SDN试验床网络虚拟化切片机制综述

未来网络体系架构和关键技术的研究需要灵活开放的测试验证环境,基于传统分布式的网络架构难以达到动态虚拟化、有效管控和新协议灵活部署的需求。随着软件定义网络（SDN）技术的出现和发展,上述问题找到了有效的解决途径,因此,基于SDN构建网络试验床成为了近年来该领域的主流研究方向之一。其中,基于SDN的网络虚拟化切片技术更是试验床中的核心支撑技术,可以根据不同试验的需求切分物理网络资源,从而提供并行、独立的网络环境。将重点研究基于SDN的试验床中使用的网络虚拟化切片机制,从“流量识别和切片网络标识”、“虚拟节点抽象”和“虚拟链路抽象”这3个关键技术出发,对当前基于SDN试验床中的典型网络虚拟化切片机制进行介绍与分析,并总结了该领域未来可行的研究方向。     

IP路由器技术发展趋势

在阐述IP路由器发展历程的基础上,结合业务发展需求,对路由器重点关注技术进行了分析与探讨.指出未来路由器应具备大容量、虚拟化、开放架构及软件可编程等特征,以推动未来IP网络向软件定义、云—网融合方向发展.     

基于虚拟化的网络创新实验环境研究

研究者针对未来网络创新研究而提出的各种创新性解决方案,需要在大规模真实网络实验环境中测试、验证.现有互联网无法支持基于后IP新型体系结构的创新实验,因此需要构建全面支持未来网络创新研究的实验环境.清华大学TUNIE平台,基于虚拟化技术,是拥有自主知识产权的未来网络创新实验环境.本文介绍网络创新实验环境的相关研究、关键技术,以及TUNIE设计目标、关键技术实现方案、平台部署情况等.目前,TUNIE平台已实现初步部署,应用于教学和科研中,并且承载一些网络创新实验.     

国外未来网络技术研究进展分析

互联网作为现代社会的基础设施,当前僵化的体系结构阻碍了它的创新和演进。未来网络体系和关键技术研究成为当前的研究热点。文章分析未来网络的主要需求和研究共识,从出发点、主要思路、关键技术、典型体系等方面,对开放可编程、基于网络虚拟化、基于内容寻址、面向服务、支持移动性等国外未来网络体系和关键技术研究进行了分析。     

面向多网络体制并存的开放式可重构路由器体系结构设计与实践

针对现有网络设备在支持可重构和多网络体制并存方面存在的不足,提出了一种面向多网络体制并存的开放式可重构路由器体系结构。通过在控制、转发和交换体系结构设计上,采用虚拟化和硬件分区配置技术,能够对控制、转发和交换进行资源划分与隔离,将路由器中同一个硬件资源虚拟化为多个功能上独立、资源上隔绝的逻辑路由器实例,提高了核心路由器设备的开放性和安全性。     

网络虚拟化的过去、现在和未来

网络虚拟化过程中主要诞生过4类过渡技术:虚拟局域网络(VLAN)、虚拟专用网络(VPN)、主动可编程网络(APN)、覆盖网络。网络虚拟化的研究现在主要集中于3个领域:云计算应用、平台化实现、软件定义网络。认为网络虚拟化的未来在性能保障、可靠性、易用性和完备性等方面需要加强,为此未来的网络虚拟化需要优化自身服务结构,并向无线网络、光网络等领域推广,此外还需要提供更加友好的可编程接口(API)以及网络功能。     

基于OpenFlow的未来互联网试验技术研究

对以OpenFlow为代表的基于可编程网络设备技术的未来互联网试验验证平台构建技术,以及OpenFlow自身的优势和不足进行了分析和研究,指出了OpenFlow是现阶段构建未来互联网试验验证平台的首要技术.     

基于可编程硬件的虚拟路由器数据平面设计与实现

未来网络体系结构创新和验证亟需建设虚拟化网络实验平台,虚拟路由器作为其中的核心组网设备,其结构和性能决定了实验平台的灵活性和承载能力.本文提出基于并行流水线的虚拟路由器数据平面结构,结合并行包分类和异步多指针轮询调度机制,在同一物理底层上实现了多个相互隔离的并行异构路由器.本设计在可编程硬件上进行了原型实现,并结合商用及软件路由器在真实的网络环境中部署、测试与实验.实验结果表明与传统单流水线结构相比,本设计能以更高灵活性和并行性支持异构的路由器实例独立运行;在逻辑资源开销和延时特性未显著增加的情况下,并行虚拟路由器可以达到与硬件可比的线速转发能力.     

虚拟化测控站体系结构设计与关键技术

随着测控任务日渐密集,任务类型的多样性、复杂性不断增长,传统测控站封闭的体系结构在应对未来测控需求方面存在较多的技术短板。在对比分析国内外同类技术发展的基础上,提出了以综合基带虚拟化和软件定义网络技术为基础、以资源池为核心的新一代测控站体系结构,分析了测控站功能域与实现方法,设计了基于OpenFlow协议的测控站网络。设计了多星测控实验,验证了虚拟化测控站的优势。实验结果表明,当前商用设备的虚拟化率不低于1.25。     

虚拟化路由交换平台转发可重构技术分析

开放性和平台化是网络交换设备体系结构的发展趋势,虚拟化路由交换平台是一种能灵活支持现有业务和未来业务的新型虚拟化网络设备。文中对虚拟化路由交换平台基本功能进行了抽象定义,分析了转发处理技术的重要性,而近年来硬件性能的持续提高,特别是网络处理器和FPGA对可编程和可重构的支持日益完善,为实现网络虚拟化创造了良好的条件。最后分析了虚拟化路由交换平台转发处理功能的3种不同实现方案,并重点对基于FPGA和网络处理器的实现方案进行了阐述。     

Using Programmable Network Management Techniques to Establish Experimental Networking Testbeds

The way in which research groups evaluate router software (QoS and routing components, for example) seems to be restricted to methodologies using mathematical modelling and simulation techniques. We believe that an experimental methodology is rarely used as the deployment of custom routing software to a testbed comprising multiple routers is a non-trivial task that is beyond the scope of most network research projects. This project intends to make experimental methodologies more accessible to researchers by using programmable networking techniques and by building a management system for a network testbed.     

Optical switch emulation in programmable software router testbed

A programmable optical router is a key enabler for dynamic service provisioning in Future Internet scenarios. It is equipped with optical switching hardware to forward information at hundreds of Gigabits/s rates and above, controlled and managed through modular and flexible procedures according to emerging standards. The possibility to test such costly optical architectures in terms of logical and physical performance, without implementing complex and expensive testbeds, is crucial to speed-up the development process of high-performance routers. To this purpose, this paper introduces the software-based emulation testbed of a programmable optical router, which is here developed and applied to test optical switching fabrics. Accurate characterization of the optical devices and physical layer aspects is implemented with the Click software router environment. Power loss and optical signal-to-noise-ratio evaluation are provided through accurate software representation of the physical characteristics of the optical devices employed. The scalability of the proposed emulation testbed is also assessed on standard PC hardware. All the obtained results prove the effectiveness of the proposed tool to emulate an optical router at different levels of granularity.     

Programmable virtual network as a service: towards a future Internet testbed based on IaaS cloud

During recently years, several OpenFlow-enabled testbeds have been deployed in world-wide research community. Typically, these OpenFlow-enabled testbeds need to stitch to other testbeds to link to virtual servers and immit experimentation traffic. From the view point of researchers, these OpenFlow-enabled testbeds only provide OpenFlow networking resource, and they have to resort to other experiment infrastructure to provide computing and storage resource. Due to the OpenFlow networking and other resource belongs to different infrastructure provider and is managed by their own control software, it is difficult to coordinate these partners to provide a full programmable experiment environment. Meanwhile, the control software of these testbeds are tight coupling with their substrate resources, which means that these substrate resources, together with virtualization technologies, are permanently dedicated to the control software and difficult to be used by other services. In this paper, a new future Internet testbed architecture based on the open Infrastructure-as-a-service cloud and software defined network (SDN) paradigm is proposed. It extends the current virtual network service by adding programmable virtual switch and controller resources that can be controlled by the researcher. Its loose coupling model allows the testbed operator decouple the experiment service from the infrastructure provider, which is a more flexible way to build the testbed. The initial prototype implementation in this paper shows that this new testbed architecture built on IaaS cloud and SDN is feasible and flexible to provide programmable virtual network service.     

Intrusion Detection Routers: Design, Implementation and Evaluation Using an Experimental Testbed

In this paper, we present the design, the implementation details, and the evaluation results of an intrusion detection and defense system for distributed denial-of-service (DDoS) attack. The evaluation is conducted using an experimental testbed. The system, known as intrusion detection router (IDR), is deployed on network routers to perform online detection on any DDoS attack event, and then react with defense mechanisms to mitigate the attack. The testbed is built up by a cluster of sufficient number of Linux machines to mimic a portion of the Internet. Using the testbed, we conduct real experiments to evaluate the IDR system and demonstrate that IDR is effective in protecting the network from various DDoS attacks.     

Internetworking based on cell switch router-architecture andprotocol overview

This paper describes an internetworking architecture and related protocol overview based on routers that have asynchronous transfer mode (ATM) cell switching capability in addition to conventional Internet protocol (IP) packet forwarding. The proposed architecture can provide high-throughput and low-latency switched paths for individual application flows or a group of application flows while retaining current router-based internetworking architecture. The proposed router is able to establish the switched path based on the characteristics of flows, e.g., arrival of a data packet with specific upper layer protocols or arrival of more than a certain amount of data packets in a predetermined period, as well as by the reception of an IP-layer resource reservation request, such as resource reservation protocol (RSVP). One important feature that is provided by the proposed router is interoperability with the emerging ATM network platform specified by the ATM Forum and the telecommunications sector of the International Telecommunications Union (ITU-T). The proposed routers can be interconnected with each other over the point-to-point synchronous optical network link as well as over the ATM network platform, which provides permanent virtual channel, virtual path, or switched virtual channel (SVC) services. That enables network carriers to provide Internet/intranet services as well as others, such as telephony, ATM/time division multiplexing leased line, or native ATM SVC services     

Mitigating the gateway bottleneck via transparent cooperative caching in wireless mesh networks

Wireless mesh networks (WMNs) have been proposed to provide cheap, easily deployable and robust Internet access. The dominant Internet-access traffic from clients causes a congestion bottleneck around the gateway, which can significantly limit the throughput of the WMN clients in accessing the Internet. In this paper, we present MeshCache, a transparent caching system for WMNs that exploits the locality in client Internet-access traffic to mitigate the bottleneck effect at the gateway, thereby improving client-perceived performance. MeshCache leverages the fact that a WMN typically spans a small geographic area and hence mesh routers are easily over-provisioned with CPU, memory, and disk storage, and extends the individual wireless mesh routers in a WMN with built-in content caching functionality. It then performs cooperative caching among the wireless mesh routers.We explore two architecture designs for MeshCache: (1) caching at every client access mesh router upon file download, and (2) caching at each mesh router along the route the Internet-access traffic travels, which requires breaking a single end-to-end transport connection into multiple single-hop transport connections along the route. We also leverage the abundant research results from cooperative web caching in the Internet in designing cache selection protocols for efficiently locating caches containing data objects for these two architectures. We further compare these two MeshCache designs with caching at the gateway router only.Through extensive simulations and evaluations using a prototype implementation on a testbed, we find that MeshCache can significantly improve the performance of client nodes in WMNs. In particular, our experiments with a Squid-based MeshCache implementation deployed on the MAP mesh network testbed with 15 routers show that compared to caching at the gateway only, the MeshCache architecture with hop-by-hop caching reduces the load at the gateway by 38%, improves the average client throughput by 170%, and increases the number of transfers that achieve a throughput greater than 1 Mbps by a factor of 3.     

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     

网络模拟中的路由器模型

文章通过对路由器体系结构和性能指标的分析,提出为网络模拟中的路由器建立模型的方法,为网络模拟网络总体设计提供了参考,给出了JuniperM160路由器和Cisco12008路由器在网络模拟中的模型实例。