[[File:INWG-arch.png|thumb|350px|Figure 7. The Internet architecture as seen by the INWG]]
Early in 1972 the [[International NetworkingNetwork Working Group]] (INWG) was created to bring together the nascent network research community. One of the early tasks it accomplished was voting an international network transport protocol, which was approved in 1976.<ref name=":0">{{cite journal |doi=10.1109/MAHC.2011.9 |title=INWG and the Conception of the Internet: An Eyewitness Account |date=2011 |last1=McKenzie |first1=Alexander |journal=IEEE Annals of the History of Computing |volume=33 |pages=66–71 |s2cid=206443072 }}</ref> Remarkably, the selected option, as well as all the other candidates, had an architecture composed of three layers of increasing scope: data link (to handle different types of physical media), network (to handle different types of networks) and internetwork (to handle a network of networks), each layer with its own address space. When TCP/IP was introduced it ran at the internetwork layer on top of the [[Network Control Protocol (ARPANET)|Host-IMP Protocol]], when running over the ARPANET. But when [[Network Control Protocol (ARPANET)|NCP]] was shut down, TCP/IP took the network role and the internetwork layer was lost.<ref name="lostlayer">{{cite book |doi=10.1109/NOF.2011.6126673 |chapter=How in the Heck do you lose a layer!? |title=2011 International Conference on the Network of the Future |date=2011 |last1=Day |first1=John |pages=135–143 |isbn=978-1-4577-1607-2 |s2cid=15198377 }}</ref> This explains the need for autonomous systems and NAT today, to partition and reuse ranges of the IP address space to facilitate administration.
===1983: First opportunity to fix addressing missed===
