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3. Updating RFC 8928

3. Updating RFC 8928​

[RFC8928] incorrectly refers to the Extended Address Registration Option (EARO) as the Enhanced Address Registration Option. This specification corrects that terminology throughout the document.

In [RFC8928], the C-Flag is specified in the EARO flags field at bit position 3, but [RFC8928] does not register its position with IANA. Later, [RFC9685] defined the P-Field in bits 2 and 3 of the EARO flags field and obtained IANA registration, causing an overlap with [RFC8928].

To resolve the conflict, this specification updates [RFC8928] by repositioning the C-Flag to bit 1 of the EARO flags field.

Figure 1 replaces Figure 1 in [RFC8928] when an EARO is used in an NS message.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |     Type      |     Length    |F|Prefix Length|    Opaque     |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |r|C| P | I |R|T|     TID       |     Registration Lifetime     |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                                                               |
 ...            Registration Ownership Verifier (ROVR)           ...
  |                  (64, 128, 192, or 256 bits)                  |
  |                                                               |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 1: Extended Address Registration Option (EARO) Format for Use in NS Messages

Figure 2 replaces Figure 1 in [RFC8928] when an EARO is used in an NA message. The difference between the two formats is in the use of bits 16 to 23.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |     Type      |     Length    | r |  Status   |    Opaque     |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |r|C| P | I |R|T|     TID       |     Registration Lifetime     |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                                                               |
 ...            Registration Ownership Verifier (ROVR)           ...
  |                  (64, 128, 192, or 256 bits)                  |
  |                                                               |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 2: Extended Address Registration Option (EARO) Format for Use in NA Messages

Fields of interest for this specification:

  • Type: 33.
  • Length: Defined in [RFC8505].
  • F: Defined in [RFC9926].
  • Prefix Length: Defined in [RFC9926].
  • Status: A 6-bit unsigned integer used only in NA(EARO) response messages to indicate registration status. It is defined in [RFC8505] and resized by [RFC9010]. It MUST be set to 0 in NS(EARO) messages unless the registration is for a prefix, in which case the F-Flag is set and the prefix length is provided.
  • Opaque: Defined in [RFC8505].
  • r (reserved): Reserved fields MUST be set to zero by the sender and MUST be ignored by the receiver.
  • C: A 1-bit flag moved from its position in Figure 1 of [RFC8928]. It is set to indicate that the ROVR field contains a Crypto-ID and that the 6LN MAY be challenged for ownership.
  • P: A 2-bit field for Registered Address Type Indicator (RATInd).
  • I, R, T, TID, Registration Lifetime, and ROVR: Defined in [RFC8505]. When the C-Flag is set, the ROVR field contains a Crypto-ID [RFC8928].
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