Siva,
The Internet Protocol was developed in order to be able to route packets from one destination to another. The various options and flags the protocol supports do not assure the packet will be delivered to its destination.
It would be a good idea to study the OSI model and then IP, followed by TCP in order for you to fully understand why this structure was created.
Since IP works on layer 3 and TCP on layer 4, 'if' IP could guarantee the delivery of a packet, then most of TCP's options would be useless, and what if you wanted to support some other type of data transmission which didn't require you to guarantee the delivery of packets; (e.g dns or tftp) Then you would be stuck with the overhead IP would produce because it sits on a lower layer than the above protocols and would add its unwanted overhead to all type of data transmissions.
Hope that helps.
Cheers,
