Establishing a data communications connection between a lightweight kernel in a compute node of a parallel computer and an input-output (`I/O`) node of the parallel computer, including: configuring the compute node with the network address and port value for data communications with the I/O node; establishing a queue pair on the compute node, the queue pair identified by a queue pair number (`QPN`); receiving, in the I/O node on the parallel computer from the lightweight kernel, a connection request message; establishing by the I/O node on the I/O node a queue pair identified by a QPN for communications with the compute node; and establishing by the I/O node the requested connection by sending to the lightweight kernel a connection reply message.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 This invention was made with Government support under Contract No. B554331 awarded by the Department of Energy. The Government has certain rights in this invention.