Re: [IPv6] Second Working Group Last Call for <draft-ietf-6man-rfc6724-update>

[Tim Chown <[e-mail]>]

Hi,

On 15 Apr 2024, at 16:23, Kyle Rose <krose=[e-mail]> wrote:

This:

Well, if we agree to the MUST (with the usual caveat of any IETF ‘MUST’ for an implementor :) then we need to review the rest of the text, which would include the default policy table, and the section David contributed.  I think you’re right, that proposed default table as is would have to change.

is part of the reason I'm uneasy with a blanket MUST for known-local.

I would be 100% fine with normative language that essentially says "IF (via some future proposed mechanism) you learn known-local prefixes and insert them into your policy table, THEN you may prefer v4/v4 to not-known-local ULA/ULA; but if you do not, then you must prefer ULA/ULA to v4/v4." My reasoning is that currently there is no specified mechanism for learning and managing known-local ULA prefixes; and it will be a long time before the long tail of stacks respond to yet-to-be-specified network signals for managing those prefixes; yet, in the absence of such an ecosystem I want ULA/ULA to take precedence over v4/v4, because under 6724 they are currently mostly useless, and I want ULA to be useful now¹, not in some distant future.

Well, it will take time for the default policy table to be changed on various platforms as well.

If your policy table is configurable, and you can manage your network devices, then you can of course configure it today for the policy you want.

We also now have two different protagonists for change here, with some overlap.  Those who want to see ULA-ULA elevated over IPv4-IPv4, but also those who want known-local ULAs to be used ahead of GUAs, which is something we didn’t originally include in even the WG-adopted -00, but it’s evolved over the last few weeks as quite a nice stretch goal from the document.

Tim