[starik36]

Don't know about TCP. In the 90s, I hand implemented a data/file transfer protocol over trunking radio - a very data unfriendly medium with pretty bad loss rates.

I thought about "I lost a packet" message, but if it got lost in transmission, sender would never know to resend the packet. Instead, the sender had the responsibility of keeping track of which packets it received an ACK for. If it didn't receive the ACK, it would resend the packet within a certain interval and wait for another ACK.