The Datagram Delivery Protocol (DDP) is an Apple protocol. It is located on the network layer and enables the addressing
and switching of datagrams in an AppleTalk network. The DDP protocol supports transmission without guaranteed datagram delivery. The Datagram Delivery Protocol (DDP) is comparable to the IPprotocol and forms the basis for the transport protocols above it in the AppleTalk protocol stack: AppleTalk Echo Protocol (AEP), AppleTalk Transaction Protocol (ATP), AppleTalk Update-based Routing Protocol (AURP) and Name Binding Protocol (NBP).