This report describes the design and implementation of a request/response protocol for the DoD Internet protocol hierarchy. The protocol enforces request/response semantics and can be used as part of a remote procedure call package. The protocol is not limited to this use, but most design decisions were made with this application in mind. The protocol was implemented in the Berkeley UNIX kernel and integrated into the inter-process communication mechanism. Measurements indicate the protocol is two to three times faster than similar protocols implemented in user level code. The protocol is as fast as other kernel protocols; users will therefore be free to choose the protocol which best matches the semantics of their distributed applications.