4. Updating RFC 4861

This document updates IPv6 Neighbor Discovery and related 6LoWPAN/RPL specifications to allow a node to register an IPv6 prefix with neighbor routers. Key protocol details are preserved below from the RFC text.

4.  Updating RFC 4861

   [RFC4861] expects that the NS/NA exchange is for a unicast address,
   which is indicated in the Target Address field of the ND message.
   Section 5.5 of [RFC8505] extends [RFC4861] to signal the Registered
   Address in the Target Address field.

   This specification updates [RFC4861] by allowing a 6LN to advertise a
   prefix in the Target Address field when the NS or NA message is used
   for a registration, per Section 5.5 of [RFC8505].  In that case, the
   prefix length MUST be indicated in the EARO of the NS message,
   overloading the field that is used in the NA response for the Status.

   If the 6LN owns at least one IPv6 address that is derived from the
   registered prefix with a non-zero interface ID, then it MUST indicate
   one of these addresses in full in the Target Address field of the
   NS(EARO) message.  Else, it MUST indicate the prefix padded with
   zeros in the Target Address field.