating nodes. When a cell is discarded due to buffer overflow, successive cells also tend to be discarded. Performance estimations show an outstanding reduction in cell loss rate     

Source-independent call acceptance procedures in ATM networks

Strategies for connection admission control in asynchronous transfer mode (ATM) networks are considered. Without any Poisson or renewal assumptions, two easily computable upper bounds on the time congestion in a finite buffer are derived. The first upper bound is valid for arbitrary peak and mean-rate-policed sources, whereas the second (and, in principle, tighter) bound is valid for sources of the on/off type. The tightnesses of the bounds are evaluated by a new periodic queuing model taking into account the maximum allowed burst duration. It is concluded that the bounds form a basis for a realization of a simple admission control algorithm. Furthermore, it is pointed out that the derivation of the on/off bound induces a decomposition of the queuing process into a cell-scale contribution and a burst-scale contribution, a decomposition which is superior to traditional Markov modulated approaches both in accuracy, and in offering insight into the queuing process     

A hybrid simulator for an ATM network

The efficient management of large interlinked broadband networks requires an efficient means of network simulation. Throughout the range of algorithms currently available, a trade‐off exists between accuracy and run‐time: Commercial cell‐level simulators successfully mimic specific network scenarios to a high degree of accuracy, but often require many hours of run‐time to produce statistically significant results. Conversely, analytical and probabilistic models yield rapid results for more general scenarios, but these usually lack the exactitude needed for network management purposes. This paper proposes a hybrid simulation structure within which an amalgam of different techniques may combine optimum accuracy within economical run‐time. The software suite applies a detailed cell‐level simulation to those regions of the network which are of specific interest, whilst using a faster but less accurate ‘fluid‐flow’ approximation to represent the network in general. This approach is shown to be both accurate and also economical in terms of computation time. Copyright © 2000 John Wiley & Sons, Ltd.