A broadband central office for ATM

Recently, a growing interest has been shown towards fast packet switching, ATD (asynchronous time division), or the more general term ATM (asynchronous transfer mode) in a number of companies and organizations such as CCITT and RACE. In Belgium a broadband experiment is planned using this technique. This paper focuses its attention on the central office (switching exchange). This exchange is a multistage network constructed with independent switching elements based on the self-routing principle. The load control in the exchange is provided by a static load control mechanism applied to the logical connections granted on these links. Simulation results show that this load control mechanism can work perfectly if used in the proper environment.     

Advanced internetwork design — today and in the future

This paper highlights the current approach to large-scale internetwork design using today's network layer routeing protocols. It describes how large internetworks can be constructed to provide stability, resilience and scalability, together with a set of best practice design guidelines for those involved in the planning of large data networks, highlighting the key issues to be considered. The paper looks at how new technologies are likely to enhance this design approach, in particular, how the full potential of cell switching can be realised through emerging technologies such as integrated switching and routeing. The paper concludes that the model proposed for large-scale networks based on current routeing protocols and technologies can be enhanced to make optimum use of switched WAN services such as ATM, through the use of newer routeing technologies.     

Advances in data networking

This paper highlights the current approach to large-scale internetwork design using today's network layer routeing protocols. It describes how large internetworks can be constructed to provide stability, resilience and scalability, together with a set of best practice design guidelines for those involved in the design of large data networks, highlighting the key issues to be considered. The paper looks at how new technologies are likely to enhance this design approach, in particular, how the full potential of cell switching can be realised through emerging technologies such as integrated switching and routeing. The paper concludes that the model proposed for large-scale networks based on current routeing protocols and technologies can be enhanced to make optimum use of switched WAN services such as ATM, through the use of newer routeing technologies.     

片上网络交换机制的研究

随着半导体技术进入超深亚微米时代,人们已经可以将越来越多的器件集成到单一芯片上来。运用传统的片上总线结构进行通信将面临诸多问题,如可扩展性差、定时困难和无法提供并行通信能力等,所以要运用片上网络来满足片上通信的带宽和能耗要求。本文研究了片上网络中的一项关键技术——交换机制。交换机制定义了消息在网络中交换的方式,并规定了沿输出端口将消息转发出去的时机。文章对片上网络中常用的电路交换、分组交换、虫孔交换和虚切通交换等进行了分析,并从能耗、面积、时延以及吞吐等性能方面进行了对比,给出了有益于片上网络沿用的结论。     

Performance of a broadcast packet switch

The results of a simulation study undertaken to evaluate a high-performance packet-switching fabric supporting point-to-point and multipoint communications are presented. This switching fabric contains several components, each based on conventional binary routing networks. The most novel element is the copy network, which performs the packet replication needed for multipoint connections. Results characterizing the performance of the copy network are presented. Several architectural alternatives for conventional binary routing networks are also evaluated. For example, the performance gains obtainable by using cut-through switching in the context of binary routing networks with small buffers are quantified. One surprising result is that networks constructed from nodes with more then two input and output ports can perform less well than those constructed from binary nodes. This result is quantified and explained     

140Mb/s宽带交换网络的设计

本文论述了宽带交换机里的关键部件——宽带交换网络的基本原理,着重讨论了在使用中规模高速集成电路设计宽带交换矩阵的过程中应注意的一些问题,并力图给出了基本的解决方法。本设计方案的指导思想之一是全部采用国内组件,这无疑对宽带网的国产化有着极重要的意义。     

Efficient algorithms for multiple destinations routeing

A number of important problems in computers and telecommunications, such as distributed databases and multipoint multimedia conferencing, all require the solution of a generic problem called multiple destinations routeing (MDR). In this paper, we formulate the MDR problem as a zero-one integer programming problem and propose a technique to reduce the computation required for the optimum solution. Three heuristics are designed for large MDR problems. Heuristic A can offer different degrees of optimality with different amounts of time allowed for the solution. Heuristic B is a modification of Prim's algorithm for the minimum spanning tree. It gives a fairly good solution with very little computation. Heuristic C is based on Heuristic B and is for minimizing the number of edges in the multicast tree (i.e. assuming that all edge weights are the same). It always gives a better solution than Heuristic B. Simulation on two example networks shows that Heuristics A and C always give better solutions (or lower cost connection paths) than the improved RS algorithm, which has up to now been the best heuristic.     

LOBS技术研究

光突发交换技术(OBS)是一种新出现的光交换技术,它综合了光波长路由和光分组交换的优点。本文的LOBS又将MPLS 和OBS这两大技术结合在一起,利用MPLS强大的控制能力为OBS网络在QoS、流量工程和网络恢复等方面提供良好的支持。文章根据LOBS的基本原理,提出并详细阐述了它的网络构成和工作机制,最后指出了LOBS网络在流量工程和网络生存性方面相对其他光网络的优越性。     

A high-performance switch fabric for integrated circuit and packet switching

This paper describes an architecture for a high-performance switching fabric that can accommodate circuit-switched and packet-switched traffic in a unified manner. The switch fabric is self-routeing and uses fixed-length minipackets within the switching fabric for all types of connections. Its kernel architecture is based on a routeing topology with individual connection paths from all inputs to all outputs and with FIFO queuing at each output. Owing to the disjoint connection paths, there is no internal blocking, and because of output queueing, output port blocking is prevented to a great extent. The uniformity in architecture allows construction of any size fabric from a single basic module which could be realized on a single chip. Larger-size configurations can be realized either as single-stage or multistage configuration. The second part of this paper discusses performance aspects and gives results and dimensioning guidelines for both circuit-switched and packet-switched traffic.     

Comparison of ATM switching architectures

Clear examination of work currently done within CCITT indicates the importance of a broadband telecommunication network. As this network should be capable of integrating all services in an efficient way—in order to reduce cost—the asynchronous transfer mode (ATM) was selected by CCITT as the target transfer mode for implementing the broadband integrated services digital network (BISDN). This selection implies that the switching nodes in the BISDN network are capable of supporting this high-speed packet and connection-orientated technique. Within the literature different switching node architectures based upon ATM have been proposed. All of these architectures should meet the high-speed and high-throughput requirements so as to cope with the delay and jitter performance objectives. In a first step this paper describes alternative switching techniques for the basic building block (switching element) of a switching node. A common model architecture of the switching element is drafted. A classification of switching elements described in the literature is derived and the influence on the complexity and performance is weighted. In a second step the switching node architecture is further elaborated according to the control and flexibility requirements. Core (switching) and edge (switching related) functions are listed, and possible functional partitionings are discussed. Finally, these ATM switching architectures are compared according to a background frame consisting of several straightforward comparison points such as the buffering strategy, the internal routeing method, the switching overhead, the connection-orientated or connectionless operation, etc.     

A Multirate Switching Network for Broadband Channels

A broadband ISDN switching network model is presented, switching the channel types H2, H3, and H4 envisaged by the CCITT. The synchronous time division multiplex technique is applied. The switching network operates at the basic bit rate of the H2-channel; H3and H4-connections are established via multichannel connections of up to four basic channels. H2-connections which are part of one H3- or H4-connection always have to use common interconnection links. This is a favorable solution to keep digit sequence integrity for multichannel connections, but influences blocking characteristics of the switching network. The implementation of an optimal path selection method plays a fundamental role. In such a multichannel switching network, blocking probabilities for H2-, H3-, and H4-connections must be distinguished. They do not only depend on the total offered load, but also on the proportions of H2-, H3-, and H4-connections (traffic mix). The simulation results presented in this paper prove that multirate switching via multichannel connections is feasible for the broadband channel types H2, H3, and H4, and that the proposed switching network has a sufficiently high traffic capacity whatever the traffic mix may be.     

Topology evolution model for ad hoc‐cellular hybrid networks based on complex network theory

Switching and routing are two important issues in the ad hoc‐cellular hybrid network. Frequently switching between different network modes will lead to the increase of time delay, and unreasonable routing will reduce information transmission efficiency and shorten the network life. In order to reduce the influence of these problems to the network, in this paper, we proposed a robust and efficient ad hoc network topology evolution model, which can reduce the switching probability and establish efficient transmission paths. In this model, the mobile users' residual energy, available channel quality, and the importance are taken into account. The model is based on Barrat, Barthelemy, and Vespignani model and the triad formation mechanism, which ensures the network topology have scale‐free and small‐world features. The topology construction process of the ad hoc network is composed of three parts: (i) new users join the network; (ii) new users establish connections with existing users; (iii) the connections between existing users were deleted because of the network optimization and the interference of cellular network. Simulation results show that the network built by this model with small‐world and scale‐free features has small average shortest path length and the robustness against random nodes failure, which will significantly improve the transmission efficiency and reduce the probability of switching between different transmission model. Copyright © 2016 John Wiley & Sons, Ltd.     

Performance of a Service Independent Switching Network with Distributed Control

This paper describes a switching network which is service independent and able to transport services of any bit rate, based on the fast packet switching concept. The control of the switching network is completely distributed; the path select is not centrally controlled, but gradually performed as the control packet is passing through the switching network. The switching network is a multistage network constructed with independent switching elements. The self-routing principle is applied. The load control of the different links between the switching elements in the network is provided by a static load control mechanism, applied to the logical connections granted on these links. Logical connections are accepted or rejected according to the already present load on each link. Possible overload caused by bursty traffic is solved by buffers within the switching elements. Simulation results are discussed, both for the static and dynamic behavior of the exchange. For both simulations, a large mix of different services is evaluated and conclusions are described.     

Nonblocking copy networks for multicast packet switching

In addition to handling point-to-point connections, a broadband packet network should be able to provide multipoint communications that are required by a wide range of applications. The essential component to enhance the connection capability of a packet network is a multicast packet switch, capable of packet replications and switching, which is usually a serial combinations of a copy network and a point-to-point switch. The copy network replicates input packets from various sources simultaneously, after which copies of broadcast packets are routed to their final destination by the switch. A nonblocking, self-routing copy network with constant latency is proposed. Packet replications are accomplished by an encoding process and a decoding process. The encoding process transforms the set of copy numbers, specified in the headers of incoming packets, into a set of monotone address intervals which form new packet headers. The decoding process performs the packet replication according to the Boolean interval splitting algorithm through the broadcast banyan network, the decision making is based on a two-bit header information. This yields minimum complexity in the switch nodes     

High-Performance Hybrid-Switching Optical Router for IP over WDM Integration

Because pure electrical routers with their bandwidth limitations can hardly keep up with the tremendous traffic growth in the Internet, optical routers based on various optical switching techniques including optical wavelength switching (OWS), optical burst switching (OBS), and optical packet switching (OPS) have been suggested to cope with this problem. However, because OBS and OPS are both in their early experimental phase and OWS only provides coarse granularity switching, a hybrid-switching optical router with combined OWS and electrical packet switching is a necessity in order to accommodate the entire multi-granularity traffic with multi-service requirements in a cost-effective manner. Its coordination capability of optical circuit switching and electrical packet switching enables efficient/intelligent usage of network resources. In this paper, we first review research and developments of such IP routers employing optical switching/interconnection techniques and examine how these techniques can be used inside routers to scale node capacity and to improve optical Internet performance. We also present and study the performance of a terabit optical router with an optical-electrical hybrid-switching fabric. The node architecture is based on the idea of IP over WDM integration with Generalized Multi-Protocol Label Switching (GMPLS). The network-level performance evaluations show that the proposed hybrid-switching optical router is a cost-effective solution for building the next generation GMPLS-based multi-granularity optical Internet.     

Peer-to-peer multipoint videoconferencing on the Internet

A peer-to-peer architecture for multipoint videoconferencing is presented. Each conference participant may have asymmetric and dissimilar bandwidth connections to the Internet. The solution does not require additional hardware, as in multipoint control units, or network infrastructure support such as multicast. Without creating any additional demand on the networking and computing resources needed for a point-to-point videoconference, this architecture can extend it into a multipoint one. A protocol for a completely distributed implementation has been developed and tested on a prototype system extending a point-to-point video phone to a multipoint one. The architecture of the prototype system along with the details of the protocol optimization is discussed. Several performance results are presented.     

下一代光传送网ASON

提出当今解决光传送网所面临问题的方法,是采用既能低成本建网又能智能化完成交换连接的自动交换光网络( ASON );介绍回顾了光传送网 ASON 技术的产生和取得的成果,以及 ASON 中几种关键控制平面技术的发展情况;阐述了 ASON 控制平面与传统传送网的本质区别、管理平面智能化管理特点所带来的 3 种优点,以及传送平面中光交叉连接( OXC )的 6 种主要交换结构、发展方向和存在的主要问题;最后综述了新一代基于数字同步系列(SDH )提供多种业务、集成传输、交换和路由功能的多业务传送平台(MSTP )技术,并描述其新功能和远期目标。     

Back-end-of-line compatible Conductive Bridging RAM based on Cu and SiO2

Conductive Bridging RAM (CBRAM) is a promising candidate for future non-volatile memories. This technology is based on the change of the cell’s resistive state, due to formation and dissolution of a metallic filament through an insulating layer. In this work we study Cu/SiO₂ cells fabricated using standard back-end-of-line (BEOL) processes, making them low-cost and easy to integrate. We show evidence of reproducible electrical switching, without the need of an annealing post-treatment. Furthermore, the kinetic behaviour of the switching mechanism was studied using electrical experiments.     

ATM交换结构——多级互连网络

ATM交换结构是ATM交换的关键技术之一,而多级互连网络(MIN)以其优异特性在 ATM交换中得到广泛应用。本文介绍了 MIN 的分类、拓扑结构、缓冲策略和控制机理。