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123 lines
4.4 KiB
Plaintext
OpenFlow Reference Release <http://openflowswitch.org>
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What is OpenFlow?
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-----------------
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OpenFlow is a flow-based switch specification designed to enable
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researchers to run experiments in live networks. OpenFlow is based on a
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simple Ethernet flow switch that exposes a standardized interface for
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adding and removing flow entries.
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An OpenFlow switch consists of three parts: (1) A "flow table" in
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which each flow entry is associated with an action telling the switch
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how to process the flow, (2) a "secure channel" connecting the switch
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to a remote process (a controller), allowing commands and packets to
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be sent between the controller and the switch, and (3) an OpenFlow
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protocol implementation, providing an open and standard way for a
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controller to talk to the switch.
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An OpenFlow switch can thus serve as a simple datapath element that
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forwards packets between ports according to flow actions defined by
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the controller using OpenFlow commands. Example actions are:
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- Forward this flow's packets to the given port(s)
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- Drop this flow's packets
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- Encapsulate and forward this flow's packets to the controller.
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The OpenFlow switch is defined in detail in the OpenFlow switch
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Specification [2].
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What's here?
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------------
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This distribution includes two reference implementations of an
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OpenFlow switch. The first implementation, which is closely tied to
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Linux because it is partially implemented in the Linux kernel, has the
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following components:
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- A Linux kernel module that implements the flow table and
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OpenFlow protocol, in the datapath directory.
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- ofprotocol, a program that implements the secure channel
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component of the reference switch.
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- dpctl, a tool for configuring the kernel module.
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- Hardware acceleration support, see README.hwtables
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The second implementation has the following components:
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- ofdatapath, which implements the same functionality as the
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Linux kernel module in userspace, at a cost in performance.
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- ofprotocol, a program that implements the secure channel
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component of the reference switch (the same program used in
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the kernel-based implementation).
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This distribution includes some additional software as well:
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- controller, a simple program that connects to any number of
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OpenFlow switches, commanding them to act as regular MAC
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learning switches.
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- vlogconf, a utility that can adjust the logging levels of a
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running ofprotocol or controller.
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- ofp-pki, a utility for creating and managing the public-key
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infrastructure for OpenFlow switches.
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- A patch to tcpdump that enables it to parse OpenFlow
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messages.
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- A regression suite that tests OpenFlow functionality, please
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see regress/README.
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- A Wireshark dissector that can decode the OpenFlow wire
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protocol. Please see utilities/wireshark_dissectors/README.
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For installation instructions, read INSTALL. Each userspace program
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is also accompanied by a manpage.
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Platform support
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----------------
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Other than the Linux kernel module and userspace switch
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implementation, the software in the OpenFlow distribution should
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compile under Unix-like environments such as Linux, FreeBSD, Mac OS X,
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and Solaris. Our primary test environment is Debian GNU/Linux.
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Please contact us with portability-related bug reports or patches.
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The Linux kernel module is, of course, Linux-specific, and the dpctl
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utility will not be useful without the kernel module. The testing of
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the kernel module has focused on Linux 2.6.28. Linux 2.6 releases
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from 2.6.15 onward should also work.
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The userspace datapath implementation should be easy to port to
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Unix-like systems. The interface to network devices, in netdev.c, is
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the code most likely to need changes. So far, only Linux is
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supported. We welcome ports to other platforms.
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GCC is the expected compiler.
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Bugs/Shortcomings
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-----------------
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- The flow table does not support the "normal processing" action.
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References
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----------
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[1] OpenFlow: Enabling Innovation in College Networks. Whitepaper.
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<http://openflowswitch.org/documents/openflow-wp-latest.pdf>
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[2] OpenFlow Switch Specification.
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<http://openflowswitch.org/documents/openflow-spec-latest.pdf>
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Contact
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-------
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Public discussion list: openflow-discuss@openflowswitch.org
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Direct e-mail: info@openflowswitch.org
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Web: http://openflowswitch.org/
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