Open vSwitch is a multilayer virtual switch licensed under the open source Apache 2 license. Our goal is to build a production quality switch for VM environments that supports standard management interfaces (e.g. NetFlow, RSPAN, ERSPAN, IOS-like CLI), and is open to programmatic extension and control. In addition, it is designed to support distribution across multiple physical servers similar to VMware’s distributed vswitch or Cisco’s Nexus 1000V.
Open vSwitch currently supports multiple virtualization technologies. It is the default switch in the Xen Cloud Platform. And it supports open source Xen, XenServer, KVM, and VirtualBox. The bulk of the code is written in platform-independent C and is easily ported to other environments.