TCP/IP Protocol – part 1

See in Portuguese.

Good evening folks. From that post, we’ll have an tutorial on the TCP/IP protocol and your details. Understand clearly how and where you use the TCP/IP protocol. You’ll understand, too, why this protocol is so important.

The fusion of two protocols

If you are reading this post, then you are using the TCP/IP protocol. The TCP/IP protocol is a union of the two protocols that make up its name: TCP and IP. Protocols can be interpreted as standards necessary for functioning the same technology. It’s like if you worked in a factory in front of a treadmill. Each employee has a specific function that, if done properly, will have the final product as a result. So each company has different roles for these employee to get the other results or even similar. It’s also well on the Internet with different protocols.

protocolo fusaoThese protocols are classified according to their layers. These are called OSI model, as we’ll see ahead.

The TCP protocol

The TCP means Transmission Control Protocol and is one of the main Internet protocols. Its function is to verify that data packets are being sent in the correct sequence and without error thus controlling the transmission of data.

informaticaThere are indications that the TCP originated in May 1974, during an article published by Vinton G. Cerf and Bob Kahn for Institute of Electrical and Electronics Engineers (IEEE) in the US. In this article, the authors described a protocol to make a connection with exchange packets, also checking for errors. The idea was well received and since then is used.

When we send the packages by the TCP protocol, we use different ways of sending, such as:

  • Connection-oriented: So the sender sends a connection request to the recipient and getting permission, transfers the data over the wire.
  • Peer-to-peer: A connection is established directly between two nodes without a network. In this case, no request is required.
  • Reliability: The TCP protocol has enough reliability guarantee to deliver the packages to the recipient. So it’s much more used than other protocols. With TCP, you can resend packets that were lost along the way or that came with error for destination. Then the information can be interpreted by the recipient exactly as the sender expected.
  • Full-duplex: simultaneously, they ‘re packets sent and received over the network. In this case, the two points are considered senders and recipients, as they receive the packages together. However, this method can cause network congestion sometimes.
  • Shipping Control: The receiver, to find that the package arrived with accurate, sends a reply message to the sender, confirming receipt. Then, the sender does not need to worry about this package because sure that it has already been submitted successfully.

How to work the sending of data in the TCP protocol?

For this, the the TCP protocol uses a “handshake” three-way: before making the connection to the recipient, the sender connects to “listen” on a port to open a connection. This process is called passive opening.

Once the passive open is established the sender can perform an active aperture, in other words, sending a SYN packet. In this second process is returned the confirmation message to the sender, called SYN + ACK packet.

The third and final part of the process, the sender sends a new packet to the server, called ACK to confirm that received the response packet.

After this, packets with data can be transferred in a full-duplex communication.


Next post, we’ll bring the continuation of the content …

Author: Esdras Nunes

Rede LAN Soluções em Informática.

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