TCP/IP model: Difference between revisions

Revision as of 06:26, 27 March 2012

Revision as of 06:29, 27 March 2012

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{{See also |Internet Protocolprotocol Suitesuite}}

The '''TCP/IP model''' is a descriptive framework for [[Protocol (computing)|computer network protocols]] created in the 1970s by [[DARPA]], an agency of the [[United States Department of Defense]].

The name derives from the two most important protocols of the networking protocol suite, the [[Transmission Control Protocol]] (TCP) and the [[Internet Protocol]] (IP). The model evolved from the operational principles of the [[ARPANET]], which was an early [[wide area network]] and a predecessor of the [[Internet]]. The [[TCP/IP]] model is formalized in the [[Internet Protocolprotocol Suitesuite]] and is sometimes called the ''Internet Modelmodel'' or the ''[[United States Department of Defense|DoD]] Modelmodel.

The TCP/IP model describes a set of general design guidelines and implementations of specific networking protocols to enable computers to communicate over a [[Computer network|network]]. TCP/IP provides end-to-end connectivity specifying how data should be formatted, addressed, transmitted, [[routing|routed]] and received at the destination. Protocols exist for a variety of different types of communication services between computers.

TCP/IP has four [[abstraction layer]]s as defined in RFC 1122. This layer architecture is often compared with the seven-layer [[OSI Reference Modelmodel]]; using terms such as ''Internet reference model'', incorrectly, however, because it is descriptive while the OSI Referencereference Modelmodel was intended to be prescriptive, hence being a reference model.

The TCP/IP model and related protocols are maintained by the [[Internet Engineering Task Force]] (IETF).

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*Link layer: This layer defines the networking methods within the scope of the local network link on which hosts communicate without intervening routers. This layer describes the protocols used to describe the local network topology and the interfaces needed to affect transmission of Internet layer datagrams to next-neighbor hosts. (cf. the OSI data link layer).

The [[Internet Protocolprotocol Suitesuite]] and the layered [[protocol stack]] design were in use before the [[OSI model]] was established. Since then, the TCP/IP model has been compared with the OSI model in books and classrooms, which often results in confusion because the two models use different assumptions, including about the relative importance of strict layering.

==Layers in the TCP/IP model==

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The [[internet layer]] has the responsibility of sending packets across potentially multiple networks. [[Internetworking]] requires sending data from the source [[computer network|network]] to the destination network. This process is called [[routing]].<ref>[http://www.comsci.us/datacom/ippacket.html IP Packet Structure]</ref>

In the Internet Protocolprotocol Suitesuite, the Internet Protocol performs two basic functions:

* ''Host addressing and identification'': This is accomplished with a hierarchical addressing system (see [[IP address]]).

* ''Packet routing'': This is the basic task of sending packets of data (datagrams) from source to destination by sending them to the next network node (router) closer to the final destination.