Abstract:  In software defined network (SDN) architecture, the network control function is separated from network devices (switches/routers) and integrated to the central node controller, while switches are used to implement functions on the data plane (data forwarding based on the flow table). On large-scale data center networks, calculation and distribution of the routing/flow table are completely processed by the central controller, and the controller has become the bottleneck and vulnerability for network performance. To solve these problems, the essay proposes a semi-centralized SDN routing technology based on the data center network. Its main idea is that each switch node constructs a basic flow table for itself without involving the controller so that the switch can implement basic data forwarding based on the flow table. Meanwhile, the controller is responsible for routing (troubleshooting) of a higher level, thus greatly reducing controller’s loads. In this paper, advanced routing for the controller, a partial roundabout troubleshooting mechanism is designed based on the basic flow table through the analysis of the characteristics and limitations of the fault recovery mechanism in the existing SDN network. In this way, the controller can detect network failures in a timely manner and can recover the failures in short time to implement troubleshooting in advanced routing on controllers.

Key words: data center network, SDN, semi-centralized SDN routing technology, basic flow table, partial roundabout troubleshooting mechanism