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

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Message-ID: <CAAedzxr75CQTPCxf4uq0CcpiOpxQ_rS3-GQRxX=5ApPojSf2wQ@mail.gmail.com>
Date:   Mon, 12 Jul 2021 10:51:19 -0700
From:   Erik Kline <ek@...gle.com>
To:     Dmytro Shytyi <dmytro@...tyi.net>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        Maciej Żenczykowski <maze@...gle.com>,
        yoshfuji <yoshfuji@...ux-ipv6.org>,
        liuhangbin <liuhangbin@...il.com>, davem <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>, David Ahern <dsahern@...il.com>,
        Joel Scherpelz <jscherpelz@...gle.com>
Subject: Re: [PATCH net-next V9] net: Variable SLAAC: SLAAC with prefixes of
 arbitrary length in PIO

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@...tyi.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@...tyi.net> wrote ----
>
>  > Hello Maciej,
>  >
>  >
>  > ---- On Sat, 19 Dec 2020 03:40:50 +0100 Maciej Żenczykowski <maze@...gle.com> wrote ----
>  >
>  >  > On Fri, Dec 18, 2020 at 6:03 PM Jakub Kicinski <kuba@...nel.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@...tyi.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.
>  >
>