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

Millions of people use this networking technology daily

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Transmission Control Protocol (TCP) and Internet Protocol (IP) 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.

Definition

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

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

  • The datalink 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 ARP (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 ICMP (Internet Control Message Protocol).
  • The transport layer handles communications between hosts and is responsible for flow control, reliability, and multiplexing. Protocols include TCP and UDP (User Datagram Protocol).
  • The application layer standardizes data exchange for applications. Protocols include HTTP, FTP, POP3, SMTP, and SNMP (respectively, 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 via a series of request and reply messages sent across the physical network.

What's the Difference?

  • 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.

Most computers users have heard the term TCP/IP even if they don't know what it means. 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. So seamlessly does the transfer of information work that millions of people use TCP/IP every day to send email, chat online, and play online games without ever having to know what it is.