The TCP/IP three-way handshake is a fundamental process in establishing reliable communication in computer networks. It works by ensuring synchronized data exchange and acknowledging receipt between two communicating devices, typically a client and a server. Here's how it works:

Step 1: Client initiates connection (SYN)

• The client sends a packet with the SYN (Synchronize) flag set. This flag indicates the client's desire to initiate a connection and also includes a randomly chosen sequence number for data packets.

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TCP packet with SYN flag set

Step 2: Server acknowledges and synchronizes (SYN-ACK)

• The server receives the SYN packet, acknowledges it by setting the ACK (Acknowledge) flag, and sends back its own SYN flag to synchronize its sequence numbers with the client.

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TCP packet with SYNACK flags set

Step 3: Client acknowledges server synchronization (ACK)

• The client receives the SYN-ACK packet and acknowledges the server's synchronization by sending an ACK packet.

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TCP packet with ACK flag set

Reliability achieved through:

• Sequence numbers: These unique numbers ensure packets arrive in the correct order and prevent duplicates.
• Acknowledgments: ACK flags confirm successful receipt of packets, triggering retransmission if one is missing.
• Three-way exchange: This guarantees both sides are ready to communicate before data transmission begins.

Benefits of the three-way handshake:

• Prevents connection attempts from being left open: If the server doesn't respond (Step 2), the client times out and retries or aborts the connection.
• Detects potential connection issues: Missing acknowledgments or unexpected flags trigger error handling mechanisms.
• Establishes synchronized communication channels: Sequence numbers and acknowledgments enable reliable data flow in both directions.

Overall, the TCP/IP three-way handshake plays a crucial role in reliable communication by ensuring proper connection establishment, synchronized data exchange, and error detection for robust network communication.

Look at serial nos 4.1 and 4.2 in the document https://tetcos.com/downloads/v14/NetSim_Experiment_Manual.pdf

They talk about TCP connection establishment and reliable data transfer.