1 Using Open vSwitch without kernel support
2 =========================================
4 Open vSwitch can operate, at a cost in performance, entirely in
5 userspace, without assistance from a kernel module. This file
6 explains how to install Open vSwitch in such a mode.
8 The userspace-only mode of Open vSwitch is considered experimental.
9 It has not been thoroughly tested.
11 This version of Open vSwitch should be built manually with "configure"
12 and "make". Debian packaging for Open vSwitch is also included, but
13 it has not been recently tested, and so Debian packages are not a
14 recommended way to use this version of Open vSwitch.
16 Building and Installing
17 -----------------------
19 The requirements and procedure for building, installing, and
20 configuring Open vSwitch are the same as those given in INSTALL.
21 You may omit configuring, building, and installing the kernel module,
22 and the related requirements.
24 On Linux, the userspace switch additionally requires the kernel
25 TUN/TAP driver to be available, either built into the kernel or loaded
26 as a module. If you are not sure, check for a directory named
27 /sys/class/misc/tun. If it does not exist, then attempt to load the
28 module with "modprobe tun".
30 The tun device must also exist as /dev/net/tun. If it does not exist,
31 then create /dev/net (if necessary) with "mkdir /dev/net", then create
32 /dev/net/tun with "mknod /dev/net/tun c 10 200".
34 On FreeBSD and NetBSD, the userspace switch additionally requires the
35 kernel tap(4) driver to be available, either built into the kernel or
38 Using the Userspace Datapath with ovs-vswitchd
39 ----------------------------------------------
41 To use ovs-vswitchd in userspace mode, create a bridge with datapath_type
42 "netdev" in the configuration database. For example:
45 ovs-vsctl set bridge br0 datapath_type=netdev
46 ovs-vsctl add-port br0 eth0
47 ovs-vsctl add-port br0 eth1
48 ovs-vsctl add-port br0 eth2
50 ovs-vswitchd will create a TAP device as the bridge's local interface,
51 named the same as the bridge, as well as for each configured internal
54 Currently, on FreeBSD, the functionality required for in-band control
55 support is not implemented. To avoid related errors, you can disable
56 the in-band support with the following command.
58 ovs-vsctl set bridge br0 other_config:disable-in-band=true
63 On Linux, when a physical interface is in use by the userspace
64 datapath, packets received on the interface still also pass into the
65 kernel TCP/IP stack. This can cause surprising and incorrect
66 behavior. You can use "iptables" to avoid this behavior, by using it
67 to drop received packets. For example, to drop packets received on
70 iptables -A INPUT -i eth0 -j DROP
71 iptables -A FORWARD -i eth0 -j DROP
76 On NetBSD, depending on your network topology and applications, the
77 following configuration might help. See sysctl(7).
79 sysctl net.inet.ip.checkinterface=1
84 Please report problems to bugs@openvswitch.org.