Game theory has been applied to study the performance of a communication system in a hostile environment. By appropriately choosing the payoff, a communication system in the presence of a hostile jammer can be modeled as a finite two‐person zero‐sum game. In this paper, we model a two‐rate communication link interfered by an on‐off jammer as a two‐person zero‐sum game and derive the optimal memoryless communication and jamming strategies. The ensemble mean of the time average throughput is considered as the payoff to the communicator. It is found that, under average jamming power constraints, the optimal memoryless jamming strategy is, in general, to allocate as much jamming power as possible to one direction. We study both symmetric and asymmetric communication strategy cases. The performance of the communication system is better if an asymmetric communication strategy is adopted. However, the system resulting from an optimal asymmetric communication strategy may become non‐ergodic.