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。     

ATM网络抗毁和自恢复技术研究

基于ATM/MPLS技术的通信网络是承载宽带多媒体业务的综合平台。为了对承载业务进行抗毁保护,对ATM的最基本的1+1、1∶1、m∶n抗毁保护结构进行了研究和总结。同时结合网络传输层,如:PDH、SDH、WDM、MPLS的保护和应用层业务,如:IP、电路交换、以太网和帧中继的抗毁迂回策略,提出了ATM的多层次抗毁自恢复组网结构,为ATM的应用研究提供了借鉴。     

话音业务的多元化发展

随着电信网络和业务的发展,传统话音业务逐渐从电话网上分离,数据网上传话音进而提上日程。ＩＰ电话标准已然成熟,但相关产品仍缺乏兼容性,话音质量也不够理想;帧中继具有传送话音的巨大潜能,有较强的竞争优势;ＡＴＭ虽然已发展多年,但在传话音方面仍存在许多问题,不能完全尽如人意。作者对话音业务的多元化发展进行了分析和比较。     

Using Frame Relay for a VPN

Frame Relay and ATM networks have been the standard for VPN networking for the last decade. More recently, IP‐based VPNs have become possible. This article discusses the key reasons for selecting each. Copyright © 2001 John Wiley & Sons, Ltd.     

Sprachübertragung über alternative Netze

The importance of multimedia can not be foreseen. However the combined transport of speech and broadband data will rapidly develop. Voice/data integration is the technology of the future and will more and more substitute the traditional way of information transport. The paper introduces UTA as the alternative to the incumbant operator und describes UTAs network infrastructure, SDH-backbone and broadband multiservice network. Three methods of voice/data integration are presented:

1. voice over ATM
2. voice over Frame Relay
3. voice over IP.

     

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     

帧中继技术及其发展

文章介绍了帧中继技术及其应用,对帧中继接口协议、帧格式、网内控制及帧中继与其他网络的互通进行了详述,最后给出了中国帧中继网的组建情况以及今后发展前景。     

ATM Forum signalling protocols and their interworking

The ATM Forum is a key body which has been developing specifications for asynchronous transfer mode (ATM) technology over the past six years. It has produced a number of signalling specifications covering the user network interface, the inter-carrier interface and private networking environments. While work continues on 'fine-tuning' these agreements, there is still discussion about how they are used in large scale networks, and in particular on the interworking of public and private network environments.This paper reviews the current status of the relevant protocols and their scope. It then explores the issues related to their interworking and discusses the role of the proposed ATM internetwork interface (AINI) as an alternative internetwork or inter-carrier interface to its broadband intercarrier interface (B-ICI).     

Mobility management in integrated wireless-ATM networks

There is an emerging interest in integrating mobile wireless communication with Broadband ISDN based on the ATM technology. Many issues arise when such integration is attempted. This paper addresses the problem of mobility management, i.e., that of tracking the current ATM addresses of mobile terminals and sustaining active ATM connections as mobiles move. The paper presents some architectural options for integrating wireless access to ATM networks and highlights an architecture based oninterworking devices to provide transparent mobility support in existing ATM networks. Location management and handoff solutions for this architecture are then presented. Also, how procedures for multiprotocol transport over ATM networks may be adopted to perform location management is described.A version of this paper appeared in the proceedings of ACM Mobicom '95.     

An empirical study of TCP/IP performance over FR/ATM service interworking

This article outlines some basic performance characteristics of the Transmission Control Protocol/Internet Protocol (TCP/IP) over Frame Relay/Asynchronous Transfer Mode (FR/ATM) Service Interworking. The conclusions are based on empirical TCP/IP performance test results collected on a FR/ATM Service Interworking testbed, architected with commercially available IP, FR, and ATM equipment. © 1998 John Wiley & Sons, Ltd.     

Service convergence using MPLS multiservice networks

Enterprises are increasingly using virtual private networks to interconnect remote sites. Traditionally, service providers have used ATM core networks to deliver layer 2 services such as frame relay, ATM, or TDM private lines, which enterprise customers have then used to build their corporate network infrastructure. Such services account for the majority of data service revenues today. However, pressure has increased on service providers to combine increased flexibility with reduced costs in the context of a highly dynamic telecommunications market. Service providers also need to generate new revenues from their IP network infrastructure, through new opportunities such as IP VPNs and virtual private LAN services, while simultaneously achieving operational efficiencies through the convergence of all of their services on a common MPLS backbone. New access and metro network technologies, such as Ethernet, are also emerging that can be used to deliver these new services to enterprise customers alongside ATM and frame relay access. This must be achieved while also supporting existing technologies such as ATM, which continue to deliver highly profitable services. This article discusses the technical challenges in meeting the often conflicting requirements of delivering both traditional layer 2 services and new layer 3 services on a converged MPLS network. We show how both network and service interworking are required, and how these must operate at the user, control, and management planes to enable profitable services to be delivered over the new converged network. The different solutions being defined in the standards bodies are described, and the distinct scenarios they address are explained.     

ATM local area networks: a survey of requirements, architectures,and standards

There is increasing interest in deploying ATM technology in local or campus networks. ATM is an ideal technology to overcome many of the limitations of today's LAN technologies. This article focuses on the application of ATM in the LAN environment to interconnect high-end host computers, and on the interworking of ATM-based LANs with legacy LANs. The authors introduce ATM LAN requirements, followed by a discussion of possible ATM LAN architectures to support these requirements. The article then covers current standards and their relation to the possible architectures, and concludes with a discussion of current ATM LAN issues and directions     

以太网流量监控方法研究

通过研究帧中继、IP、ATM等分组业务的流量监控算法,提出了可适用于光传输网络的以太网流量的2种监控算法:PIR/CIR和CIR/EIR。通过比较发现CIR/EIR算法的可控性和准确性比PIR/CIR高。最后通过计算机仿真和ATM平台移植对理论分析进行了验证。     

Performance management issues of currently operated ATM enterprisenetworks

The author proposes a solution for the allocation and balancing of resources to maximize available bandwidth shared among corporate users. Currently established broadband virtual private networks (BVPNs) based on asynchronous transfer mode (ATM) technology comprise ATM cross-connects (ATM-CCs) and a lot of intelligent customer premises equipment (CPE). The CPE, an intelligent ATM service switcher or ATM multiplexer, enables the corporate user to connect routers, private branch exchanges (PBXs), or codecs onto the ATM network. One fundamental characteristic of CPE is that it is capable of accumulating asynchronous and synchronous traffic which may belong to different corporate users' sites. A typical example given of a BVPN configuration serving two corporate network users with four user sites each. In general, each user site needs to exchange asynchronous (connectionless) data streams for the inter-local area network (LAN) communication and synchronous (connection-oriented) data streams with constant bit rates for video/voice communication. The configuration and the performance aspects of inter-LAN communications employing a connectionless server (CLS) are discussed. The bandwidth allocation aspects of the BVPN having to convey synchronous and asynchronous traffic in an ATM environment without a CLS are discussed, including the bandwidth allocation algorithm. The important characteristics of the proposed algorithm is also summarised     

Implementing the Orwell protocol over a fibre-based high-speed ATMnetwork

Asynchronous transfer mode (ATM) has emerged as a possible contender for the next generation switching system and fundamental transport basis for the broadband integrated services digital network (B-ISDN) and telecommunications in the future. It is widely thought of as the network to accommodate the uncertain requirements of future public communications because of its high degree of flexibility and service independency. The Orwell protocol developed by British Telecom can provide a communication base to meet the requirements of such a network. Orwell is used as a slotted ring protocol designed to carry a mixture of services which form the basis of an ATM network. The authors describe the realisation of a 155.52 Mbit/s fibre-optic physical layer from the Orwell protocol based on an ATM technology, and also discuss how the Orwell protocol can offer broadband transport capabilities and can provide access to and interwork with existing networks, such as telephone networks and 64 kbit/s based ISDNs     

IP/ATM integrated services over broadband access coppertechnologies

A rich set of broadband access copper technologies is available in the market today, and more are coming out of the laboratories, rapidly moving to standardization. The most likely future scenario will be one where many different technologies coexist. This multi-access-technology paradigm poses an interesting internetworking problem where interoperability and capability to support today's and future user services play a major role in the design of a network architecture. This article begins with an overview of current and new xDSL access technologies to continue describing an access network design that harmonizes the interconnection between PON, xDSL, and native ATM transport technologies. The use of ATM technology for the interface to the broadband access and transport networks is then presented and justified. The article continues studying the protocol architectures proposed for access to network service providers, considered a driver application for broadband access deployment. Finally, different protocol architectures that can provide integrated services support at the user equipment are analyzed     

ATM支持中低速话音业务的新方案

时延和效率问题是ＡＴＭ不能很好地支持中、低速话音业务的关键,因此,ＩＴＵ－Ｔ提出了新型ＡＡＬ２规程－组合信元技术。ＡＡＬ２规程的基本思想是用一个ＡＴＭ连接支持多个ＡＡＬ２用户信息流,从而减少时延。ＡＡＬ２由公共部分子层（ＣＰＳ）和业务特定会聚子层（ＳＳＣＳ）组成,其中面向话音应用的ＳＳＣＳ是中、低速话音业务解决方案的核心,文中对其功能、业务、等时同步问题的解决等作了详细介绍。最后,还介绍了有关标准     

Technology interworking for SMDS: from the DXI/SNI to the ATM UNI

As service providers introduce asynchronous transfer mode (ATM) into their networks, they are faced with the issue of technology interworking: for a given service, can a customer who has an ATM user-network interface (UNI) communicate with a customer who does not have an ATM UNI? For switched multimegabit data service (SMDS), technology interworking is well defined. In fact, SMDS is supported by several technology platforms that can interwork with each other. The three major platforms which support SMDS are: a frame-based platform based on the SMDS data exchange interface (DXI), a cell-based platform based on the IEEE 802.6-1990 standard, and a cell-based platform based on ATM. This article examines how SMDS is supported by each of these platforms and how these platforms interwork. Furthermore, this article presents how the major interworking functions required for these platforms appear to be straightforward for suppliers to implement,     

Transport architecture evolution in UMTS/IMT‐2000 cellular networks

Mobile evolution from the second generation (2G) to the third generation (3G) raises several important questions for operators and manufacturers. How to ensure that the old and current investments can still be utilized in the future? What is the optimum architecture? ATM or IP? Voice or data? There is no single correct answer to these questions, as it all depends on individual cases. In this paper, we discuss the transport architecture evolution for the universal mobile telecommunications system (UMTS)/international mobile telecommunications—year 2000 (IMT‐2000), or 3G cellular networks and interworking aspects between 2G and 3G cellular networks. The interfaces between access nodes in a cellular network and the changes incorporated to support packet data services are described. Emerging services such as mobile data, virtual private networks (VPN) and location aware networking are described. Role of ATM and IP in this new transport architecture is presented. Control and data plane interworking issues between different transport technologies are described. The new ATM standard, ATM adaptation layer type 2 (AAL2) and its applicability for transporting compressed speech in an ATM based cellular network is described. A similar approach in IP, multiplexing in real‐time transport protocol (RTP) payload to transport compressed speech on selective interfaces of 3G network, is introduced. Transport network architecture evolution within four different scenarios is evaluated. Special interest is focused on the protocol stacks and flexible layered solutions that allow smooth migration from one transport technology to another. Copyright © 2000 John Wiley & Sons, Ltd.     

Traffic management for TCP/IP over satellite ATM networks

Several Ka-band satellite systems have been proposed that will use ATM technology to seamlessly transport Internet traffic. The ATM UBR, GFR, and ABR service categories have been designed for data. However, several studies have reported poor TCP performance over satellite ATM networks. We describe techniques to improve TCP performance over satellite ATM networks. We first discuss the various design options available for TCP end systems, IP-ATM edge devices, as well as ATM switches for long-latency connections. We discuss buffer management policies, guaranteed rate services, and the virtual source/virtual destination option in ATM. We present a comparison of ATM service categories for TCP transport over satellite links. The main goal of this article is to discuss design and performance issues for the transport of TCP over UBR, GFR, and ABR services for satellite ATM networks