The growth of the Internet in terms of number of devices, the number of networks associated to each device and the mobility of devices and users makes the operation and management of the Internet network infrastructure a very complex challenge. In order to address this challenge, innovative solutions and ideas must be tested and evaluated in real network environments and not only based on simulations or laboratory setups.OFELIA is an European FP7 project and its main objective is to address the aforementioned challenge by building and operating a multi-layer, multitechnology and geographically distributed Future Internet testbed facility, where the network itself is precisely controlled and programmed by the experimenter using the emerging OpenFlow technology. This paper reports on the work done during the first half of the project, the lessons learned as well as the key advantages of the OFELIA facility for developing and testing new networking ideas. An overview on the challenges that have been faced on the design and implementation of the testbed facility is described, including the OFELIA Control Framework testbed management software. In addition, early operational experience of the facility since it was opened to the general public, providing five different testbeds or islands, is described.
IEEE 802.11 contains a mechanism for transmission of data with realtime constraints known as Point Coordination Function. This supplementary medium access protocol resides on top of the basic medium access mechanism Distributed Coordination Function and uses a centralized polling approach. Due to the complexity of a PCF implementation and the predicted inefficiency of the PCF several proposals have been presented for providing QoS support without the need of a centralized scheduler. Those solutions suffer from the fact that they are shifting implementation complexity from the access point to the mobile nodes. In this paper we compare the suitability of the basic DCF and PCF protocols for the transmission of audio data in an interactive scenario. We show that a simple priority mechanism used on the mobiles as well as the access point is suitable for providing improved QoS in terms of bandwidth and without the need of an extended DCF protocol. In combination with the PCF an adequate delay characteristic for audio flows is achievable as well. To overcome the limitations in channel capacity caused by the PCF we suggest an implicit signaling scheme for improving the channel capacity by avoiding unsuccessful PCF polling attempts.
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