基于混合SDN的多路径负载均衡策略研究

发布时间：2018-11-15 22:44

【摘要】：近年来,网络规模迅速扩大,互联网应用的飞速发展,网络业务流对链路带宽提出了越来越大的需求。作为优化网络性能的重要手段,网络链路的负载均衡技术正受到网络运营商越来越多的重视。当前使用OSPF协议的IP网络,一般都是利用优化网络链路权重来实现网络业务流的均衡分布。链路权重优化属于局部优化,在网络的瓶颈链路容易形成拥塞,造成很大的延迟,从而无法满足不同网络应用的需求。SDN是一个最新出现的网络架构,把传统网路的控制层和数据转发层进行了解耦。SDN控制器可以整合全网的链路状态信息,从全局优化的角度为网络的业务流计算最优的路由路径,满足各种互联网应用的QoS需求,实现对全网的集中控制,提高网络的链路带宽利用率,从而更加充分的利用网络资源。将传统IP网络全部替换成SDN设备成本太高,而且SDN技术还不成熟,还需要长时间的发展。在未来的发展进程中,SDN设备逐渐替换传统的IP网络路由器,在网络中出现SDN设备和传统路由器共存的场景,也就是混合SDN网络架构。针对当前SDN研究中,SDN控制器在进行流量优化时,仍然使用单路径路由的问题,本文提出了一种新的不相交多路径路由算法,并将其部署在SDN控制器上。结合SDN设备可以任意多路径转发的优点,该路由算法可以使网络流量在全网更均衡的分布。针对混合SDN网络架构下的负载均衡问题,本文接下来进行了深入的研究,提出了一种新的完全多项式时间近似算法(Fully Polynomial Time Approximation Scheme,FPTAS)。实际上,混合SDN网络架构下的负载均衡问题,与传统的多商品流问题中的最大并行流问题非常相似,通过分析网络中流量分布的特点,我们为该问题建立了数学模型,然后根据最大并行流问题的启发式算法,并结合SDN设备的多路径路由,我们提出了混合SDN网络架构下的SDN网络流转发的负载均衡算法。在对混合SDN网络架构下的网络链路负载均衡算法进行仿真实验和分析后,发现该算法相对于传统基于OSPF协议和现有SDN的负载均衡优化效果更好,最大网络链路利用率更小,网络资源得到了更充分的利用。
[Abstract]:In recent years, with the rapid expansion of network scale and the rapid development of Internet applications, network traffic has put forward a growing demand for link bandwidth. As an important means to optimize network performance, network link load balancing technology is being paid more and more attention by network operators. At present, in IP networks using OSPF protocol, the optimal network link weights are generally used to realize the balanced distribution of network traffic. The link weight optimization belongs to the local optimization, and it is easy to form congestion in the bottleneck link of the network, resulting in great delay, which can not meet the needs of different network applications. SDN is a new network architecture. The traditional network control layer and data forwarding layer are decoupled. The SDN controller can integrate the link state information of the whole network and calculate the optimal routing path for the traffic flow of the network from the perspective of global optimization. To meet the QoS requirements of various Internet applications, the centralized control of the whole network is realized, and the utilization of link bandwidth is improved, so that the network resources can be utilized more fully. It is too expensive to replace the traditional IP network with SDN equipment, and the SDN technology is not mature and needs a long time development. In the process of future development, SDN devices gradually replace the traditional IP network routers. In the network, SDN devices and traditional routers coexist, that is, hybrid SDN network architecture. In view of the problem that SDN controller still uses single path routing in current SDN research, a new disjoint multipath routing algorithm is proposed and deployed on SDN controller. Combined with the advantage of arbitrary multipath forwarding in SDN devices, the routing algorithm can distribute network traffic more evenly across the network. To solve the load balancing problem in hybrid SDN networks, a new complete polynomial time approximation algorithm (Fully Polynomial Time Approximation Scheme,FPTAS) is proposed in this paper. In fact, the load balancing problem under the hybrid SDN network architecture is very similar to the maximum parallel flow problem in the traditional multi-commodity flow problem. By analyzing the characteristics of the traffic distribution in the network, we establish a mathematical model for the problem. Then, according to the heuristic algorithm of the maximum parallel flow problem and the multipath routing of SDN devices, we propose a load balancing algorithm for SDN network flows under the hybrid SDN network architecture. After the simulation and analysis of the network link load balancing algorithm under the hybrid SDN network architecture, it is found that the algorithm is better than the traditional load balancing algorithm based on OSPF protocol and existing SDN, and the maximum network link utilization ratio is smaller. Network resources have been more fully utilized.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP393.0

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