PARES: Packet Rewriting on SDN-Enabled Edge Switches for Network Virtualization in Multi-Tenant Cloud Data Centers

Multi-tenant data centers for cloud computing require the deployment of virtual private networks for tenants in an on-demand manner, providing isolation and security between tenants. To address these requirements, network virtualization techniques such as encapsulation and tunneling have been widely used. However, these approaches inherently incur processing overhead on end-points (such as the host hypervisor), reducing the effective throughput for the tenant virtual network compared to the native network. This problem is exacerbated with increases in line rates, now exceeding 10Gbps. In this paper, we introduce PARES (PAcket REwriting on SDN), a novel technique which uses the packet rewriting feature of SDN switches to provide multi-tenancy in data center networks at edge switches, thereby reducing the load on end-point hypervisors and improving the throughput, compared to tunneling. Experiments in an SDN testbed show that our proposed data center arhictecture with PARES achieves near line-rate multi-tenancy virtualization with 10Gbps links (compared to 20% of line-rate for VXLAN tunneling), without incurring processing overhead at end-point hypervisors or guest servers. Additionally, the paper evaluates the scalability of PARES for ARP protocol handling and with respect to number of SDN flow entries.