基于SDN的IPRAN目标架构与组网模型探讨

在新型业务需求和新技术涌现的双重驱动下,软件定义网络(SDN)成为互联网应用提供商、运营商、IT系统和网络设备提供商共同关注的新型网络架构和技术。这种网络控制与转发能力分离的架构,可以支持更灵活的网络控制和业务能力提供。从SDN的概念和总体架构出发,分析IP RAN对SDN的需求,提出了在IP RAN中引入SDN技术的目标网络结构和网络模型,并对基于SDN的IP RAN应用策略进行了探讨。     

An SDN approach to route massive data flows of sensor networks

With the advent of the Internet of Things (IoT), more and more devices can establish a connection with local area networks and use routing protocols to forward all information to the sink. But these devices may not have enough resources to execute a complex routing protocol or to memorize all information about the network. With proactive routing protocols, each node calculates the best path, and it needs enough resources to memorize the network topology. With reactive routing protocols, each node has to broadcast the message to learn the right path that the packets must follow. In all cases, in large networks such as IoT, this is not an appropriate mechanism. This paper presents a new software‐defined network (SDN)–based network architecture to optimize the resource consumption of each IoT object while securing the exchange of messages between the embedded devices. In this architecture, the controller is in charge of all decisions, and objects only exchange messages and forward packets among themselves. In the case of large networks, the network is organized into clusters. Our proposed network architectures are tested with 1000 things grouped in five clusters and managed by one SDN controller. The tests using OpenDayLight and IoT embedded applications have been implemented on several scenarios providing the ability and the scalability from dynamic reorganization of the end‐devices. This approach explores the network performance issues using a virtualized SDN‐clustered environment which contributes to a new model for future network architectures.     

SDN‐DMM for intelligent mobility management in heterogeneous mobile IP networks

Mobility management applied to the traditional architecture of the Internet has become a great challenge because of the exponential growth in the number of devices that can connect to the network. This article proposes a Software‐Defined Networking (SDN)‐based architecture, called SDN‐DMM (SDN‐Distributed Mobility Management), that deals with the distributed mode of mobility management in heterogeneous access networks in a simplified and efficient way, ensuring mainly the continuity of IP sessions. Intent‐based mobility management with an IP mapping schema for mobile node identification offers optimized routing without tunneling techniques, hence, an efficient use of the network infrastructure. The simplified mobility control API reduces both signaling and handover latency costs and provides a better scalability and performance in comparison with traditional and SDN‐based DMM approaches. An analytical evaluation of such costs demonstrated the better performance of SDN‐DMM, and a proof of concept of the proposal was implemented in a real environment.     

SDN/NFV‐based handover management approach for ultradense 5G mobile networks

With the great increase of connected devices and new types of applications, mobile networks are witnessing exponential growth of traffic volume. To meet emerging requirements, it is widely agreed that the fifth‐generation mobile network will be ultradense and heterogeneous. However, the deployment of a high number of small cells in such networks poses challenges for the mobility management, including frequent, undesired, and ping‐pong handovers, not to mention issues related to increased delay and failure of the handover process. The adoption of software‐defined networking (SDN) and network function virtualization (NFV) technologies into 5G networks offers a new way to address the above‐mentioned challenges. These technologies offer tools and mechanisms to make networks flexible, programmable, and more manageable. The SDN has global network control ability so that various functions such as the handover control can be implemented in the SDN architecture to manage the handover efficiently. In this article, we propose a Software‐Defined Handover (SDHO) solution to optimize the handover in future 5G networks. In particular, we design a Software‐Defined Handover Management Engine (SDHME) to handle the handover control mechanism in 5G ultradense networks. The SDHME is defined in the application plane of the SDN architecture, executed by the control plane to orchestrate the data plane. Simulation results demonstrate that, compared with the conventional LTE handover strategy, the proposed approach significantly reduces the handover failure ratio and handover delay.     

Dynamic switch migration towards a scalable SDN control plane

Distributed control plane is a promising approach to scalable software‐defined networking (SDN). Live migration of switches from controllers that are overloaded to those that are underutilized may be a solution to handle peak switch traffic using available control resource. However, such migration has to be performed with a well‐designed mechanism to fully utilize available resources in all three resource dimensions: CPU, bandwidth, and memory. In this article, we first provide a resource model for SDN and reduce the switch migration decision to a centralized resource utilization maximization problem under constraints of CPU, bandwidth, and memory. Second, we show that the problem of maximizing resource utilization in an SDN is equivalent to that of maximizing game players' profits in the context of non‐cooperative game theory. Taking controllers and switches as game players and commodities respectively, the player policy is how to migrate switches among the control plane. Finally, we implement a proof of concept, called GAME‐Switch Migration (GAME‐SM). The numerical experiments using Mininet emulator validate nice properties of our game model in enhancing the performance of control plane in SDN. Copyright © 2016 John Wiley & Sons, Ltd.     

SDN在IP层与光融合中的应用研究

分析了SDN在IP层与光层的协同应用,论述了基于SDN的IP与光融合架构,阐述了智能控制在IP与光协同中的演进。     

Power savings in software defined data center networks via modified hybrid genetic algorithm

In modern data centers, power consumed by network is an observable portion of the total energy budget and thus improving the energy efficiency of data center networks (DCNs) truly matters. One effective way for this energy efficiency is to make the size of DCNs elastic along with traffic demands by flow consolidation and bandwidth scheduling, i.e., turning off unnecessary network components to reduce the power consumption. Meanwhile, having the instinct support for data center management, software defined networking (SDN) provides a paradigm to elastically control the resources of DCNs. To achieve such power savings, most of the prior efforts just adopt simple greedy heuristic to reduce computational complexity. However, due to the inherent problem of greedy algorithm, a good-enough optimization cannot be always guaranteed. To address this problem, a modified hybrid genetic algorithm (MHGA) is employed to improve the solution's accuracy, and the fine-grained routing function of SDN is fully leveraged. The simulation results show that more efficient power management can be achieved than the previous studies, by increasing about 5% of network energy savings.     

Routing algorithm design of satellite network architecture based on SDN and ICN

In view of the problems of low routing efficiency, complex control process, and difficult network management in big data environment in the traditional integrated space‐terrestrial network, in the paper, we propose a satellite network architecture called software‐defined information centric satellite networking (SDICSN) based on software‐defined networking (SDN) and information‐centric networking (ICN), and we design a virtual node matrix routing algorithm (VNMR) under the SDICSN architecture. The SDICSN architecture realizes the flexibility of network management and business deployment through the features of the separation of forwarding and controlling by the SDN architecture and improves the response speed of requests in the network by the centric of “content” as the ICN idea. According to the periodicity and predictability of the satellite network, the VNMR algorithm obtains the routing matrix through the relative orientation of the source and destination nodes, thus reducing the spatial complexity of the input matrix of the Dijkstra algorithm and then reducing the time complexity of the routing algorithm. For forwarding information base (FIB), the mechanism of combination of event driven and polling can be quickly updated in real time. Finally, the advantages of the SDICSN architecture in routing efficiency, request delay, and request aggregation are verified by simulation.     

Energy efficient virtual network embedding for federated software‐defined networks

In this paper, we focus on energy efficient virtual network embedding in federated (multidomain) software‐defined networks (SDNs). We first formulate an optimization problem as an integer linear program (ILP) that minimizes the energy consumption of the network links, while at the same time adhering to the bandwidth and CPU requirements of the virtual network requests. We then propose a polynomial‐time heuristic algorithm, which consists of three stages. In the first stage, the top SDN controller decides on whether to partition the virtual network request into smaller subrequests and give subrequests to multiple domains or give the enitre virtual network request to a single domain, while in the second stage, each SDN controller implements virtual network embedding in its own domain. Finally, in the third stage, the algorithm performs interdomain routing if partitioning decision had been made in the first stage. Our simulation results demonstrate that our proposed algorithm yields close performance to the solutions obtained by using the optimization software CPLEX that implements our ILP.     

Dynamic switch migration with noncooperative game towards control plane scalability in SDN

As software‐defined networking (SDN) is a logically centralized technology, the control plane scalability in SDN is increasingly important with the network scale increasing. Load balancing and maximizing resource utilization are very critical to the control plane in SDN, while switch migration is an effective approach to achieve these two performance metrics. However, switch migration is NP‐hard problem because it belongs to the problem of combinatorial optimization. To avoid the NP‐hard problem, we propose a switch migration scheme by adopting noncooperative game to improve the control plane scalability in SDN. First, we design a novel load balancing monitoring scheme to detect the load imbalance between controllers and trigger migrating switches. Then, we use noncooperative game among controllers to decide switch migration to get the maximizing overall profits. Last, we prove that our proposed approach can get Pareto optimality. Extensive simulations prove that our method is able to achieve a more scalable control plane with load balancing and maximizing resource utilization.     

面向SDN的数据中心网络更新研究综述

近年来,由于软件定义网络(SDN)的控制平面与数据平面分离、集中式控制的特点,被广泛应用于数据中心网络(DCN).分四个部分对DCN更新的相关研究进行了综述.首先,介绍了DCN和SDN的基本概念及研究现状;随后,详细说明了传统DCN在更新方面遇到的缺陷;其次,重点讨论了基于SDN的数据中心网络(SD-DCN)更新场景的研究现状与存在的不足,同时指出了一些方案存在的缺点;最后,对基于SDN的数据中心网络未来研究方向进行了展望,以期为SD-DCN的研究与应用提供一定的参考.     

Dynamic handover algorithm with interference cancellation in 5G networks for emergency communication

The integration of 5G networks with cognitive radio (CR) technology enables the software‐defined networking (SDN) infrastructure to support emergency applications. In future, CR can be integrated with 5G and many wireless networks like Wi‐Fi, WSN, and MANET for efficient spectrum utilization with higher data rate and lower latency. This CR technology allows unlicensed users to access the licensed spectrum, whenever it is free. In this paper, an efficient SDN architecture with cognitive ability for emergency network is proposed in which the SDN controller prolong communication between disaster victims and first responders and so the first responders can arrive at the spot directly and rescue the victims. The SDN controller has cognitive ability so that the victims can utilize the vacant licensed band to communicate with the first responders, thereby improving the spectrum utilization of the network. Another two main challenges during emergency are the occurrence of interference and link failure. The proposed dynamic handover algorithm with interference cancellation (DHAIC) cancels the interference between the nodes inside the network and performs dynamic handoff, whenever link failure occurs between the cluster head (CH) and the controller. An optimum throughput and minimal delay is achieved to ensure the network performance.     

Secure access of resources in software‐defined networks using dynamic access control list

Software‐defined networking (SDN) creates a platform to dynamically configure the networks for on‐demand services. SDN can easily control the data plane and the control plane by implementing the decoupling concept. SDN controller will regulate the traffic flow and creates the new flow label based on the packet dump received from the OpenFlow virtual switches. SDN governs both data information and control information toward the destination based on flow label, but it does not contain security measure to restrict the malicious traffic. The malicious denial‐of‐service (DoS) attack traffic is generated inside the SDN environment; it leads to the service unavailability. This paper is mainly focused on the detection of DoS attacks and also mitigates the malicious traffic by dynamically configuring the firewall. The SDN with dynamic access control list properties is emulated by mininet, and the experimental results exemplify the service unavailable gap between acceptance and rejection ratio of the packets.     

SDN技术在电信网络中应用的关键问题探讨

通过对软件定义网络(SDN)技术总体架构的分析,提出了SDN技术在电信网络中规模应用面临的4个方面的问题,包括数据平面构建问题、控制平面构建问题、与应用的整合问题以及如何在电信网络内平滑演进的问题。并参考业内主流的解决技术,给出了SDN技术应用在电信网络中的解决方案。     

TILAK: A token‐based prevention approach for topology discovery threats in SDN

Software‐defined networks (SDNs) decouple the data plane from the control plane. Thus, it provides logically centralized visibility of the entire networking infrastructure to the controller. It enables the applications running on top of the control plane to innovate through network management and programmability. To envision the centralized control and visibility, the controller needs to discover the networking topology of the entire SDN infrastructure. However, discovering and maintaining a global view of the underlying network topology is a challenging task because of (i) frequently changing network topology caused by migration of the virtual machines in the data centers, mobile, end hosts and change in the number of data plane switches because of technical faults or network upgrade; (ii) lack of authentication mechanisms and scarcity in SDN standards; and (iii) availability of security solutions during topology discovery process. To this end, the aim of this paper is threefold. First, we investigate the working methodologies used to achieve global view by different SDN controllers, specifically, POX, Ryu, OpenDaylight, Floodlight, Beacon, ONOS, and HPEVAN. Second, we identify vulnerabilities that affect the topology discovery process in the above controller implementation. In particular, we provide a detailed analysis of the threats namely link layer discovery protocol (LLDP) poisoning, LLDP flooding, and LLDP replay attack concerning these controllers. Finally, to countermeasure the identified risks, we propose a novel mechanism called TILAK which generates random MAC destination addresses for LLDP packets and use this randomness to create a flow entry for the LLDP packets. It is a periodic process to prevent LLDP packet‐based attacks that are caused only because of lack of verification of source authentication and integrity of LLDP packets. The implementation results for TILAK confirm that it covers targeted threats with lower resource penalty.     

一种基于SDN的CCN集中控制缓存决策方法

在软件定义网络(SDN)和内容中心网络(CCN)融合架构下,为了充分利用控制层对网络拓扑和缓存资源的全局感知,在全网中实现缓存资源的优化使用,提出了一种集中控制的缓存决策优化方案.在该方案中,应用粒子群优化算法(PSO)并且根据节点边缘度、节点重要度以及内容流行度对缓存资源和内容进行集中缓存决策,使得内容在不同的节点进行合理的缓存.仿真结果表明,通过评估缓存大小对缓存性能的影响,PSO缓存决策方法取得了比LCE、PROB缓存决策策略更优的缓存命中率和路径延展率,明显降低了缓存节点的缓存替换数,使得缓存达到了整体缓存优化.     

浅析SDN在广电网络IP化中的应用

新一代信息技术的发展离不开IP技术,物联网、WiFi、IPv6、5G等均与IP技术密不可分。通过分析广电网络现有架构,从网络安全、组网成本、网络传输能力等方面探讨基于SDN的组网方案与传统的组网方案的区别。针对传统网络架构存在的不足,将网络设备上的控制权分离出来,统一由集中的控制器管理,从而无须再依赖底层网络设备,屏蔽了来自底层网络设备的差异,自定义实现网络路由和传输规则策略,取消了一些不必要的中间传输环节,使广电网络传输更安全、智能、高效。     

Software‐defined networking to improve handover in mobile edge networks

Mobility management and handover for a seamless connection are among all‐time challenges of wireless networks. Software‐defined networking (SDN) has opened new horizons toward research by adding intelligence in edge networks while decoupling the control and data planes. The flexibility and centralized nature of SDN further improve the handover decision algorithms. In this paper, we have improved the network performance with respect to the number of handovers and the handover delay by applying an LTE‐SDN architecture and a novel handover decision algorithm based on predicting the future locations of a moving vehicle. The proposed algorithm decouples the handover procedure into two phases of preparation and execution. In the preparation phase, which occurs in the control plane, the handover decision and resource allocation take place, and in the execution phase, handover gets executed similar to the LTE architecture. The results of our research indicate that our proposed LTE‐SDN performance is improved with respect to the number of handovers, handover delay, and signaling overhead by 24%, 16%, and 20%, respectively. On the other hand, average Reference Signal Received Quality (RSRQ) value is decreased by 4% as a tradeoff for the improvements gained.     

Energy‐efficient power control for uplink spectrum‐sharing heterogeneous networks

This article considers energy‐efficient power control schemes for interference management in uplink spectrum‐sharing heterogeneous networks that maximize the energy efficiency of users, protect the macro base station, and support users with QoS consideration. In the first scenario, we define the objective function as the weighted sum of the energy efficiencies and develop an efficient global optimization algorithm with global linear and local quadratic rate of convergence to solve the considered problem. To ensure fairness among individual user equipments (UEs) in terms of energy efficiency, we consider the max‐min problem, where the objective is defined as the weighted minimum of the energy efficiencies, and a fractional programming theory and the dual decomposition method are jointly used to solve the problem and investigate an iterative algorithm. As by‐products, we further discuss the global energy efficiency problem and consider near‐optimal schemes. Numerical examples are provided to demonstrate significant improvements of the proposed algorithms over existing interference management schemes.     

SDN与NFV技术在云数据中心的规模应用

以云数据中心为切入点,首先对SDN领域中的叠加网络、SDN控制器、VxLAN 3种重要技术的特点进行了研究,然后对NFV领域中的通用服务器性能、服务链两类关键问题展开具体分析.最后,阐述了前期开展的SDN/NFV技术试验工作进展及相关结论,并对VDC应用产品进行了展望.