This document introduces OpenFlow, an open platform that allows researchers to test new network ideas by giving them access and control over flow tables in switches. It describes OpenFlow's architecture and key components like the OpenFlow protocol, OpenFlow switches, and OpenFlow controllers like NOX that can be used to write network control software. It also provides illustrations of how packets are processed and forwarded in an OpenFlow network. The goal of OpenFlow is to provide a test environment for future Internet technologies at the flow level and packet level.

1. Introduction to OpenFlow
MEULLE Michael, DAAR Waqas
CORE-TPN-RIV
23 July 2010
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2. Outline
 Background
 Motivation
 OpenFlow overview
 OpenFlow Concept
 OpenFlow protocol
 OpenFlow Messages
 How OpenFlow works?
 Conclusion
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3. Background
 Internet is closed for Innovations
 We like to do new experiments
 Mobility management
 New naming/address schemes
 Network access control
 ……
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4. What is OpenFlow?
 Put an open platform in hands of researchers/students to test
new ideas at scale through production networks.
 An open development environment for all researchers
 Give access to flow tables in switches
 lookup tables, access control list, etc..
 Control packet forwarding in routers and switches.
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5. OpenFlow Architecture
Figure 1: OpenFlow Architecute [1]
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6. OpenFlow Protocol
Support three message types
Controller

 Controller-to-switch messages OpenFlow
protocol
• Configuring the switch
• Exchanging switch capabilities
• Managing the Flow table
 Symmetric messages
OpenFlow switch
• Send in either direction
• Diagnose problems in switch controller connection
 Asynchronous messages
• From switch to the controller
• Announce change in network state, swtich state etc.
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7. OpenFlow Controller
 Openflow controller is a centralized entity for the entire
OpenFlow network.
 NOX [4] is an open source OpenFlow controller.
 simplified platform for writing network control software in C++/
Python.
 Researchers can write a software and plugin to NOX for
testing their idea.
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8. Packet processing in OpenFlow Network
Figure 2: Processing of a packet in Openflow network [1]
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9. OpenFlow Table Entry
Figure 3: OpenFlow Table Entry [2]
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10. OpenFlow switching mechanism
Figure 4: Switching of packets in OpenFlow network [3]
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11. Conclusion
 Test environment for future Internet technologies
 Setup experiments at the flow level
 Setup experiments at the packet level
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12. Reading Material
 OpenFlow switch specification; URL:
www.openflowswitch.org/documents/openflow-spec-v0.8.9.pdf
 N McKeown; ‘OpenFlow: Enabling Innovation in Campus Networks’; URL:
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.141.2269
 Labsetup of Openflow network; URL:
http://www.openflowswitch.org/foswiki/bin/view/OpenFlow/Deployment/HOWTO
/LabSetup#4_Controller_Setup
 NOX controller; URL: http://noxrepo.org/noxwiki/index.php/Main_Page
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13. References
1. Nick McKeown;“Clean state design for Internet”; URL:
www.openflowswitch.org/documents/FOpenFlow.ppt&ei=K3xITN3cHIqOjAfo7Li0Dg&usg=AFQjCNGBQJM8
FlhrVJAF7iy_BcehOKkqqw&sig2=WFzjw1dzcG_Hwy3lxSMAZg
2. Peter Sjodin, Markus Heidell, Georgia Kontesidou, Kyriakos Zarifis, “Network virtualization based on flows”
3. HIDEyuki Shimonishi; „Virtualized Network Infrastructure using Openflow‟;
4. NOX; URL: http://noxrepo.org/wp/
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