Explain the mechanism of the three-way handshake process in the TCP protocol.

The three-way handshake in the TCP protocol is a process that ensures a reliable connection is established between the client and the server.

The process consists of three steps:

1. SYN: The client sends a segment to the server with the SYN (synchronize) flag to initiate the connection and specify the initial sequence number.

2. SYN-ACK: The server responds with a segment with SYN and ACK (acknowledge) flags, confirming receipt of the SYN from the client and sending its own initial sequence number.

3. ACK: The client sends a segment with the ACK flag to the server, confirming receipt of the SYN-ACK.

After this, the connection is considered established, and the parties can exchange data.

Example:

• Client -> Server: SYN, seq = x
• Server -> Client: SYN-ACK, seq = y, ack = x+1
• Client -> Server: ACK, ack = y+1

This mechanism guarantees that both parties are ready for data transfer and are synchronized on sequence numbers, which is important for TCP reliability.