Ericsson SSW Cisco This document looks at different data flows through LLN (Low-Power and Lossy Networks) where RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) is used to establish routing. The document enumerates the cases where RFC 6553, RFC 6554 and IPv6-in-IPv6 encapsulation is required. This analysis provides the basis on which to design efficient compression of these headers.