Reliable communication may be implemented using various underlying transport mechanisms, where the underlying transport mechanisms may be reliable or non-reliable. When data is sent from a source to a destination, the source may sent acknowledgment requests (RACKs) to the destination, and may await acknowledgments (ACKs) from the destination. The RACKs and ACKs are sent over the underlying transport mechanism. The rate at which the data source requests acknowledgments from the destination may be varied, depending on the underlying transport mechanism, to achieve lower overhead and to optimize throughput. For example, RACKs may be sent relatively less frequently when the underlying mechanism implements guaranteed delivery, and may be sent relatively more frequently when the underlying transport does not provide guaranteed delivery.