Talk: "Flow-based tunneling for SR-IOV using switchdev API" (Ilya Lesokhin, Haggai Eran, Or Gerlitz)


SR-IOV devices present improved performance for network virtualization, but pose limitations today on the ability of the hypervisor to manage the network. For instance, UDP and IP tunnels that are commonly used on the cloud are not supported today with SR-IOV. Flow based approaches like Open vSwitch and TC are common in managing virtual machine traffic. Both technologies are not supported with today's SR-IOV Linux driver model, which only allows to program MAC or MAC+VLAN based forwarding for virtual function traffic.

We present a design that facilitates SR-IOV performance while maintaining flow-based management for both non-tunneled and VXLAN tunneled flows and uses the switchdev framework to program the SR-IOV eSwitch. Our prototype uses hardware offloads for most traffic, and a software fallback for traffic we cannot offload.

We expose a representor netdev for each port in the SR-IOV eSwitch, one per virtual function and another for the uplink, to enable the management of these ports by the kernel and also the send and receive packets through the software fallback path. Our implementation currently uses open-vswitch for managing flows. It should be possible to extend it to other management schemes such as TC. A flow's match and actions are reflected to the underlying device using extended switchdev APIs. For tunneling we also propagate information about the tunnel FDB, and the kernel routing table and neighbor table.