Re: Updated IID length text

Brian E Carpenter <brian.e.carpenter@gmail.com> Fri, 20 January 2017 06:11 UTC

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Subject: Re: Updated IID length text
To: Lorenzo Colitti <lorenzo@google.com>
References: <148406593094.22166.2894840062954191477.idtracker@ietfa.amsl.com> <m2d1frhjfn.wl-randy@psg.com> <18e6e13c-e605-48ff-4906-2d5531624d64@gmail.com> <CAKD1Yr1cvZ8Y3+bHeML=Xwqr+YgDspZGnZi=jqQj4qe2kMc4zw@mail.gmail.com> <m2lguffnco.wl-randy@psg.com> <CAKD1Yr1TrTiPRdyutobmb_77XJ7guNzLrg=H_p7qi4BfQ8V=GA@mail.gmail.com> <m2d1frfm6m.wl-randy@psg.com> <CAKD1Yr2Njjd8_Mr+6TRFF6C5pdcX4yFgpFVyEkykDuytu2B8mg@mail.gmail.com> <2A5073777007277764473D78@PSB> <4596c3d4-a337-f08e-7909-f14270b7085f@gmail.com> <CAN-Dau06R3iYRpYLADhvHox4C9qdsJCuxFsJapRhOQcWT4qk_g@mail.gmail.com> <CAO42Z2weZcoHiBzN94QAQ9WGhWR16PmMMFNg=5YLmr_dhPjjpA@mail.gmail.com> <fcc7f136-b5da-527e-b495-5a2d7f7a3ce8@gmail.com> <55bb8bdbfbf4439da0aa702e5bc03e2c@XCH15-06-11.nw.nos.boeing.com> <bb79ce41f2cc465dab0a7f26466be26f@XCH15-06-11.nw.nos.boeing.com> <ed9fe2df-0dce-0ddc-bdee-561217d089bb@gmail.com> <e8b4d426-55b4-bd2e-ea4f-f8e56e831d44@gmail.com> <CAKD1Yr1no52iZ2NwfKse6tXi0QpOP+Qe-vU68M4g1ZhmsgQadg@mail.gmail.com>
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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Date: Fri, 20 Jan 2017 19:11:16 +1300
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On 20/01/2017 17:38, Lorenzo Colitti wrote:
> On Fri, Jan 20, 2017 at 4:41 AM, Brian E Carpenter <
> brian.e.carpenter@gmail.com> wrote:
> 
>> However, correct use of Stateless Address Autoconfiguration
>>    (SLAAC)[RFC4862] requires all interfaces on a link to use the same
>> length
>>    of Interface ID. Furthermore, to guarantee robust interoperability of
>> SLAAC,
>>    a consistent length of Interface ID is desirable. For this reason,
> 
> 
> I object to the text "for this reason", because SLAAC is not the only
> reason. There are many reasons, many of which are written in 7421, and two
> sentences in this paragraph are not sufficient to describe them. I propose
> the following alternative, which I believe to be normatively identical:
> 
>    IPv6 routing is based on prefixes of any valid length up to 128 [BCP198].
>    For example, [RFC6164] standardises 127 bit prefixes on point-to-point
>    links. However, the Interface ID of all currently allocated unicast addresses,
>    except those that start with the binary value 000, is required to be 64 bits
>    long. The rationale for the 64 bit boundary in IPv6 addresses can be found in
>    [RFC7421].

Yes, I'll buy 'however'.

   Brian