The ch_nexus device uses Nexus for its underlying communication layer and for process management. Nexus is discussed elsewhere . This device is still in a preliminary state, and has so far only been tested in a Solaris environment.
The most interesting use of ch_nexus is that Nexus provides multimethod communication, which can use optimized communication where possible. ch_nexus thus provides an interoperability mechanism to allow MPI to run efficiently on clusters of heterogeneous systems.