The TCP 3-Way Handshake : What It Is & Why It's Important
TCP : Transmission Control Protocol → As the name suggests protocols meaning set of rules, it is a set of rules for data transmission on the internet. TCP works on 3-way handshake process. 3-way handshake is a crucial process of creating a reliable communication channel. TCP ensures both devices agree on connection parametersbefore data exchange takes place.
What is the TCP 3-Way Handshake?
3-way handshake is the process used to initiate a connection between a client and a server in a TCP/IP network.
Emphasize its role in ensuring reliable communication by establishing synchronisation and acknoledgement between devices.
Steps of the TCP 3-Way Hanshake
SYNC (Synchronise)
→ The client sends a SYNC packet to the server to request a connection.
→ This packet contains the client’s Initial Sequence Number (ISN), which helps track data packets.
SYNC-ACK (Synchronise + Acknowledge)
→ The server responds with a SYNC-ACK packet.
→ This packet acknowledges the client’s SYNC request and includes the server’s own ISN.
ACK (Acknowledge)
→ The client sends an ACK packet back to the server, confirming receipt of the SYNC-ACK.
→ At this point, the connection is established, and data transfer can begin.
Why is the 3-Way Handshake Important?
Reliability :
→ Ensures both parties are ready to communicate before data exchange.
→ Avoid data loss by synchronising sequence numbers.
Security :
→ Prevents unauthorizes devices from initiating connections, as responses are expected.
→ Enables systems to identify and handle connection requests properly.
Error Detection :
→By acknowledging each step, devices can detect errors or dropped packets early.
Real World Example
Let’s use the process of opening a webpage as an example
Client sends Sync
→ You open a browser (e.g., Chrome) and type “google.com” in the address bar.
→ Your browser sends a Sync packet to the web server hosting “google.com”.
→ This packet includes the client Initial Sequence Number (ISN) to synchronise communication.
Example in action :
The client say’s, “Hi, I would like to connect and my sequence number is (12345). Are you ready?”
Server responds with Sync + Ack
→ The server receives the Sync request and responds witha Sync + Ack packet.
→ The Sync + Ack packet contains the server’s own ISN and acknowledges the client’s sequence number.
Example in action :
The server replies, “Hello, I recieved your request and sequence number is (67890). I am ready to connect”.
Client sends Ack packet
→ The client receives the Sync + Ack packet from the server and sends an Ack packet back.
→ This acknowledges the server’s sequence number and confirms the connection.
Example in action :
The client responds, “Great, I received your sequence number. Let’s start communicating.
