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IP(v4) The Rules

1. Every node/host connected to the Internet needs an IP Address. An IP Address consists of 4 whole numbers separated by a full stop, each being able of storing a range from 0 to 255, e.g. This layout is known as dotted decimal notation.

2. All communication is carried out using packets of information.

3. Each packet consists of a header and a body.

4. The packet header contains the source and destination IP Addresses

At the network layer, packets may be lost and not received; they also may arrive in the wrong order. Therefore, IP

The layer at which IP works is known as providing a "best effort delivery" service for packets. Therefore, packets may not arrive or may arrive in the wrong order. It is the responsibility of the layer above to provide "reliable" data communications, by re-transmission of lost packets and the re-ordering of packets that have arrived in the wrong order.

TCP works at the Transport layer, with its main duty being to make sure that communication takes place accurately. The transport layer will also provide a transparent interface for the layer above, the Application layer. By doing this, the process of developing network applications does not require programmers to be concerned about Transport layer issues.

TCP uses a technique called Positive Acknowledgment with Retransmission (PAR) to guarantee the reliability of packet transfer.

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