Hi Julien
You are right, but it is *really easy* for the reader to confuse "stateful
capability" with "update capability" and "active stateful capability". Case in
point: I just confused them in my reply to Lionel.
We should fix each of the three points below to make this clearer.
Cheers
Jon
-----Original Message-----
From: Julien Meuric [mailto:julien(_dot_)meuric(_at_)orange(_dot_)com]
Sent: 11 April 2017 16:00
To: Jonathan Hardwick <Jonathan(_dot_)Hardwick(_at_)metaswitch(_dot_)com>;
Lionel Morand <lionel(_dot_)morand(_at_)orange(_dot_)com>;
ops-dir(_at_)ietf(_dot_)org
Cc: draft-ietf-pce-stateful-pce(_dot_)all(_at_)ietf(_dot_)org;
pce(_at_)ietf(_dot_)org; ietf(_at_)ietf(_dot_)org
Subject: Re: [Pce] Review of draft-ietf-pce-stateful-pce-18
Jon, Lionel,
I believe Lionel got confused by the wording introduced in RFC 8051:
- no report, no update means stateless PCE;
- report, no update means passive stateful PCE;
- report and update means active (stateful) PCE.
More details below, [JM].
Thanks for the work,
Julien
Apr. 11, 2017 - Jonathan(_dot_)Hardwick(_at_)metaswitch(_dot_)com:
=====
[LM] active/passive mode are not advertized in PCEP. s/if active
stateful PCE capability was not advertised/if stateful PCE capability
was not advertised
Jon> ACK
=====
[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.
=====
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.
=====
[LM] Would it be useful to discover (using another TLV) whether the
PCE is an active/passive stateful PCE, as in IGP-based capabilities
discovery mechanism?
Jon> This can be inferred immediately from the U flag in the
STATEFUL-PCE-CAPABILITY TLV. Passive mode is synonymous with not
sending / handling PCUpd messages.
=====
[JM] The mechanism is there, but section 7.1.1 may deserve an explicit use of
the "passive/active" terms, to make sure the capability terminology is aligned
with the vocabulary in the IGP section.