Re: IID length text

[Fernando Gont <[e-mail]>]

On 01/17/2017 06:31 PM, Behcet Sarikaya wrote:
> On Tue, Jan 17, 2017 at 2:55 PM, Fernando Gont <[e-mail]> wrote:
>> Hello, Behcet,
>>
>> On 01/17/2017 02:39 PM, Behcet Sarikaya wrote:
>>> On Mon, Jan 16, 2017 at 4:09 PM, Fernando Gont <[e-mail]> wrote:
>>>> On 01/16/2017 06:22 PM, Behcet Sarikaya wrote:
>>>>> On Mon, Jan 16, 2017 at 2:46 PM, Fernando Gont <[e-mail]> wrote:
>>>>>> On 01/16/2017 05:42 PM, Behcet Sarikaya wrote:
>>>>>>> On Mon, Jan 16, 2017 at 2:27 PM, Alexandre Petrescu
>>>>>>> <[e-mail]> 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.

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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