A data processing system and method are provided. A host computing device comprises at least one processor. A network interface device is arranged to couple the host computing device to a network. The network interface device comprises a buffer for receiving data for transmission from the host computing device. The processor is configured to execute instructions to transfer the data for transmission to the buffer. The data processing system further comprises an indicator store configured to store an indication that at least some of the data for transmission has been transferred to the buffer wherein the indication is associated with a descriptor pointing to the buffer.