1. Introduction

1. Introduction

Address-Protected Neighbor Discovery for Low-Power and Lossy Networks (AP-ND) [RFC8928] defined the C-Flag in the Extended Address Registration Option (EARO). The flag indicates that the Registration Ownership Verifier (ROVR) field contains a Crypto-ID and that the 6LoWPAN Node (6LN) may be challenged for ownership of the registered address.

[RFC8928] originally placed the C-Flag at bit position 3 in the EARO. Later, [RFC9685] defined the P-Field in bits 2 and 3 of the EARO flags field and registered that assignment with IANA, causing an overlap with the C-Flag location shown in [RFC8928].

This specification updates [RFC8928] by moving the C-Flag to bit 1 of the EARO flags field, preventing that conflict.