Saturday, December 22, 2012

Internet Protocol (IP)

The Internet Protocol is the key tool used today to build scalable, heterogeneous internetworks. It was originally known as the Kahn-Cerf protocol after its inventors. 

The IP service model can be thought of as having two parts: 
1) An addressing scheme, which provides a way to identify all hosts in the internetwork.
2) A datagram (connectionless) modelofdatadelivery.

This service model is sometimes called best effort because, although IP makes every effort to deliver datagrams, it makes no guarantees. If something goes wrong and the packet gets lost, corrupted, misdelivered, or in any way fails to reach its intended destination, the network does nothing—it made its best effort, and that is all it has to do. It does not make any attempt to recover from the failure. This is sometimes called an unreliable service. Best-effort delivery does not just mean that packets can get lost. Sometimes they can get delivered out of order, and sometimes the same packet can get delivered more than once. The higher-level protocols or applications that run above IP need to be aware of all these possible failure modes.

Computer Networks: Peterson and Davie

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