Re: [Pana] Switching to direct communication [was Re: PANA relay draft]

["Alper Yegin" <[e-mail]>]

> Let me create a new thread on this specific topic.
> 
> It has been identified that switching from relay to direct
> communication requires not only change of PaC's address but also
> change of PAA's address.
> 
> But RFC 5191 supports change of PaC's address for a given PANA session
> but does not support change of PAA's address.

Yes, RFC 5191 has an explicit support for that.


> So it seems that switching to direct communication requires to go
> through a full PANA authentication.

I don't think that's necessary at all.

If the PaC learns another (or new) IP address of the PAA by some out-of
scope mechanism, then it can start using that IP address. And that's the
case in Zigbee.

Alper




> So if we mention "direct IP routing MAY be available" then we may also
> need to mention that "switching to direct communication requires a
> full PANA authentication using the new PaC's and PAA's addresses."
> 
> What do you think?
> 
> Yoshihiro Ohba
> 
> 
> (2010/11/24 21:32), Alper Yegin wrote:
> >>
> >> [Rafa] In my opinion, after the successful PAA authentication, I
> >> believe that it would be better that PaC does not require the PRE
> >> anymore. In other words, the PaC and the PAA know each other.
> Moreover
> >> I assume that after the successful PAA authentication the PaC will
> be
> >> able to contact directly the PAA without the assistance of the PRE.
> If
> >> these assumptions are reasonable, there will not be PAA-initated
> >> messages that go through the PRE.
> >
> > I think this spec shall not mandate or prohibit use of PRE after the
> first
> > successful PANA auth. Spec shall allow both, and the consumers
> (deployments,
> > architectures) shall decide.
> >
> >>>>   If direct IP routing becomes available (e.g., after the
> successful
> >>>>   PANA authentication as in the case of Zigbee IP),
> >>>>
> >>>> [Rafa]. Is the PRE informed by the PAA?. If it is, how?. In other
> >>>> words, how is this enabled after a successful PANA authentication?
> >>>
> >>> The PRE is not informed by the PAA when direct IP routing becomes
> >> available.
> >>
> >> [Rafa] I mean that it is mentioned that direct IP routing is
> available
> >> , how is this enabled after a successful PANA authentication? is the
> >> PaC enabled to use a non link-local IPv6 address?.
> >
> > I think the spec shall say "direct IP routing MAY be available". In
> the
> > specific case of zigbee, PaC receives RA and configures a global IPv6
> > address. Such details belong to zigbee spec.
> >
> >>>> On the other hand, what entity is acting as EP?.
> >>>>
> >>>
> >>> An EP may reside in the PRE, or it could be a separate entity from
> >> the PRE.
> >>>
> >>>> the PaC may choose
> >>>>   to directly communicate with the PAA without use of the relay
> >>>>   operation.
> >>>>
> >>>> [Rafa] However, it has been said that PaC that "From the PaC's
> >>>> perspective, the PRE appears as the PAA."
> >>>> This sentences seems to mean that PaC knows that it is talking
> with
> >>>> a relay first.
> >>>
> >>> The PaC may not know that it is talking with a relay first.  OTOH,
> >>> the PaC may know, after successful PANA authentication, that it was
> >> talking with a relay, by using some out-of-band mechanism.  But this
> >> does not mean that switching to direct communication is needed.  The
> >> point here is that we try to describe possible cases as much as
> >> possible.
> >>
> >>>
> >>>> The IP address update procedure defined in [RFC5191] may
> >>>> be performed to switch to non-relay operation.
> >>>>
> >>>> [Rafa] Who is sending this notification?
> >>>
> >>> The notification is generated locally by the node that has updated
> an
> >> IP address.
> >>
> >> [Rafa] What is that node? the PAA? the PaC? both?. I mean to switch
> to
> >> non-relay operation, under PaC point of view the PAA is switching
> the
> >> IP address (PaC thought the PAA was the PRE but now it is the real
> PAA)
> >
> > That's right. Both PaC's and PAA's IP address are changing for the
> given
> > PANA session.
> >