Boeing Research & Technology IP packets (both IPv4 and IPv6) contain a single unit of upper layer protocol data which becomes the retransmission unit in case of loss. Upper layer protocols including the Transmission Control Protocol (TCP) and transports over the User Datagram Protocol (UDP) prepare data units known as "segments", with traditional arrangements including a single segment per IP packet. This document presents a new construct known as the "IP Parcel" which permits a single packet to carry multiple upper layer protocol segments, essentially creating a "packet-of-packets". IP parcels provide an essential building block for improved performance, efficiency and integrity while encouraging larger Maximum Transmission Units (MTUs) in the Internet.