| Speaker : | Micheal Ment |
| Univ. of Tübingen | |
| Date: | 21/10/2011 |
| Time: | 10:30 am - 11:30 am |
| Location: | LINCS Meeting Room 40 |
Abstract
Resilience analysis in packet-based communication networks quantifies the risk of link overload due to rerouted traffic and the risk of disconnectivity. Proactive optimization of routing and rerouting may reduce the first risk, improvement of the network topology the second one. Recently, IP fast reroute mechanisms have been suggested by the IETF. Loop-free alternates (LFAs) are simple, but they may not cover all single element failures. The IETF has recently defined Pre-Congestion Notification (PCN) for Differentiated Services networks. It uses simple load-dependent packet re-marking to communicate load conditions to edge. This information is used for admission control and flow termination. The latter is useful to remove overload that occurs in spite of admission control due unexpected events. However, termination can be avoided if admissible rate thresholds are set low enough, which is the principle of resilient admission control. Today’s access networks suffer from a minority of heavy users who are responsible for most traffic and compromise the quality of experience for a majority of light users. Some ISPs rate-limit the user access, others use deep packet inspection to classify and downgrade some traffic which violates network neutrality. To tackle that problem, the IETF defines Congestion Exposure (ConEx). It makes congestion visible to any IP device along a flow’s path. This information may be used to throttle the user access to achieve per-user fairness rather than per-flow fairness, to improve traffic engineering, and to enhance SLAs.
Biography: Michael Menth is a full professor at the Department of Computer Science at the University of Tuebingen/Germany and head of the Communication Networks chair. He received a Diploma and PhD degree in 1998 and 2004 from the University of Wuerzburg/Germany. Prior he was studying computer science at the University of Texas at Austin and worked at the University of Ulm/Germany. His special interests are performance analysis and optimization of communication networks, resource management, resilience issues, and Future Internet. He holds numerous patents and received various scientific awards for innovative work.