Re: Objection to draft-ietf-6man-rfc4291bis-07.txt - /63 and /65 RAs on linux

Alexandre Petrescu <alexandre.petrescu@gmail.com> Thu, 02 March 2017 12:44 UTC

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Subject: Re: Objection to draft-ietf-6man-rfc4291bis-07.txt - /63 and /65 RAs on linux
To: Mikael Abrahamsson <swmike@swm.pp.se>
References: <20170223134026.GI5069@gir.theapt.org> <CAL9jLaYO=uYgVfSZ0SoSe0SujJ1xgwEKE8WLzo_keJHywgXTtg@mail.gmail.com> <CAN-Dau1vJV5O_Ythp6THkAu4-YZXV82Upny1V+ybbjCVZQQX=A@mail.gmail.com> <27cce319-18ac-5c0e-3497-af92344f0062@gmail.com> <de4988be-6031-08d9-84ce-21c3fa4f9bc9@gmail.com> <98401ef7-cf41-b4a0-4d11-a7d840181bd0@gmail.com> <1047f5fc-ae40-be52-6bab-27f31fe5e045@gmail.com> <9a94feac-8d59-b153-d41c-04fc371e4db4@gmail.com> <CAO42Z2z7v4gDk91b6Of-1sczV88m3B9kzn0MeJU_VBJ416k6Ww@mail.gmail.com> <ae35b45a-0398-840f-fc0d-1f64dd2fcc58@gmail.com> <37851ee3-03be-8bee-6190-f4d28df86305@gmail.com> <alpine.DEB.2.02.1703012051590.30226@uplift.swm.pp.se> <b5784622-c24e-a531-4e68-249b03701941@gmail.com> <CAAedzxrSTFe0GgYuvtXPNE=R_ZCXotxL7HbKdj5A4-869rncmw@mail.gmail.com> <ba025be6-709d-87b4-f388-d6f143408277@gmail.com> <alpine.DEB.2.02.1703021029010.30226@uplift.swm.pp.se> <4e17a9f4-6daf-787f-0321-3327fe601d70@gmail.com> <alpine.DEB.2.02.1703021319450.30226@uplift.swm.pp.se>
From: Alexandre Petrescu <alexandre.petrescu@gmail.com>
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Date: Thu, 2 Mar 2017 13:44:19 +0100
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Le 02/03/2017 à 13:20, Mikael Abrahamsson a écrit :
> On Thu, 2 Mar 2017, Alexandre Petrescu wrote:
>
>> How about the /63 case?  Do you think it is normal that linux
>> kernel does not configure an IP address on Ethernet when receiving
>> a plen==63?
>
> As far as I am aware, the only documents we have regarding
> autoconfigration of adresses on ethernet says to only do this on plen
> == 64. Thus it shouldn't be done on any other plen.

Mikael,

I explained separately something I think makes sense, but here it is
briefly anyways.

IPv6-over-Ethernet RFC2464 says a certain plen must be 64, but it's not
clear whether that plen is the plen of the prefix in RA, or the plen of
the LL address.

If the plen that RFC refers to is that of the LL address (not that of
the plen of the prefix in the RA) then linux shouldnt reject prefixes in
RA with plen==65.

Besides, no spec stops somebody from forming a /64 out of a /63 received
in RA plus a 0.  Or somehow else.

Anyways, you seem to be two thinking and reading specs otherwise than I
do, so I may not insist...

Alex

>