OpenFlow based Load Balancing for Fat-Tree Networks with Multipath Support

Data center networks are designed for satisfying the data transmission demand of densely interconnected hosts in the data center. The network topology and routing mechanism can affect the performance and latency significantly. Nowadays, the fat-tree network is one of the most widely used topologies for data center networks. Network engineers also adopt load balancing methods in the design of routing algorithms. However, the requirement of load balancing routing in fat-tree networks cannot be fully satisfied by traditional approaches. The main reason is the lack of efficient ways to obtain network traffic statistics from each network device. As a solution, the OpenFlow protocol enables monitoring traffic statistics by a centralized controller. To achieve high performance and low latency, we present a load balancer for OpenFlow based data center networks. We implement a dynamic routing algorithm in the load balancer. The task of the algorithm is to distribute traffic of upcoming network flows and make each alternative path receive equal amounts of traffic load. It can apply to large scale networks and schedule data flows dynamically. Our implementation uses the OpenFlow controller Beacon and network emulator Mininet. The evaluation results demonstrate that our dynamic load balancing routing algorithm is superior over not only the none load balancing routing algorithm but also the static load balancing algorithm.