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

["Pascal Thubert (pthubert)" <[e-mail]>]

Hello Michael and all:

> -----Original Message-----
> From: Roll <[e-mail]> On Behalf Of Michael Richardson
> Sent: mercredi 16 décembre 2020 19:02
> To: Erik Kline <[e-mail]>; Routing Over Low power and Lossy
> networks <[e-mail]>
> Subject: Re: [Roll] Erik Kline's Discuss on draft-ietf-roll-useofrplinfo-42: (with
> DISCUSS and COMMENT)
> 
> 
> Erik Kline via Datatracker <[e-mail]> 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