CLEO - The Cisco Router in Low Earth Orbit

CLEO was a demonstration of commercial off the shelf (COTS) networking hardware operating on a commercial spacecraft (SSTL's UK-DMC), that launched in 2003. It was used within a number of important collaborative experiments and technology demos over several years, including IPv4, IPv6, IPsec, and others, involving NASA Glenn Research Center, SSTL, Cisco, and other partners. A 2008 IEEE article summarizes several of the important accomplishments.

In general, CLEO proved the basic concepts around adapting a router for use in space, and helped to create understandings of operating practices, configurations, and the overall value of in-space routing. It led to later work including Cisco's Internet Routing in Space (IRIS) program.

Lloyd Wood hosts an extensive page on CLEO, which is recommended for additional information and references on CLEO.

There is also a fair Wikipedia article on CLEO.