Re: [Pce] Review of draft-ietf-pce-stateful-pce-18

[Julien Meuric <[e-mail]>]

Hi Lionel,

Thank you for following up. I think we're almost done. My answers below
as [JM2].

Julien


Apr. 12, 2017 - <[e-mail]:

[snip]

>>> =====
>> [JM] NACK! ;-) Actually, the passive mode is advertised using the 
>> Stateful-capability-object TLV with the U bit unset, the active 
>> mode by setting the U bit.
>> 
> [LM2] "il faut être sorti de Saint-Cyr pour comprendre" as we say in
>  french :)

[JM2] Let me check with my colleague next door... ;-)

> Could be good to add something like "(as indicated by the U-bit clear
> in Stateful-capability-object)"

[JM2] ACK!

> 
>>> =====
>>> 
>>> Note that even if the update capability has not been advertised,
>>>  a PCE can still accept LSP Status Reports from a PCC and build 
>>> and maintain an up to date view of the state of the PCC's LSPs.
>>> 
>>> [LM] I don't undersand. Is it not in contradiction with
>>> 
>>> "If the PCEP Speaker on the PCE supports the extensions of this 
>>> draft but did not advertise this capability, then upon receipt of
>>> a PCRpt message from the PCC, it MUST generate a PCErr with 
>>> error- type 19 (Invalid Operation), error-value 5 (Attempted LSP
>>>  State Report if active stateful PCE capability was not 
>>> advertised) (see Section 8.5) and it SHOULD terminate the PCEP 
>>> session."
>>> 
>>> Or does it mean that there is another way than PCRpt message for
>>>  the PCC to send LSP status reports to the PCE?
>>> 
>>> Jon> ACK.  I think that the statement in the draft is bogus and
>>> I propose to delete this sentence from it.
>>> 
>>> =====
>> [JM] I do not think that the text is bogus: - case 1: no advertised
>> capability on update but advertised on report (i.e. passive
>> stateful) => no error message; - case 2: no advertised capability
>> on update nor report (i.e. stateless) => error.
> [LM2] After multiple readings and thanks to your explanation, I think
> I have understood. Am I correct saying that the PCE will accept LSP
> Status Reports from a PCC ONLY if the stateful PCE capability has
> been advertised (i.e. Stateful Capability TLV with the 'LSP Update'
> Flag cleared)? 

[JM2] Almost... but not fully! Your main sentence is true, your
parenthesis is not. The latter should be rephrased as "i.e. inclusion of
the Stateful Capability TLV". Indeed, passive (report, no update) and
active (report + update) are two possible modes within stateful, i.e. we
do not care about the 'LSP Update' flag when talking about
Report/"stateful at large".

If it is the case, is it really required to keep this
> text, as in the previous paragraph we find the conditions to
> accept/reject reports from the PCC?

[JM2] AFAIU, the sentence clarifies the fact that an error on an update
attempt does not lead to an error on the report feature.

[JM2] Side note to the (RFC?) editor, on page 11: s/this draft/this
document/