This document specifies the Compressed IPFIX protocol that serves for transmitting smart metering data in 6LoWPAN networks [RFC4944]. Compressed IPFIX is derived from IPFIX [RFC5101] and adopted to the needs of constrained networks. This documents specifies how the Compressed IPFIX Data and Template Records are transmitted in 6LoWPAN networks and how Compressed IPFIX data can be converted into uncompressed IPFIX data in a proxy device.