Non-tunneling Edge-Overlay Model Using OpenFlow for Cloud Datacenter Networks

In current SDN paradigm, an edge-overlay (distributed tunneling) model using L2-in-L3 tunneling protocols, such as VXLAN, has attracted attentions for multi-tenant data center networks. The edge-overlay model can establish rapid-deployment of virtual networks onto existing traditional network facilities, ensure flexible IP/MAC address allocation to VMs, and extend the number of virtual networks regardless of the VLAN ID limitation. However, such model has performance and incompatibility problems on the traditional network environment. For L2 data center networks, this paper proposes a pure software approach that uses Open Flow virtual switches to realize yet another edge-overlay without IP tunneling. Our model leverages a header rewriting method as well as a host-based VLAN ID usage to ensure address space isolation and scalability of the number of virtual networks. In our model, any special hardware equipments like Open Flow hardware switch are not required and only software-based virtual switches and the controller are used. In this paper, we evaluate the performance of the proposed model comparing with the tunneling model using GRE or VXLAN protocol. Our model showed better performance and less CPU usage. In addition, qualitative evaluations of the model are also conducted from a broader perspective.