When a communication system is used to transmit many short messages, it is important to reduce the amount of control overhead for creation and destruction of logical process-to-process connections and for reliable communication. Different end-to-end control procedures are described, and they are studied with respect to the possibility of losing a message or accepting a duplicate. It is shown (under certain assumptions about the communication network) that all end-to-end protocols either allow for loss of a message or can deliver duplicates of a message.