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Re: [Pce] Stateful PCE: inconsistency in "resource limit" text

Jonathan Hardwick <Jonathan.Hardwick@metaswitch.com> Wed, 17 May 2017 13:43 UTC

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From: Jonathan Hardwick <Jonathan.Hardwick@metaswitch.com>
To: Robert Varga <nite@hq.sk>, Ramon Casellas <ramon.casellas@cttc.es>, "stephane.litkowski@orange.com" <stephane.litkowski@orange.com>, Dhruv Dhody <dhruv.ietf@gmail.com>, Julien Meuric <julien.meuric@orange.com>
CC: "pce@ietf.org" <pce@ietf.org>
Thread-Topic: [Pce] Stateful PCE: inconsistency in "resource limit" text
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Date: Wed, 17 May 2017 13:37:08 +0000
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Subject: Re: [Pce] Stateful PCE: inconsistency in "resource limit" text
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Hi all

Thanks for your feedback on this issue.  I think we are probably in a position to close this issue down.  To summarize:

- The original intent was that the PCE MUST close the session.
- It seems that nobody has implemented the "exiting resource limit exceeded state" notification.

On the other hand, if we did weaken "MUST close" to "MAY close", then the draft provides no guidance about what the PCC and PCE are supposed to do next with this session in which only part of the state has been kept by the PCE.  I don't want to start drafting that guidance at this late stage.

My conclusion is that we should specify that the PCE MUST close the session, and we should release the code point currently allocated to the "exiting resource limit exceeded state" notification.

If anyone has strong objections to this, please shout ASAP.

Many thanks
Jon


-----Original Message-----
From: Pce [mailto:pce-bounces@ietf.org] On Behalf Of Robert Varga
Sent: 17 May 2017 12:52
To: Ramon Casellas <ramon.casellas@cttc.es>; pce@ietf.org
Subject: Re: [Pce] Stateful PCE: inconsistency in "resource limit" text

On 09/05/17 10:50, Ramon Casellas wrote:
> Hi Julien,
> 
> This is indeed making me raise more questions than expected.
> 
> - Reading the section I got the feeling that any event preventing to 
> reach full sync state caused a PCErr (now PCNtf) and a MUST session 
> close. was it the intent?

Hello Ramon,

with a co-author hat on, but without loading the draft completely into brain again, yes, this was the intent. The reasoning behind is to provide an initial baseline for the state present on the PCC, agreed by both PCE and PCC.

This simplifies the protocol design a bit, as we do not have to deal with state synchronization being half-done.

Furthermore it gives the PCE a chance to attempt to re-negotiate the session parameters based on the problem it has seen with the PCRpt.

Regards,
Robert

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