This article is about the data-oriented protocol. For the set of communications protocols, see Internet protocol suite.
The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork.
IP is a network layer protocol in the Internet protocol suite and is encapsulated in a data link layer protocol (e.g., Ethernet). As a lower layer protocol, IP provides the service of communicable unique global addressing amongst computers.
The IP (Internet Protocol) is a protocol that uses datagrams to communicate over a packet-switched network. The IP protocol operates at the network layer protocol of the OSI reference model and is a part of a suite of protocols known as TCP/IP.
The Internetwork Protocol (IP) [RFC791] provides a best effort network layer service for connecting computers to form a computer network. Each computer is identified by one or more gloablly unique IP addresses. The network layer PDUs are known as either "packets" or "datagrams". Each packet carries the IP address of the sending computer and also the address of the intended recipient or recipients of the packet. Other management information is also carried.
The IP network service transmits datagrams between intermediate nodes using IP routers. The routers themselves are simple, since no information is stored concerning the datagrams which are forwarded on a link. The most complex part of an IP router is concerned with determining the optimum link to use to reach each destination in a network. This process is known as "routing". Although this process is computationally intensive, it is only performed at periodic intervals.
An IP network normally uses a dynamic routing protocol to find alternate routes whenever a link becomes unavailable. This provides considerable robustness from the failure of either links or routers, but does not guarentee reliable delivery. Some applications are happy with this basic service and use a simple transport protocol known as the User Datagram Protocol (UDP) to access this best effort service.
Most Internet users need additional functions such as end-to-end error and sequence control to give a reliable service (equivalent to that provided by virtual circuits). This reliability is provided by the Transmission Control Protocol (TCP) which is used end-to-end across the Internet.
In a LAN environment, the protocol is normally carried by Ethernet, but for long distance links, other link protocols using fibre optic links are usually used. Other protocols associated with the IP network layer are the Internet Control Message Protocol (ICMP) and the Address Resolution Protocol (arp).
IP the Next Generation, IPv6
The IPv4 protocol although widely used, is slowly being superceded by IPv6, a next-generation network-layer protocol. IPv6 is now widely implemented, and deployed in many networks.
Why name the next version after IPv4 as IPv6?
The new protocol is IPv6. (The version number "5" had already been used for an experimental protocol, called ST-2, which has not stood the test of time.
