Department of Computer Science Colloquium
Tuesday April 9, 2002 at 4:15pm 
Upson Hall B17

Session-Based Mobility: An End-to-End Approach

Alex Snoeren

Massachusetts Institute of Technology


Today's Internet is increasingly mobile, fueled by the ever-expanding deployment of laptops and hand-held PDAs. These devices are most useful when they interact with others across the Internet, and, typically, use a number of different mechanisms to do so (Ethernet, 802.11, Bluetooth, etc.). By their very nature, however, mobile nodes are prone to unexpected disconnections, which vary greatly in duration. Despite the prevalence of these multi-homed mobile devices, today's Internet systems lack fine-grained support for the various aspects of mobility. This talk argues for a system session abstraction that handles both changes in communication end points and periods of disconnection. We present a UNIX-based implementation exporting this abstraction and show that sessions are a flexible, robust, and efficient way to manage changing end points, even for legacy applications. In addition, we extend the session abstraction to consider the novel notion of a session continuation that enables system support for "suspend/resume" Internet operation. Our results show that the session abstraction is easy to use in popular applications and that session continuations provide efficient resumption from widely varying periods of disconnection.


Alex Snoeren is a Ph.D. candidate at the Massachusetts Institute of Technology, where he is advised by Hari Balakrishnan and Frans Kaashoek. His research interests lie in computer systems, particularly networking, operating systems, and mobile and distributed computing. Alex received B.S. degrees in computer science and applied mathematics and an M.S. degree in computer science from the Georgia Institute of Technology. He is also a Network Scientist with the Internetworking Research Department of BBN Technologies.