Using Open vSwitch without kernel support ========================================= Open vSwitch can operate, at a cost in performance, entirely in userspace, without assistance from a kernel module. This file explains how to install Open vSwitch in such a mode. The userspace-only mode of Open vSwitch is considered experimental. It has not been thoroughly tested. This version of Open vSwitch should be built manually with `configure` and `make`. Debian packaging for Open vSwitch is also included, but it has not been recently tested, and so Debian packages are not a recommended way to use this version of Open vSwitch. Building and Installing ----------------------- The requirements and procedure for building, installing, and configuring Open vSwitch are the same as those given in [INSTALL.md]. You may omit configuring, building, and installing the kernel module, and the related requirements. On Linux, the userspace switch additionally requires the kernel TUN/TAP driver to be available, either built into the kernel or loaded as a module. If you are not sure, check for a directory named /sys/class/misc/tun. If it does not exist, then attempt to load the module with `modprobe tun`. The tun device must also exist as `/dev/net/tun`. If it does not exist, then create /dev/net (if necessary) with `mkdir /dev/net`, then create `/dev/net/tun` with `mknod /dev/net/tun c 10 200`. On FreeBSD and NetBSD, the userspace switch additionally requires the kernel tap(4) driver to be available, either built into the kernel or loaded as a module. Using the Userspace Datapath with ovs-vswitchd ---------------------------------------------- To use ovs-vswitchd in userspace mode, create a bridge with datapath_type "netdev" in the configuration database. For example: ovs-vsctl add-br br0 ovs-vsctl set bridge br0 datapath_type=netdev ovs-vsctl add-port br0 eth0 ovs-vsctl add-port br0 eth1 ovs-vsctl add-port br0 eth2 ovs-vswitchd will create a TAP device as the bridge's local interface, named the same as the bridge, as well as for each configured internal interface. Currently, on FreeBSD, the functionality required for in-band control support is not implemented. To avoid related errors, you can disable the in-band support with the following command. ovs-vsctl set bridge br0 other_config:disable-in-band=true Firewall Rules -------------- On Linux, when a physical interface is in use by the userspace datapath, packets received on the interface still also pass into the kernel TCP/IP stack. This can cause surprising and incorrect behavior. You can use "iptables" to avoid this behavior, by using it to drop received packets. For example, to drop packets received on eth0: iptables -A INPUT -i eth0 -j DROP iptables -A FORWARD -i eth0 -j DROP Other settings -------------- On NetBSD, depending on your network topology and applications, the following configuration might help. See sysctl(7). sysctl net.inet.ip.checkinterface=1 Bug Reporting ------------- Please report problems to bugs@openvswitch.org. [INSTALL.md]:INSTALL.md