Internet Protocol

The Internet Protocol ( IP ) is a protocol used for the routing of the packages on the networks. Its role is to select the best way through the networks for the routing of the packages. IP is a protocol of level 3 of OSI model (level 2 of the model TCP/IP) allowing a single service of addressing for the whole of the connected terminals.

Operation

At the time of a communication between two stations, the data coming from the protocols of the roadbases are encapsulated in packages with their passage on the level of the layer network by protocol IP. These packages are then transmitted to the data link layer (level 2 of OSI model) in order to be encapsulated there in screens.

When two terminals communicate between them via this protocol, no circuit for the transfer of the data is established in advance: it is said that the protocol is not directed connection . By opposition, for a system like the traditional phone network, the way by which will pass the voice (or the data) is established at the beginning of connection: one speaks about protocol directed connection

Services delivered by protocol IP

Protocol IP as well as possible ensures the routing ( best-effort delivery ) of the packages, not-directed connection. IP is not worried contents of the packages, but research a way to lead them to destination.

Reliability

IP is regarded as being a not-reliable protocol . That does not mean that it correctly does not send the data on the network, that means that it does not offer any guarantee for the packages sent for any the following points:

  • corruption of data
  • order of arrival of the packages (a package has can be sent before a package B, but the package B can arrive before the package A)
  • loss or destruction of package
  • D-emission of the packages in the event of non-reception

In term of reliability, the only service offered by IP is to make sure that the headings of transmitted packages do not comprise errors thanks to the use of Somme of control (checksum). If the heading of a package includes/understands an error, its checksum will not be valid and the package will be destroyed without being transmitted. In the event of destruction of packages, no notification is sent to the shipper (still that a package ICMP can be sent).

To guarantee these points of reliability that IP does not offer, a protocol of higher level must be used.

The primary reason of this absence of management of reliability on level IP is the will to reduce the level of complexity of the routers and thus to enable them to have a greater speed. The intelligence is then off-set towards the points of ends of the network.

History of the versions

IP is the protocol most usually used today on Internet just like on the private networks. The most widespread version currently is version 4: IPv4.

The lack more and more shouting of addresses available on the public network involved the creation of a new version IPv6. IPv4 uses 32 bits of addresses (either approximately 4 billion combinations) while IPv6 uses 128 bits of addresses (or approximately 3.4× 1038 combinations). The adaptation and the passage to the IPv6 protocol are done gently, but one can think that the need growing for the number of addresses for countries like the China or the India will force to accelerate its adoption.

See too

Simple: Internet Protocol

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