Re: [Roll] Erik Kline's Discuss on draft-ietf-roll-useofrplinfo-42: (with DISCUSS and COMMENT)

Hi!

Where are we with this?   It is not clear whether we need to update the
document or if we’re all agreeing. ;-)

Erik/Pascal?

Thanks!

Alvaro.

On December 18, 2020 at 10:42:24 AM, Pascal Thubert (pthubert) (
pthubert=40cisco.com@dmarc.ietf.org) wrote:

Hello Michael and all:

> -----Original Message-----
> From: Roll <roll-bounces@ietf.org> On Behalf Of Michael Richardson
> Sent: mercredi 16 décembre 2020 19:02
> To: Erik Kline <ek.ietf@gmail.com>; Routing Over Low power and Lossy
> networks <roll@ietf.org>
> Subject: Re: [Roll] Erik Kline's Discuss on
draft-ietf-roll-useofrplinfo-42: (with
> DISCUSS and COMMENT)
>
>
> Erik Kline via Datatracker <noreply@ietf.org> wrote:
> > I might recommend instead referring to RFC 6554 S4.2 for how to
> > handle RH3's if the node is also a RPL-aware router and say it MUST
> > drop the packet if segments left is non-zero and it's not a RPL-aware
> > router.
>
> > Related: I'd also recommend:
>
> > "It should just be noted that an incoming RH3 must be fully consumed,
> > or very carefully inspected."
>
> ->
>
> > "It should just be noted that an incoming RH3 MUST be fully
> > consumed."
>
> I think that Pascal and I, when we write the "carefully inspected", is
that we
> are imagining situations where the topology is a bit subtle.

Yes, I expected policies that would validate the right of a Leaf to
participate to a DODAG ,or to remap the information from the leaf (could be
the RPI, the opaque field in the EARO, or the 6-tuple) into an RPI.

> Perhaps there are firewalls involved.
> Perhaps a device has multiple interfaces (many radios for instance) and
the
> extra segments address the other interfaces.
>
> Also draft-ietf-anima-autonomic-control-plane uses storing mode, so never
> has
> RH3 headers, but imagine if it did.
>
> One could have a situation where the physical system containing one or
more
> layers of container was not the ultimate last hop from a logical point of
view.
> Rather than inner container was. So, it's all the same stack actually. In
that
> case, an optimization might be to process more than one segment in that
> stack.
> (The ANIMA ACP definitely supports having VMs and containers inside
> routers)
>
> So, I can live with your suggestion, because in my case above, we can
argue
> that it's still "consumed"
>
> > * I'm confused by the use of "consumed" here. Is the final RH3 entry
> > RUL's address? I guess you could say RH penultimate hop "consumes" the
> > header because the ultimate destination address is put in the header DA
> > field. Seems a bit odd though.
>
> Yes, that's what we mean.

Yes, as I said in my response I thought it was quite common. I'm surprised
to find little art to quote.

> Once that ultimate destination is in the DA, then the RH3 is a dummy, but
one
> we are aren't supposed to remove.
>
> > I assume 6LR_n gets RUL's address from the last segment in RH3.
>
> > "Consumed" means segments left == 0, I guess? I suppose should have
> > picked up on this terminology when it was first used in Section 2.
> > Maybe clarify what it means in that section (2)?
>
> Yes.

Cool, we're good!

Pascal
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