Michael,
I hadn't fully understood your comment on Friday. I do now, thanks.
Thomas

On Fri, Apr 22, 2016 at 7:06 PM, Prof. Diego Dujovne <
[email protected]> wrote:

> Michael,
>              Thank you!
>
>                           Diego
>
> 2016-04-22 14:02 GMT-03:00 Michael Richardson <[email protected]>:
>
>>
>> Pascal Thubert (pthubert) <[email protected]> wrote:
>>     > * Michael: Layer3 (meaning and above NOTNT) Only one per
>>     > packet. Payload is
>>     > already 1000 bytes layer 2 on every packet. not reduce layer 2
>> security,
>>     > repeat it on every fragment. Cannot eliminate in that layer.
>>
>> To clarify.
>>
>> If one has a 1000 byte CoAP packet, split up into 8 layer-2 fragments, the
>> layer-3 security will be applied once.  So the overhead of the layer-3
>> security may be much lower *on average* than the layer-2 security.
>>
>> The layer-2 security will get repeated on each of the 8 layer-2 fragments.
>> It would be wonderful if that layer-3 security could be used to eliminate
>> the
>> overhead of the layer-2 security, but that would open up our LLNs to being
>> used to carry bogus traffic.
>>
>> (The OSCOAP layer-3 security can not be checked on a hop-by-hop basis
>> without
>> sharing the session key everywhere)
>>
>> Obviously, if one has an 80-byte CoAP packet, this calculation is not the
>> same.
>>
>> --
>> Michael Richardson <[email protected]>, Sandelman Software Works
>>  -= IPv6 IoT consulting =-
>>
>>
>>
>>
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>>
>
>
> --
> DIEGO DUJOVNE
> Académico Escuela de Ingeniería en Informática y Telecomunicaciones
> Facultad de Ingeniería UDP
> www.ingenieria.udp.cl
> (56 2) 676 8125
>
> _______________________________________________
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> https://www.ietf.org/mailman/listinfo/6tisch
>
>


-- 
_______________________________________

Thomas Watteyne, PhD
Research Scientist & Innovator, Inria
Sr Networking Design Eng, Linear Tech
Founder & co-lead, UC Berkeley OpenWSN
Co-chair, IETF 6TiSCH

www.thomaswatteyne.com
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