Wireless ATM network architectures

Emulated LAN technology supports mobile hosts in wireless ATM networks. This paper introduces virtual LAN (VLAN) services using ATM LAN emulation technology which operates on a client/server model. One of the attractive features of the VLAN is the capability to group users into a broadcast domain. The focus of this paper is the issue of supporting quality of service to mobiles in a wireless ATM network. Copyright © 2001 John Wiley & Sons, Ltd.     

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)     

LAN emulation on an ATM network

The authors evaluate architecture alternatives relating to the provision of a LAN emulation service over a connection-oriented ATM network, and present the LAN emulation architecture as actually adopted by the ATM Forum LANE SWG. The role of servers is discussed as is the provision of broadcast/multicast services     

ATM LAN emulation

Many of the most common protocols at layers two (media access), three (network), and above expect to operate over broadcast media such as IEEE 802.3/Ethernet or IEEE 802.5/token ring. LAN emulation provides a widely applicable means for transitioning these protocols to the connection-oriented ATM environment. A combination of centralized and distributed intelligence allows a star-plus-mesh topology of ATM virtual circuits to emulate broadcast media, while providing most of the advantages of connection-oriented media     

混合的ATM技术

ＡＴＭ协议体系结构分为物理层，ＡＴＭ层，ＡＬＬ层和高层，如果在终端用户处完全实现这些功能，不仅造价大，还要放弃用户在网卡，网络软件上的投资。而在终端用户的协议栈中采用混全的方案，则能保留现有网络技术的一些协议层次，又加入ＡＴＭ的协议层次，可以在将用户接入ＡＴＭ网的同时，保护用户已有的网络投资。     

Data communication in ATM networks

An increasing number of customers require LAN access with high bandwidth and low delay over long distances. To satisfy these needs, several high-speed network techniques have been developed. Asynchronous transfer mode (ATM) is superior compared to other networking technologies, as it offers high bandwidth and is scalable in the sense that the bandwidth capacity of an ATM system is not fundamentally limited to the technology itself. Initial ATM installations will operate as subnetworks of existing networks and MAC layer protocols. One of the main challenges in ATM is the transparent support of existing connectionless LAN services. Several activities have been launched within international standard bodies and forums to specify ways of providing data communication services over ATM. Most notable examples are Switched Multimegabit Data Service (SMDS) and the similar Connectionless Broadband Data Service (CBDS) supported mostly by public network service providers. But also other approaches such as IP over ATM, and LAN emulation that show more adherence to the existing local and campus area networking paradigms. The article presents the requirements and architecture of the LAN emulation service. It describes the alternative methods for carrying IP packets over ATM, a public broadband service architecture and CBDS. The traffic management aspects of the data communication services are also discussed     

ATM网支持IP协议的研究

ＡＴＭ网络是面向连接的，而ＩＰ是采用数据报方式的无连接协议。讨论ＩＰ协议数据格式与ＡＴＭ信元格式之间转换方法、ＡＴＭ地址与ＩＰ地址映射方法及利用信令系统建立虚通路连接传输ＩＰ业务的方法。     

Multicast forwarding over ATM: Native approaches

Multicasting is growing in importance as new multimedia applications are devised. Throughout this article, multicasting is understood as the efficient multipoint-to-multipoint transmission of information (in terms of network resource consumption) between the members of a group. Most multicast services have been designed up to now to work over connectionless environments. The approach adopted by connection-oriented networks has been to try to imitate these connectionless multicast schemes with the aim of supporting IP multicast or network-layer broadcast. However, these solutions present drawbacks in terms of delay or signaling overhead. The goal of native ATM multicasting is to provide multicast communications support by taking into account the characteristics of ATM. Therefore, the design philosophy of multicast must be rethought by making it more suitable for connection-oriented networks. Native ATM multicasting is based on mechanisms implemented at the switches to allow the correct ATM-layer multicast forwarding of information. These mechanisms seek to avoid the delay and signaling problems of current solutions, e.g., LAN emulation and IP multicast over ATM. This article provides a survey of the literature on the strategies that offer multicast communications in ATM environments, with special stress on native ATM multicast forwarding mechanisms. Other aspects, such as signaling, quality of service, traffic control, and routing, are not addressed in detail in this article.     

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     

Performance benchmarking of signaling in ATM networks

The overhead associated with establishing switched virtual circuits (SVCs) in high-speed wide area ATM networks is an important performance factor in applications with client/server architectures, including the World Wide Web and low-latency applications such as command/control and modeling/simulation. This article quantifies this overhead by describing a benchmarking framework implemented in a reliable, portable, and easily expandable toolset designed to conduct measurements of well-defined parameters and performance metrics on equipment that is either isolated or connected to a live network. The usefulness of this toolset is then demonstrated in a test suite applied to assess call rates and connection establishment latency of point-to-point and point-to-multipoint ATM connections in the MAGIC, ATDnet, and AAI WANs, on the campus ATM LAN at NRL, and on individual switches in our laboratories     

在ATM网上实现局域网功能的困难及对策

ＡＴＭ网络作为下一代网络，终装成为网络的主流。但量ＡＴＭ网要在目前传统局域网点主导地位的环境下成为今后的主流和发展的方向，就必须解决二个问题；首先必须使已有的众多的网络应用软件能在ＡＴＭ工作站上使用；第二，ＡＴＭ网应能很容易和传统的局域网连在一起的工作站一起动作。     

Flight of the FALCON [ATM]

The fabric-based ATM oriented local connectivity (FALCON), an ATM-based customer premises network (CPN), is described. FALCON supports access using traditional local area networks (LANs) such as Ethernet and token rings and supports a LAN emulation mode for its native ATM interface. This service allows a set of terminals, workstations, and servers to connect to the switch-based network and to interact as if they were attached to a traditional LAN. FALCON's backbone structure is based exclusively on ATM technology, all following CCITT or industry standards wherever they apply. The FALCON control structure is outlined     

无线ATM局域网的移动和连接管理

提出了在无线ＡＴＭ局域网中的越区切换、定位和连接管理的方法。通过把交换功能建立在基站上,并且使用一种建立在虚拟树上的网络连接方案,可以在保持码元序列和服务质量的同时,实现快速越区切换。     

Provider link state bridging

Wide area communications technology has been challenged to virtualize large numbers of Ethernet LAN segments. This is a consequence of a mismatch between the broadcast nature of the LAN segment and the extremely constrained connectivity implied by the p2p connections or tunnels available in the WAN environment, which have been combined to create virtual LAN segments. PBB-TE has been a practical demonstration of how filtering applied to a broadcast media can result in a connection. This article introduces provider link state bridging (PLSB), which adds a control plane to the PBB data plane in order to extend the techniques for manipulation of Ethernet bridges for unicast paths pioneered by PBB-TE. PLSB solves the problem of largescale virtualization of LAN segments over an Ethernet infrastructure by applying advances in computation performance to the multicast capabilities inherent in the Ethernet data plane. The result is that the fundamental primitives of connectivity today, the broadcast LAN segment and the connection, can be virtualized in a scalable manner on a common (but substantially larger and better utilized) Ethernet-based infrastructure.     

ATM网络上的LAN仿真技术

本文比较ＡＴＭ网络和ＬＡＮ的区别。对ＡＴＭ局域网技术作了论述，内容包括ＡＴＭＬＡＮ仿真的组成、工作原理及其特点。     

Interworking IEEE 802/FDDI LANs via the ISDN frame relay bearerservice

The author presents a generic architecture for interconnecting LANs (local area networks) through the ISDN (integrated services digital network) bearer services, particularly the frame relay bearer service. The architecture is derived from the IEEE 802.1 MAC (medium access control) bridge and ISDN frame relay standards. An algorithm for MAC/ISDN address resolution that makes minimal use of the WAN (wide area network) bandwidth (which is potentially the most expensive resource) is presented. The algorithm uses a MAC/ISDN address resolution server to resolve addresses for new stations, the resolution in all other cases (e.g. stations moving from the ISDN address to another) being fully distributed. To prevent a server failure from inhibiting communication to new stations, a backup server may be provided. A practical implementation of the architecture has been found capable of supporting full throughput at ISDN hyperchannel rates (384-1920 kb/s) for all IEEE 802.3 frame lengths. Frame relay is seen as having a number of important advantages for LAN interconnection, including the following: a large number of virtual circuits available, giving the potential for a rich interconnection architecture with single-hop connections across the ISDN; and low processing overhead enabling efficient use of ISDN channels, including ISDN hyperchannels (384-1920 kb/s)     

ATM技术在校园网中的实时性应用

讨论了ＡＴＭ论坛关于局域网仿真技术的基本思想及其协议体系的工作过程，并介绍了利用局域网仿真技术在校园网中应用ＡＴＭ技术实现视频传输的方法。     

虚拟局域网

虚拟局域网是网络用户独立于网络物理配置和位置的一个逻辑组合，综结合了网络交换和管理功能，使网络根据用户需要分割成多个逻辑网，管理员对分布于各个网段的用户视作在同一逻辑网中进行管理，在网络性能、保护用户投资及向ＡＴＭ过渡方面具有很好的性能。本文对虚拟局域网技术进行综述。     

Experience with PACS in an ATM/Ethernet switched networkenvironment

Legacy local area network (LAN) technologies based on shared media concepts are not adequate for the growth of a large-scale picture archiving and communication system (PACS) in a client-server architecture. First, an asymmetric network load, due to the requests of a large number of PACS clients for only a few main servers, should be compensated by communication links to the servers with a higher bandwidth compared to the clients. Secondly, as the number of PACS nodes increases, the network throughput should not measurably cut production. These requirements can easily be fulfilled using switching technologies. Here asynchronous transfer mode (ATM) is clearly one of the hottest topics in networking because the ATM architecture provides integrated support for a variety of communication services, and it supports virtual networking. On the other hand, most of the imaging modalities are not yet ready for integration into a native ATM network. For a lot of nodes already joining an Ethernet, a cost-effective and pragmatic way to benefit from the switching concept would be a combined ATM/Ethernet switching environment. This incorporates an incremental migration strategy with the immediate benefits of high-speed, high-capacity ATM (for servers and high-sophisticated display workstations), while preserving elements of the existing network technologies. In addition, Ethernet switching instead of shared media Ethernet improves the performance considerably. The LAN emulation (LANE) specification by the ATM forum defines mechanisms that allow ATM networks to coexist with legacy systems using any data networking protocol. This paper points out the suitability of this network architecture in accordance with an appropriate system design     

Multiple access control protocols for wireless ATM: problemsdefinition and design objectives

The concept of wireless ATM is now being actively considered as a potential framework for next-generation wireless communication networks capable of supporting integrated multimedia services with different QoS requirements. Several key subsystem design issues for wired ATM and wireless networks need to be readdressed in the scope of the wireless ATM. One of the main key subsystem issues is the development of the appropriate medium access control (MAC) protocol, which has the capability to extend the statistical multiplexing of the wired ATM network into the wireless medium. In this article the authors address the problem of a suitable MAC protocol for the specification of a wireless ATM network and outline the design objectives. In addition, the authors address some other challenging key issues that the wireless medium and wireless network architecture impose on the ATM stack protocol