| Acknowledgment is the process used to guarantee a reliable end to end data delivery. |
| A protocol driver at one station guarantees reliable communications by requiring an acknowledgment for every data frame received. |
| The protocol detects and recovers from errors by retransmitting unacknowledged data frames and handling the possibility for duplicate data frame receipt. |
| After waiting a set amount of time without any acknowledgment the protocol simply retransmits a data frame. |
| During this time the original data frame may have disappeared or may simply be held up somewhere in the network duplicate frames result when both the original and the retransmitted data frames arrive at the destination. |
| The receiving station ignores the duplicate data frame. |