The development of performance and availability standards forsatellite ATM networks

ATM services can be transported successfully over satellites provided adequate consideration is given to the specific characteristics of satellite communication systems and their interoperability with the terrestrial network. To establish end-to-end performance and availability standards, the ITU has developed recommendations for ATM intended to provide the quality of service and availability required by the end user. This article discusses the work of ITU-R Working Party 4B in developing recommendations that deal with the performance of ATM over satellites and with the availability objectives for ATM transport over satellites. Several issues are also identified for future work, in particular those pertaining to the characteristics of the new proposed satellites (LEOs, MEOs, GEOs) that will operate at frequencies higher than 15 GHz and those that plan to deploy ATM onboard processing or switching and intersatellite links     

TMN-based customer network management for ATM networks

Effective end-to-end management of today's globalized heterogeneous corporate customer networks, a mixture of ATM WANs and ATM LANs, is essential for customers at the cutting edge of technology. ATM WAN and ATM LAN management systems generally have different management policies and management information models. Studies on the customer network management system (CNMS) to realize end-to-end customer network management have thus adopted the telecommunications management network (TMN) interoperability concept, which is based on CNM manager and agent interoperation. This article proposes an end-to-end customer network management method that realizes interoperation. In order to realize configuration management, fault management, and performance management, the CNM agent extracts the information needed by CNMS from the ATM transport network operations system and controls the operations system accordingly     

利用DWDM实现核心网络的光网络互联

光网络互联实现了综合ＩＰ、ＡＴＭ、ＳＯＮＥＴ／ＳＤＨ和ＤＷＤＭ技术的低成本网络。ＤＷＤＭ技术彻底改变了核心网络,在ＤＷＤＭ配置的第二阶段,ＩＰ路由器和ＡＴＭ设备直接连接到ＤＷＤＭ,省去了ＳＯＮＥＴ／ＤＳＨ和ＡＴＭ,降低了成本,简化了扩容。光网络互联多数利用了现有标准,但新技术、新网络元素的引入同多带来了互操作问题,因此必须建立开放的ＤＷＤＭ系统,这也将推动光网络互联标准的发展。     

Trends in the standardization of telecommunications on GII,multimedia, and other network technologies and services

Global standardization is becoming more and more important in achieving a global information infrastructure (GII). Telecommunication and information standardization organizations such as the International Telecommunications Union (ITU) and International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) Joint Technical Committee (JTC) have each set up special groups to focus on determining standards for GII. This article presents the activities of these organizations as they relate to GII. It also reviews the current status of standards for multimedia, asynchronous transfer mode (ATM)/broadband integrated services digital network (B-ISDN), Universal Personal Telecommunications (UPT), Future Public Land Mobile Telecommunication System (FPLMTS), and telecommunications management network (TMN), which are all key elements in GII     

TMN-based broadband ATM network management

ATM has rapidly transitioned from a standards and prototyping concept to become the next-generation switching technology used in products available on the market. With the rapid introduction of ATM switches into networks, there is an urgent need to manage them. The article discusses the telecommunication management network (TMN) interfaces being defined for management systems to communicate with ATM network elements (NEs) and other management systems. ATM management systems will have to communicate with ATM NEs in their jurisdiction using TMN interfaces. Networks will usually contain equipment from different suppliers. Thus, it is vital that there be standard management interfaces so that these different NEs can be managed. Some standard interfaces for ATM networks are defined, while others are being defined. The status of these interfaces is reviewed in the article. Communication between different networks is also needed, both between public networks and between public and private networks. Management personnel of one network need to exchange information with other networks for certain functions (e.g., initial service provisioning), and so management systems of different networks will exchange information through a combination of mechanized and manual interfaces. The status of these interfaces is also reviewed in the article     

网元观点的PDH光传输系统信息模型研究（续前）

本文采用在ＩＴＵ－Ｔ Ｇ．８０５建议中定义的传送网通用功能结构模型,建立了ＰＤＨ传送网功能结构模型;在这一传送网功能结构模型的基础上,结合ＰＤＨ光传输系统的网管要求,建立了网元观点的ＰＤＨ光传输系统信息模型。     

ATM信令适配层规范

ＡＴＭ网络的信令系统是参照ＩＴＵ－ＴＱ．９３Ｂ建议来实现的，它通过ＡＡＬ５进行适配以进入ＡＴＭ网络，此时的ＡＡＬ称为信令ＡＡＬ（ＳＡＡＬ），它由业务特定协调功能（ＳＳＣＦ），业务特定面向连接协议（ＳＳＣＯＰ），公共部分汇聚子层（ＣＰＣＳ）和分段重装子层（ＳＡＲ）组成，本文着重介绍了ＳＳＣＦ、ＳＳＣＯＰ的原语、帧格式、状态转移图和有关的操作。     

INQIRE: a software approach to monitoring QoS in ATM networks

Unlike traditional best-effort packet networks, ATM networks support a wide range of services by providing a specified QoS on each ATM connection. Currently, QoS can be measured with specialized high-speed testing equipment but their complexity and cost prevent them from wide field use. This article describes the INQIRE project approach based on software for enabling common personal computers (with an ATM network interface card) to function as QoS monitoring stations at the edges of an ATM network. The main objective is to develop a low-cost, off-the-shelf alternative to broadband testing equipment. An INQIRE station, consisting of a PC running the INQIRE application, can actively probe any selected connection and collect sample measurements of the QoS. The monitoring approach is intended to be non-intrusive and work with any ATM network without requiring any modifications to existing ATM switch equipment or interruptions to active services     

Network management considerations for interworking ATM networkswith non-ATM services

Rapid progress has been made on standards and implementation agreements for interworking ATM networks with frame relay, DS1/DS3 circuits, and SMDS. This article examines ATM network management issues in these interworking environments, with an emphasis on how each interworking environment has unique requirements for network management     

Voice over ATM: an evaluation of network architecture alternatives

This article describes eight application scenarios in which there is a business case for voice over ATM. It then evaluates alternative network architectures for implementing the required network functionality. The article incorporates much of the ongoing work of the ATM Forum and the ITU, but does not restrict itself to standards and implementation agreements. In addition, it evaluates nonstandardized alternatives for ATM transport of voice traffic. There are two main areas: N×64 kb/s structured data transfer, also known as composite cell transport-a network operator may aggregate individual voice calls into N×64 kb/s blocks for transport to an intermediate point in the network. At that point the individual calls need to be remapped into new M×64 kb/s blocks for the next stage of their transport. Architectural alternatives and advantages of remapping are investigated. Interworking of signalling is of two types: network interworking, in which the end users are connected to non-ATM networks and an ATM network is used for backbone transport; and service interworking, in which an ATM user is connected to a non-ATM user. Functionality and architectural alternatives for network and service interworking are evaluated     

Management and control functions in ATM switching systems

As research has progressed, it has become clear that the main difficulties in ATM pertain to its operational details rather than the concept. And it seems likely that these control issues will be much more complicated and costly for ATM switches when compared with current telephone circuit switches. The asynchronous transfer mode (ATM) is the target switching technique for the future public broadband integrated services digital network (B-ISDN). The purpose of this article is to examine the management and control functions in ATM switching systems implied by current industry standards and agreements on OAM and traffic control. Until now, ATM research in the areas of switch design and traffic control have progressed essentially independently. First, we briefly review the B-ISDN Protocol Reference Model and its representation of the different information flows in ATM. Network management and traffic control principles in ATM, and in particular OAM, are overviewed. With this information as background, we attempt to infer their implications on the functional blocks of an ATM switching system. An example switch architecture model with distributed management and control functions is outlined, and some design issues are discussed     

WDM deployment in the local exchange network

This article examines the complex issues surrounding deployment of wavelength-division multiplexing technology in the local exchange network. It discusses demand, economics, technology advantages/disadvantages, saleability, operations, interoperability, and optical networking. The emphasis is on economics and manageability. After a review of these issues, the article looks forward to the optical network in a multi-vendor interoperable environment and to the continuing evolution of standards that will expedite the deployment of optical networking technology     

Internetworking based on cell switch router-architecture andprotocol overview

This paper describes an internetworking architecture and related protocol overview based on routers that have asynchronous transfer mode (ATM) cell switching capability in addition to conventional Internet protocol (IP) packet forwarding. The proposed architecture can provide high-throughput and low-latency switched paths for individual application flows or a group of application flows while retaining current router-based internetworking architecture. The proposed router is able to establish the switched path based on the characteristics of flows, e.g., arrival of a data packet with specific upper layer protocols or arrival of more than a certain amount of data packets in a predetermined period, as well as by the reception of an IP-layer resource reservation request, such as resource reservation protocol (RSVP). One important feature that is provided by the proposed router is interoperability with the emerging ATM network platform specified by the ATM Forum and the telecommunications sector of the International Telecommunications Union (ITU-T). The proposed routers can be interconnected with each other over the point-to-point synchronous optical network link as well as over the ATM network platform, which provides permanent virtual channel, virtual path, or switched virtual channel (SVC) services. That enables network carriers to provide Internet/intranet services as well as others, such as telephony, ATM/time division multiplexing leased line, or native ATM SVC services     

Development of an integrated network manager for heterogeneousnetworks using OSI standards and object-oriented techniques

The Federal Aviation Administration (FAA) is using an increasing number of interconnected, heterogeneous telecommunications networks. The FAA is looking at new ways of automating the operations and maintenance activities of these networks in a cost-effective manner in a rapidly changing environment. Open system interconnection (OSI) standards provide a structure for dealing with multivendor systems and network management problems, including mechanisms for monitoring, controlling, and coordinating resources, as well as protocol standards for communicating information about these resources. An example of a standards-based open system for network and services management is a prototype system being developed by the Center for Advanced Aviation System Development (CAASD) and the FAA for managing telecommunications networks and services at Air Route Traffic Control Centers (ARTCCs). This system, the Telecommunications ARTCC Prototype (TAP), is being developed to integrate the various existing communications management capabilities at the ARTCC into a single management system. Following OSI standards and object-oriented techniques provides a concept and structure for a distributed management architecture. The syntax and semantics for management information and functions specified in the standards provide an understanding and definition of the operations to be performed and the information to be collected and communicated. The paper provides an overview of the prototype architecture, describes how OSI standards and object-oriented techniques were applied and interpreted to meet the specific requirements of the ARTCC     

Managing networks in a multi-vendor environment

The Unified Network Management Architecture (UNMA), developed by AT&T to provide a base for network management in a multilevel environment, is discussed. The functions of data management addressed by UNMA are delineated. These comprise five functional areas recognized by the standards groups working in network management, namely configuration, faults, performance, accounting, and security, as well as the four functional areas of planning, operations, programmability, and integrated control specified by AT&T. The family of products introduced to support UNMA is described     

An approach to the cooperative management of multitechnologynetworks

This article presents a TMN-compliant X interface, the so-called Xcoop interface, as a fundamental component of an operations system developed to cope with the challenges of multidomain, multitechnology networks. Defined at the network level, between operations systems of different TMN domains, it is intended as a support for the management of broadband connectivity services with end-to-end QoS and scheduling constraints in backbones operated by many network operators. The key feature of the present approach, distinguishing it from other existing Xcoop solutions, is in handling the integrated ATM and SDH technologies, covering both the configuration management and fault management functional areas     

新一代网络管理标准的研究

ITU－T在网络管理标准方面的制定大体经历了三个阶段，即1997年以来的第一代经典TMN阶段、1997至2000年的第二代扩展TMN阶段和从2001年开始的包括TMN在内的第三代网络管理阶段。“十五”期间我国的网络管理标准研究工作将放在第三代移动通信、IP网络、光网络3个重点领域。     

Intelligent network: a key platform for PCS interworking andinteroperability

The Tl and TIA standards committees in the United States have worked jointly on the development of the first phase of personal communication services (PCS) standards, which were approved in December 1995. PCS systems based on these standards are currently under development. As these systems are deployed, the variety of wireless systems will grow, making interworking and interoperability a key challenge. This article provides an overview of PCS standards and explores how the different types of wireless systems (PCS and cellular) will utilize the capabilities of the intelligent network to provide seamless roaming     

The five challenges of managing global networks

The challenges facing corporations attempting to reach rapidly expanding global markets are discussed. It is argued that to meet those challenges, corporations must address five major areas of networking: technical knowledge, network design and planning, country-by-country service requirements, network management operations, and network management interoperability. Each area is described, and the ways in which corporations currently achieve a certain level of network management support as a basic element of their long-distance service are reviewed     

Monitoring and control of ATM networks using special cells

This article describes a framework for monitoring and controlling ATM networks based on the use of management cells. By management cells we refer to a broad class of special cells that circulate around the network to perform a variety of useful functions for monitoring and optimizing the operation of the network. The proposed framework includes current ATM-layer OAM (operations and maintenance) methods as well as new mechanisms for more sophisticated long-term network management. This article explores various existing and new uses of management cells for performance monitoring, traffic control, fault management, and network administration