Internet Protocol Suite

Overview

The Internet Protocol Suite, also known as TCP/IP, is the conceptual model and set of communications protocols used in the Internet and similar computer networks. It is named after two of the most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were the first two networking protocols defined in this standard.

Image of a network of computers connected by lines representing data transmission

History

The Internet Protocol Suite was developed by the Defense Advanced Research Projects Agency (DARPA), an agency of the United States Department of Defense. It was developed as a part of the research project known as ARPANET (Advanced Research Projects Agency Network) in the late 1960s and early 1970s. The first major version of IP, Internet Protocol Version 4 (IPv4), is still in dominant use today, despite the ongoing deployment of its successor, Internet Protocol Version 6 (IPv6).

Image of a vintage computer from the 1970s

Architecture

The Internet Protocol Suite, like many protocol suites, may be viewed as a set of layers. Each layer solves a set of problems involving the transmission of data, and provides a well-defined service to the upper layer protocols based on using services from some lower layers. Upper layers are logically closer to the user and deal with more abstract data, relying on lower layer protocols to translate data into forms that can eventually be physically transmitted.

Image of a computer with layers of software and hardware represented

Link Layer

The Link Layer is the networking scope of the local network connection to which a host is attached. This is the lowest component layer of the Internet protocols, as it is only concerned with the local network topology and interfaces to the physical network.

Internet Layer

The Internet Layer has the task of exchanging datagrams across network boundaries. It is therefore also referred to as the network layer. The internet protocol performs two basic functions: Host addressing and identification and fragmentation and reassembly of datagrams.

Transport Layer

The Transport Layer is responsible for delivering data to the appropriate application processes on the network. This layer includes the Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).

Application Layer

The Application Layer is the scope within which applications create user data and communicate this data to other applications on another or the same host. The applications, or processes, make use of the services provided by the underlying, lower layers, especially the Transport Layer which provides reliable or unreliable pipes to other processes.

Image of a computer screen with various applications open

Protocols

The Internet Protocol Suite includes a large collection of protocols that have been issued as Internet standards by the Internet Engineering Task Force (IETF). These include Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and many others.

Security

Security in the Internet Protocol Suite is provided at various levels and with different methods, including the use of cryptographic methods and protocols such as IPsec, SSL/TLS, and others.