tcp stands for transmission control protocol ,its use to transer data one end to other end ,

its working on set of rules ,tcp working as bridge between software like our chrome,

or any application to connect lower network.

2. Problems TCP is designed to solve

suppose there we not used tcp to sending data, so there are many problems occures such as:

1. packates missing

2.change data ordering

3. less reliable

4.no reverse chaking whether all data recived or not

this some problems solved by tcp protocol. its gives us benifites such as :

1. reverse chaking all data packets recieved

2. more relaible

3. maintaing ordering the data

4. etc

3. TCP 3-Way Handshake

for the initialize the connection between server and client need to handshak both the praties ,

both parties should have permited and acknoledge the connction for communication.

4. Step-by-step working of SYN, SYN-ACK, and ACK

step 1:

first client send sync flag request to server and

segment number(eg.1001) for establishing connection.

example , assume you want to connect some random girl the first step to identifying the name or sending

message to her.

step2 :

then server if its accepts then responding flag sync-ack and

segment no(eg.2000) means server to be ready to connection.

exmaple: after message part she will sync means see the message and acknolegde with replie

step3:

then cilent sends acknolege flag ,syn-ask server sends and

set the acknolege sengment number (eg.2001) this means now you ready to communicates.

exmple: then you sends message then she replies this is how u established communication

5. How data transfer works in TCP'

in tcp there is 3 way handshake happend when client intiate reqest server ,firstly client sent sync req,after

server requested sync+ack req after last client sent ack request so here connection established.

after data bracking into segments, tcp does not share info in single block ot always make segment or small data packets ,each segment wrap into tcp headers.

the header contains sequence Number,this ensure the data packet go in safly order in reciver end.

6.How TCP ensures reliability, order, and correctness

tcp actually build for giving this three piller:

1. reliability

TCP ensures reliability by guaranteeing that all transmitted data reaches the receiver correctly.

• Acknowledgments (ACKs):
  Every segment sent by the sender must be acknowledged by the receiver. If an acknowledgment is not received within a specific time, the sender retransmits the data.

• Retransmission Mechanism:
  Lost or corrupted segments are retransmitted using timeout and duplicate ACK detection.

• Sequence Numbers:
  Each byte of data is assigned a sequence number, allowing TCP to detect missing data.

2. order

TCP ensures that data is delivered to the application in the same order in which it was sent.

• Sequence Numbers in TCP Header:
  Sequence numbers help the receiver arrange received segments in the correct order.

• Reordering at Receiver Side:
  If segments arrive out of order, TCP temporarily stores them and rearranges them before delivering to the application.

3. correctness

TCP ensures correctness by detecting and handling errors during transmission.

• Checksum:
  Each TCP segment contains a checksum that verifies the integrity of the data. If the checksum fails, the segment is discarded.

• Error Detection and Recovery:
  Corrupted segments are detected and retransmitted to ensure correct data delivery.

7. How a TCP connection is closed

tcp use four way handshak technique to ensure that all data is delivered before the connection is closed.

Step 1: FIN

client or server send FIN sengment to other side.

Step 2: ACK

receiving side sends an ACK to confirm the FIN.

Step 3: FIN → other side fin

When the second side finishes sending its data, it sends its own FIN.

Step 4: Final ACK

The first side sends an ACK for the second FIN.

Now this connection is fully closed.