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

[Rafa Marin Lopez <[e-mail]>]

Hi all,

my apologies for answering a bit late to this.

I do not completely understand the sentence:

"The PaC IP address update procedure defined in [RFC5191] may additionally be performed to switch to non-relay operation, using the directly reachable IP address of the PAA."

I think that the PaC IP address update procedure defined in [RFC5191] is useless for this scenario where the PAA "changes" its IP address. I believe what PaC must simply do is to update the IP address in the PANA session with the PAA's IP address obtained with this out of band mechanism.

This, my suggestion would be to remove that sentence.

Best regards.

El 01/12/2010, a las 14:50, Robert Cragie escribió:

> Maybe I'm missing something but switching to direct communication has nothing to do with a *change* in the PAA address. I would suggest the following:
> 
> "If direct IP routing becomes available[1] and the PaC is notified about the PAA's[2] 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 PaC[3] IP address update procedure defined in [RFC5191] may additionally[4] be performed to switch to non-relay operation, using the directly reachable IP address of the PAA."
> 
> [1] Removed ZigBee IP reference
> [2] "the change of PAA's" -> "the PAA's"
> [3] Added PaC as per Alper's suggestion
> [4] Added "additionally" as this is independent from getting the PAA address
> 
> Comments?
> Robert Cragie (Pacific Gas & Electric)
> 
> Gridmerge Ltd.
> 89 Greenfield Crescent,
> Wakefield, WF4 4WA, UK
> [phone]
> [phone]
> http://www.gridmerge.com
> 
> 
> On 30/11/2010 9:20 PM, Alper Yegin wrote:
>> 
>> Looks good to me.
>> 
>> One minor update:
>> 
>> "The IP address update procedure" --> "PaC IP address update procedure"
>> 
>> 
>> Alper
>> 
>> 
>>> -----Original Message-----
>>> From: Yoshihiro Ohba [mailto:[e-mail]]
>>> Sent: Tuesday, November 30, 2010 3:52 AM
>>> To: Alper Yegin
>>> Cc: 'Rafa Marin Lopez'; [e-mail]; 'Ralph Droms';
>>> [e-mail]; 'Samita Chakrabarti'; 'Paul Duffy
>>> (paduffy)'
>>> Subject: Re: Switching to direct communication [was Re: PANA relay
>>> draft]
>>> 
>>> 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: [phone] Fax: [phone] e-mail: [e-mail]
>>>>> -------------------------------------------------------
>>>>> 
>>>>> 
>>>> 
>>>> 
>> 

-------------------------------------------------------
Rafael Marin Lopez, PhD
Dept. Information and Communications Engineering (DIIC)
Faculty of Computer Science-University of Murcia
30100 Murcia - Spain
Telf: [phone] Fax: [phone] e-mail: [e-mail]
-------------------------------------------------------