Re: Updated IID length text

Brian E Carpenter <brian.e.carpenter@gmail.com> Fri, 20 January 2017 02:41 UTC

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Subject: Re: Updated IID length text
To: David Farmer <farmer@umn.edu>
References: <148406593094.22166.2894840062954191477.idtracker@ietfa.amsl.com> <m2fukqbbwv.wl-randy@psg.com> <F6953234-3F85-4E28-9861-433ADD01A490@gmail.com> <m2wpdzhncn.wl-randy@psg.com> <82245ef2-cd34-9bd6-c04e-f262e285f983@gmail.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> <CAN-Dau1cAQKPmU-S29_wTSYO+PXqenCiMqWm=XBKYqOFr0poTA@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 15:40:55 +1300
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On 20/01/2017 14:47, David Farmer wrote:
> I liked the following in the previous version;
> 
>    Note that this value is an arbitrary choice and might be changed for
>    some future allocation of unicast address space.
> 
> What was the issue with it?

I've lost track of who said what, but there was a lot of griping
at the word 'arbitrary' and FUD about the 'might be changed.'
Lif is compromise...

    Brian

> 
> Thanks
> 
> On Wed, Jan 18, 2017 at 6:37 PM, Brian E Carpenter <
> brian.e.carpenter@gmail.com> wrote:
> 
>> OK, after all that discussion, here is a revised proposal. There is
>> nothing new here at all, IMHO; just clarification:
>>
>> OLD
>>    For all unicast addresses, except those that start with the binary
>>    value 000, Interface IDs are required to be 64 bits long.  Background
>>    on the 64 bit boundary in IPv6 addresses can be found in [RFC7421].
>>
>> NEW
>>    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, consistent use of Stateless Address Autoconfiguration
>>    (SLAAC)[RFC4862] requires that all interfaces on a link use the same
>> length
>>    of Interface ID. To guarantee interoperability of SLAAC, a fixed length
>> of
>>    Interface ID is necessary. For all currently allocated unicast
>> addresses,
>>    except those that start with the binary value 000, Interface IDs are
>>    required to be 64 bits long.  Background on the 64 bit boundary in IPv6
>>    addresses can be found in [RFC7421].
>>
>> Regards
>>    Brian
>>
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> 
> 
>