Understanding Transmission Control Protocol/Internet Protocol (TCP/IP)

Millions of people use this networking technology daily

Transmission Control Protocol and Internet Protocol are two distinct computer network protocols. TCP and IP are so commonly used together, however, that TCP/IP has become standard terminology for referring to this suite of protocols.

A protocol is an agreed-upon set of procedures and rules. When two computers follow the same protocols—the same set of rules—they understand each other and exchange data.

TCP/IP Functionality

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TCP/IP functionality is divided into four layers, each with its own set of agreed-upon protocols:

  • The link layer consists of methods and protocols that operate only on a link, which is the network component that interconnects nodes or hosts in the network. Protocols in the layer include Ethernet and Address Resolution Protocol.
  • The internet (or networking) layer connects independent networks to transport the packets containing the data across network boundaries. Protocols are IP and Internet Control Message Protocol.
  • The transport layer handles communications between hosts and is responsible for flow control, reliability, and multiplexing. Protocols include TCP and User Datagram Protocol.
  • The application layer standardizes data exchange for applications. Protocols include HyperText Transfer Protocol, File Transfer Protocol, Post Office Protocol Version 3, Simple Mail Transfer Protocol, and Simple Network Time Protocol.

TCP/IP technically applies to network communications in which the TCP transport is used to deliver data across IP networks. Known as a connection-oriented protocol, TCP works by establishing a virtual connection between two devices through a series of request-and-reply messages sent across the physical network.

  • TCP divides a message or file into packets that are transmitted over the internet and then reassembled when they reach their destination.
  • IP is responsible for the address of each packet so that it gets to the correct destination.

The average person on the internet works in a predominately TCP/IP environment. Web browsers, for example, use TCP/IP to communicate with web servers. The transfer of information work so seamlessly that millions of people use TCP/IP every day to send email, chat online, and play online games without ever being aware of it.

  • Which network services or protocols use TCP/IP port 22?

    Generally, the network protocol Secure Shell (SSH) uses port 22. That number is also often used for secure logins, file transfers, and port forwarding.

  • What's the difference between TCP and IP?

    Since TCP and IP are two different protocols, they perform two different functions. IP is responsible for finding the address where information is going to be sent, while TCP is responsible for delivering that information to the address.

  • What is known as the TCP/IP Swiss Army Knife?

    The "TCP/IP Swiss Army Knife" is a common nickname for Netcat, a tool that's used to write data across networks using TCP or UDP protocols.

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