AfterBuilding on the [[NPLpacket networkswitching]] pioneeredconcepts proposed by [[packetDonald switchingDavies]], the first [[communication protocol]] on the [[ARPANET]] was a reliable packet delivery procedure to connect its hosts via the [[BBN Report 1822|1822 interface]].<ref name="J. Gillies, R. Cailliau">{{cite book|last1=Gillies|first1=J.|url=https://books.google.co.uk/books?id=pIH-JijUNS0C&lpg=PA25&ots=MKZj0F7pJN&pg=PA25#v=onepage&q&f=false|title=How the Web was Born: The Story of the World Wide Web| first1last2=J. Cailliau| last1=Gillies | first2=R.| last2=Cailliau | date=2000|publisher=[[Oxford University Press]]|ISBN=0192862073|pages=23-25}}</ref><ref thename=":2">{{cite [[ARPANET]]journal|last1=Roberts|first1=Dr. providedLawrence aG.|date=November reliable1978|title=The packetEvolution deliveryof procedurePacket toSwitching|url=http://www.ismlab.usf.edu/dcom/Ch10_Roberts_EvolutionPacketSwitching_IEEE_1978.pdf|journal=IEEE itsInvited connectedPaper|volume=|pages=|accessdate=September hosts10, via2017|quote=In itsnearly [[BBNall Reportrespects, 1822|1822Davies’ interface]]original proposal, developed in late 1965, was similar to the actual networks being built today.|via=}}</ref> A host computer simply arranged the data in the correct packet format, inserted the address of the destination host computer, and sent the message across the interface to its connected [[Interface Message Processor]] (IMP). Once the message was delivered to the destination host, an acknowledgment was delivered to the sending host. If the network could not deliver the message, the IMP would send an error message back to the sending host.
Meanwhile, the developers of [[CYCLADES]] and of [[ALOHAnet]] demonstrated that it was possible to build an effective computer network without providing reliable packet transmission. This lesson was later embraced by the designers of [[Ethernet]].
