The Active Bridge
Scott Alexander, Marianne Shaw, Scott Nettles, Michael Hicks, Jon Moore, 
Angelos D. Keromytis and Jonathan Smith

Distributed Systems Lab
University of Pennsylvania

The Active Bridge is a proof-of-concept experiment as part of the
SwitchWare (www.cis.upenn.edu/~switchware) project at the University
of Pennsylvania. The active loader permits dynamic loading of
switchlets for execution on a per packet basis. The bridge makes the
following transitions:
	learning bridge -> 
	bridge using DEC based protocol with spanning tree ->
	bridge based on IEEE 802.1D algorithm (w/ error detection) ->
	if error detected: bridge using DEC based protocol with spanning tree

For more details, see http://www.cis.upenn.edu/~switchware/papers/sigcom97.ps.

The active loader is written in OCaml running in the Linux
environment.  (This release has been tested with Red Hat 5.0.)  The
Active Bridge is a series of OCaml switchlets that are dynamically
downloaded into the loader to be executed.