Re: IID length text

Behcet Sarikaya <sarikaya2012@gmail.com> Wed, 18 January 2017 17:21 UTC

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From: Behcet Sarikaya <sarikaya2012@gmail.com>
Date: Wed, 18 Jan 2017 11:21:12 -0600
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Subject: Re: IID length text
To: Fernando Gont <fgont@si6networks.com>
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Cc: Alexandre Petrescu <alexandru.petrescu@gmail.com>, 6man <ipv6@ietf.org>
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On Tue, Jan 17, 2017 at 4:08 PM, Fernando Gont <fgont@si6networks.com> wrote:
> On 01/17/2017 06:31 PM, Behcet Sarikaya wrote:
>> On Tue, Jan 17, 2017 at 2:55 PM, Fernando Gont <fgont@si6networks.com> wrote:
>>> Hello, Behcet,
>>>
>>> On 01/17/2017 02:39 PM, Behcet Sarikaya wrote:
>>>> On Mon, Jan 16, 2017 at 4:09 PM, Fernando Gont <fgont@si6networks.com> wrote:
>>>>> On 01/16/2017 06:22 PM, Behcet Sarikaya wrote:
>>>>>> On Mon, Jan 16, 2017 at 2:46 PM, Fernando Gont <fgont@si6networks.com> wrote:
>>>>>>> On 01/16/2017 05:42 PM, Behcet Sarikaya wrote:
>>>>>>>> On Mon, Jan 16, 2017 at 2:27 PM, Alexandre Petrescu
>>>>>>>> <alexandru.petrescu@gmail.com> wrote:
>>>>>>>>> Le 14/01/2017 à 20:49, Brian E Carpenter a écrit :
>>>>>>>>>>
>>> [....]
>>>>>>>
>>>>>>> What does a layer-2 EUI have to do with a layer-3 address?
>>>>>>
>>>>>> I don't know, you tell me :-)
>>>>>
>>>>> Answer: Nothing. The fact that we've been embedding layer-2 "addresses"
>>>>> into layer-3 addresses should not be taken as a reason for the two of
>>>>> them of having to do anything with each other. So, yes, the 64-bit IID
>>>>> length is, in reality, arbitrary. They could have been e.g. 32-bits or
>>>>> 48-bits (yes, multiples or 64 or 32 tend to be nicer)
>>>>>
>>>>
>>>> I don't think you know much about MAC addresses and its history.
>>>
>>> I don't know much about elephants, either. Whatever the history (which
>>> you imply I don't know), it is irrelevant, because it doesn't change the
>>> fact that you don't need to screw your layer-3 protocol with your
>>> layer-2 IDs/"addresses".
>>>
>>
>> Good luck then running SLAAC or ARP :-)
>
> SLAAC: Yes, mac addresses used to be embedded in the IID, That's an
> artifact of history, not a design principle. And we're heading towards
> replacing that with RFC7217 (which, for many implementations, is already
> the case) -- and has always been the case for, e.g., RFC4941.
>
> Neighbor Discovery: NS/NA messages employ link-layer address options,
> which essentially convey the link-layer address as an opaque value.
> That's used for learning the layer-2 address when sending a packet on a
> link, which is a totally different thing from exposing such layer-2
> address at layer-3.
>
> There's no reason or requirement that I communicate my layer-2 address
> in my layer-3 protocol when, e.g., I connect with a web server. That has
> been an artifact of history (which may have happened as such for
> multiple (possibly valid) reasons), but please don't confuse that with a
> design principle or some sort of law from nature.
>

My friend Fernando, here is a quote from RFC 4941:

Note that an IPv6 identifier does not
   necessarily have to be 64 bits in length, but the algorithm specified
   in this document is targeted towards 64-bit interface identifiers.

 I believe you will always need to send a packet on a link, even when
connecting with a web server.

I think you should read a basic telecom book such as from Jim Kurose.
Also I think you and I are in agreement. No worries.


Regards,

Behcet
> Thanks,
> --
> Fernando Gont
> SI6 Networks
> e-mail: fgont@si6networks.com
> PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
>
>
>
>