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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:9.0pt;font-family:"Arial","sans-serif";color:blue'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:blue'>Richard Wang will present his master’s thesis talk on Friday April 22 at 10:30AM in <o:p></o:p></span></p><p class=MsoNormal><span style='color:blue'>Room 301. His advisor is Jen Rexford. Everyone is invited to attend his talk. His <o:p></o:p></span></p><p class=MsoNormal><span style='color:blue'>abstract follows below.<o:p></o:p></span></p><p class=MsoNormal><span style='color:blue'>--------------------</span><br>abstract:<br>Today's data centers host online services on multiple servers, with a front-end load balancer directing each client request to a particular replica. Dedicated load balancers are expensive and quickly become a single point of failure and congestion. The OpenFlow standard enables an alternative approach where the commodity network switches divide traffic over the server replicas, based on packet-handling rules installed by a separate controller. However, the simple approach of installing a separate rule for each client connection (or "microflow") leads to a huge number of rules in the switches and a heavy load on the controller. We argue that the controller should exploit switch support for <i>wildcard</i> rules for a more scalable solution that directs large aggregates of client traffic to server replicas. We present algorithms that compute concise wildcard rules that achieve a target distribution of the traffic, and automatically adjust to changes in load-balancing policies without disrupting existing connections. We implement these algorithms on top of the NOX OpenFlow controller, evaluate their effectiveness, and propose several avenues for further research. <br><br><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>