Re: [PATCH net-next V9] net: Variable SLAAC: SLAAC with prefixes of arbitrary length in PIO

["Maciej Żenczykowski" <maze@google.com>]

On Sun, Aug 11, 2024 at 10:16 AM Dmytro Shytyi <dmytro@shytyi.net> wrote:
>
> Hello Erik Kline,
>
>   You stated that, VSLAAC should not be accepted in large part because
>   it enables a race to the bottom problem for which there is no solution
>   in sight.
>
>   We would like to hear more on this subject:
>   1. Would you be kind to send us the explanation of
>   "race to the bottom problem" in IP context with examples.
>
>   2. Would you be kind to explain howt he possibility of configuration of
>   prefix lengths longer that 64, enables "race to the bottom problem"?

This has been discussed multiple times in IETF (and not only), I don't
think this is the right spot for this sort of discussion.

>
>   We look forward for your reply.

NAK: Maciej Żenczykowski <maze@google.com>
>
> Best regards,
> Dmytro SHYTYI, et Al.
>
>  >
>  >
>  >
>  > ---- On Mon, 12 Jul 2021 19:51:19 +0200 Erik Kline ek@google.com> wrote ---
>  >
>  > VSLAAC is indeed quite contentious in the IETF, in large part because
>  > it enables a race to the bottom problem for which there is no solution
>  > in sight.
>  >
>  > I don't think this should be accepted.  It's not in the same category
>  > of some other Y/N/M things where there are issues of kernel size,
>  > absence of some underlying physical support or not, etc.
>  >
>  >
>  > On Mon, Jul 12, 2021 at 9:42 AM Dmytro Shytyi dmytro@shytyi.net> wrote:
>  > >
>  > > Hello Jakub, Maciej, Yoshfuji and others,
>  > >
>  > > After discussion with co-authors about this particular point "Internet Draft/RFC" we think the following:
>  > > Indeed RFC status shows large agreement among IETF members. And that is the best indicator of a maturity level.
>  > > And that is the best to implement the feature in a stable mainline kernel.
>  > >
>  > > At this time VSLAAC is an individual proposal Internet Draft reflecting the opinion of all authors.
>  > > It is not adopted by any IETF working group. At the same time we consider submission to 3GPP.
>  > >
>  > > The features in the kernel have optionally "Y/N/M" and status "EXPERIMENTAL/STABLE".
>  > > One possibility could be VSLAAC as "N", "EXPERIMENTAL" on the linux-next branch.
>  > >
>  > > Could you consider this possibility more?
>  > >
>  > > If you doubt VSLAAC introducing non-64 bits IID lengths, then one might wonder whether linux supports IIDs of _arbitrary length_,
>  > > as specified in the RFC 7217 with maturity level "Standards Track"?
>  > >
>  > > Best regards,
>  > > Dmytro Shytyi et al.
>  > >
>  > > ---- On Mon, 12 Jul 2021 15:39:27 +0200 Dmytro Shytyi dmytro@shytyi.net> wrote ----
>  > >
>  > >  > Hello Maciej,
>  > >  >
>  > >  >
>  > >  > ---- On Sat, 19 Dec 2020 03:40:50 +0100 Maciej Żenczykowski maze@google.com> wrote ----
>  > >  >
>  > >  >  > On Fri, Dec 18, 2020 at 6:03 PM Jakub Kicinski kuba@kernel.org> wrote:
>  > >  >  > >
>  > >  >  > > It'd be great if someone more familiar with our IPv6 code could take a
>  > >  >  > > look. Adding some folks to the CC.
>  > >  >  > >
>  > >  >  > > On Wed, 16 Dec 2020 23:01:29 +0100 Dmytro Shytyi wrote:
>  > >  >  > > > Variable SLAAC [Can be activated via sysctl]:
>  > >  >  > > > SLAAC with prefixes of arbitrary length in PIO (randomly
>  > >  >  > > > generated hostID or stable privacy + privacy extensions).
>  > >  >  > > > The main problem is that SLAAC RA or PD allocates a /64 by the Wireless
>  > >  >  > > > carrier 4G, 5G to a mobile hotspot, however segmentation of the /64 via
>  > >  >  > > > SLAAC is required so that downstream interfaces can be further subnetted.
>  > >  >  > > > Example: uCPE device (4G + WI-FI enabled) receives /64 via Wireless, and
>  > >  >  > > > assigns /72 to VNF-Firewall, /72 to WIFI, /72 to Load-Balancer
>  > >  >  > > > and /72 to wired connected devices.
>  > >  >  > > > IETF document that defines problem statement:
>  > >  >  > > > draft-mishra-v6ops-variable-slaac-problem-stmt
>  > >  >  > > > IETF document that specifies variable slaac:
>  > >  >  > > > draft-mishra-6man-variable-slaac
>  > >  >  > > >
>  > >  >  > > > Signed-off-by: Dmytro Shytyi dmytro@shytyi.net>
>  > >  >  > >
>  > >  >
>  > >  >  > IMHO acceptance of this should *definitely* wait for the RFC to be
>  > >  >  > accepted/published/standardized (whatever is the right term).
>  > >  >
>  > >  > [Dmytro]:
>  > >  > There is an implementation of Variable SLAAC in the OpenBSD Operating System.
>  > >  >
>  > >  >  > I'm not at all convinced that will happen - this still seems like a
>  > >  >  > very fresh *draft* of an rfc,
>  > >  >  > and I'm *sure* it will be argued about.
>  > >  >
>  > >  >  [Dmytro]
>  > >  > By default, VSLAAC is disabled, so there are _*no*_ impact on network behavior by default.
>  > >  >
>  > >  >  > This sort of functionality will not be particularly useful without
>  > >  >  > widespread industry
>  > >  >
>  > >  > [Dmytro]:
>  > >  > There are use-cases that can profit from radvd-like software and VSLAAC directly.
>  > >  >
>  > >  >  > adoption across *all* major operating systems (Windows, Mac/iOS,
>  > >  >  > Linux/Android, FreeBSD, etc.)
>  > >  >
>  > >  > [Dmytro]:
>  > >  > It should be considered to provide users an _*opportunity*_ to get the required feature.
>  > >  > Solution (as an option) present in linux is better, than _no solution_ in linux.
>  > >  >
>  > >  >  > An implementation that is incompatible with the published RFC will
>  > >  >  > hurt us more then help us.
>  > >  >
>  > >  >  [Dmytro]:
>  > >  > Compatible implementation follows the recent version of document: https://datatracker.ietf.org/doc/draft-mishra-6man-variable-slaac/ The sysctl usage described in the document is used in the implementation to activate/deactivate VSLAAC. By default it is disabled, so there is _*no*_ impact on network behavior by default.
>  > >  >
>  > >  >  > Maciej Żenczykowski, Kernel Networking Developer @ Google
>  > >  >  >
>  > >  >
>  > >  > Take care,
>  > >  > Dmytro.
>  > >  >
>  > >
>  >
>  >
>  >
>

--
Maciej Żenczykowski, Kernel Networking Developer @ Google