TCP Flow Control

Retransmissions and duplicate ACKs are reactive TCP functions designed to recover from packet loss. TCP would be a poor protocol if it didn’t include some form of proactive method for preventing packet loss, but luckily it does.

TCP implements a sliding-window mechanism to detect when packet loss may occur and adjust the rate of data transmission to prevent this. The sliding window mechanism leverages the data recipient’s receive window to control the flow of data.

The receive window is a value specified by the data recipient and stored in the TCP header (in bytes) that tells the transmitting device how much data it is willing to store in its TCP buffer space. This buffer space is where data is stored temporarily until it can be ...

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