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Ben Pfaff d4317804f2 Discovery.
2008-07-18 14:16:40 -07:00

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Installation Instructions for OpenFlow Reference Release
This document describes how to build, install, and execute the
reference implementation of OpenFlow. Please send any comments to:
<info@openflowswitch.org>
Prerequisites
-------------
To compile the userspace programs in the OpenFlow reference
distribution, you will need the following software:
- A make program, e.g. GNU make
(http://www.gnu.org/software/make/). BSD make should also work.
- The GNU C compiler (http://gcc.gnu.org/). We generally test
with version 4.1 or 4.2.
- libssl, from OpenSSL (http://www.openssl.org/), is optional but
recommended. libssl is required to establish confidentiality
and authenticity in the connections among OpenFlow switches and
controllers. To enable, compile with --enable-ssl=yes
If you are working from a Git tree or snapshot (instead of from a
distribution tarball), or if you modify the OpenFlow build system, you
will also need the following software:
- Autoconf version 2.59 or later (http://www.gnu.org/software/autoconf).
- Automake version 1.10 or later (http://www.gnu.org/software/automake).
- pkg-config (http://pkg-config.freedesktop.org/wiki/). We test
with version 0.22.
The optional Linux module has additional prerequisites, described
later in the section "Building and Testing the Linux Kernel-Based
Switch".
Building Userspace Programs
---------------------------
The OpenFlow distribution includes two implementations of the switch:
one entirely in userspace, for portability and ease of installation,
and another with a Linux kernel module component that is more
difficult to install but should also yield better performance. These
instructions describe how to build the userspace components of the
OpenFlow distribution. Refer to "Building and Testing the Linux
Kernel-Based Switch", below, for additional instructions on how to
build the optional Linux kernel module.
1. In the top source directory, configure the package by running the
configure script. You can usually invoke configure without any
arguments:
% ./configure
To use a specific C compiler for compiling OpenFlow user programs,
also specify it on the configure command line, like so:
% ./configure CC=gcc-4.2
The configure script accepts a number of other options and honors
additional environment variables. For a full list, invoke
configure with the --help option.
2. Run make in the top source directory:
% make
The following binaries will be built:
- Switch executable: switch/switch. This executable is built
only if the configure script detects a supported interface to
network devices. Refer to README for a list of OSes whose
network device interfaces are supported.
- Secure channel executable: secchan/secchan.
- Controller executable: controller/controller.
- Datapath administration utility: utilities/dpctl.
- Runtime logging configuration utility: utilities/vlogconf.
3. (Optional) Run "make install" to install the executables and
manpages into the running system, by default under /usr/local.
Testing Userspace Programs
--------------------------
0. The commands below must run as root, so log in as root, or use a
program such as "su" to become root temporarily.
1. Start the OpenFlow controller running in the background, by running
the "controller" program with a command like the following:
# controller ptcp: &
This command causes the controller to bind to port 975 (the
default) awaiting connections from OpenFlow switches. See
controller(8) for details.
2. On the same machine, use the "switch" program to start an OpenFlow
switch, specifying network devices to use as switch ports on the -i
option as a comma-separated list, like so:
# switch tcp:127.0.0.1 -i eth1,eth2
The network devices that you specify should not have configured IP
addresses.
3. The controller causes each switch that connects to it to act like a
learning Ethernet switch. Thus, devices plugged into the specified
network ports should now be able to send packets to each other, as
if they were plugged into ports on a conventional Ethernet switch.
Troubleshooting: if the commands above do not work, try using the -v
or --verbose option on the controller or switch commands, which will
cause a large amount of debug output from each program.
Remote switches: These instructions assume that the controller and the
switch are running on the same machine. This is an easy configuration
for testing, but a more conventional setup would run a controller on
one machine and one or more switches on different machines. To do so,
simply specify the IP address of the controller as the first argument
to the switch program (in place of 127.0.0.1). (Note: The userspace
switch must be connected to the controller over a "control network"
that is physically separate from the one that the switch and
controller are controlling. The kernel-based switch does not have
this limitation.)
Secure operation over SSL
-------------------------
The instructions above set up OpenFlow for operation over a plaintext
TCP connection. Production use of OpenFlow should use SSL[*] to
ensure confidentiality and authenticity of traffic among switches and
controllers. The source must be configured with --enable-ssl=yes to
build with SSL support.
To use SSL with OpenFlow, you must set up a public-key infrastructure
(PKI) including a pair of certificate authorities (CAs), one for
controllers and one for switches. If you have an established PKI,
OpenFlow can use it directly. Otherwise, refer to "Establishing a
Public Key Infrastructure" below.
To configure the controller to listen for SSL connections on port 976
(the default), invoke it as follows:
# controller -v pssl: --private-key=PRIVKEY --certificate=CERT \
--ca-cert=CACERT
where PRIVKEY is a file containing the controller's private key, CERT
is a file containing the controller CA's certificate for the
controller's public key, and CACERT is a file containing the root
certificate for the switch CA. If, for example, your PKI was created
with the instructions below, then the invocation would look like:
# controller -v pssl: --private-key=ctl-privkey.pem \
--certificate=ctl-cert.pem --ca-cert=pki/switchca/cacert.pem
To configure a switch to connect to a controller running on port 976
(the default) on host 192.168.1.2 over SSL, invoke it as follows:
# switch -v ssl:192.168.1.2 -i INTERFACES --private-key=PRIVKEY \
--certificate=CERT --ca-cert=CACERT
where INTERFACES is the command-separated list of network device
interfaces, PRIVKEY is a file containing the switch's private key,
CERT is a file containing the switch CA's certificate for the switch's
public key, and CACERT is a file containing the root certificate for
the controller CA. If, for example, your PKI was created with the
instructions below, then the invocation would look like:
# secchan -v -i INTERFACES ssl:192.168.1.2 --private-key=sc-privkey.pem \
--certificate=sc-cert.pem --ca-cert=pki/controllerca/cacert.pem
[*] To be specific, OpenFlow uses TLS version 1.0 or later (TLSv1), as
specified by RFC 2246, which is very similar to SSL version 3.0.
TLSv1 was released in January 1999, so all current software and
hardware should implement it.
Establishing a Public Key Infrastructure
----------------------------------------
If you do not have a PKI, the ofp-pki script included with OpenFlow
can help. To create an initial PKI structure, invoke it as:
% ofp-pki new-pki
which will create and populate a new directory named "pki" under the
current directory.
The pki directory contains two important subdirectories. The
controllerca subdirectory contains controller certificate authority
related files, including the following:
- cacert.pem: Root certificate for the controller certificate
authority. This file must be provided to the switch or secchan
program with the --ca-cert option to enable it to authenticate
valid controllers.
- private/cakey.pem: Private signing key for the controller
certificate authority. This file must be kept secret. There is
no need for switches or controllers to have a copy of it.
The switchca subdirectory contains switch certificate authority
related files, analogous to those in the controllerca subdirectory:
- cacert.pem: Root certificate for the switch certificate
authority. This file must be provided to the controller program
with the --ca-cert option to enable it to authenticate valid
switches.
- private/cakey.pem: Private signing key for the switch
certificate authority. This file must be kept secret. There is
no need for switches or controllers to have a copy of it.
After you create the initial structure, you can create keys and
certificates for switches and controllers with ofp-pki. To create a
controller private key and certificate in files named ctl-privkey.pem
and ctl-cert.pem, for example, you could run:
% ofp-pki req+sign ctl controller
ctl-privkey.pem and ctl-cert.pem would need to be copied to the
controller for its use at runtime (they could then be deleted from
their original locations). The --private-key and --certificate
options of controller, respectively, would point to these files.
Analogously, to create a switch private key and certificate in files
named sc-privkey.pem and sc-cert.pem, for example, you could run:
% ofp-pki req+sign sc switch
sc-privkey.pem and sc-cert.pem would need to be copied to the switch
for its use at runtime (they could then be deleted from their original
locations). The --private-key and --certificate options,
respectively, of switch and secchan would point to these files.
Building and Testing the Linux Kernel-Based Switch
--------------------------------------------------
The OpenFlow distribution also includes a Linux kernel module that can
be used to achieve higher switching performance at a cost in
portability and ease of installation. Compiling the kernel module has
the following prerequisites in addition to those listed in the
"Prerequisites" section above:
- A supported Linux kernel version. Please refer to README for a
list of supported versions.
The OpenFlow datapath requires bridging support (CONFIG_BRIDGE)
to be built as a kernel module. (This is common in kernels
provided by Linux distributions.) The bridge module must not be
loaded or in use. If the bridge module is running (check with
"lsmod | grep bridge"), you must remove it ("rmmod bridge")
before starting the datapath.
- The correct version of GCC for the kernel that you are building
the module against:
* To build a kernel module for a Linux 2.6 kernel, you need
the same version of GCC that was used to build that kernel
(usually version 4.0 or later).
* To build a kernel module for a Linux 2.4 kernel, you need an
earlier version of GCC, typically GCC 2.95, 3.3, or 3.4.
- A kernel build directory corresponding to the Linux kernel image
the module is to run on. Under Debian and Ubuntu, for example,
each linux-image package containing a kernel binary has a
corresponding linux-headers package with the required build
infrastructure.
To build the kernel module, follow the build process described under
"Building Userspace Programs" above, but pass the location of the
kernel build directory as an additional argument to the configure
script, as described under step 1 in that section. Specify the
location on --with-l26 for Linux 2.6, --with-l24 for Linux 2.4. For
example, to build for a running instance of Linux 2.6:
% ./configure --with-l26=/lib/modules/`uname -r`/build
To build for a running instance of Linux 2.4:
% ./configure --with-l24=/lib/modules/`uname -r`/build
If you wish to build OpenFlow for an architecture other than the architecture
used for compilation, you may specify the kernel architecture string using the
KARCH variable when invoking the configure script. For example, to build
OpenFlow for MIPS with Linux 2.4:
% ./configure --with-l24=/path/to/linux-2.4 KARCH=mips
If you have hardware that supports accelerated OpenFlow switching, and
you have obtained a hardware table module for your hardware and
extracted it into the OpenFlow reference distribution source tree,
then you may also enable building support for the hardware switching
table with --enable-hw-tables. For example, if your hardware
switching table is in a directory named datapath/hwtable-foomatic, you
could compile support for it with the running Linux 2.6 kernel like
so:
% ./configure --with-l26=/lib/modules/`uname -r`/build \
--enable-hw-tables=foomatic
For more information about hardware table modules, please read
README.hwtables at the root of the OpenFlow distribution tree.
In addition to the binaries listed under step 2 in "Building Userspace
Programs" above, "make" will build the following kernel modules:
datapath/linux-2.6/openflow_mod.ko (if --with-l26 was specified)
datapath/linux-2.4/openflow_mod.o (if --with-l24 was specified)
"make" will also build a kernel module for each hardware switch table
enabled with --enable-hw-tables.
Once you have built the kernel modules, activating them requires only
running "insmod", e.g.:
(Linux 2.6)
% insmod datapath/linux-2.6/openflow_mod.ko
(Linux 2.4)
% insmod datapath/linux-2.4/compat24_mod.o
% insmod datapath/linux-2.4/openflow_mod.o
After you load the openflow module, you may load one hardware switch
table module (if any were built) to enable support for that hardware
switching table.
The insmod program must be run as root. You may need to specify a
full path to insmod, which is usually in the /sbin directory. To
verify that the modules have been loaded, run "lsmod" (also in /sbin)
and check that openflow_mod appears in the result.
Testing the Kernel-Based Implementation
---------------------------------------
The OpenFlow kernel module must be loaded, as described in the
previous section, before it may be tested.
0. The commands below must run as root, so log in as root, or use a
program such as "su" to become root temporarily.
1. Create a datapath instance. The command below creates a datapath with
ID 0 (see dpctl(8) for more detailed usage information).
# dpctl adddp 0
In principle, openflow_mod supports multiple datapaths within the
same host, but this is rarely useful in practice.
If you built a support module for hardware accelerated OpenFlow
switching and you want to use it, you must load it before creating
the datapath with "dpctl adddp".
2. Use dpctl to attach the datapath to physical interfaces on the
machine. Say, for example, you want to create a trivial 2-port
switch using interfaces eth1 and eth2, you would issue the following
commands:
# dpctl addif 0 eth1
# dpctl addif 0 eth2
You can verify that the interfaces were successfully added by asking
dpctl to print the current status of datapath 0:
# dpctl show 0
3. (Optional) You can manually add flows to the datapath to test using
dpctl add-flows and view them using dpctl dump-flows. See dpctl(8)
for more details.
4. The simplest way to test the datapath is to run the provided sample
controller on the host machine to manage the datapath directly using
netlink:
# controller -v nl:0
Once the controller is running, the datapath should operate like a
learning Ethernet switch. You may monitor the flows in the datapath
flow table using "dpctl dump-flows" command.
The preceding instructions assume that the controller and the switch
are running on the same machine. This is an easy configuration for
testing, but a more conventional setup would run a controller on one
machine and one or more switches on different machines. Use the
following instructions to set up remote switches:
1. Start the datapath and attach it to two or more physical ports as
described in the previous section.
2. Run the controller in passive TCP mode on the host which will act as
the controller. In the example below, the controller will bind to
port 975 (the default) awaiting connections from secure channels.
# controller -v ptcp:
(See controller(8) for more details)
Make sure the machine hosting the controller is reachable by the switch.
3. Arrange so that the switch can reach the controller over the
network. There are two ways to do this:
- Use a "control network" that is completely separate from the
"data network" to be controlled ("out-of-band control"). To
do so, configure a network device (one that has not been added
to the datapath with "dpctl addif") to access the control
network in the usual way.
- Use the same network for control and for data ("in-band
control"). For this purpose, each datapath nl:K has a
corresponding virtual network device named ofK.
When in-band control is used, the location of the controller
may be configured manually or discovered automatically:
* Manual configuration: Start by bringing up of0 before
you start the secure channel:
# ifconfig of0 up
Before the secure channel starts up, the of0 device
cannot send or receive any packets, so the next step
depends on whether connectivity is required to configure
the device's IP address:
. If the switch has a static IP address, you may
configure its IP address now, e.g.:
# ifconfig of0 192.168.1.1
. If the switch does not have a static IP address,
e.g. its IP address is obtained dynamically via
DHCP, then proceed to step 4. The DHCP client will
not be able to contact the DHCP server until the
secure channel has started up.
* Controller discovery: No special setup is required at
the switch, but you must specially configure a DHCP
server to give out the switch's IP address and to tell
it the location of the controller. See secchan(8) for
details.
4. Run secchan on the datapath host to start the secure channel
connecting the datapath to a remote controller. (See secchan(8)
for usage details). The details depend on how you configured the
network in step 3:
- If you are using in-band control and controller discovery,
invoke secchan something like this:
# secchan -v nl:0
The secure channel should connect to the controller after it
obtains its own IP address and the controller's location via
DHCP. This can take a few seconds. Switch setup is now
complete.
- Otherwise, the secure channel should be configured to connect
to the controller's IP address on the port configured in step
2. If the controller is running on host 192.168.1.2 port 975
(the default port) and the datapath ID is 0, the secchan
invocation would look like:
# secchan -v nl:0 tcp:192.168.1.2
If you are using out-of-band control, or if you are using
in-band control and the switch has a static IP address, the
secure channel should quickly connect to the controller.
Setup is now complete. Otherwise, proceed to step 5.
5. If you are using the same network for control and data, and the
switch obtains its IP address dynamically, then you may now obtain
the switch's IP address, e.g. by invoking a DHCP client. The
secure channel will only be able to connect to the controller after
an IP address has been obtained.
Bug Reporting
-------------
Please report problems to:
info@openflowswitch.org
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