Research on the IP alias resolution technology

IP alias resolution,the procedure of identifying IP addresses belonging to the same router,is a critical step in Internet topology inference.It can convert the Internet logical topology into physical topology,and bridge the gap between the virtual world and real world.First the concept of IP alias resolution was introduced and the classical IP alias relationships were analyzed.Then the IPv4 alias resolution algorithms and the IPv6 alias resolution algorithms were discussed in detail separately.Finally,through the comprehensive analysis and comparison of all the algorithms,the research directions in the future especially in IPv6 alias resolution were pointed out in three folds such as alias target set selection,fingerprint selection and inference methods.     

Mobile and Multicast IP Services in PACS: System Architecture, Prototype, and Performance

Traditionally, wireless cellular communication systems have been engineered for voice. With the explosive growth of Internet applications and users, there is an increasing demand on providing Internet services to mobile users based on the voice-oriented cellular networks. However, Internet services add a set of radically different requirements on to the cellular wireless networks, because the nature of communication is very different from voice. It is a challenge to develop an adequate network architecture and necessary systems components to meet those requirements.This paper describes our experience on developing Internet services, in particular, mobile and multicast IP services, in PACS (Personal Access Communication Systems). Our major contributions are five-fold: (i) PACS system architecture that provides wireless Internet and Intranet access by augmenting the voice network with IP routers and backbone links to connect to the Internet; (ii) simplified design of RPCU (Radio Port Controller Unit) for easy service maintenance and migration to future IP standards such as IPv6; (iii) native PACS multicast to efficiently support dynamic IP multicast and MBone connectivity; (iv) optimization and incorporation of Mobile IP into PACS handoff mechanism to efficiently support roaming within a PACS network as well as global mobility between PACS networks and the Internet; (v) successful prototype design of the new architecture and services verified by extensive performance measurements of IP applications. Our design experience and measurement results demonstrate that it is highly feasible to seamlessly integrate the PACS networks into the Internet with global IP mobility and IP multicast services.     

利用BGP虚拟下一跳技术实现IP地址快速封堵

通过在BGP的路由反射器（RR）把需要封堵的IP地址通过BGP信息向全网发布并携带特定的BGP虚拟下一跳信息,而在IP骨干网的边缘路由器设置该特定虚拟下一跳IP地址的黑洞路由。以至于在IP骨干网的边缘路由器都会自动把访问该需要封堵IP地址的流量丢弃,达到快速封堵IP地址的目的。     

基于IP地址推断的网络拓扑发现方法

In order to discover more detailed topology information of a certain network, a lightweight approach is proposed, in which only one probe source is required. In this approach, a heuristic method in using the“traceroute”tool is introduced to collect more topology pieces. Based on those traces, subnets (or point-to-point links) in the backbone can be identified. With those identified information, a set of rules is developed to resolve router IP aliases. Experiments with both this approach and existing topology discovery methods are carried out on two real networks, i.e., TUNET, the Tsinghua University campus network, and CERNET (AS4538), the third largest ISP network of China. According to the comparison, the approach in this paper can get much higher quality information about IP addresses, links, and routers. In conclusion, a more complete and accurate topology can be gained with this approach.     

IP over optical networks: architectural aspects

The Internet transport infrastructure is moving toward a model of high-speed routers interconnected by intelligent optical core networks. A consensus is emerging in the industry on utilizing an IP-centric control plane within optical networks to support dynamic provisioning and restoration of lightpaths. At the same time, there are divergent views on how IP routers must interact with optical core networks to achieve end-to-end connectivity. This article describes the architectural alternatives for interconnecting IP routers over optical networks, considering the routing and signaling issues. Also, the application of IP-based protocols for dynamic provisioning and restoration of lightpaths, as well as the interworking of multivendor optical networks is described     

Fast Duplicate Address Detection for Seamless Inter-Domain Handoff in All-IPv6 Mobile Networks

In All-IP networks, each computer or communication equipment needs an IP address. To supply enough IP addresses, the new Internet protocol IPv6 will be used in next generation mobile communication. Although IPv6 improves the existing Internet protocol (IPv4), Duplicate Address Detection (DAD) mechanism may consume resources and suffer from long delay. DAD is used to make sure whether the IP address is unique or not. When a mobile node performs an inter-domain handoff, it will first generate a new IP and perform a DAD procedure. The DAD procedure not only wastes time but also increases the signaling load on Internet. In this paper, we propose a new DAD mechanism to speed up the DAD procedure. We create a DAD table in access or mobility routers in All-IP networks and record all IP addresses of the area. When a new IP address needs to perform DAD, it can just search in the DAD table to confirm the uniqueness of the address. Furthermore, we propose a new method, Fast Duplicate Address Detection (Fast DAD), to reduce data search time. Simulation results show that our method outperforms the existing DAD methods.     

A Transparent Failover Mechanism for a Mobile Network with Multiple Mobile Routers

In a mobile network that is multihomed by multiple mobile routers, a mobile router that loses link connectivity can be replaced by the other mobile routers. We propose a transparent failover mechanism (TFM) to provide seamless Internet services to nodes in the mobile network, which is validated by implementing a real test-bed. Compared to the network mobility basic support protocol, TFM does not require the nodes attached to the failed mobile router to change their addresses, and hence has two advantages: (a) IP connectivity is maintained transparently, and (b) failover is quickly accomplished by avoiding the address re-configuration process in each node.     

Flow Routing and its Performance Analysis in Optical IP Networks

Optical packet-switching networks deploying buffering, wavelength conversion and multi-path routing have been extensively studied in recent years to provide high capacity transport for Internet traffic. However due to packet-based routing and switching, such a network could result in significant disorder and delay variation of packets when they are received by end users, thus increasing the burstiness of the Internet traffic and causing higher-layer protocol to malfunction. This paper addresses a novel routing and switching method for optical IP networks — flow routing, and its facilitating protocol. Flow routing deals with packet-flows to reduce flow corruption due to packet out-of-order, delay variation and packet loss, without using complicate control mechanism. Detailed performance analysis is given for output-buffered optical routers adopting flow routing. Two flow-oriented discarding techniques, i.e., flow discard (FD) and early flow discard (EFD), are discussed. Compared with optical packet-switching routers, a remarkable improvement of good-throughput is obtained in the optical flow-routers, especially under high congestion periods. We conclude that EFD behaves as a robust technique, which is more tolerant than FD to the change of traffic and transmission system factors.     

IP over SONET

IP over SONET technology is being deployed today in IP backbone networks to provide efficient, cost-effective, high-speed transport between fast routers. The authors present an overview of the architectural considerations in the deployment of IP over SONET technology. In addition, an overview of the developments in IP over SONET interface design and specification is provided. Finally, the authors conclude with an examination of the future of high-speed Internet transport     

Strategies Towords Next Generation IP Over Optical Networks

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On wavelength-converted optical routers employing flow routing

Optical networks have been extensively investigated in recent years to provide high capacity for the Internet traffic. Among them the optical packet-switching network deploying buffering, wavelength conversion and multipath routing could be the most suitable one. It cannot only provide high capacity transport for Internet traffic but also achieve high utilization of the network resources. However due to the packet-oriented routing and switching, such a network can result in a large amount of packets out-of-order, packet loss and/or with various delays upon arriving at end systems, causing TCP flows that comprise those packets corrupted. Large amount of corrupted flows can increase the burstiness of the Internet traffic and cause higher-layer protocol to malfunction. This paper presents a novel routing and switching method for optical IP networks-flow routing. Without using a complicate control mechanism flow routing deals with packet-flows to reduce the amount of corrupted flows. The performance of the wavelength-converted optical flow router is investigated, based on a novel analytical model. A performance metric, i.e., good-throughput, is used, measuring the ratio of the amount of packets comprised in the noncorrupted flows to total amount of packets. Comparing with optical packet-switching routers, a remarkable improvement of good-throughput can be obtained by using optical flow routers. More important, using wavelength conversion can greatly improve the good-throughput of optical flow routers.     

A next-generation optical regional access network

We describe an optical regional access network which combines electronic IP routing with intelligent networking functionality of the optical WDM layer. The optical WDM layer provides such networking functions as network logical topology reconfiguration, optical flow switching to offload traffic and bypass IP routers, wavelength routing of signals, protection switching and restoration in the optical domain, and flexible network service provisioning by reconfigurable wavelength connectivity. We discuss key enabling technologies for the WDM layer and describe their limitations. The symbiosis of electronic and optical WDM networking functions also allows support for heterogeneous format traffic and will enable efficient gigabit-per-second user access in next-generation Internet networks     

Edge Mobility Architecture — Routeing and Hand-off

This paper presents a network architecture for supporting edge mobility, and goes on to consider IP networks in which the core topology is fixed but where the hosts at the edge of the network may be mobile, as is the case in cellular networks. Within this architecture, mobile enhanced routeing (MER) protocols are used to support the prefix-routed requirements of the fixed Internet, along with the movement of IP addresses allocated to mobile nodes. Specific components for the support of such edge mobility (EMA:MER) are then outlined; these offer fixed/mobile IP network convergence, homogeneous IP handoff across heterogeneous access technologies, and inter-domain roaming across heterogeneous large-scale IP domains.     

CNGI核心网CERNET2的设计

文章介绍了中国下一代互联网(CNGI)示范工程核心网建设项目CERNET2的网络设计方案,包括总体设计、主干网设计、核心节点设计、接入方案设计、CNGI国际/国内互连中心设计等.CERNET2以2.5 Gb/s～10 Gb/s速率连接中国20个主要城市的25个主干网核心节点,具有4个主要特点:主干网采用纯IPv6协议,而不是IPv4/IPv6双协议栈技术,是世界上规模最大的纯IPv6网络;为中国研制的IPv6核心路由器提供测试和试运行环境,并开展了不同厂商设备的互连、互通、互操作测试和试验;利用IPv6地址空间充分大的特性,进行真实IPv6地址网络相关技术的试验研究,为构建安全可信的下一代互联网奠定了基础;开发了下一代互联网的重要应用.     

Active networks for efficient distributed network management

The emerging next generation of routers exhibit both high performance and rich functionality, such as support for virtual private networks and QoS. To achieve this, per-flow queuing and fast IP filtering are incorporated into the router hardware. The management of a network comprising such devices and efficient use of the new functionality introduce new challenges. A truly distributed network management system is an attractive candidate to address these challenges. We describe how active network techniques can be used to allow fast and easy deployment of distributed network management applications in IP networks. We describe a prototype system where legacy routers are enhanced with an adjunct active engine, which enables the safe execution and rapid deployment of new distributed management applications in the network layer. This system can gradually be integrated in today's IP network, and allows smooth migration from IP to programmable networks. This is done with an emphasis on efficient use of network resources, which is somewhat obscure by many of today's high-level solutions     

专题：移动互联网的发展趋势和技术方向——移动互联网中的若干问题研究

对移动互联网的商业模型、移动互联网所使用的两种网络（移动网和无线局域网）的网络特性、移动智能终端、移动网的网络特性和资源管理、移动互联网中的IP地址和寻址等5个问题进行讨论,指出其存在的问题和可能的解决方法,认为这些深层次问题的解决,可使核心技术获得突破性进展.     

IP network configuration for intradomain traffic engineering

The smooth operation of the Internet depends on the careful configuration of routers in thousands of autonomous systems throughout the world. Configuring routers is extremely complicated because of the diversity of network equipment, the large number of configuration options, and the interaction of configuration parameters across multiple routers. Network operators have limited tools to aid in configuring large backbone networks. Manual configuration of individual routers can introduce errors and inconsistencies with unforeseen consequences for the operational network. In this article we describe how to identify configuration mistakes by parsing and analyzing configuration data extracted from the various routers. We first present an overview of IP networking from the viewpoint of an Internet service provider and describe the kinds of errors that can appear within and across router configuration files. To narrow the scope of the problem, we then focus our attention on the configuration commands that relate to traffic engineering-tuning the intradomain routing protocol to control the flow of traffic through the ISP network. We present a case study of a prototype tool, developed in collaboration with AT&T IP Services, for checking the configuration of the AT&T IP Backbone and providing input to other systems visualization and traffic engineering     

Internet电视点播系统实现方案

本文首先介绍了当前Internet业务和广播电视相互融合的两种形式,并比较它们的优缺点;然后,对Internet电视点播系统的组成及其系统实现方案作了详尽的讲述;最后,介绍了两种目前最具有代表性的系统实现－IP／TV和Resal系统。     

IP over optical cross-connect architectures [Topics in Optical Communications]

IP over optical network architectures have been extensively discussed within the research literature over the past few years. However, although signaling protocols between IP routers and optical cross-connect networks have been standardized, large IP backbones are not typically deployed over optical cross-connect networks with automatic reconfigurability features, such as automatic restoration or dynamic establishment of new IP links. One of the most important criteria in determining whether an IP backbone should be carried over such an optical cross-connect network is economic viability. In this article we analyze and explore four architectures for a typical large ISP backbone. In contrast with some other published claims, our results suggest it is more economically attractive to bypass an intermediate cross-connect network, given current equipment and IP backbone network design requirements. However, for ISPs who also provide a large volume of private line services, we propose an integrated architecture for IP over optical cross-connect networks that may provide an attractive alternative for providing rapid and cost-effective restoration from network failures     

IP switching and gigabit routers

To cope with the growth in the Internet and corporate IP networks, we require IP routers capable of much higher performance than is possible with existing architectures. This article examines two approaches to the design of a high-performance router, the gigabit router and the IP switch, and then provides some detail on the implementation of an IP switch and the protocols associated with IP switching