As described in RCF 791, there are three primary functions that the IP is designed to provide for networks. In section 1.2 of that specification, the scope of the protocol is explicitly limited to just the functions necessary to deliver a package of bits (an internet datagram) from a source to a destination over an interconnected system of networks.
You'll note that nowhere in this definition do the authors mention reliability, ordered delivery, or connection negotiation. This is very much an intentional omission on their part. As they stated in IEN 2, attempting to account for those functions with a network layer protocol will be violating the boundaries of the OSI network stack. And that's not simply speculation on my ...
