TCP 3-Way Handshake Process

Overview

• The TCP 3-Way Handshake is a fundamental process to establish a reliable connection between two devices over a TCP/IP network.
• It involves three steps: SYN (Synchronize), SYN-ACK (Synchronize-Acknowledge), and ACK (Acknowledge).
• Ensures both parties are synchronized and ready for communication.
• Key for secure and stable communication.

What is TCP 3-Way Handshake?

• Used in Transmission Control Protocol (TCP) to establish a connection between a client and a server.
• Ensures both client and server have synchronized initial sequence numbers.

TCP Segment Structure

• Consists of data bytes and a header.
• Header fields:
  • Source Port Address: 16-bit, sender's port.
  • Destination Port Address: 16-bit, receiver's port.
  • Sequence Number: 32-bit, first byte sequence number.
  • Acknowledgement Number: 32-bit, next byte expected.
  • Header Length (HLEN): 4-bit, length of TCP header.
  • Control Flags: 6 1-bit fields controlling various aspects.
    • URG, ACK, PSH, RST, SYN, FIN.
  • Window Size: TCP window size in bytes.
  • Checksum: Error control checksum.
  • Urgent Pointer: Points to urgent data.

TCP 3-way Handshake Process

1. SYN (Synchronize):
   • Client sends SYN segment to initiate a connection.
   • Indicates sequence number for communication.
2. SYN + ACK:
   • Server responds with SYN-ACK.
   • Acknowledges receipt and provides its sequence number.
3. ACK (Acknowledge):
   • Client sends ACK to acknowledge server's segment.
   • Connection established, ready for data transfer.

Importance

• Provides reliable communication using Positive Acknowledgement with Re-transmission (PAR).
• Resends data units until acknowledged.
• Ensures segments are not damaged using checksum.
• Establishes a reliable TCP connection with three exchanged segments.

Conclusion

• TCP 3-Way Handshake is crucial for establishing a secure and reliable connection.
• Ensures synchronization and readiness for data transmission, a key element of TCP/IP networks.