OpenvSwitch

Open vSwitch (OVS) is an open-source multilayer virtual switch designed to enable network automation in virtualized and cloud environments. It provides switching, routing, and policy enforcement for virtual machines, containers, and workloads, and can be controlled by external SDN controllers via the OpenFlow protocol. OVS operates in Linux-based virtualization stacks and supports integration with network controllers to program network behavior.

The architecture of Open vSwitch includes a kernel datapath, a userspace control plane, and a configuration database. The kernel module implements the datapath, while the vswitchd daemon manages flow rules and events. The ovsdb-server component stores configuration in a relational database, accessed by tools such as ovs-vsctl and ovs-appctl. Management commands like ovs-vsctl, ovs-ofctl, and ovs-appctl provide bridge, port, and flow configuration and status queries.

OVS supports bridging between virtual machines and containers, VLAN tagging, and advanced traffic control features. It also provides tunneling and overlay networking capabilities (such as VXLAN, GRE, and Geneve) to connect remote endpoints over IP networks. For performance, OVS offers a kernel datapath, a userspace datapath, and a DPDK-based datapath for high-throughput workloads. It can leverage hardware offloads on compatible NICs and works with OpenFlow controllers for centralized policy management. Telemetry options include NetFlow, sFlow, and IPFIX.

Open vSwitch is widely used in cloud and virtualization stacks, including OpenStack Neutron, and serves as a common solution for virtual networking in Linux hypervisors. It is released under the Apache License 2.0 and maintained by a broad community of contributors.