TCP/IP (Transmission Control Protocol/Internet Protocol)

Contributor(s): Kate Gerwig

TCP/IP, or the Transmission Control Protocol/Internet Protocol, is a suite of communication protocols used to interconnect network devices on the internet. TCP/IP can also be used as a communications protocol in a private network (an intranet or an extranet).

The entire internet protocol suite -- a set of rules and procedures -- is commonly referred to as TCP/IP, though others are included in the suite.

TCP/IP specifies how data is exchanged over the internet by providing end-to-end communications that identify how it should be broken into packets, addressed, transmitted, routed and received at the destination. TCP/IP requires little central management, and it is designed to make networks reliable, with the ability to recover automatically from the failure of any device on the network.

The two main protocols in the internet protocol suite serve specific functions. TCP defines how applications can create channels of communication across a network. It also manages how a message is assembled into smaller packets before they are then transmitted over the internet and reassembled in the right order at the destination address.

IP defines how to address and route each packet to make sure it reaches the right destination. Each gateway computer on the network checks this IP address to determine where to forward the message.

How TCP/IP works

TCP/IP uses the client/server model of communication in which a user or machine (a client) is provided a service (like sending a webpage) by another computer (a server) in the network.

Collectively, the TCP/IP suite of protocols is classified as stateless, which means each client request is considered new because it is unrelated to previous requests. Being stateless frees up network paths so they can be used continuously.

The transport layer itself, however, is stateful. It transmits a single message, and its connection remains in place until all the packets in a message have been received and reassembled at the destination.

TCP/IP and OSI model illustrated

The TCP/IP model differs slightly from the seven-layer Open Systems Interconnection (OSI) networking model designed after it, which defines how applications can communicate over a network.

TCP/IP model layers

TCP/IP functionality is divided into four layers, each of which include specific protocols.

  • The application layer provides applications with standardized data exchange. Its protocols include the Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Post Office Protocol 3 (POP3), Simple Mail Transfer Protocol (SMTP) and Simple Network Management Protocol (SNMP).
  • The transport layer is responsible for maintaining end-to-end communications across the network. TCP handles communications between hosts and provides flow control, multiplexing and reliability. The transport protocols include TCP and User Datagram Protocol (UDP), which is sometimes used instead of TCP for special purposes.
  • The network layer, also called the internet layer, deals with packets and connects independent networks to transport the packets across network boundaries. The network layer protocols are the IP and the Internet Control Message Protocol (ICMP), which is used for error reporting.
  • The physical layer consists of protocols that operate only on a link -- the network component that interconnects nodes or hosts in the network. The protocols in this layer include Ethernet for local area networks (LANs) and the Address Resolution Protocol (ARP).

Importance of TCP/IP

TCP/IP is nonproprietary and, as a result, is not controlled by any single company. Therefore, the internet protocol suite can be modified easily. It is compatible with all operating systems, so it can communicate with any other system. The internet protocol suite is also compatible with all types of computer hardware and networks.

TCP/IP is highly scalable and, as a routable protocol, can determine the most efficient path through the network.

The history of TCP/IP

The Defense Advanced Research Projects Agency (DARPA), the research branch of the U.S. Department of Defense, created the TCP/IP model in the 1970s for use in ARPANET, a wide area network that preceded the internet. TCP/IP was originally designed for the Unix operating system, and it has been built into all of the operating systems that came after it.

The TCP/IP model and its related protocols are now maintained by the Internet Engineering Task Force.

This was last updated in July 2019

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What changes do you think should be made to make the internet protocol suite more effective for use in increasingly virtualized networks?
I want to know how to use it.
I'm sorry, but that grammar just isn't correct.
I'm sorry but that is not relevant. Also check yourself before checking someone else.
That is mean every messages sending from Computer A, assembling as a packet in higher level (TCP) and then going vi lower level (IP) form receiving in Computer B in lower level (IP) then to higher level (TCP), then reassembling messages.
Thanks TechTarget. I have some query before read your post but now I'm clear on some points.
Hi TechTarget,
Can you tell and give me some Example about TCP/IP? I don't really know about this so I want example. Maybe make me better to understand.
The Internet's protocol suite is called Transmission Control Protocol/Internet Protocol and is known as TCP/IP. It used by the internet and by all intranet and extranets. It consists of five layers of protocols that can be related to the several layers of the OSP architecture.
Thank you for your good explanation.
Trust me, you guys are the best. You make these terms seems so easy to read and comprehend. Thanks a lot and continue the good work.
TCP/IP is a suite of internet protocols. Nice and precise information.
The diagram which is showing TCP/IP layers is wrong. There is no Physical layer in TCP/IP suit.
Is there a way of knowing the input/output of data transfers (Network TCP/IP Traffic)? I'm looking for something that will give me a numeric value of these transfers. I want to use it on my LPARs. Thank you.
if you can write about TCP/IP Stack is will be nice!!
I want to know how to use it.


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