PARC Universal Packet

The PARC Universal Packet (PUP or PuP, although the original documents usually use Pup) was one of the two earliest internetworking protocol suites; it was created by researchers at Xerox PARC in the mid-1970s. (Technically, the name "PUP" only refers to the internetwork-level protocol, but it is also applied to the whole protocol suite.) The entire suite provided routing and packet delivery, as well as higher level functions such as a reliable byte stream, along with numerous applications.