Re: [6tisch] Alvaro Retana's Discuss on draft-ietf-6tisch-enrollment-enhanced-beacon-13: (with DISCUSS and COMMENT)

Alvaro Retana <> Fri, 21 February 2020 20:58 UTC

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From: Alvaro Retana <>
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Date: Fri, 21 Feb 2020 12:58:13 -0800
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To:, Michael Richardson <>
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Subject: Re: [6tisch] Alvaro Retana's Discuss on draft-ietf-6tisch-enrollment-enhanced-beacon-13: (with DISCUSS and COMMENT)
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On February 21, 2020 at 3:21:29 PM, Michael Richardson wrote:
> Alvaro Retana wrote:
> > The text you propose helps a little, but it makes me uneasy that a
> > significant part of the (1!) structure defined in a Standards Track
> > document is experimental. Also, the fact that the WG does not in
> > general have a clear prescription and that there's work to be done in
> > RPL, makes the text sound speculative.
> > It would be more appropriate (again, for a Standards Track document) to
> > simply declare the specific use and determination of the different
> > priorities as out of scope (vs the subject of future research). You
> > might still want to include a separate non-normative section (or an
> > appendix) to deal with "future work", but having that discussion while
> > the fields are being specified does not seem right to me.
> I understand your point.
> I think that it's not much different than BGP4's MED attribute.
> I think that 80% of operators still have no idea how to set it :-)

Very different!  Setting policies in BGP is not straight forward for
some, specially when some of the attributes interact with someone
else's policy, which is unknown.  Operators may have a hard time
setting the MED, but its behavior is clearly specified.

> We don't know how to *set* the value, but we *do* know how to interpret
> different values.

Interpreting and acting on the values is exactly the piece I have a
problem with.  The rank priority is an "indication of how willing this
6LR is to serve as an RPL [RFC6550] parent".  How is the receiver
expected to that the value into account for parent selection?  That
part is not specified.  The same for the pan priority; the text says
that a receiver "MAY consider this value when looking for an eligible
parent device",