无线ATM/IPOA的移动性支持

无线 ATM (WATM)能够对终端和无线接入连接提供移动性支持。文中论述了无线 ATM的网络结构 ,无线ATM的位置管理、越区切换 ,并提出 IPOA (IP Over ATM)支持移动性的两种方法。     

A new ATM adaptation layer for TCP/IP over wireless ATM networks

This paper describes the design and performance of a new ATM adaptation layer protocol (AAL‐T) for improving TCP performance over wireless ATM networks. The wireless links are characterized by higher error rates and burstier error patterns in comparison with the fiber links for which ATM was introduced in the beginning. Since the low performance of TCP over wireless ATM networks is mainly due to the fact that TCP always responds to all packet losses by congestion control, the key idea in the design is to push the error control portion of TCP to the AAL layer so that TCP is only responsible for congestion control. The AAL‐T is based on a novel and reliable ARQ mechanism to support quality‐critical TCP traffic over wireless ATM networks. The proposed AAL protocol has been validated using the OPNET tool with the simulated wireless ATM network. The simulation results show that the AAL‐T provides higher throughput for TCP over wireless ATM networks compared to the existing approach of TCP with AAL 5. This revised version was published online in July 2006 with corrections to the Cover Date.     

IP over SDH和IP over ATM技术

随着Internet的快速发展,对广域网的带宽提出了更高的要求,目前在广域上采用的两种技术是IP over ATM和IP over SDH。本文简要介绍了SDH和ATM以及实现IP over ATM和IP over SDH所需的协议栈,着重比较了这两技术在协议开销,宽带管理,服务质量（QoS),寻址选路以及流量控制等技术。     

Mobility management in wireless ATM networks

Mobile ATM offers a common wired network infrastructure to support mobility of wireless terminals, independent of the wireless access protocol. In addition, it allows seamless migration to future wireless broadband services, such as wireless ATM, by enabling mobility of end-to-end ATM connections. In spite of the diversity in mobile networking technologies (e.g., cellular telephony, mobile-IP, packet data services, PCS), all of them require two fundamental mechanisms: location management and handoff. This article describes different schemes for augmenting a wired ATM network to support location management of mobile terminals and handoff protocols for rerouting a connection data path when the endpoint moves. A prototype implementation of mobile ATM integrating mobility support with ATM signaling and connection setup, is presented. It shows how mobile ATM may be used to provide mobility support to an IP terminal using non-ATM wireless access     

Mobility management and control protocol for wireless ATM networks

The introduction of wireless ATM (WATM) in customer premises network environments necessitates the design of mobility protocols, since the existing versions of B-ISDN signaling do not support terminal mobility. Such protocols can be deployed either as extensions to the standard signaling capabilities, or as individual solutions that have little or no impact on existing infrastructures (switches, signaling software, etc.). A WATM architecture that adopts the latter approach is presented. After a discussion of the problems encountered in the integration of wireless networking and B-ISDN ATM technologies, a mobility management and control (MMC) protocol is proposed. Finally, in the framework of the proposed MMC protocol, algorithms for implementing mobility procedures (handover and registration) are described     

ATM与IP技术的融合分析

分别从ATM和IP技术特点出发,讨论了IPoverATM技术的2种模型及其中几种方案,然后分析了IP与ATM结合的性能以及发展前景.     

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     

电信辞库

ATM上的IP传输ATM上的IP传输（IPOA）技术,即只对数据流的第一个数据包进行路由地址处理,按路由转发,随后按已计算的路由在ATM网上建立虚电路（VC）,以后的数据包沿着VC以直通（Cut－through）方式进行传输,不再经过路由器,从而将数据包的转发速度提高到第二层交换的速度。目前IP与ATM的结合方式主要有重叠模型和集成模型两类。重叠模型有Internet工程任务组（IETF）推荐的CIPOA、ATM论坛（ATMF）推荐的局域网仿真（LANE）和ATM上的多协议规范（MPOA）等,集成模型有IPSwitching、多协议标记交换（MPLS）等…     

Mobility support in wireless Internet

The tremendous advancement and popularity of wireless access technologies necessitates the convergence of multimedia (audio, video, and text) services on a unified global (seamless) network infrastructure. Circuit-switched proprietary telecommunication networks are evolving toward more cost-effective and uniform packet-switched networks such as those based on IP. However, one of the key challenges for the deployment of such wireless Internet infrastructure is to efficiently manage user mobility. To provide seamless services to mobile users, several protocols have been proposed over the years targeting different layers in the network protocol stack. In this article we present a cross-layer perspective on the mobility protocols by identifying the key features of their design principles and performance issues. An analysis of the signaling overhead and handoff delay for some representative protocols in each layer is also presented. Our conclusion is that although the application layer protocol is worse than the protocols operating in the lower layers, in terms of handoff delay and signaling overhead, it is better suited as a potential mobility solution for the next-generation heterogeneous networks, if we consider such factors as protocol stack modification, infrastructure change, and inherent operational complexity.     

在公用ATM网上传送IP的解决方案

已采用ATM(异步传送模式)技术的运营商,面对IP业务的飞速发展,正在积极寻求使用ATM传送IP的最佳方案,目前普遍认为MPLS(多协议标签交换)是未来公用骨干网的解决方案。MPLS首先将在公用ATM骨干网上引入。它采用集成模式,将IP技术与ATM技术结合在一起,从而具备了ATM的高速性能、QoS(服务质量)性能、流量控制性能以及IP的灵活性、可扩充性。它不仅能够解决当前网络中存在的一些问题,而且能够支持许多新的功能,是一种较为理想的IP骨干网技术。ITU-T已将IP标准的研究放在首位,1999年9月SG13的Ip专家组会议针对采用MPLS的解决方案提出了公用A T M网上传送I P的建议草案I.ipatm。全面提出了网络的总体要求、网络体系结构、协议体系结构、业务映射的要求等,并对推荐采用的MPLS解决方案作了明确的说明。     

IP/ATM over xDSL技术

随着Internet和Intranet的发展,人们对访问速度的要求越来越高,出现了多种接入技术来满足用户对高速数据接入的需求,如:数字用户环路(xDSL)、混合光纤同轴电缆网(HFC)、基于ATM的无源光网络(APON)、多点分配系统(xMDS)等.     

Extension of Classical IP over ATM to support QoS at the application level

After the introduction of the basic concepts of Classical IP over ATM (CLIP), this paper presents an extension to this standard as well as a full analysis of the technical viability of the extension proposal. One of the major drawbacks of CLIP is the co-existence of IP and ATM without Quality of Service (QoS) support. By extending the functionality of CLIP and redefining the mapping of IP and ATM addresses, QoS can be brought to IP-based applications without requiring any specific definition or implementation changes at the IP layer or above. QACLIP (QoS for Applications using CLIP), the newly defined extension, allows applications to request specific QoS for their data transfer use. This revised version was published online in August 2006 with corrections to the Cover Date.     

Error recovery for ATM transmission over wireless channels

The authors present a technique for efficient recovery from transmission errors to be used when transmitting ATM-like data packets in a wireless channel affected by bursty errors (jamming). Issues related to packet format error protection code structure and retransmission protocol are discussed and simulation results are shown that prove the effectiveness of the proposed approach     

Design and evaluation of multicast GFR for supporting TCP/IP over hybrid wired/wireless ATM

The major challenges of designing multicast traffic control protocols for a combined wired/wireless network are the varying transmission characteristics (bandwidth, error, and propagation delay) of the wireless and wired media, and the different, possibly conflicting frame rate requests from multiple sources. To address these issues, in this paper we design and evaluate new unicast and multicast guaranteed frame rate (GFR) schemes for supporting TCP/IP traffic over a combined wired/wireless ATM network. We first propose a new, flexible weighted buffer management, and a frame‐based virtual spacing (VS) mechanism implementing weighted fair queueing. The unicast GFR scheme is based on the integration of the new weighted buffer management, and either cell‐based or frame‐based VS. It is then extended to support multicast GFR flows. The multicast scheme presented in this paper is the first multicast GFR scheme appeared in the literature. These schemes are carefully evaluated over several network configuration, supporting heterogeneous TCP/IP traffic with various frame rates. Simulation results show that the new schemes guarantee the minimum rates requested, provide excellent fairness, and achieve reasonably high efficiency. The new schemes may be extended to provide differentiated service in both IP and mobile IP frame work. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mobility and connection management in a wireless ATM LAN

This paper proposes algorithms for handoff, location, and connection management in a wireless asynchronous transfer mode (ATM) local-area network (LAN). Fast handoffs while maintaining cell sequence and quality-of-service (QoS) guarantees are achieved by distributing switching functionality to base stations, and using a networking scheme based on provisioned virtual trees. A new distributed location management scheme using a minimal registration procedure and broadcasts on wired links is proposed for this LAN. The detailed signaling procedures that support the algorithms for mobility and connection management are described. Finally, an implementation of these procedures and an analysis of the measured data is presented. Measurements of service times obtained from this implementation indicate that over 100 calls/s. can be handled by each node in 50-node network with a high-percentage of mobiles (75%) relative to fixed endpoints. This is comparable to current wired ATM switch call handling throughputs, in spite of the fact that these nodes perform additional handoff and location management functions. The data also indicates handoff latency times of 1.3 ms. This validates our proposal for maintaining cell sequence while performing handoffs     

IP应用在ATM网络中的协议开销

探讨ＡＴＭ网络中与ＩＰ应用相关的开销问题,计算并分析了在不同传输协议上数据帧的开销以及不同应用数据单元对传输效率的影响。     

Wormhole IP over (connectionless) ATM

High-speed switches and routers internally operate using fixed-size cells or segments; variable-size packets are segmented and later reassembled. Connectionless ATM was proposed to quickly carry IP packets segmented into cells (AAL5) using a number of hardware-managed ATM VCs. We show that this is analogous to wormhole routing. We modify this architecture to make it applicable to existing ATM equipment: we propose a low-cost, single-input, single-output wormhole IP router that functions as a VP/VC translation filter between ATM subnetworks. When compared to IP routers, the proposed architecture features simpler hardware and lower latency. When compared to software-based IP-over-ATM techniques, the new architecture avoids the overheads of a large number of labels, or the delays of establishing new flows in software after the first few packets have suffered considerable latencies. We simulated a wormhole IP routing filter, showing that a few tens of hardware-managed VCs per outgoing VP usually suffice. We built and successfully tested a prototype, operating at 2×155 Mb/s, using one field programmable gate array (FPGA) and DRAM. Simple analysis shows that operation at 10 Gb/s and beyond is feasible today     

TCP/IPoverATM的性能研究

 本文讨论将传统的TCP拥塞控制机制和CIPOA用于采用ER(FB)算法和EFCI(CCR)算法的ATM网络时可用比特率业务(ABR)和未确定比特率业务(UBR)的性能.仿真结果表明,无论在缓冲区的需求、带宽分配的公平性、吞吐量和链路利用率方面ABR业务的TCP性能均明显优于UBR业务.对于较简单的网络模型ER(FB)算法的TCP性能优于EFCI(CCR)算法,更优于传统的EFCI算法.     

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     

IP over ATM技术及其应用模式

说明了IP技术与ATM技术结合的必要性以及结合的优势,介绍了IP over ATM技术的原理及其应用模式,其中包括经典IP模式、捷径IP模式和集成IP模式,最后简要分析了IP over ATM技术的发展趋势。