Contents
What are TCP connections and TCP sessions?
When it comes to Internet communication, TCP (Transmission Control Protocol) plays a crucial role in ensuring reliable and orderly delivery of data packets between devices. In this blog post, we will explain the concepts of TCP connections and TCP sessions, shedding light on their functionalities and importance in the world of networking.
The Basics: TCP
TCP is one of the core protocols in the Internet protocol suite. It operates at the Transport layer and is responsible for establishing a connection-oriented communication between devices. Unlike the User Datagram Protocol (UDP), which is connectionless, TCP ensures that data packets arrive in the same order they were sent and guarantees delivery, making it ideal for applications that require reliability.
TCP Connections
At its core, a TCP connection refers to a logical pathway between two devices over which data is transmitted and received. When establishing a TCP connection, a three-way handshake occurs:
- The initiating device sends a SYN (synchronize) segment to the receiving device to start the connection establishment.
- The receiving device responds with a SYN-ACK (synchronize-acknowledgment) segment, indicating its willingness to establish the connection.
- The initiating device sends an ACK (acknowledgment) segment in reply, finalizing the connection setup.
Once the connection is established, data can be exchanged in both directions between the devices. It is important to note that TCP connections are full-duplex, meaning that data can flow in both directions simultaneously.
TCP Sessions
A TCP session refers to the entire duration of a TCP connection, from its establishment to its termination. During a TCP session, data is reliably transmitted using sequence numbers, acknowledgments, and windowing mechanisms. These mechanisms ensure that data loss is minimized, packets are retransmitted if necessary, and congestion in the network is avoided.
Moreover, TCP sessions also incorporate flow control and congestion control algorithms to optimize the data transfer process. Flow control regulates the amount of data sent by the sender to match the receiver’s processing capabilities, while congestion control monitors the network to avoid congestion ensure the efficient use of available resources.
Once the data transfer is complete, the TCP session is terminated through a four-way handshake:
- The initiating device sends a FIN (finish) segment to the receiving device, indicating its desire to end the session.
- The receiving device acknowledges the FIN segment, giving its consent to terminate the session.
- The receiving device then sends its own FIN segment to the initiating device.
- The initiating device acknowledges the FIN segment, completing the session termination process.
By properly managing TCP connections and sessions, the Internet can support various applications like web browsing, email communication, and file transfers, ensuring reliable and efficient data exchange.
So, the next time you browse the web or send an email, remember that behind the scenes, TCP connections and sessions are diligently working to make it all happen seamlessly.
Reference Articles
Read also
[Google Chrome] The definitive solution for right-click translations that no longer come up.