TY - CONF AB - Video streaming is in high demand by mobile users. In cellular networks, however, the unreliable wireless channel leads to two major problems. Poor channel states degrade video quality and interrupt the playback when a user cannot sufficiently fill its local playout buffer: buffer underruns occur. In contrast, good channel conditions cause common greedy buffering schemes to buffer too much data. Such over-buffering wastes expensive wireless channel capacity. Assuming that we can anticipate future data rates, we plan the quality and download time of video segments ahead. This anticipatory download scheduling avoids buffer underruns by downloading a large number of segments before a drop in available data rate occurs, without wasting wireless capacity by excessive buffering.We developed a practical anticipatory scheduling algorithm for segmented video streaming protocols (e.g., HLS or MPEG DASH). Simulation results and testbed measurements show that our solution essentially eliminates playback interruptions without significantly decreasing video quality. AU - Dräxler, Martin AU - Blobel, Johannes AU - Dreimann, Philipp AU - Valentin, Stefan AU - Karl, Holger ID - 252 T2 - Proceedings of the 2nd International Conference on Networked Systems (NetSys) TI - SmarterPhones: Anticipatory Download Scheduling for Wireless Video Streaming ER - TY - CONF AB - The size of modern data centers is constantly increasing. As it is not economic to interconnect all machines in the data center using a full-bisection-bandwidth network, techniques have to be developed to increase the efficiency of data-center networks. The Software-Defined Network paradigm opened the door for centralized traffic engineering (TE) in such environments. Up to now, there were already a number of TE proposals for SDN-controlled data centers that all work very well. However, these techniques either use a high amount of flow table entries or a high flow installation rate that overwhelms available switching hardware, or they require custom or very expensive end-of-line equipment to be usable in practice. We present HybridTE, a TE technique that uses (uncertain) information about large flows. Using this extra information, our technique has very low hardware requirements while maintaining better performance than existing TE techniques. This enables us to build very low-cost, high performance data-center networks. AU - Wette, Philip AU - Karl, Holger ID - 287 T2 - Proceedings of the 4th European Workshop on Software Defined Networks (EWSDN 2015) TI - HybridTE: Traffic Engineering for Very Low-Cost Software-Defined Data-Center Networks ER - TY - CONF AB - Multi-rooted trees are becoming the norm for modern data-center networks. In these networks, scalable flow routing is challenging owing to vast number of flows. Current approaches either employ a central controller that can have scalability issues or a scalable decentralized algorithm only considering local information. In this paper we present a new decentralized approach to least-congested path routing in software-defined data center networks that has neither of these issues: By duplicating the initial (or SYN) packet of a flow and estimating the data rate of multiple flows in parallel, we exploit TCP’s habit to fill buffers to find the least congested path. We show that our algorithm significantly improves flow completion time without the need for a central controller or specialized hardware. AU - Schwabe, Arne AU - Karl, Holger ID - 247 T2 - Proceedings of the 4th European Workshop on Software Defined Networks (EWSDN 2015) TI - SynRace: Decentralized Load-Adaptive Multi-path Routing without Collecting Statistics ER - TY - THES AU - Wette, Philip ID - 264 TI - Optimizing Software-Defined Networks using Application-Layer Knowledge ER - TY - CONF AU - A. Aranda-Gutierrez, Pedro AU - Karl, Holger AU - Rojas, Elisa AU - Leckey, Alec ID - 739 T2 - 2015 European Conference on Networks and Communications, EuCNC 2015, Paris, France, June 29 - July 2, 2015 TI - On Network Application representation and controller independence in {SDN ER - TY - CONF AU - Blanckenstein, Johannes AU - Nardin, Cristina AU - Klaue, Jirka AU - Karl, Holger ID - 742 T2 - {IEEE} International Conference on Communication, {ICC} 2015, London, United Kingdom, June 8-12, 2015, Workshop Proceedings TI - Error characterization of multi-access point WSNs in an aircraft cabin ER - TY - CONF AU - Schwabe, Arne AU - Karl, Holger ID - 743 T2 - 2015 IEEE International Conference on Communications, ICC 2015, London, United Kingdom, June 8-12, 2015 TI - Topology model to generate realistic latency for simulations ER - TY - CONF AU - Dräxler, Martin AU - Blobel, Johannes AU - Karl, Holger ID - 745 T2 - 8th IFIP Wireless and Mobile Networking Conference, WMNC 2015, Munich, Germany, October 5-7, 2015 TI - Anticipatory Download Scheduling in Wireless Video Streaming with Uncertain Data Rate Prediction ER - TY - CONF AU - Wette, Philip AU - Schwabe, Arne AU - Splietker, Malte AU - Karl, Holger ID - 746 T2 - Proceedings of the 1st {IEEE} Conference on Network Softwarization, NetSoft 2015, London, United Kingdom, April 13-17, 2015 TI - Extending Hadoop's Yarn Scheduler Load Simulator with a highly realistic network & traffic model ER - TY - CONF AU - Auroux, Sébastien AU - Karl, Holger ID - 747 T2 - 26th IEEE Annual International Symposium on Personal, Indoor, and Mobile Radio Communications, PIMRC 2015, Hong Kong, China, August 30 - September 2, 2015 TI - Flexible reassignment of flow processing-aware controllers in future wireless networks ER -