NEAX61程控交换机设备配置浅析

介绍了NEAX61程控交换机的基本容量参数——话务负荷能力、呼叫处理能力和出线数;运行环境及环境参数(用户话务量、局间话务量和平均呼叫占用时长)的准确取值;如何配置NEAX61程控交换机设备。     

日本电气公司的NEAX61交换系统正向宽带ISDN发展

NEAX61交换系统是一种数字交换系统,它的容量可以从几百门直到十万门。NEAX61交换系统是使用所谓“一部机器的概念”来设计的,模块化结构和模块间的标准接口便于容量增加和开展ISDN业务时进行积木式的扩展。NEAX61交换系统可以具有ISDN性能。它的一个显著特点是对于所有类型的配置都使用相同的人机接口(MMI)。NEAX61交换系统的ISDN应用同时提供了基本入口和一次群入口的接口。然而,为了支援更高速的和频带更宽的电     

NEAX61E程控数字交换机

本文概要介绍了NEAX61E程控数字交换系统的应用和容量范围、硬件系统结构和功能实现,及其软件系统的组成、功能和特征,可供了解程控交换机的人参考,也有助于对NEAX61E系统进行深入的探讨。     

NEAX61正在1002个交换网络中服务

据《Telephony》1987年4月刊报道:NEC数字交换设备——NEAX16系统在世界上各数字网络中起着重要的作用。这种交换机为模块式结构,它采用了先进的硬件和软件技术,能给用户提供优质服务。现在NEAX61已在37个国家1002个交换局中运营。     

NEAX61Σ与其它交换机ISUP信令的配合

通过对NEAX61Σ交换机ISUP信令中的iam信号进行分析和局数据的修改,以及利用该交换机所具备的局数据信号屏蔽功能,解决了NEAX61Σ交换机与其它制式交换机之间ISUP信令配合的问题,提高了NEAX61Σ交换机的适应能力。     

天津NEC举办NEAX61∑综合业务交换机技术交流会

由中国通信学会、天津NEC共同组织的天津NEAX61Σ综合业务交换机技术研讨会于6月13日—14日在天津举行。来自全国部分省、自治区、直辖市邮电管理局局长、、总工、计建处、电信处、引进办等部门的主要领导和专业人员100多人参加了此次研讨会。 NEAX61Σ是未来ATM通用网络的交换平台,它将提供未来多媒体业务,增加ATM交换功能使业务节     

NEAX61Σ虚拟用户交换机的功能

介绍了虚拟用户交换机(Centrex)的概念、编号方案 ,以及NEAX61Σ交换系统所提供的Centrex功能的特点、商业用户组的建立及用户附加业务等等。     

几种制式的数字程控交换机控制系统及话路系统比较

本文从硬件角度介绍广东省引进的主要三种制式（NEAX61、AXE10、S1240）的数字程控交换机其两大组成部分－控制系统和话路系统的结构特点、工作方式，定性定量地加以论述。着重从可靠性，初次投资、处理机的呼叫处理能力（BHCA）等方面对上述三种制式交换机的控制方式进行比较；并从用户级结构及交换网络结构的特点总结出三种机型的话务负荷能力，以便对这三种制式交换机不同的性能、特点进行比较。     

NEAX61∑交换机利用现有的资源提高接通率的两种方式

介绍了灵活运用NEAX61∑交换饥现有的软硬件资源，修改adc和rlst数据后能使用语音信箱的有关功能，进而提高落地接续接通率的两种方法。     

NEAX61∑虚拟用户交换机的功能

介绍了虚拟用户交换机(Centrex)的概念、编号方案,以及NEAX61∑交换系统所提供的Centrex功能的特点、商业用户组的建立及用户附加业务等等。     

Resource allocation for broadband networks

The major benefit of a broadband integrated ATM (asynchronous transfer mode) network is flexible and efficient allocation of communications bandwidth for communications services. However, methods are needed for evaluating congestion for integrated traffic. The author suggests evaluating congestion at different levels, namely the packet level, the burst level, and the call level. Congestion is measured by the probabilities of packet blocking, burst blocking, and call blocking. He outlines the methodologies for comparing these blocking probabilities. The author uses the congestion measures for a multilayer bandwidth-allocation algorithm, emulating some function of virtual circuit setup, fast circuit switching, and fast packet switching at these levels. The analysis also sheds insight on traffic engineering issues such as appropriate link load, traffic integration, trunk group and switch sizing, and bandwidth reservation criteria for two bursty services     

ATM traffic management and congestion control using fuzzy logic

The paper focuses on the use of fuzzy logic in network management, ATM congestion control, and ATM switching. The ATM network management ensures traffic agreement at the source level in order to prevent congestion situations from occurring. The paper reviews work in the area of traffic policing and introduces a scheme for improving the performance of a fuzzy policer. The ATM fuzzy switch introduced, enhances the capabilities of the ATM switch, one of the most critical elements in the ATM network     

Edge‐Node Deployed Routing Strategies for Load Balancing in Optical Burst Switched Networks

Optical burst switching is a promising switching paradigm for the next IP‐over‐optical network backbones. However, its burst loss performance is greatly affected by burst contention. Several methods have been proposed to address this problem, some of them requiring the network to be flooded by frequent state dissemination signaling messages. In this work, we present a traffic engineering approach for path selection with the objective of minimizing contention using only topological information. The main idea is to balance the traffic across the network to reduce congestion without incurring link state dissemination protocol penalties. We propose and evaluate two path selection strategies that clearly outperform shortest path routing. The proposed path selection strategies can be used in combination with other contention resolution methods to achieve higher levels of performance and support the network reaching stability when it is pushed under stringent working conditions. Results show that the network connectivity is an important parameter to consider.     

基于多令牌桶流量整形算法的研究与设计

针对高速数据网络包交换系统中存在的拥塞问题,分析研究现有解决网络拥塞的流量整形技术,提出支持多组队列整形的多令牌桶算法,并通过VLSI设计方法实现了该算法．采用SMIC0．13μm标准CMOS工艺库综合,工作频率达到185MHz,行为级仿真及综合结果表明,该算法硬件实现简单,能有效的对包交换网络进行流量整形．     

ATM交换机IP业务QoS的设计与实现

ATM（异步转送模式）交换机由于执行了严格的基于连接的流量管理和拥塞控制,能为用户提供良好的QoS（服务质量）保证,在骨干网中得到了广泛应用。但是随着IP业务应用越来越广泛,如何解决IP Over ATM（基于ATM的IP数据传输）在各种情况的QoS,是ATM交换机设计面临的重要问题。文中以ATM交换机互连的以太网接口（IP接口）和中继接口（ATM接口）为例,对ATM交换机如何实现IP业务的QoS,提出了一套完整的设计和实现方案。     

Performance analysis of reactive congestion control for ATMnetworks

In ATM networks, preventive congestion control is widely recognized for efficiently avoiding congestion, and it is implemented by a conjunction of connection admission control and usage parameter control. However, congestion may still occur because of unpredictable statistical fluctuation of traffic sources even when preventive control is performed in the network. The authors study another kind of congestion control, i.e., reactive congestion control, in which each source changes its cell emitting rate adaptively to the traffic load at the switching node (or at the multiplexer). The intention is that, by incorporating such a congestion control method in ATM networks, more efficient congestion control is established. They develop an analytical model, and carry out an approximate analysis of reactive congestion control algorithm. Numerical results show that the reactive congestion control algorithms are very effective in avoiding congestion and in achieving the statistical gain. Furthermore, the binary congestion control algorithm with push-out mechanism is shown to provide the best performance among the reactive congestion control algorithms treated     

一种基于跳数和时延的MPLS自适应流量工程算法

提出了一种基于跳数和时延的MPLS自适应流量工程算法，该算法根据LSP的跳数和时延来进行流量分配，从而减少由传统路由算法而引起的网络拥塞，优化网络资源的利用。仿真结果表明，该算法简单易行，性能良好。     

Congestion control for multimedia services

The problem of congestion control in high-speed networks for multimedia traffic, such as voice and video, is considered. It is shown that the performance requirements of high-speed networks involve delay, delay-jitter, and packet loss. A framing congestion control strategy based on a packet admission policy at the edges of the network and on a service discipline called stop-and-go queuing at the switching nodes is described. This strategy provides bounded end-to-end delay and a small and controllable delay-jitter. The strategy is applicable to packet switching networks in general, including fixed cell length asynchronous transfer mode (ATM), as well as networks with variable-size packets     

Request rate control for QA services in DQDB/SMDS–ATM gateways

By the advancement of B-ISDN, ATM has been accepted as the future technology to integrate a variety of services as it is a fine comprise between circuit switching technology and packet switching technology. A cost-effective and simple way to realize the global network is to implement a backbone such as DQDB to interconnect the existing LANs and MANs to ATM. The major advantages of DQDB are the complete compatibility of different layers, the capability of handling real-time and non-real-time traffic and little degradation in delay performance with increase in network span and density. However, a major issue of concern in the design of a DQDB/SMDS–ATM gateway is the transparent transfer of non-real-time traffic, as ATM is basically connection-oriented in nature. In the absence of flow control schemes in high-speed networking, some sort of congestion control mechanism becomes an absolute necessity to reduce the cell loss ratio to the minimum and thus wastage in the network resources. In this paper we discuss the transfer of connectionless traffic in a DQDB–ATM interconnection. One of the two congestion control mechanisms for DQDB networks that we have proposed is discussed in detail. In the request rate control mechanism the bandwidth utilization in DQDB is restricted by controlling the request rate from the gateway. DQDB networks interconnected by gateways are modelled and simulated. The request rate congestion control mechanism is evaluated. Simplicity in implementation and effectiveness in performance are the highlights. © 1998 John Wiley & Sons, Ltd.     

Dynamic burst discarding scheme for deflection routing in optical burst switching networks

This paper proposes a dynamic burst discarding scheme for deflection routing in optical burst switching networks. In general, deflection routing is effective in lightly loaded situations, whereas it has a contrary effect in congested networks because deflected bursts accelerate network congestion. Thus deflection routing should be employed in lightly loaded networks. Incoming traffic, however, varies in time and location, so that temporal and/or local congestion cannot be avoided. Our proposed scheme resolves this problem in the following way. Each node autonomously detects congestion with local information, and bursts to be deflected are discarded in a probabilistic manner, based on the degree of detected congestion and the numbers of elapsed and remaining hops of those bursts. Simulation experiments show that when congestion happens temporarily, the proposed scheme reduces the burst loss probability, and it utilizes network resources efficiently when local congestion happens.