There are 7 messages in total sent between the client and server, just to reliably send 1 packet of data. What is the use of each of these messages? Are they all necessary?
In: Technology
TCP assumes that the connection is not reliable, but that the message *must* be delivered correctly, and in full. This is a protocol that was developed in the early days of the Internet, when we did not have many high speed digital connections. Typically, modems were used, and those could have quite a high amount of transmission errors. TCP sends verifications back and forth to ensure that the entire message gets across the line. If any pieces get corrupted or go missing, those extra messages detect and correct that by having the sender retransmit the corrupted part. Retransmissions slow a connection down – something older folks who had to deal with dialup (or poor sods who still do) may be familiar with.
There is also a connectionless protocol, UDP, that just does best effort delivery. The sender sends the packet and basically, must hope that it arrives. Less overhead, but no guaranteed delivery. UDP is often used in streaming services where retransmissions aren’t an option.
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