OpenFlow Reference Release <http://openflowswitch.org>

What is OpenFlow?
-----------------

OpenFlow is a flow-based switch specification designed to enable
researchers to run experiments in live networks.  OpenFlow is based on a
simple Ethernet flow switch that exposes a standardized interface for
adding and removing flow entries.

An OpenFlow Switch consists of three parts: (1) A "flow table" in
which each flow entry is associated with an action telling the switch
how to process the flow, (2) a "secure channel" connecting the switch
to a remote process (a controller), allowing commands and packets to
be sent between the controller and the switch, and (3) an OpenFlow
protocol implementation, providing an open and standard way for a
controller to talk to the switch.

An OpenFlow Switch can thus serve as a simple datapath element that
forwards packets between ports according to flow actions defined by
the controller using OpenFlow commands.  Example actions are:

    - Forward this flow's packets to the given port(s)
    - Drop this flow's packets
    - Encapsulate and forward this flow's packets to the controller.

The OpenFlow Switch is defined in detail in the OpenFlow Switch
Specification [2].

What's here?
------------

This distribution includes a Linux-specific reference implementation
of an OpenFlow switch, comprising:

	- A Linux kernel module that implements the flow table and
          OpenFlow protocol.

	- secchan, a program that implements the secure channel
          component of the reference switch.

	- dpctl, a tool for configuring the kernel module.

This distribution includes some additional software as well:

	- controller, a simple program that connects to any number of
          OpenFlow switches, commanding them to act as regular MAC
          learning switches.

        - vlogconf, a utility that can adjust the logging levels of a
          running secchan or controller.

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

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

For installation instructions, read INSTALL.  This distribution also
includes manpages for each of its userspace programs, in the man/
directory.

Platform support
----------------

Other than the Linux kernel module, the software in the OpenFlow
distribution should compile under Unix-like environments such as
Linux, FreeBSD, Mac OS X, and Solaris.  Our primary test environment
is Debian GNU/Linux.  Please contact us with portability-related bug
reports or patches.

The Linux kernel module is, of course, Linux-specific, and the secchan
and dpctl utilities will not be as useful without the kernel module.
The testing of the kernel module has focused on Linux 2.6.23.  Linux
2.6 releases from 2.6.15 onward and Linux 2.4 releases from 2.4.20
onward should also work.

GCC is the expected compiler.

Bugs/Shortcomings
-----------------

- The current flowtable does not support all statistics messages
  mentioned in the Type 0 OpenFlow spec.

- The flowtable does not support the "normal processing" action.

- Configure/build system does not support separate build directory for
  the datapath.  ./configure must be run from the source root.

- dpctl dump-flows may freeze when large numbers of flows are in the
  flow table.  This has no effect on the datapath.

References
----------

    [1] OpenFlow: Enabling Innovation in College Networks.  Whitepaper.
        <http://openflowswitch.org/alpha/openflow-wp-v0.1.pdf>

    [2] OpenFlow Switch Specification.
        <http://openflowswitch.org/alpha/openflow-spec-v0.2.pdf>        

Contact 
-------

e-mail: info@openflowswitch.org
www: http://openflowswitch.org/