# What Is Open vSwitch?

## Overview

Open vSwitch is a multilayer software switch licensed under the open source Apache 2 license. Our goal is to implement a production quality switch platform that supports standard management interfaces and opens the forwarding functions to programmatic extension and control.

Open vSwitch is well suited to function as a virtual switch in VM environments. In addition to exposing standard control and visibility interfaces to the virtual networking layer, it was designed to support distribution across multiple physical servers. Open vSwitch supports multiple Linux-based virtualization technologies including Xen/XenServer, KVM, and VirtualBox.

The bulk of the code is written in platform-independent C and is easily ported to other environments. The current release of Open vSwitch supports the following features:

- Standard 802.1Q VLAN model with trunk and access ports

- NIC bonding with or without LACP on upstream switch

- NetFlow, sFlow(R), and mirroring for increased visibility

- QoS (Quality of Service) configuration, plus policing

- Geneve, GRE, VXLAN, STT, and LISP tunneling

- 802.1ag connectivity fault management

- OpenFlow 1.0 plus numerous extensions

- Transactional configuration database with C and Python bindings

- High-performance forwarding using a Linux kernel module

The included Linux kernel module supports Linux 3.10 and up.

Open vSwitch can also operate entirely in userspace without assistance from a kernel module. This userspace implementation should be easier to port than the kernel-based switch. OVS in userspace can access Linux or DPDK devices. Note Open vSwitch with userspace datapath and non DPDK devices is considered experimental and comes with a cost in performance.

## What’s here?

The main components of this distribution are:

- ovs-vswitchd, a daemon that implements the switch, along with a companion Linux kernel module for flow-based switching.

- ovsdb-server, a lightweight database server that ovs-vswitchd queries to obtain its configuration.

- ovs-dpctl, a tool for configuring the switch kernel module.

- Scripts and specs for building RPMs for Citrix XenServer and Red Hat Enterprise Linux. The XenServer RPMs allow Open vSwitch to be installed on a Citrix XenServer host as a drop-in replacement for its switch, with additional functionality.

- ovs-vsctl, a utility for querying and updating the configuration of ovs-vswitchd.

- ovs-appctl, a utility that sends commands to running Open vSwitch daemons.

Open vSwitch also provides some tools:

- ovs-ofctl, a utility for querying and controlling OpenFlow switches and controllers.

- ovs-pki, a utility for creating and managing the public-key infrastructure for OpenFlow switches.

- ovs-testcontroller, a simple OpenFlow controller that may be useful for testing (though not for production).

- A patch to tcpdump that enables it to parse OpenFlow messages.