Kenneth P. Birman Professor
Ph.D. University of California, Berkeley, 1981

My research is concerned with reliability and security in modern networked environments. The Ensemble system offers tools that assist the application in guaranteeing these sorts of properties, even in settings where failures or dynamic reconfiguration may be needed or where the network may be under some form of attack. Examples of some practical goals for 1997 include the use of Ensemble to provide security and coordinated management in the Next Generation Internet; the integration of the Ensemble tools into Microsoft's NT-servers such as those managed by Wolfpack; and the use of Ensemble interfaced to Java to support distributed collaboration.

The key to our approach is to focus on "process-group communication structures". Ensemble tracks process group membership, reporting changes to the members, and provides reliable multicast within each group. Over this, we offer a variety of tools, sometimes integrated into the operating system or the network in a manner that will "transparently" extend the application without requiring any changes and sometimes used more explicitly by the developer. Research topics include the integration of Ensemble with internet security protocols, the development of very high-performance reliable multicast protocols for large-scale systems, using the NuPrl system (developed by Bob Constable's group) to prove the correctness of our protocols, and implementing special kinds of network "quality of service" options. We are especially excited about recent work on a probabilistically reliable multicast protocol that turns out to be exceptionally stable and scalable. This protocol was developed jointly with Mark Hayden; Yaron Minsky and Mihai Budiu played a big role in helping to evaluate its performance in very large networks.

The Ensemble project is directed by myself, Robbert van Renesse, and Werner Vogels. Other researchers are Roy Friedman and Carl Lagoze.

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Last modified: 1 October 1997 by Karla Consroe (