Internet Protocol

Internet Protocol
Name	Internet Protocol
Developer	Vint Cerf, Bob Kahn, DARPA
Introduced	0 1981
Based on	Transmission Control Program
Osi layer	Network layer
Rfc	RFC 791

Internet Protocol. It is the principal communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking and essentially establishes the Internet. The protocol was first implemented in the ARPANET and is fundamental to all modern digital networking.

Overview

The protocol provides a logical addressing system that identifies devices on a network, such as the widely used IPv4 and its successor IPv6. It operates at the network layer of the TCP/IP model, which corresponds to Layer 3 of the OSI model. This layer is responsible for the end-to-end delivery of packets, including tasks like fragmentation and reassembly. Key development was led by researchers like Vint Cerf and Bob Kahn under projects funded by DARPA. The first formal standard was published as RFC 791 by the Internet Engineering Task Force.

Technical details

The core operation is a connectionless datagram service, meaning it does not guarantee delivery, ordering, or duplicate protection. This design philosophy is often called "best-effort delivery." Each datagram consists of a header and a payload. The header contains fields for the source address, destination address, and other control information. Critical functions include time to live to prevent infinite loops, a header checksum for error detection, and protocol identification for the payload. These datagrams are encapsulated within the data link layer frames of technologies like Ethernet or Wi-Fi.

Versions

The dominant version for decades has been IPv4, which uses 32-bit addresses, limiting the address space to about 4.3 billion unique addresses. To address exhaustion, IPv6 was developed, standardized in RFC 2460, and uses a 128-bit address format. The transition between versions involves various mechanisms, including dual-stack implementations, tunneling protocols like 6to4, and translation services. Other historical or experimental versions include IPv5, which was designated for an experimental streaming protocol, and the early ARPANET host protocol.

Addressing and routing

Each device interface is assigned a unique address, such as an IPv4 address like 192.0.2.1. These addresses are hierarchically structured into subnetworks to enable efficient routing. The process of directing packets from a source to a destination across multiple networks is called routing, performed by specialized hardware like routers and gateways. Key supporting protocols include the Border Gateway Protocol for inter-domain routing on the global Internet, and Open Shortest Path First for routing within an autonomous system. Address assignment is managed by organizations like the Internet Assigned Numbers Authority and regional Internet registries.

Security

The original design did not incorporate inherent security features, making communications vulnerable to threats like eavesdropping, spoofing, and man-in-the-middle attacks. To address these issues, the IPsec suite of protocols was developed to provide authentication, integrity, and confidentiality at the network layer. IPsec is widely used in establishing secure virtual private networks. Other security mechanisms operate at higher layers, such as Transport Layer Security for web traffic and Secure Shell for remote access. Ongoing threats are monitored and addressed by entities like the Computer Emergency Response Team.

Related protocols

It is a core component of the larger Internet protocol suite, often simply called TCP/IP. Its most common pairing is with the Transmission Control Protocol, which provides reliable, connection-oriented communication, forming the basis for much of the Internet's traffic. The User Datagram Protocol offers a simpler, connectionless alternative. Essential supporting protocols include the Internet Control Message Protocol for diagnostic and error messages, the Address Resolution Protocol for mapping addresses to hardware addresses, and the Dynamic Host Configuration Protocol for automatic address configuration. Management and configuration are aided by protocols like the Simple Network Management Protocol.

Category:Internet protocols Category:Internet architecture Category:Network layer protocols