Implementation and Performance Analysis of STT Tunneling Using vNIC Offloading Framework (CVSW)

Network Virtualization Overlays (NVO3) provides multi-tenancy services in cloud data centers with existing networking equipment. IP tunneling is an essential technology to logically separate each virtual traffic, in particular, Stateless Transport Tunneling (STT) is considered to achieve better performance using TCP Segmentation Offload (TSO) feature. Currently, there is no openly available implementation of STT, and its implementation and performance characteristics have not been studied in academic field so far. We have therefore implemented STT protocol and conducted performance evaluation by comparing with VXLAN protocol. In practice, the STT implementation has been done using a virtual NIC offloading framework, co-virtual switch (CVSW). CVSW is a software component that extends virtual NICs and provides high-level packet processing framework such as Open Flow Match-Action. In this paper, we describe implementation details of STT and performance evaluation results from various perspectives. The results showed that the actual performance of STT was almost equal to non-tunneling VM-to-VM communication and was two-times higher than that of VXLAN. Furthermore, we clarify the high-performance nature of STT is brought from both byte-stream characteristic of TCP and Generic Receive Offload (GRO) feature rather than widely believed TSO.