1 Replacing a Linux Bridge with Open vSwitch
2 ==========================================
4 This file documents how Open vSwitch may be used as a drop-in
5 replacement for a Linux kernel bridge in an environment that includes
6 elements that are tightly tied to the Linux bridge tools
7 (e.g. "brctl") and architecture. We recommend directly using the
8 management tools provided with Open vSwitch rather than these
9 compatibility hooks for environments that are not tightly tied to the
10 Linux bridging tools; they are more efficient and better reflect the
11 actual operation and status.
13 Installation Procedure
14 ----------------------
16 The procedure below explains how to use the Open vSwitch bridge
17 compatibility support. This procedure is written from the perspective
18 of a system administrator manually loading and starting Open vSwitch
19 in bridge compatibility mode, but of course in practice one would want
20 to update system scripts to follow these steps. If you do edit your
21 system configuration files to start Open vSwitch at boot time, make
22 sure that it starts up before any bridge configuration (e.g. before
23 any calls to "brctl" or "ifup" of any bridge interfaces), to ensure
24 that the Open vSwitch kernel modules are loaded before the Linux
27 1. Build, install, and start up the Open vSwitch kernel modules and
28 userspace programs as described in INSTALL.Linux.
30 It is important to run "make install", because some Open vSwitch
31 programs expect to find files in locations selected at installation
32 time. The instructions below assume that files are installed in
33 their default locations, under /usr/local.
35 2. Load the brcompat kernel module (which was built in step 1), e.g.:
37 % insmod datapath/linux-2.6/brcompat_mod.ko
39 (openvswitch_mod.ko should already have been loaded.)
41 3. Start ovs-brcompatd:
43 % ovs-brcompatd --pidfile --detach -vANY:console:EMER \
44 unix:/usr/local/var/run/openvswitch/db.sock
46 (ovsdb-server and ovs-vswitchd should already have been loaded.)
48 4. Now you should be able to manage the Open vSwitch using brctl and
49 related tools. For example, you can create an Open vSwitch bridge,
50 add interfaces to it, then print information about bridges with the
54 % brctl addif br0 eth0
55 % brctl addif br0 eth1
58 Each of these commands actually uses or modifies the Open vSwitch
59 configuration database, then notifies the ovs-vswitchd daemon of
60 the change. For example, after executing the commands above
61 starting from an empty configuration file, "ovs-vsctl list-ports
62 br0" should show that bridge br0 contains two ports, eth0 and eth1.