OK. How about the following change?
Current text:
"If direct IP routing becomes available (e.g., after the successful
PANA authentication as in the case of Zigbee IP), the PaC may
choose to directly communicate with the PAA without use of the relay
operation. The IP address update procedure defined in
[RFC5191] may be performed to switch to non-relay operation."
Propose text:
"If direct IP routing becomes available (e.g., after the successful
PANA authentication as in the case of Zigbee IP) and the PaC is
notified about the change of PAA's IP address using an out-of-band
mechanism that is not specified in this document, the PaC may choose
to directly communicate with the PAA without use of the relay
operation. The IP address update procedure defined in [RFC5191] may
be performed to switch to non-relay operation, using the directly
reachable IP address of the PAA."
Yoshihiro Ohba
(2010/11/29 21:10), Alper Yegin wrote:
Rafa,
El 26/11/2010, a las 08:21, Alper Yegin escribió:
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.
[Rafa] What I believed is that a new PANA authentication was necessary
when you switch the PAA's interface, as Yoshi has mentioned. It does
not mean that it is the best option of course, but what happens is that
there is no support for PAA's address change. I believe this scenario
was not considered in RFC 5191.
We didn't envision this scenario. Hence RFC 5191 is "silent" about it.
In other words, there is no explicit facility to realize that (PAA IP
address change), and there is no prohibition against it either. Which means,
if some implementation/SDO/deployment can figure out a way to enable that
w/o breaking the RFC, it's OK. And that's the case with this Zigbee Alliance
usage.
In the same way that "In order to
maintain the PANA session, the PAA needs to be notified about the
change of PaC address.", I would expect a mechanism saying that: "In
order to maintain the PANA session, the PaC needs to be notified about
the change of PAA address."
We can say something to that affect in the relay I-D.
Alper
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.
-------------------------------------------------------
Rafael Marin Lopez, PhD
Dept. Information and Communications Engineering (DIIC)
Faculty of Computer Science-University of Murcia
30100 Murcia - Spain
Telf: +34868888501 Fax: +34868884151 e-mail: r...@um.es
-------------------------------------------------------
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