[IPv6]Re: rfc8504bis

[Tom Herbert <[e-mail]>]

On Tue, Jul 21, 2026 at 7:04 AM Tim Chown <Tim.Chown=
[e-mail]> wrote:

> So “be conservative in what you do, be liberal in what you discard from
> others”? 😉
>

That seems to be reality on the Internet  with regards to extension headers.

Tom


> On 21/07/2026, 15:55, "Tom Herbert" <tom=[e-mail]>
> wrote:
>
>
>
> On Tue, Jul 21, 2026 at 12:41 AM Bonica, Ron <ronald.bonica=
> [e-mail]> wrote:
>
> Tom,
>
> To the contrary, I think the draft should say:
>
> "A host MAY discard any incoming packet, according to its local policy".
>
>
> Ron,
>
> Then why not just say "Any node MAY discard any incoming packet, according
> to its local policy"? That would immediately bring all hosts and routers on
> the Internet into protocol compliance :-)
>
>
> All rules subsumed by that rule should be deleted because they are
> redundant.
>
>
> Yep, problem solved!
>
> Tom
>
>
>
>
>      Ron
> ------------------------------
> *From:* Tom Herbert <tom=[e-mail]>
> *Sent:* Tuesday, July 21, 2026 2:52 AM
> *To:* Bonica, Ron <[e-mail]>
> *Cc:* 6man <[e-mail]>
> *Subject:* Re: [IPv6]rfc8504bis
>
>
>
> On Mon, Jul 20, 2026, 8:41 AM Bonica, Ron <ronald.bonica=
> [e-mail]> wrote:
>
> Folks,
>
> RFC8504bis says:
>
> "A host MAY disallow unknown options in destination options or hop-by-hop
> options. This SHOULD be configurable where the default is to accept unknown
> options and process them per [RFC8200]. If a packet with unknown options is
> received and the host is configured to disallow them, then the packet
> SHOULD be silently discarded."
>
> At first glance, this appears to be a violation of 8200. However, this
> rule applies to hosts only and a host can discard any packets that violate
> its policy.
>
> I recommend replacing the word "disallow" with "discard" amplifying the
> fact that this rule applies to host only, and not routers.
>
>
> Hi Ron,
>
> I don't see why this change is necessary. It's clear from the requirement
> and the section title that the requirement and the others in the section
> are only applicable to hosts.
>
> Of course, in the real world routers do drop various packets with
> extension headers at their leisure which directly violates RFC8200.
> However, I don't think router vendors would bother to twist RFC8504 to
> somehow legitimize that.
>
> Tom
>
>
>
>    Ron
>
>
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