IP switching-ATM under IP

Internet protocol (IP) traffic on the Internet and private enterprise networks has been growing exponentially for some time. This growth is beginning to stress the traditional processor-based design of current-day routers. Switching technology offers much higher aggregate bandwidth, but presently only offers a layer-2 bridging solution. Various proposals are under way to support IP routing over an asynchronous transfer mode (ATM) network. However, these proposals hide the real network topology from the IP layer by treating the data-link layer as a large opaque network cloud. We argue that this leads to complexity, inefficiency, and duplication of functionality in the resulting network. We propose an alternative in which we discard the end-to-end ATM connection and integrate fast ATM hardware directly with IP, preserving the connectionless nature of IP. We use the soft-state in the ATM hardware to cache the IP forwarding decision. This enables further traffic on the same IP flow to be switched by the ATM hardware rather than forwarded by IP software. We claim that this approach combines the simplicity, scalability, and robustness of IP, with the speed, capacity, and multiservice traffic capabilities of ATM     

IP和ATM在Internet结合使用

主要说明Ｉｎｔｅｒｎｅｔ正在朝宽带网和提高业务质量的方向发展，简述ＩＰ选寻路由和ＡＴＭ交换相结合的方法，并介绍无线ＡＴＭ与ＩＰ结合的移动通信。     

IP multicasting over ATM networks

The Internet protocol (IP) multicast model involves a combination of intrasubnet and intersubnet multicast mechanisms. Technologies supporting a given subnet are expected to have native mechanisms for supporting intrasubnet forwarding of packets sent to multicast destinations. Multicast routers attach to subnets and provide intersubnet forwarding of multicast packets, using interdomain multicast routing protocols developed by the Internet Engineering Task Force (IETF). Unfortunately, ATM networks based on UNI 3.0 or UNI 3.1 signaling service do not provide the native multicast support expected by IP. This has led the IETF to develop the “MARS model”-a fairly complex mechanism for emulating intrasubnet multicast support required when running IPs over ATMs. This paper takes a high level look at the IP multicast service, examines the limitations of the ATM point-to-multipoint virtual channel service, and describes the major architectural points of the MARS model     

Analysis and design of backbone architecture alternatives for IP optical networking

The unprecedented growth of IP traffic is leading Internet service providers and network operators worldwide to investigate architectural alternatives for cost effective, reliable, scalable, and flexible multiterabit IP backbones. In this paper, several overlay, service, and transport layer networking architectures, which employ IP, MPLS, SONET/SDH, and DWDM technologies, are proposed and analyzed. Multiple parameters, such as network capacity, cost, restoration strategy, reconfigurability, and accommodation of preemptable traffic, are considered for the architectural comparison. Detailed network design and economic analysis are provided for the different alternatives considering a typical nationwide U.S. backbone with projected IP traffic in approximately three years. Several sensitivity analysis results are also shown, to evaluate the effect of cost changes in some of the critical technological factors in these architectures, such as 10 Gb/s optics cost or IP router cost. The results show the value of transport layer networking architectures for multiterabit IP backbones, and how, when compared to service layer architectures, they provide additional desirable features such as wavelength reconfigurability and restoration scalability.     

Scalable QoS-based IP multicast over label-switching wireless ATMnetworks

A Mobile IP multicast prototype that integrates a label-switching wireless asynchronous transfer mode, the mobile core-based multicast architecture, and an Internet multicast infrastructure is presented. MCOM creates multiple core-based layer 2 multicast trees that are independently established in member networks. They are interconnected via the Internet using layer 3 multicast routing. Gateways on the border of the Internet and wireless ATM networks convert ATM multicast traffic to suitable IP packets as well as converting from IP packets to ATM cells for MCOM. To solve the cell interleaving problem that results, ATM block transfer/immediate transmission capability is reasonably modified. Additionally, class-based block buffer management for ATM multicast connections is built into wireless ATM switches for soft quality of service control. Dynamic group management, multicast channel rerouting, and reliable multicasting are also studied in relation to existing Internet protocols like Mobile IP, Internet group management protocols, and multicast routing protocols     

Buffer management and scheduling schemes for TCP/IP over ATM‐GFR

Today ATM technology is facing challenges from integrated service IP, IP switching, gigabit IP router and gigabit ethernet. Although ATM is approved by ITU‐T as the standard technology in B‐ISDN, its survivability is still in question. Since ATM‐UBR (unspecified bit rate) provides no service guarantee and ATM‐ABR (available bit rate) is still unattainable for most users, many existing users have little or no incentives to migrate to ATM technology. The guaranteed frame rate (GFR) service is introduced to deal with this dilemma. The GFR can guarantee the minimum cell rate (MCR) with fair access to excess bandwidth. This paper studies various schemes to support the GFR. We have studied different discarding and scheduling schemes, and compared their throughput and fairness when TCP/IP traffic is carried. Through simulations, it is shown that only per‐VC queueing with weighted round robin (WRR) can guarantee minimum cell rate. Among all the schemes that have been explored, we recommend dynamic threshold–early packet discard (DT–EPD) integrated with MCR+ (a WRR variant) to support the GFR service. Copyright © 2001 John Wiley & Sons, Ltd.     

宽带综合IP网的MPLS技术及其应用

多协议标记交换（MPLS）技术是综合利用网络第二层交换技术的有效性和第三层IP路由的灵活性等优点而产生的多层交换技术。通过在传统的IP包里加入标记，使路由转发依赖于标记，大大地提高IP包的转发速度，同时可使传统IP网络具有服务质量（QoS）能力。现主要分析MPLS体系结构，指出MPLS的一些应用。     

Multicast for RSVP switching: An extended multicast model with QoS for label swapping in an IP over ATM environment

The ubiquity of IP associated with the acknowledgment of ATM as a key switching technology has motivated an increasing interest towards the design of a more efficient way of operating IP over ATM networks. This approach is known under the name Label Swapping. A few studies have addressed the primary issue of providing simultaneously quality of service and multicast. We propose a solution where we mix an RSVP architecture with one Label Swapping technique called IP Switching. We discuss problems that arise when using cut-through associated with an RSVP multicast model and propose an application for an IPv6 environment over an ATM switching hardware.     

IP电信网的传送技术

文章介绍了几种主要的IP业务传送技术；ATM，POS，DWDM和以太网的实现方案，分析了它们的优缺点；进一步还介绍了弹性分组环，多协议标记交换等技术。最后指出了在向IP电信网演进的过程中上述技术的发展趋势。     

IP over DTM技术及其应用

与ＩＰｏｖｅｒＡＴＭ和ＩＰｏｖｅｒＳＤＨ不同,由动态同步传送模式（ＤＴＭ）提供的ＩＰｏｖｅｒＤＴＭ（ＩＰＯＤ）解决方案,以其高效的协议、灵活的业务支持、强大的可扩展能力等显著优点,引起了ＥＴＳＩ等标准化组织的重视。文章从ＤＴＭ原理出发,分析ＩＰＯＤ模型及其两种转发机制,探讨ＩＰＯＤ的应用实例和发展前景。     

Mobility support for IP over wireless ATM

A wireless ATM system consists of a core network infrastructure that provides mobility support to end terminals and a wireless access link. This article outlines two schemes for supporting mobility of IP terminals in this network. In the first scheme, location management and handoff support is integrated within the ATM signaling and control framework (“mobile ATM”), and mobility is transparently supported at the IP layer by mobile ATM underneath. In the second approach, the IP protocol stack is directly executed on ATM switches (without an intermediate ATM signaling stack) using an IP switching technique called IPSOFACTO (IP Switching Over Fast ATM Cell Transport), and terminal mobility is supported via mobile IP     

IP Over ATM的QOS探讨

文章对因特网的“集成服务”、ATM的QOS要求以及IPover ATM的QOS要求进行了探讨,并在此基础上提出了运用资源预保留协议将ATM集成到因特网上的实现方案。     

ATM交换机IP业务QoS的设计与实现

ATM（异步转送模式）交换机由于执行了严格的基于连接的流量管理和拥塞控制,能为用户提供良好的QoS（服务质量）保证,在骨干网中得到了广泛应用。但是随着IP业务应用越来越广泛,如何解决IP Over ATM（基于ATM的IP数据传输）在各种情况的QoS,是ATM交换机设计面临的重要问题。文中以ATM交换机互连的以太网接口（IP接口）和中继接口（ATM接口）为例,对ATM交换机如何实现IP业务的QoS,提出了一套完整的设计和实现方案。     

IP与ATM综合

介绍IP与ATM综合的各种技术、概念与原理，包括IP交换、CSR。Tag交换、ANIS和MPLS。最后给出用这些技术及有关技术研制的多层交换产品现状。     

POS技术及发展趋势

本文介绍了通过ＳＤＨ直接传送ＩＰ分组的方法－ＰＯＳ。文章详述了ＰＯＳ所涉及的两个主要问题：协议数据的封装,高速路由器的实现。文章还针对其它ＩＰ五ＡＴＭ结合的方案,给出了ＰＯＳ技术几个突出的优点,即高效率,可扩展性和简单可靠,并结合数据运营商的实际,描绘了ＰＯＳ技术的应用前景。     

IP网络及其实时业务展望

本文讨论了目前通信领域的２个热闹话题：ＩＰ网的网络组成和ＩＰ网上的实时业务。关于ＩＰ网的网络组成,本文讨论了ＩＰｏｖｅｒ ＡＴＭ．ＩＰ ｏｖｅｒ ＳＤＨ和ＩＰ ｏｖｅｒ ＷＤＭ技术。关于ＩＰ网上的实时业务,本文讨论了ＩＰ电话、ＩＰ会议和ＩＰ网的信息点播业务。     

An IP transport and routing architecture for next-generationsatellite networks

Over the past several years, a number of new satellite systems have been proposed to provide high-speed Internet and multimedia services to businesses and home users. These proposals have been driven by the desire of network operators to reach end users that do not have cost effective access to other alternatives such as fiber, DSL, and cable, and by the availability of new spectrum (Ka-band) for use by new satellite services. The proposed systems generally employ multiple high-power spot beams, an onboard fast packet switch, and a demand-assigned multiple access scheme to provision IP-based services. In this article we concentrate on a geosynchronous satellite system where packet transport and switching within the satellite system are based on ATM. We describe an IP/ATM interworking and IP routing architecture that is driven by three main requirements: (1) the ability to support ATM SVCs between hundreds of thousands of satellite terminals by a single ATM switch located onboard; (2) a scalable IP routing architecture that does not result in large volumes of routing traffic to be transported over the satellite; and (3) the ability to segment the satellite terminals for routing and administrative control by ISPs and enterprise networks     

IP和ATM网络技术的综合发展

本文主要介绍了ＩＰ和ＡＴＭ网络综合发展的现状以及目前ＩＰ和ＡＴＭ结合中还存在的关键技术问题，如多播、业务综合和路由选择以及它们对网络结构的影响。     

Scalable multi-QoS IP+ATM switch router architecture

This article proposes a scalable multi-QoS IP+ATM switch router architecture. The proposed switch router is based on a core ATM switching system with multi-QoS capability. Forwarding engines and a routing engine are attached in front of the line cards of the ATM switching system. The FEs and RE are interconnected with each other via internal VCs. A novel longest matching algorithm is employed at the FE to achieve packet forwarding at wire-speed of OC-12c rate (622.08 Mb/s). Wire-speed unicast and multicast packet forwarding are performed using point-to-point and point-to-multipoint VCs in a unified way. Because FEs and RE are decoupled from the base ATM switching system, the full spectrum of ATM QoS capability is nicely applied for IP QoS control with a packet classification at the edge of the network. The core switching fabric is scalable from 40 to 160 Gb/s capacity (371 MPPS in terms of packet forwarding throughput). Feedback rate control is employed at each line card to eliminate congestion in the high-speed core switching fabric even with a small amount of buffer.     

基于ATM和SDH的宽带IP网及光因特网

本文首先简要介绍了 IP、ATM、SDH、波分复用 (WDM)等技术 ,然后综述了 IP over ATM和 IPover SDH的特点和优缺点 ,简要阐述了提出光因特网技术的缘由。最后指出了在电信与计算机融合成信息产业的过程中 ,IP over ATM和 IP over SDH将长期共存互补 ,在各自最佳应用场合和领域发挥作用 ,最终它们将过渡到光因特网。