Question

How does TCP’ 3-way handshake mechanism address the following problems?

(a) Delayed arrival of SYN Packet

(b) Delayed arrival of ACK Packet

Answer 1

a) Opening regular TCP connections requires a three-way handshake. Thus, TCP aims to establish reliable communication by synchronizing the message exchanging between two parties. This action prevents delayed arrival of SYN packet.

b) ACK-delay time can usually be adjusted globally as a system parameter. Linux offers a TCP_QUICKACK option, as a flag to setsockopt(), to disable delayed ACKs on a per-connection basis, but only until the next TCP system call. It must be invoked immediately after every receive operation to disable delayed ACKs entirely.