Subject: [6lo] Future extensibility for the DAR/DAC

From: "Pascal Thubert (pthubert)" <[email-masked]>
Date: Wed, 25 Apr 2018 09:53:47 +0000

Dear all :

As it stands in RFC 6775 update, the fact that the DAR and DAC messages are in fact extended DAR and DAC is indicated by the ICMP code of 1.
In that case, the size of the message determines the size of the ROVR field that carries the ex-EUI-64 field, now ROVR field, which can be extended up to 256 bits for use as a cryptographic proof of ownership in AP-ND.
Keeping it that way may be problematic if we want to add future extensions (e.g., options at the end of the message) and stay backward compatible.
An alternate way is to block 2 bits of the ICMP code and use the values 0, 1, 2, and 3 denoting a ROVR size of 64, 128, 192 and 256 bits respectively.

Should we / shouldn't we do that?

Pascal