A mechanism is provided for managing a process-to-process intra-cluster communication request. A call from a first application is received in a first operating system in a first data processing system. The first operating system passes the call from the first operating system to a first host fabric interface controller in the first data processing system without processing the call. The first host fabric interface controller processes the call without intervention by the first operating system to determine a second data processing system in the plurality of data processing systems with which the call is associated. The first host fabric interface controller initiates an intra-cluster connection to a second host fabric interface controller in the second data processing system. The first host fabric interface controller then transfers the call to the second host fabric interface controller in the second data processing system via the intra-cluster connection.