Introduction

Tools and Protocols

Demonstrations

Conclusions

References

WIRELESS VIRTUALIZATION USING THE OPENFLOW PROTOCOLKevin Han1, Mohd Hazeeq Hannafi1, Prabhat Tiwary1, Heming Wen1, Robert Morawski1, and Professor Tho Le-Ngoc1

SURE 2012Broadband Communication Research Lab, McGill University, 3480 University Street, Montreal, Quebec, H3A 0E9

The OpenFlow communications protocol remains one of the most used protocols for network virtualization today. This protocol has received widespread adoption and support from companies such as Google, Cisco, IBM, and Hewlett-Packard.

The continued research in networking virtualization has given rise to another topic of interest, wireless virtualization. The OpenFlow wireless extension adds wireless virtualization support to the OpenFlow protocol, allowing the same network virtualization control to both wired and wireless networks.

Testbed Setup

Software ToolsOpenFlow Communications ProtocolA protocol used extensively in software defined networking. OpenFlow gives a remote controller access to the forwarding plane of any OpenFlow supported network switch over the network.

NOXKnown as a network operating system, NOX gives OpenFlow developers the ability to develop OpenFlow controllers in both C++ and Python.

Open vSwitchOpen vSwitch is a multi-layer, OpenFlow compatible virtual switch. It is used to split a single physical port into multiple virtual ports.

CapsulatorCapsulator is an Open vSwitch extension which allows packets to be encapsulated and tunnelled through the network between two virtual ports.

FlowvisorFlowvisor is a special OpenFlow controller that acts as a proxy between OpenFlow switches and one or many OpenFlow controllers, effectively splitting a network into multiple slices.

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Hardware ToolsPC Engine Access Points

The wireless access points used are based on the PC Engine chipset. These access points have a Debian based operating system running OpenFlow, Open vSwitch, Capsulator and SNMP.

The tunnelling termination server has one physical port attached to the BCRL network, as well as one physical port split via Open vSwitch into three virtual ports. These virtual ports are linked via tunnelling to each corresponding virtual port on the access points, which are also created using Open vSwitch.There are two OpenFlow controllers running in the testbed. Depending on the demonstration, different types of controllers will be run. The example below shows a bicast controller used for the bicast video streaming demonstration.

Figure 1 – Testbed Network Configuration

Figure 2 – Bicast NOX Controller

The bicast controller is a custom controller written by the wireless virtualization team at McGill. It analyzes incoming packets and determines whether or not to learn the source MAC address. It then proceeds to forward each packet to its destination.

OpenFlow Wireless Bicast Video StreamingThis demonstration requires the bicast controller and a wireless client (laptop) with two bonded wireless network interface cards (NIC), each connected to a different access point on the network. A video is streamed from the BCRL network to the wireless client. The bicast controller detects which access point(s) the client is connected to and

forwards the correct packets to those access points. Periodically, the client will disconnect one NIC from its access point and reconnect it to another access point. The bicast controller will then reroute the packets accordingly, resulting in a seamless video streaming transition, free of video scrambling as seen to the left.

Figure 3 – Scrambled Video

Flowvisor Network Slicing and Resource Allocation

Using Flowvisor, the network is split into two separate slices, one for bicasting and one for downloading. Both slices have enforced isolation resulting in increased safety and stability. Flowvisor is also used to manage resource allocation among each slice.

Figure 4 – Flowvisor Slice Configurations

Using OpenFlow in conjunction with the OpenFlow wireless extension gives network professionals a powerful set of networking tools. The power and control that an OpenFlow controller has over the network is witnessed in the bicasting demonstration. The ability to separate one physical network into multiple slices is shown by the Flowvisor demonstration. These tools, along with the many other tools available to OpenFlow, can help create both simple and complex networks. The versatility and continued adoption of OpenFlow cements the OpenFlow protocol as a frontrunner for network and wireless virtualization.

[1] H. Wen, P. Tiwary, K. Han, M.H. Hannafi, R. Morawski, and T. Le-Ngoc, “Multicasting Handover for Wireless Access Points using OpenFlow”, SAVI Annual General Meeting, July 2012.