VMware, Inc. VMware, Inc. Network Virtualization places unique requirements on tunneling protocols. This draft describes STT (Stateless Transport Tunneling), a tunnel encapsulation that enables overlay networks to be built in virtualized networks. STT is particularly useful when some tunnel endpoints are in end-systems, as it utilizes the capabilities of the network interface card to improve performance. This draft documents the protocol and the rationale for its design, and highlights issues that may arise in deployments.