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

[Michael Richardson <[e-mail]>]

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.
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.
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.


--
Michael Richardson <[e-mail]>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide