Recursive copy generation for multicast ATM switching

This paper describes the structure of a multicast asynchronous transfer mode (ATM) switching node employing a recursive copy generation algorithm, based on a self-routing network with a limited copying capability and a few added elements. With the network generates only a few copies a time of an input multicast cell, the remaining are obtained by recycling the output copies to the corresponding inputs as many times as necessary. The proposed recursive copy generation is also suitable to dynamically include new destinations and to delete old ones. The performance of the proposed structure, that has been implemented in a test-bed prototype, is also evaluated in terms of throughput and delay, via computer simulation, showing a possible performance improvement for multicast traffic with respect to an equivalent unicast input traffic. The cell loss probability in such structure is also evaluated     

Performance study of ATM multicast switching systems

We evaluate the performance of an N × N ATM discrete time multicast switch model with input queueing operating under two input access disciplines. First we present the analysis for the case of a purely random access discipline and subsequently we concentrate on a cyclic priority access based on a circulating token ring. In both cases, we focus on two HOL (head-of-line) packet service disciplines. Under the first (one-shot transmission discipline), all the copies generated by each HOL packet seek simultaneous transmission during the same time slot. Under the second service discipline (call-splitting), all HOL copies that can be transmitted in the same time slot are released while blocked copies compete for transmission in subsequent slots. In our analysis the performance measures introduced are the average packet delay in the input buffers as well as the maximum throughput of the switch. A significant part of the analysis is based on matrix geometric techniques. Finally, numerical results are presented and compared with computer simulations.     

Queueing analysis of ATM multicast switching models

The performance of a multicast switching system with a cyclic priority input access scheme is evaluated by means of an analytic model which may treat two distinct multicast switches in a unified way. The performance measure is the packet delay at the input buffer of the system. The analysis is subsequently performed using matrix-geometric techniques and the numerical results are compared with simulations     

Photonic access concentrator for ATM gigabit switching fabrics

In future broadband communication networks the interest for purely photonic switches is due to the bandwidth mismatch between optical transmission networks and electronic switching nodes. Photonic ATM switching fabrics mainly based on wavelength-switching stages are therefore being studied, to implement high capacity switches with also concentration, multiplexing and demultiplexing functions, using state-of-the-art photonic technology. The architecture of an ATM photonic access concentrator is described in this paper, illustrating the design and implementation of its basic subsystems, the traffic concentrator and the cell multiplexer. The design guidelines are outlined in detail referring to an example, where 128 user lines at 622 Mb/s are given access to 4 outlets at 2.488 Gb/s. The corresponding implementation, based on the systematic use of cell wavelength encoding, makes use either of well-known photonic components, such as Fabry-Perot filters, fiber delay lines, splitters and combiners, either of recently developed devices, like high-speed optical gates and tunable filters and lasers. Finally, the system feasibility is demonstrated presenting the results obtained on a reduced size and speed experimental setup of the cell multiplexer     

A dynamic packet reservation multiple access scheme for wireless ATM

The dynamic packet reservation multiple access (DPRMA) scheme, a medium access control protocol for wireless multimedia applications, is proposed and investigated. DPRMA allows the integration of multiple traffic types through a single access control mechanism that permits users to specify their immediate bandwidth requirements. The primary feature of DPRMA is the dynamic matching of the traffic source generation rates with the assigned portion of the channel capacity. This is accomplished by a control algorithm that regulates the actual amount of channel capacity assigned to users. To support multimedia communication, channel capacity assignments are prioritized by traffic type. The performance of the scheme is evaluated and the scheme is shown to perform well in a system with voice, video conferencing, and data users present. It is also shown to provide improved performance over a system with a modified version of the packet reservation multiple access (PRMA) scheme. Furthermore, several system parameters are studied and optimized.     

A multiple access scheme for multimedia traffic in wireless ATM

This paper proposes a multiple access scheme for the forthcoming wireless ATM (Asynchronous Transfer Mode) system. Such ATM compatible wireless systems are motivated by the rapidly increasing demand for wireless extensions to broadband networks, which are expected to support mixed broadband services including Constant Bit Rate (CBR), Variable Bit Rate (VBR), and Available Bit Rate (ABR) traffic. Since these different traffics have very different performance requirements, the multiple access scheme design is very challenging. In this paper, we propose a multiple access scheme called Dynamic Time Division Multiple Access with Piggybacked Reservation (DTDMA/PR), attempting to achieve higher statistical multiplexing efficiency in the mixed VBR/CBR/ABR traffic scenario. The basic idea is to exploit two levels of reservation. The first level deals with the isochronous nature of CBR and VBR traffic and the bursty nature of ABR traffic by using the ALOHA reservation procedure. The second level exploits the piggybacked reservation approach to cope with the dynamic feature of VBR traffic in order to increase the multiplexing efficiency. An analytical model is also developed in this paper and verified by simulation. Numerical examples are given to gain some insight into the protocol itself.     

The split-switching network (SSN): A high-performance multicast ATM switch

This paper proposes a new high-performance multicast ATM switch architecture. The switch, called the split-switching network (SSN), is based on banyan networks. The SSN achieves multicasting in a way that is non-typical for banyan-based switches: copying and routeing of multicast cells are carried out simultaneously and within the same fabric. Thus, cells are copied only when needed as they traverse the switch towards the appropriate output ports. The SSN consists of successive spliting stages, and buffering is provided in front of each stage. The SSN is non-blocking with complexity of order Nlog2/2N for a switch of size N, and is characterized by distributed and parallel control. The throughput-delay performance of the SSN is shown to be similar to that of a non-blocking output-buffering switch under different mixtures of unicast/multicast traffic. In particular, the SSN achieves a maximum throughput of 100 per cent and the cell delay and delay variation remain small for loads just below the maximum throughput.     

New retiming and synchronisation scheme for optical ATM switching systems

A new signal format and retiming method for optical ATM switching systems is proposed. An input signal is transformed to an optical signal with a unique word as a guard time for switching. A common optical receiver can be used for bit synchronisation, and logic gates can achieve cell synchronisation using this new optical signal format.<>     

Tbit/s switching scheme for ATM/WDM networks

A new high capacity, reservation-based switch architecture for ATM/WDM networks is presented. The scheme is contention-free and highly flexible yielding a powerful solution for high-speed broadband packet-switched networks. Switching management and control are studied for data rates of up to 10 Gbit/s/port, providing and aggregated throughput of over 1 Tbit/s     

点对多点ATM交换网络的实现与性能分析

本文中 ,我们基于Knockout交换结构 ,提出了一种能实现点到多点交换的ATM交换结构 ,并对其性能进行了分析 ,然后通过模拟证明该方法有较好的性能     

A note on optimal input control policy for an Aloha access scheme

Input control policies had been proposed previously (e.g. in Lam and Kleinrock, 1975; and Fayolle et al., 1977) to improve the delay-throughput performance of Aloha access schemes. Through simulation results, Lam and Kleinrock observed that the optimal control policies were in general of control limit type. The authors discuss input control policies for one such Aloha access scheme and prove analytically that the optimal policy is indeed of the control limit type. The optimal policy is found to be extremely simple for the access scheme discussed. This policy is to accept the newly arrived packet if the present system state is either zero or one, and to reject the packet otherwise     

SDRAM: a SD channel-based multicast scheme on ATM networks for multimedia transmissions

Multicast delivery has become more and more important in modern multimedia applications. VoD and videoconferences are two examples. Multimedia integrates texts, audios, videos and still images in a variety of applications. The data in this media can be time critical in terms of maximum delay and delay jitter. In order to satisfy all these applications, the network needs to have an efficient multicasting mechanism using the true capability of ATM networks. In the native solution, a separate connection can be set up from the source to each group node, also called full connectivity. The full connectivity needs O(N/sup 2/) connections, where N is the number of nodes in a group. Instead, we can have one tree spanning all the participants. Multicast using a single shared tree has become the trend. In this paper, we propose a bi-directional multipoint-to-multipoint multicast scheme, a SD channel-based Multicast with Round-robin Access (SDRAM), for ATM networks, which uses a single tree for a multicast group consisting of multiple participants that are either senders, receivers, or a mix of both. We first discuss why the resequencer model will not be suitable for multimedia traffic, then propose the SDRAM scheme to solve the problems, and finally compare our scheme with the resequencer model through simulation. Results show the mean queuing delays and mean inter-PDU delays of our scheme are not sensitive to mean PDU size while the mean queuing delays and mean inter-PDU delays of the resequencer scheme are very sensitive to mean PDU size.     

Queueing performance of copy networks with dynamic cell splittingfor multicast ATM switching

This paper analyzes and compares the queueing performance of copy networks for multicast ATM switching. Both nonbuffered and input-buffered copy networks are studied. Particularly, the shared-input-buffering approach is investigated, and the performance improvement obtained by employing the buffer in the network is demonstrated. The effectiveness of the dynamic cell splitting scheme is presented as well     

A multiple access scheme for wireless access to a broadband ATM LANbased on polling and sectored antennas

An adaptive polling scheme for multiple access in a broadband wireless local area networks (LANs) is proposed. It is designed to accommodate asynchronous transfer mode (ATM) traffic with a large and variable range of bit rates. The radio architecture is microcellular, with switched sectored-beam antennas and a small frequency reuse factor. Features of the multiple access scheme include polling rate depending on a terminal's average bit rate, fixed-length frames divided into segments corresponding to base antenna sectors, and automatic-repeat-request (ARQ) for error control, combined with randomized sector segment ordering. The steady-state performance (cell loss, call blocking and dropping probabilities, waiting time, and buffer occupancy) are evaluated by simulation for an open indoor environment, and for handoff, ARQ, and simple power control enhancements; focusing mainly on the effects of the propagation and interference conditions     

A large scalable ATM multicast switch

This paper focuses on designing a large N×N high-performance broad-band ATM switch. Despite advances in architectural designs, practical switch dimensions continue to be severely limited by both the technological and physical constraints of packaging. Here, we focus on augmentation in a “single-switch” design: we provide ways to construct arbitrarily large switches out of modest-size components and retain overall delay/throughput performance. We propose a growable switch architecture based on several key principles: 1) the knockout principle exploits the statistical behavior of cell arrivals, and thereby reduces the interconnect complexity; 2) output queueing yields the best possible delay/throughput performance; 3) distributed control in routing (multicast) cells through the interconnect fabric without internal path conflicts; and 4) simple basic building blocks facilitate scalability. Other attractive features of the proposed architecture include: 1) intrinsic broadcast and multicast capabilities; 2) built-in priority sorting functionality; and 3) the guarantee of first-in, first-out cell sequence, To achieve 10^-14 cell loss probability, only maximum size 32×16 basic building modules are required, and no crossover interconnects exist between modules in a three-dimensional configuration     

A nonpreemptive priority-based access control scheme for broadbandad hoc wireless ATM local area networks

The DQRUMA (distributed-queueing request update multiple access) protocol has been considered as an access protocol for the BAHAMA (broadband ad hoc wireless ATM local area network). However, it cannot support the service discipline of integrated multimedia traffic since it does not include any priority and access control policy. In this paper, we propose a nonpreemptive priority-based access control scheme for the DQRUMA protocol. Under such a scheme, modifying the CSMA/CA protocol in the contention period supports many levels of priorities such that user mobility (handoff) can be supported in BAHAMA. Besides, the proposed transmit-permission policy and adaptive bandwidth allocation scheme provide various QoS (quality-of-service) guarantees while maintaining high bandwidth utilization. Simulations show that it provides a good performance in ad hoc wireless ATM LAN environments     

Write policies for multicast ATM switches

A unicast and multicast-pushout write policy for shared-memory ATM switches is proposed. The scheme allocates buffers based on the service rates of unicast and multicast cells to ensure that maximum throughput can be maintained     

Fast scheduling algorithm for input and output buffered ATM switchwith multiple switching planes

A new scheduling method is presented, two-dimensional round-robin scheduling with multiple selections (2DRRMS), for an input and output buffered ATM switch. In the switch, both input and output ports are divided into several groups and multiple switching planes are used. In the 2DRRMS method the multiple cells for transfer to an input buffer module are selected and the switching planes which the selected cells are to use in the transmission are concurrently determined     

A novel switching architecture for ATM networks

It is known that the flexibility and capacity of asynchronous transfer mode (ATM) networks can meet the bandwidth requirements of multimedia applications. In ATM networks, switching is one of the major bottlenecks of end-to-end communication. We propose using a multiple partitionable circular bus network (MPCBN) as an ATM switch. Connection requests are first transformed into a graph where vertices and edges represent connection requests and conflicts among connection requests, respectively. We then use a graph traversal algorithm to select a maximal set of requests for execution in physically partitioned buses. An approach of using finite projective planes is then used to reduce the number of switch points from O(N²) to O(N √N), where N is the number of ports of a switch. A performance evaluation for both uniform and bursty data sources shows that the approach of using finite projective planes to reduce the number of switch points results in a small increase of cell loss probability     

有/无线ATM网的组播选路算法

本文提出一种组播选路算法,在组播连接路由树的代价函数中计入了移动成员的越区切换发生概率,使为移动成员服务的接入节点（ＡＰ）尽可能成为组播路由树的树叶节点。当移动成员发生越区切换以后,可减去原来为之服务的ＡＰ和相应的树枝通道链路,从而保证了网络资源得以有效地利用。数值模拟分析的结果表明,我们提出的算法达到了这一目的。