Note on naming conventions:
OVS – Refers to the Open vSwitch distribution within DOCA framework
OVS-DOCA – Describes the datapath offloading layer (DPIF) that utilizes the DOCA Flow library for offloading tasks. This layer is a component of OVS, along with additional DPIF implementations that facilitate offloading via DPDK or Kernel, known respectively as OVS-DPDK and OVS-Kernel.
NVIDIA advises utilizing the OVS-DOCA DPIF to maximize efficiency, performance, scalability, and feature support.
The DPDK and Kernel DPIFs are maintained in their current form primarily for backward compatibility and are not planned to be updated with new features.
Open vSwitch (OVS) is a software-based network technology that enhances virtual machine (VM) communication within internal and external networks. Typically deployed in the hypervisor, OVS employs a software-based approach for packet switching, which can strain CPU resources, impacting system performance and network bandwidth utilization. Addressing this, NVIDIA’s Accelerated Switching and Packet Processing (ASAP2) technology offloads OVS data-plane tasks to specialized hardware, like the embedded switch (eSwitch) within the NIC subsystem, while maintaining an unmodified OVS control-plane. This results in notably improved OVS performance without burdening the CPU.
NVIDIA’s DOCA-OVS extends the traditional OVS-DPDK and OVS-Kernel data-path offload interfaces (DPIF), introducing OVS-DOCA as an additional DPIF implementation. DOCA-OVS, built upon NVIDIA’s networking API, preserves the same interfaces as OVS-DPDK and OVS-Kernel while utilizing the DOCA Flow library with the additional OVS-DOCA DPIF. Unlike the use of the other DPIFs (DPDK, Kernel), OVS-DOCA DPIF exploits unique hardware offload mechanisms and application techniques, maximizing performance and features for NVIDA NICs and DPUs. This mode is especially efficient due to its architecture and DOCA library integration, enhancing e-switch configuration and accelerating hardware offloads beyond what the other modes can achieve.
NVIDIA OVS installation contains all three OVS flavors. The following subsections describe the three flavors (default is OVS-Kernel) and how to configure each of them.
When OVS is combined with NICs and DPUs (such as NVIDIA® ConnectX®-6 Lx/Dx and NVIDIA® BlueField®-2 and later), it utilizes the hardware data plane of ASAP2. This data plane can establish connections to VMs using either SR-IOV virtual functions (VFs) or virtual host data path acceleration (vDPA) with virtio.
In both scenarios, an accelerator engine within the NIC accelerates forwarding and offloads the OVS rules. This integrated solution accelerates both the infrastructure (via VFs through SR-IOV or virtio) and the data plane. For DPUs (which include a NIC subsystem), an alternate virtualization technology implements full virtio emulation within the DPU, enabling the host server to communicate with the DPU as a software virtio device.
When using ASAP2 data plane over SR-IOV virtual functions (VFs), the VF is directly passed through to the VM, with the NVIDIA driver running within the VM.
When using vDPA, the vDPA driver allows VMs to establish their connections through VirtIO. As a result, the data plane is established between the SR-IOV VF and the standard virtio driver within the VM, while the control plane is managed on the host by the vDPA application.