Re: [Roll] WGLC for draft-thubert-6man-flow-label-for-rpl-03

Philip Levis <pal@cs.stanford.edu> Sat, 02 August 2014 06:02 UTC

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From: Philip Levis <pal@cs.stanford.edu>
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Cc: roll Lossy networks <roll@ietf.org>, ipv6@ietf.org
Subject: Re: [Roll] WGLC for draft-thubert-6man-flow-label-for-rpl-03
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On Aug 1, 2014, at 1:27 PM, Pascal Thubert (pthubert) <pthubert@cisco.com> wrote:

> Phil,
> 
> Though I attended the discussions and have a clear reading of this work I'll certainly defer to Brian on whether there is a violation or not. 
> 
> OTOH you need to understand that there is no need for a bis to update a MUST in an RFC. We recognize the imperfection in our work and are always ready to revise and amend after due consideration.
> 
> This process takes is another RFC and best judgement from the original group that the new text is indeed valuable and not breaking the original objectives.
> 
> We are going through that process.


If the proposal is to have an Updates: 6437 (such that someone looking up 6437 will see a forward reference and know there's an update), I'm all in favor! That seems entirely reasonable. In that way, as I've always said, I think using the flow label is an excellent solution. I just also think doing so is significant in the context of 6437 and so should correctly acknowledge so. Someone reading 6437 should be able to easily learn there's another exception. It seems like an Updates: would do that well. 

That being said, I don't think the energy claims in the current document will hold up to much experimental scrutiny or actual network measurements. Xavier's back-of-the-envelope calculations don't include preambles, slot padding, or idle listening. TSCH is nice in that it has much lower idle listening costs than ad-hoc algorithms, but they are far from zero. Reducing overhead is valuable due to the corresponding increase in MSS and reduced memory pressure: the energy argument is a red herring.

Phil