Doubt on TCP

[sheikhashar35]

Need to know whether TCP is connection-oriented or Connection- less service?

[marce1000]

 - FYI : https://docs.oracle.com/cd/E19620-01/805-4041/6j3r8iu2f/index.html#:~:text=TCP%20is%20an%20example%20of,processes%20before%20data%20is%20exchanged.

 M.

[sheikhashar35]

Thanks a lot for sharing this but I have a doubt. As per my understanding a service is called as connection oriented if we have created a circuit for connection and we will not tear it down even after the transmission however in connection less we will create the circuit at the time of transmission and after the transmission we will tear down the circuit.

Also TCP doesn’t have any protocol for connection oriented service like OSI which have x.25 and CLNP.  As per my understanding the connection oriented service can be enable in p2p network and in Ethernet also we cannot enable that as Ethernet already have a service named PMTUD. So how TCP could be connection oriented when we don’t have any protocol for that ?

[Kasun Bandara]

as i understood, you got some misconception regarding the connection oriented and connection less related to protocols. TCP itself doing connection oriented checking stuff.

Simply TCP verifies connection between source and destination is available. if source is not able to contact destination, TCP will not send any data. so connections between source and destination must be available and thats we call Connection oriented. 

Other hand, UDP is connection less. its not checks the availability of destination and keep sending data.

http://www.tcpipguide.com/free/t_ConnectionOrientedandConnectionlessProtocols-3.htm

[MHM Cisco World]

TCP sure is connection orient why?
two point 
1- before the client and Server exchange the data they need to handshake,
2- after handshake if one side send data without receive ACK then it retransmit, 
this two important point sure make TCP connection orient.