There is provided a network interface module, and a method of implementing deterministic response frame transmission therein. The network interface module comprises a processor core arranged to execute a set of threads, the set of threads comprising at least one transmit thread arranged to cause a response frame to be transmitted upon expiry of a minimum response period from a response triggering event occurring. The network interface module further comprises a timing component arranged to output a masking timeout signal indicating expiration of successive masking timeout intervals, and a masking component arranged to mask the transmit thread from being scheduled for execution by the processing core. The masking component being further arranged to receive the masking timeout signal output by the timing component and to unmask the transmit thread upon expiry of a masking timeout interval.