ATM与帧中继互连技术

ＡＴＭ技术是ＩＴＵ－Ｔ推荐的Ｂ－ＩＳＤＮ交换技术，而帧中继在提供广域网业务方面很成功。因此，在ＡＴＭ发展的初期不可避免地会与帧中继技术并存。本文阐述了ＡＴＭ与帧中继网络互加和业务互连的相关技术及其存在的问题。     

Applying ATM to mobile infrastructure networks

In response to the explosive increase in the number of mobile subscribers and the ever stronger demand for mobile multimedia services, the authors propose introducing the ATM technique for next-generation mobile network infrastructures in order to handle a high volume of traffic and develop multimedia communications. First, this article clarifies mobile-specific requirements for and advantages of applying ATM to mobile infrastructure networks. However, it is risky for network operators en bloc to replace the conventional STM-based infrastructure by ATM. Therefore, this article shows a smooth evolution path for the mobile network infrastructure to convert from conventional STM to ATM as mobile multimedia services mature. Even in future mobile networks, the main traffic may still be voice communications, whose bit rate is too low for efficient use of the radio frequency band. Applying ATM to such very-low-bit-rate mobile voice streams is inefficient due to the delay in filling out the payload of an ATM cell; this “packetization delay” degrades the quality of service. This problem can be solved by using a layered cell structure for the mobile ATM network. This cell structure enables the efficient transfer of voice signals ranging from very-low-bit-rate signals to high-speed multimedia signals with little delay. Standardization of this cell structure is progressing in ITU-T and the ATM Forum. Transmission efficiency is estimated by simulation     

The estimation of signaling delay in ATM networks

In multimedia applications over ATM networks, more stringent quality of services are required, because these applications are especially sensitive to the time delay. In this letter, a simple estimation of signaling delay is presented using Erlang service models according to ITU-T “Q.2931”. Additionally, the call blocking probability of a realistic network is considered. The simulation results show that the proposed model can be an effective tool to estimate the setup delay. If the connection setup delay can be effectively estimated according to the network load, then the users may decide whether or not to join this congested network, and thus contributes to the load balance of ATM networks     

Technology interoperation in ATM networks: the REFORM system

This article addresses the applicability and interoperation of standards and emerging technologies for the operation and management of ATM networks. The issue is tackled from a practical perspective based on experiences gained through the design, realization, and experimentation of a system developed by the ACTS AC208 REFORM project. Assuming an ATM-based network infrastructure offering a range of services with distinct QoS guarantees, the REFORM system encompasses the required functions for ensuring cost-effective network survivability and availability; fast-responding reliable fault detection and self-healing mechanisms, distributed dynamic routing functions with inherent load balancing capabilities, efficient VP layer design, and dynamic network reconfiguration functions. A number of standards and emerging technologies were used for designing and realizing the wide spectrum of functionality incorporated within the REFORM system, including ITU-T OAM 1.610 and Q.2931, ATM Forum UNI 3.0 and PNNI v. 1, OMG CORBA and Component Model, TINA NRA and ISO/OSI, and ITU-T TMN. Based on the experience gained, the article discusses and draws conclusions on the applicability, coexistence, and interoperation of the adopted technologies. It is shown that these technologies can coexist, through careful design, to the benefit of network design and operation     

南京ATM宽带多媒体网络的建设

ＡＴＭ技术在经济ＩＴＵ－Ｔ和ＡＴＭ论坛多年的研究与论证后,已开始在多个领域得到广泛运用。本文介绍了南京市ＡＴＭ的网络的建设情况,包括基本组成、网络业务及网络的测试等。     

Mobile multi-user ATM platforms: architectures, design issues, andchallenges

Rapid growth in use of the Internet at and away from the workplace has spurred tremendous interest in the provision of anytime-anywhere network connectivity to mobile users. Commonly studied mobility scenarios involve users equipped with portable data terminals roaming around at slow to moderate speeds within a coverage area. Mobile IP and wireless ATM are examples of protocols designed for providing network connectivity to such mobiles in IP and ATM networks. A different application involving mobile multi-user platforms (MMUP) equipped with onboard private ATM networks is discussed in this article. Examples of such mobile platforms include airplanes, trains, and ships. The presence of an onboard network, multiple users, and potentially high speed of travel presents unique challenges in provision of internetwork connectivity to these MMUPs. Specific characteristics of MMUPs, architectural issues in design of the underlying cellular network, subnetwork mobility within ATM internetworks, location management of MMUPs, and multi-user connection handoffs on MMUP moves are the main issues addressed in the article. Network architectures and protocols developed for terminal mobility scenarios are evaluated for applicability in the present context, and new solutions are presented for problems unique to the MMUP application scenario     

ATM network resilience

With the prospect of widespread deployment of ATM by public network operators, it is crucial to ensure resilience to network outages caused by cable breaks and node failures. The general aim of resilience is to make network failures transparent to users. If a failure happens to affect a circuit, it would be very desirable to reconfigure that circuit as quickly as possible with no information loss. However, if this functionality incurs a significant cost overhead, it may be necessary to charge customers according to the resilience they receive. Since user requirements vary from service to service, it is highly likely that different customers will demand variable levels of resilience. For example, mission-critical business-oriented data services will rely on virtually fault-transparent service, whereas residential customers may tolerate breaks in service as long as they do not occur frequently or last a long time. Fortunately, different ATM restoration mechanisms are possible which suit varied customer requirements. This article summarizes a range of research papers describing ATM restoration techniques. The viable options to provide ATM network resilience are discussed, along with the customer requirements which they satisfy and aspects of ATM resilience being assessed by standards bodies. Taking all such matters into consideration, conclusions are drawn on the current and future scope for ATM resilience     

APON的MAC协议设计

本文结合以ＡＴＭ为基础的无源光网络（ＡＰＯＮ）的Ｇ．９８３建议,提出了一种低信元时延变化（ＣＤＮ）、低信元时延（ＣＤ）、无碰撞、公平,高效的媒质接入控制（ＭＡＣ）协议,并对该协议的性能进行了分析。     

Quality of service in telecommunications. I. Proposition of a QoSframework and its application to B-ISDN

The the quality of service (QoS) concept is becoming an ever more important issue in telecommunication and computer communication. The article focuses on the QoS notion and concept. The definition of QoS in the International Telecommunications Union-Telecommunications Sector (ITU-T) recommendations and the International Standards Organization (ISO) standards is analysed. Little is known about the asynchronous transfer mode (ATM) performance requirements of the broadband integrated services digital network (B-ISDN) services, especially for multimedia applications. This is because the ATM performance requirements of multimedia applications depend not only on the diverse QoS requirements from application and user, but also on the protocol stacks and scheduling in end systems. Therefore, in order to guarantee QoS to the user, it is necessary to introduce a set of QoS parameters whose properties indicate the nature and requirements of the layered protocol stack. We describe how a proposed QoS framework can be applied to B-ISDN as a specific network. The QoS aspects related to B-ISDN signaling (the control plane) and the QoS aspects related to layer and plane management (the management plane) are described. We also describe how the QoS framework resides in a protocol stack and works together with the B-ISDN network management and signaling     

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     

B—ISDN和ATM与宽带通信业务

本文首先通过对宽带业务发展情况，ＡＴＭ标准，ＡＴＭ适配层的分析引出了ＡＴＭ对Ｂ－ＩＳＤＮ发展的作用及向Ｂ－ＩＳＤＮ过渡的步骤，并指出工发具ＳＭＤＳ和ＦＲ业务接口的ＡＴＭ交换机，对实现Ｎ－ＩＳＤＮ向Ｂ－ＩＳＤＮ过渡具有积极现实意义，其次介绍和分析了ＩＴＵ－Ｔ，日本ＮＴＴ及欧洲各国关于ＡＴＭ和Ｂ－ＩＳＤＮ的标准化活动，应用试验等情况。     

Subscriber premises' network architectures in a broadband ATM environment

In future broadband networks residential and business users will be distinguished, each with their own characteristic requirements. Whereas business users almost exclusively need interactive switched services, the huge number of residential users, on the country, mainly aim at entertainment services, either switched or distributed, at a low, possibly fixed, price. Based on the user requirements a twotier SPN architecture is derived, consisting of a TDN (terminal distribution network) and a BBN (broadband backbone network). Alternative structures for TDN are analysed and compared. A passive tree solution is found to be most suitable for the above-mentioned needs. Although the physical appearance may be quite different, all the given examples have a number of elements in common. This enables common components to be developed. Inside the SPN, especially the residential SPN, the absence of any channel aggregate in ATM is of great advantage. Only the total available bandwidth imposes a restriction on the set up of new calls. This is very important, because SPN encounters a wide variety of user needs, together with a relatively small amount of users. In order to preserve the advantages of ATM in the subscriber area, it is essential to bring ATM down to the terminal.     

Evolution of the North Carolina Information Highway

As the first information highway of its kind, the North Carolina Information Highway is likely to set an example for ATM broadband deployment not only in the BellSouth region but also in the rest of the country. The article outlines an evolutionary path for new network architectural features and additional video and data services that can be supported by the NCIH. These architectures will support the introduction of on-demand video services (e.g. the distance learning service), and other associated vertical services. As standard procedures are developed, users will be able to use data services like TCP/IP and frame relay over large-bandwidth ATM connections. In addition, they will have opportunities to use their existing applications in the legacy LANs, as well as with ATM endpoints. As ATM standards agreements are realized over the next few years, and the ATM technology cost curve continues to improve, the NCIH will prove to be a very cost-effective and high-performance alternative for all the high-speed communication needs of the North Carolina State Government     

ITU-T QoS standards for IP-based networks

To support IP/PSTN convergence, future IP networks will need to provide reliable differentiated QoS to a diverse set of user applications, including telephony. To achieve end-to-end QoS solutions, IP network providers will need to agree on a common set of IP packet transfer performance parameters and QoS objectives. This article describes two new ITU-T Recommendations, Y.1540 and Y.1541, that document such an agreement.     

Network management in a fast packet environment

StrataCom specializes in Asynchronous Transfer Mode (ATM) technology — a method of rapid wide-area distribution of all forms of traffic in cell format. This article will look at how StrataCom approaches network management for ATM switches.     

Signaling alternatives in a wireless ATM network

The world of wireless telecommunications is rapidly changing. The capabilities of wireless networks are improving at a steady pace. This paper presents two possible protocols for implementing mobility for wireless users in an asynchronous transfer mode (ATM) network. The vision of the authors is of one “wireless ATM telecommunications network” that is capable of supporting a variety of today's applications with room to grow for advanced applications of the future. We first visit database architectures that can support mobility in a wireless ATM network. We then discuss one of two signaling architecture alternatives, the “overlay signaling”, for overlay support of mobile users in the ATM-based wireless telecommunications network. “Overlay signaling” aims at minimizing the modification needed to the existing ATM protocols. We then describe a native “migratory signaling” approach that further integrates wireless and wireline users into one global wireless ATM network at the expense of requiring some modifications to the existing ATM protocols. A performance analysis of the proposed signaling architecture alternatives is also presented. We conclude by pointing out some challenges in merging ATM with wireless telecommunications     

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     

SingAREN: the Singapore Advanced Research and Education Network

Singapore is the first country in the world to have a nationwide broadband network infrastructure deployed. What started as an experimental ATM testbed network in 1995 has now become a nationwide broadband infrastructure called Singapore ONE, launched in 1997 to provide residential broadband access via ADSL or CATV cable modem technologies, and business access via ATM. As of June 1998, Singapore ONE supported more than 10,000 users with over 120 commercial applications. More than 100,000 users are projected by the end of 1999, increasing to 400,000 by the year 2001. In order to support the technological needs of broadband communications under Singapore ONE, and to address the national R&D agenda in this area, an advanced research network called the Singapore Advanced Research and Education Network (SingAREN) was established in late 1997. This article gives an overview of the broadband infrastructure initiatives in Singapore, focusing on the SingAREN project. The goals of SingAREN, its network configuration, the research programs and activities to date, and plans for the future are described     

移动多媒体网络中的无缝切换

第三代移动通信（3G）面临的一个重要的挑战就要要无缝集成固定和移动网络中的多媒体业务。对于移动用户来讲,网络支持的业务有图像、多媒体、数据以及不同服务级别的话音业务。为了满足以上业务需求,3G系统必须具有丰富的性能。如今普遍采用ATM技术的同质网络虽然支持很多用户,但此种网络结构不可能成为最终的解决方案（至少从学术界、网络设备制造商的观点来看）。而以太网家族中高速设备的快速发展,已经部分代替了ATM。同时基于因特网业务的爆炸性增长,已经确保IP仍将成为下一代系统网络层协议。本文讨论了IP网因支持移动业务而产生的问题,以及对切换技术进行的分析。