Internet Protocol (IP) as it is commonly known, was developed by Bob Kahn and Vinton Cerf, and is a protocol operating at layer 3 (network layer) of the OSI model. The primary function of the IP is to transfer datagrams from source to destination and provide a network transport service. As noted in the preceding section, IP as defined in the TCP/IP model operates in a connectionless mode, and hence is sometimes referred to as Send and Pray protocol, as there is no acknowledgement/guarantee that the IP datagrams sent by the source have been received by the destination. This function is left to the upper layers of the protocol stack.
Figure 5 shows the structure and fields of an IPv4 header. The IPv4 header is defined ...
