Pup is the name of an internet packet format (PARC Universal Packet), a hierarchy of protocols, and a style of internetwork communication. The fundamental abstraction is an end-to-end media-in dependent internetwork datagram. Higher levels of functionality are achieved by end-to-end protocols that are strictly a matter of agreement among the communicating end processes. This report explores important design issues, sets forth principles that have guided the Pup design, discusses the present implementation in moderate detail, and summarizes experience with an operational internetwork. This work serves as the basis for a functioning internetwork system that provides service to about 1000 computers, on 25 networks of 5 different types, using 20 internetwork gateways.

The Bay Area Packet Radio Network has been integrated into an existing architecture for network interconnection: it can be used to provide radio communications for directly connected hosts, or as an alternative packet transport mechanism to carry traffic between two local networks. The radio link is operational, and can support regular internetwork communications at rates ranging from 12 to 20 kilobits/second, with the current Packet Radio equipment.