Open vSwitch (OVS) is an open-source virtual switch, featuring programmable switch forwarding capability. The forwarding plane of OVS can be dynamically controlled by an external network controller, such as OpenFlow controller, which enables key innovation called software-defined networking in large-scale virtual environments.
OVS is included in the Linux kernel 3.3 or higher. For earlier versions of Linux kernel, you can install OVS via standard package installation (e.g., Ubuntu 12.04), or can build OVS from the official source tree at openvswitch.org.
If you have OVS already installed on your machine, you can check Open vSwitch version as follows.
ovs-vswitchd (Open vSwitch) 1.8.90 Compiled Oct 23 2012 15:39:36 OpenFlow versions 0x1:0x1
The above output indicates that the OVS version is 1.8.90, and that it supports OpenFlow specification version 1.1.
How to check Open vSwitch version and supports OpenFlow version
原文：http://www.cnblogs.com/yangpigao/p/3566976.html