Applications of ATM in global networks

This article describes the market drivers, objectives, and consequences of introducing ATM into public and private networks. To serve the diverse needs of environments and applications, ATM presents a broad choice of characteristics to users and providers. To harness this diversity and bring structure to the choices, this article discusses ATM transfer capabilities (ATCs) and quality of service (QoS) classes as specified in ITU-T Study Group 13. Industry aims to achieve consistency between the ITU-T and ATM Forum specifications. This article includes consideration of AALs and interworking in developing network strategies. Providers will offer a selection of the possible services defined for ATM. Also, each provider will communicate their strategy for preferred network utilization and efficient traffic through incentives to users     

VTOA/VolP/N-ISDN Telephony Gateway

This article presents the architecture and implementation of a telephony gateway for interworking between N- ISDN, ATM and IP telephony. In this way, interworking is achieved both within private networks and with the PSTN, address translation being performed according to both the vtoa (atm interface) and H .323 (ip interface) specifications. The gateway implementation is based on a PC, presenting a cost- effective alternative to the equipment currently available on the market. Moreover, its highly modular software architecture allows new telephony interfaces to be easily added.     

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     

MPOA（Multiprotocol over ATM）规范研究与分析

ＭＰＯＡ规范是继局域网仿真（ＬＡＮＥ）、ＩＰｏｖｅｒＡＴＭ技术规范之间提出的又一个针对ＡＴＭ民传统网络协议间互操作问题的解决方案。ＭＰＯＡ规范综合了上述两种技术方案的优点并加以了完善了发展。本文对ＭＰＯＡ规范进行了较为详尽的阐述和分析，并对比说明了ＭＰＯＡ技术规范与其它技术规范的异同点。     

The ATM Forum's private network/network interface

The ATM Forum completed the first version of its private network/network interface (PNNI) in March 1996 and many ATM switch manufacturers are now offering early implementations. PNNI offers a different type of internetwork or internodal interface from the traditional Signalling System No 7 based approach favoured to date by 'public' network operators, such as BT. In spite of its name, however, PNNI may find its place in network service provider networks as well as in 'private' or customer networks. Some of the perceived limitations of the current specification for such an environment are currently being addressed in version 2, tentatively due for completion in the second half of 1998.The PNNI really consists of two parts, a signalling protocol based around the ATM Forum's UNI signalling specification, and a dynamic source routeing protocol. This paper aims to provide an overview of the functionality and mechanics of PNNI, and to compare and contrast with the functionality offered by ITU-T's B-ISUP.     

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,     

Internetworking connectionless and connection oriented networks

The use of connection-oriented (CO) networks for the transport of IP traffic is seen to have value to both users and service providers. Given the expectation that most endpoint-generated traffic will be in the form of connectionless (CL) IP datagrams, we address the problem of how to internetwork a CL (IP) network with a CO network. CO networks can be packet-switched or circuit-switched. Examples of packet-switched CO networks include ATM and MPLS networks, in which resource reservations are made at the ATM or shim layer, and IP-switch-based networks, in which resource reservations are made at the IP layer. Examples of circuit-switched networks include SONET/SDH and WDM networks that consist of programmable optical crossconnects. We consider the internetworking problem for two modes of operation of CO networks: provisioned, in which connections are set up a priori, and switched, in which connections are set up on demand. The main focus of this article is on the more complex problem: the internetworking of CL IP networks with CO networks operated in a switched mode. Our solution consists of (i) interworking user plane protocols with protocol conversion in some cases instead of always using protocol encapsulation, (ii) interworking routing protocols by either simply having gateways know routing information of both networks or having all nodes know routing information of both networks, and (iii) interworking signaling protocols by using application- or transport-layer end-to-end handshakes to trigger connection setups through the CO network. We demonstrate throughput improvements with our integrated routing interworking scheme over the MPOA IP-ATM internetworking solution for two example networks     

Wireless ATM LAN with and without infrastructure

We consider wireless ATM concepts for small LANs, especially for SOHO and future consumer applications. We describe a wireless ATM LAN framework architecture that supports wireless ATM communications in environments with and without fixed ATM infrastructure. For the configuration with an ATM infrastructure, a distributed ATM switched backbone is proposed, which enables a smart ATM switching element to be embedded in every wireless and fixed access point. For bandwidth efficiency and ease of operation (place-and-play), we also propose an ad hoc wireless ATM LAN concept based on the same 5 GHz wireless ATM air interface as is currently under standardization in the ETSI/BRAN and ATM Forum. Unlike CSMA-based ad hoc systems such as HIPERLAN and IEEE802.11, our ad hoc wireless ATM system makes QoS management feasible in an infrastructureless environment by using resource reservation and scheduled medium access protocol. Since cost scalability is essential throughout our system design, we consider forwarding between ad hoc subnets and interworking with the fixed network as important but optional features     

Designing a practical ATM LAN

The adaptor cards and driver software for workstations and local asynchronous transfer mode (ATM) switches and switch control software used in an ATM local area network (LAN) system are discussed. It is shown that the ATM hardware and software components together provide services that are essential for ATM to be considered a realistic alternative to current shared-media LANs. These services include: completely transparent support for the TCP/IP protocol suite, an application programming interface for full access to the underlying ATM capabilities, support for AAL5, AAL3/4, and the null AAL, both connection-oriented and connectionless service, dynamic connection establishment or switched virtual circuits, resource reservation of guaranteed bandwidth and quality of service, full-bandwidth multicast and broadcast, virtual path and channel routing among multiple switches, automatic configuration and failure recovery, dynamic address assignment and internetwork address resolution, and network management via the simple network management protocol (SNMP)     

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     

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.     

Frame relay and ATM interworking

Frame relay has proven to be a very successful wide area networking service, and ATM is gaining momentum in the industry to become the preferred common backbone technology for supporting a wide variety of network services, including native ATM cell relay service and frame relay service. In the years ahead, ATM is poised to become the dominant networking technology. Since frame relay and cell relay services will coexist for a long time to come, it is imperative that the network and service interworking specifications be defined and implemented. This article focuses on the topic of frame relay and ATM cell relay service and network interworking. The authors provide the rationale, the standards-based methodology, the major open issues, and a likely evolution scenario for the interworking of frame relay and ATM cell relay networks and services     

帧中继承载业务的ATM传输技术

在帧中继网络协议模型的基础上,对继帧中继承载业务的ＡＴＭ传输中关网络互通,虚连接复用,参数映射等技术问题进行了讨论,并对帧中继业务与ＡＴＭ宽带业务互通问题进行了简要介绍。     

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.     

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     

ITU-T standardization of audiovisual communication systems in ATMand LAN environments

This paper presents the ITU-T Study Group 15 development of H-series Recommendations that allow interworking between different audiovisual communication terminals manufactured by different equipment providers. The paper focuses on H.310 and H.321 systems for broad-band ATM environments and H.322 and H.323 systems for LAN environments where the quality of service may or may not be guaranteed. The paper first lists the Recommendations developed by the ITU-T for audiovisual communication systems and the network environments in which they may be used. It then describes the design philosophy, the network specific characteristics, and hardware trials for each system. Then it describes the communication control protocol defined in H.245 which is used commonly by different audiovisual communication systems. Finally, the paper discusses interworking scenarios for communication between the different types of terminal on different networks     

The sink tree paradigm: connectionless traffic support on ATM LAN's

Asynchronous transfer mode (ATM) is a connection-oriented technology in which all communication is based on virtual connections established prior to the transfer of data. It is expected that the bulk of traffic carried by the ATM network will be data traffic, e.g., local area network (LAN) internetwork traffic. Hence, a major issue regarding ATM is the support for connectionless (datagram) traffic. A scheme for the efficient support for connectionless traffic in ATM LANs based on trees of virtual connections is proposed. In this scheme, a sink tree is built for every switch in the LAN. Each tree provides an efficient means of routing connectionless traffic from any switch in the network to the sink switch (root) of the tree. The sink tree solution may also be used to broadcast connectionless messages in the reverse direction. The trees can easily be updated to adapt to topological changes or congestion in the network. A protocol for refreshing the tree structure using the ATM switch routing tables is described. An adaptive rate control solution, in conjunction with fast back pressure at the ATM layer, is presented. It is shown that this scheme achieves high utilization of available bandwidth for connectionless traffic, has low cell loss probability, and small overhead     

Efficient use of protocol stacks for LAN/MAN-ATM interworking

Connectionless (CL) services as already developed in LANs, have to interwork with emerging asynchronous transfer mode (ATM) connection-oriented (CO) networks. MANs are a significant evolutionary step and CO MANs, in particular, constitute a technically appealing method to integrate both environments and provide shared medium access for all services. The functions required for enhancing distributed-queue dual-bus (DQDB) MANs with CO services in a way compatible with ATM are described. Within the integrating framework of B-ISDN, the practically useful scenarios for interworking LANs, CO and CL MANs, and ATM are investigated and classified in order to exploit the advantages of an efficient protocol relay utilizing the resources of the lowest possible layer. This is aimed at assisting interworking unit (IWU) designers and implementors to decide on key options in this versatile and evolving environment. The CO DQDB case emerges as the most advantageous development in terms of interworking simplicity and robustness     

ATM和MPLS网络互通的比较及其研究

ATM网络与MPLS网络的互通是一个尚待解决的问题，目前国际上对ATM和MPLS之间的互通还没有形成最终方案。ATM论坛的两个ATM-MPLS网络互通规程分别从不同的角度对ATM—MPLS网络互通提出了实现方案。本文先对ATM—MPLS网络互通规程作了一些实现上的比较，之后重点探讨了后来新发展的方面。     

Multimedia service interworking over heterogeneous networkingenvironments

This article discusses technical issues related to delivery of multimedia services, such as video-on-demand, over heterogeneous networking environments. In particular, it describes the design and implementation of an experimental system for multimedia service interworking between a DAVIC (Digital Audio Visual Council) domain and an Internet domain. The system, called MIDDLEMEN (middlemen for multimedia environment), consists of the broker and the interworking unit, which work together to provide multimedia services across different types of networks in a seamless manner. The broker acts as a guide to multimedia services, and complements servers or clients that are not equipped with full functionality. The broker also controls the resources in MIDDLEMEN. The interworking unit performs various translation functions under the control of the broker, including stream transport protocol conversion, traffic monitoring and bit-rate control, service gateway conversion, and stream control conversion. Current implementation supports the delivery of a DAVIC-compliant VOD service from an ATM network to an IP network