Building Hierarchical Switch Network Using OpenFlow

No single layers and technologies can construct a large scale network, thus networks are organized as a physical structure of variety of layers. For example in data center, networks are typically consists of access and aggregation L2 switches and core L2/L3 switches networks. However, new trends for server virtualization can change traffic dynamics, i.e. virtualized host can be located at any locations in the network and connections among servers are set up independently from physical network structure. Therefore static network structure cannot stay optimal and thus, we propose a network architecture whose structure is logically defined and flexibly reconfigurable. The network uniformly consists of OpenFlow switches and constructs a logical routing hierarchy defined by the software at OpenFlow controller. We evaluated our scheme to construct an efficient data center core network. We discussed types of logical structures and path selection algorithms with the constraint of flow table usage, which is one of the most critical constraints for scalable OpenFlow networks. Our simulation evaluation indicates that (1) full-mesh, hypercube and ring-based networks are the realistic logical structure design and that (2) hyperbolic path selection scheme has doubled the path capacity.