新一代Internet对高速路由器研究的挑战

高速路由器是实现下一代IP网络的基础,本文对下一代IP网络的特点和设计高速路由器的关键技术进行了探讨。     

改进BGP实现大型复杂IP网络的负载均衡

通过多条等价链路实现流量的负载分担,是大型IP网络设计的基本方法.IGP能够很好地支持等价路径的负载分担,但是BGP引入路由反射器(RR)后,不能配合IGP实现等价路径的负载分担和最短路径的选择,造成流量分布的不均衡.本文提出了两种BGP扩展方法,用于解决大型IP网络中的负载均衡问题:多反射路径(multi-reflection path,MRP)和下一跳撤销反射(next-hop designated withdraw reflection,NHDWR).通过这两种方法,解决了自治系统内部穿透流量的负载均衡和最短路径的选择.     

A multilayer IP security protocol for TCP performance enhancement in wireless networks

Transmission control protocol (TCP) performance enhancement proxy (PEP) mechanisms have been proposed, and in some cases widely deployed, to improve TCP performance in all-Internet protocol (IP) wireless networks. However, this technique is conflicted with IP-security (IPsec)-a standard IP security protocol that will make inroad into wireless networks. This paper analyzes the fundamental problem behind this conflict and develops a solution called multilayer IP-security (ML-IPsec). The basic principle is to use a multilayer protection model and a fine grain access control to make IP security protocols compatible with TCP PEP. It allows wireless network operators or service providers to grant base stations or wireless routers limited and controllable access to the TCP headers for performance enhancement purposes. Through careful design, implementation, and evaluation, we show that we can easily add ML-IPsec to existing IPsec software and the overhead is low. We conclude that ML-IPsec can help wireless networks provide both security and performance.     

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     

IP/SDH接口的分析与设计

;IP/SDH接口技术是IP骨干网上千兆路由器高速互连的经济并且有效的解决方式.首先介绍IP/SDH的接口规范,然后主要对其中存在的问题和可能造成的影响进行了分析.为提高网络的可靠性,讨论了一种加扰码的改进的接口设计.     

Compact $$3\times 3$$ wavelength routing for photonic integrated circuits

Photonic integrated circuits are the future of optical communication networks. The demand for high bandwidth has added a remarkable increase in the capacity of transmission and routing techniques for optical networks. With massive growth in photonic integrated circuits, communication within them (PIC) is an area that needs to be explored and addressed. The signal path between different components in the circuit has to be established for an optimal path with high transmission efficiency. This could be achieved using routers. With this being the intention, this paper proceeds with a design of two \(3\,\times \,3\) optical passive wavelength routers using photonic crystal ring resonators. The designed router connects three transmitters to three receivers with desired characteristics such as low crosstalk, less propagation delay, low insertion loss and can be easily fabricated because of its less complex design. The routers are designed to operate in third transmission window wavelength with basic building blocks of \(1\,\times \,2\) routers. The designed layout of routers exhibits good performance which can be used for all optical communication networks and has a good technological compatibility for chip level integration in PIC. The layout is simulated using finite difference time domain and plane wave expansion methods.     

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     

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 heuristic algorithm for the point of presence design problem in IP networks

We propose a heuristic algorithm for the point of presence (POP) design problem in Internet protocol (IP) networks, where a POP is a node composed of several interconnected co-located routers. This problem consists of selecting the number of routers and their types, selecting the interface card types, connecting the access and the backbone links to the ports and selecting the link types between the co-located routers. A systematic set of experiments is designed to assess the performance of the proposed heuristic algorithm. The results show that quasioptimal solutions can be found with the proposed heuristic.     

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 over WDM网络中能耗自感知的混合疏导专有保护算法

针对绿色生存性IP over WDM网络中资源开销大、网络阻塞率高的问题,提出一种能耗自感知的混合疏导专有保护(HG-PA-DPP)算法。首先在IP层的核心路由器对低粒度业务请求集中疏导;然后通过实时感知WDM层的链路负载和双层器件带来的链路能耗状态定义链路权值,基于分层图在不同波长平面上为各业务请求寻找权值小且链路分离的工作路径和保护路径,同时在业务的中间节点处对不需要光-电-光转换的光路进行光旁路处理;最后,将空闲或保护资源设置为休眠模式以实现节能。仿真结果表明,所提算法在高负载时有着更好的节能效果,且在大网络拓扑下资源开销(RO)为传统算法的76.5%,阻塞率(BP)仅为传统算法的61.1%。     

IP/MPLS over WDM网中考虑链路 负载平衡的保护设计

利用网络链路资源被占用的部分信息实现保护资源共享,可以极大地改善网络对业务的丢弃性能.这对采用多协议标记交换(MPLS,Multiprotocol Label Switching)技术的IP over WDM网络来说,并不需要太大的代价.基于此,本文提出了在IP over WDM网中考虑通路保护的动态路由算法.对工作通路的选取,算法对选路成本和路由长度作了折衷考虑;而对于保护通路,则对其共享能力和路由长度作了权衡.仿真结果表明,本文算法不管是对业务的丢弃性能,还是对网络的链路负载平衡度,均取得了较满意的结果.     

基于IPv6的大规模接入汇聚路由器的设想和实现

针对下一代互联网面临的新业务拓展和安全性服务问题,本文综述了对未来网络的可运营、可管理和可控制的综合要求,提出了基于IPv6的大规模接入汇聚路由器(converging router access,ACR)的新概念,并分析了ACR工程实现的若干关键问题.ACR的提出不仅打破了大容量高性能路由器仅在核心骨干网络中使用的传统观念,开辟了大容量高性能路由器新的应用环境,而且为在下一代互联网中开展大规模、高速稳定和安全可靠的宽窄带新业务提供了创新的技术途径.     

On the performance and improvement of alias resolution methods for Internet core networks

The Internet is a huge interconnection of thousands of networks with different technologies, equipment, configurations, and administrative owners. This, added to the lack of public information about those individual infrastructures, makes it a difficult task to provide a so-called Internet map: a topological map with information of routers, interconnections between routers, and IP addressing configuration. Traditional topology discovery methods based on traceroutes only provide IP addresses in the path between end-nodes. Some of those IP addresses can belong to the same router, and this identification is made by alias resolution methods. Therefore, alias resolution allows to provide router-level map of the Internet with important applications in network simulation, protocol design, network management, network security, network service design, and geolocation. In this paper, alias resolution methods are analyzed in Internet core networks (GlobalNOC, Canet4, and Geant). This allows to identify peculiar behaviors in these core networks, improving alias resolution methods. Simultaneously, reduction methods are used to decrease the number of probing packets in alias resolution methods.     

适合多跳Ad Hoc网络的移动因特网路由器的设计

未来将使用移动路由器来实现移动AcIHoe用户与因特网的连接。本文介绍了移动因特网路由器的设计原理：使用移动IP来实现移动支持，使用无线局域网WLAN(IEEE802．11b)和蜂窝系统(GPRS)来连接多跳Ad Hoe网络(AODV)。     

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.     

Multicast Flow Aggregation in IP over Optical Networks

It is widely believed that IP over optical networks will be a major component of the next generation Internet However, it is not efficient to map a single multicast IP flow into one light-tree, since the bandwidth of an IP flow required is usually much less than that of a light-tree. In this paper, we study the problem of multicast flow aggregation (MFA) in the IP over optical two-layered networks under the overlay model, which can be defined as follows: given a set of head ends (i.e. optical multicasting sources), each of which can provide a set of contents (i.e. multicast IP flows) with different required transmission bandwidth, and a set of requested content at the access routers (i.e. optical multicasting destinations), find a set of light-trees as well as the optimal aggregation of multicast IP flows in each light-tree. We model MFA by a tri-partite graph with multiple criteria and show that the problem is NP-complete. Optimal solutions are designed by exploiting MFA to formulate an integer linear programming (ILP), with two parameters: the multicast receiving index alpha and the redundant transmitting index beta. We also propose a heuristic algorithm. Finally, we compare the performance of MFA for different combination of alpha and beta via experiments and show our heuristic algorithm is effective for large-scale network in numerical results     

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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MPLS: the magic behind the myths [multiprotocol label switching]

This article reviews the key differences between traditional IP routing and the emerging multiprotocol label switching (MPLS) approach, and identifies where MPLS adds value to IP networking. In various corners of the industry MPLS has been held up as the solution to IP QoS, gigabit forwarding, network scaling, and traffic engineering. Each of these expectations is critically considered in the light of developments in conventional gigabit IP routers. It is shown that MPLS adds the ability to forward packets over arbitrary non-shortest paths, and emulate high-speed “tunnels” between IP-only domains-capabilities critical to service providers who need to better manage resources around their backbones, or who are planning IP VPN services. However, it is also argued that the technology required to support IP QoS and gigabit forwarding is not unique to MPLS. A network of gigabit IP routers or switches may be entirely sufficient for QoS and performance if traffic engineering is not a requirement