Boeing Research & Technology IP packets (both IPv4 and IPv6) are understood to contain a unit of data which becomes the retransmission unit in case of loss. Upper layer protocols such as the Transmission Control Protocol (TCP) prepare data units known as "segments", with traditional arrangements including a single segment per packet. This document presents a new construct known as the "IP Parcel" which permits a single packet to carry multiple segments. The parcel can be opened at middleboxes on the path with the included segments broken out into individual packets, then rejoined into one or more repackaged parcels to be forwarded further toward the final destination. Reordering of segments within parcels is unimportant; what matters is that the number of parcels delivered to the final destination should be kept to a minimum, and that loss or receipt of individual segments (and not parcel size) determines the retransmission unit.