Jon, While I do not have an issue with enforcing the PST TLV be included in the below message types, we still need to answer Stephane's last question in his original email. That is whether the PST is allowed to change during the lifetime of the LSP. I am hoping the answer is no meaning that once a LSP with a PLSP-ID is established, a subsequent PCUpd message with a PST type that does not match the type in the original message which created that PLSP-ID (PCReq or PCInitiate) should result in the PCC returning a PCErr message with Error-Type = 21 (Traffic engineering path setup error) and Error-Value = 2 (Mismatched path setup type).
If that is the understanding of this group, we should explicitly document it in draft-ietf-pce-lsp-setup-type. Mustapha. > -----Original Message----- > From: Pce [mailto:[email protected]] On Behalf Of Jonathan Hardwick > Sent: Thursday, November 16, 2017 6:19 AM > To: Julien Meuric <[email protected]>; [email protected] > Cc: [email protected] > Subject: Re: [Pce] Clarifications on PST handling in > draft-ietf-pce-lsp-setup-type & > draft-ietf-pce-segment-routing > > Hi Julien, see [Jon]s below... > > -----Original Message----- > From: Julien Meuric [mailto:[email protected]] > Sent: 16 November 2017 17:28 > To: Jonathan Hardwick <[email protected]>; > [email protected] > Cc: [email protected] > Subject: Re: [Pce] Clarifications on PST handling in > draft-ietf-pce-lsp-setup-type & > draft-ietf-pce-segment-routing > > Hi, > > Glad to see we are converging. To make sure we are on the same page (solution > (2) referring to a shortcut), the conclusion is that, as soon as PST is not 0 > (i.e. > RSVP-TE), we always include the PST TLV in PCReq, PCRep, PCUpd, PCRpt and > PCInitiate: is that right? > > [Jon] Yes. > > This leads me to another question. Over a PCEP session supporting multiple > types, we do not have a mean to send a PCReq leaving the type selection to the > PCE (no TLV implying type 0). Do we consider a mean to support that? (Could be > 0xFF or a flag from the "Reserved" field.) > > [Jon] It could be done, but do we need it? This could be added later without > penalty. > > Thanks, > > Julien > > > Nov. 16, 2017 - [email protected]: > > > > Hi Stephane > > > > > > > > OK, let's go with solution (2). That is, if the PATH-SETUP-TYPE is > > not present in a message, then it unambiguously means that the path > > setup type is RSVP-TE. Then implementations don't have to try to > > infer the path setup type from other objects or previous messages. > > > > > > > > I am revising draft-ietf-pce-lsp-setup-type at the moment to address > > an earlier comment from Julien, so I will include this clarification > > in the next revision. > > > > > > > > Thanks for the input! > > > > Cheers > > > > Jon > > > > > > > > > > > > *From:*[email protected] > > [mailto:[email protected]] > > *Sent:* 15 November 2017 13:52 > > > > > > > > Hi Jon, > > > > > > > > Thanks for your feedback. > > > > I see two possibilities here. > > > > 1. When the PATH-SETUP-TYPE is not present in a PCUpd, it should be > > inferred from the latest one received (in a PCInitiate or in a > > PCUpd). When initiating an LSP, the PCInitiate contains the PST to > > let the PCC know about the path type. Then, it can be omitted in > > further PCUpd except when the PCE wants to change the path type. > > At that time, it sends a PCUpd with a new PATH-SETUP-TYPE value > > and then it does not need to include it in further updates until > > the PCE needs to change it again. > > 2. We mandate the PCE to put the PATH-SETUP-TYPE in all PCUpd. > > > > > > > > IMO, solution 2) is easier for implementations and operation. > > > > > > > > Brgd, > > > > > > > > Stephane > > > > > > > > > > > > *From:*Jonathan Hardwick [mailto:[email protected]] > > *Sent:* Wednesday, November 15, 2017 09:28 > > *To:* LITKOWSKI Stephane OBS/OINIS; [email protected] <mailto:[email protected]> > > *Subject:* RE: Clarifications on PST handling in > > draft-ietf-pce-lsp-setup-type & draft-ietf-pce-segment-routing > > > > > > > > I think it should be acceptable for the PCUpd not to include the > > PATH-SETUP-TYPE, with the implication that there is no change to the > > path type. > > > > > > > > Although I'm not convinced it would be a good idea operationally, I > > don't think there's any need to prevent the path type changing on the > > PCUpd, if an explicit PATH-SETUP-TYPE is given. That is, > > draft-ietf-pce-lsp-setup-type, as a base draft, should allow that > > flexibility. A given device may choose not to allow that, of course. > > > > > > > > Does that sound reasonable? > > > > Cheers > > > > Jon > > > > > > > > > > > > *From:*Pce [mailto:[email protected]] *On Behalf Of > > *[email protected] <mailto:[email protected]> > > *Sent:* 14 November 2017 00:38 > > *To:* [email protected] <mailto:[email protected]> > > *Subject:* [Pce] Clarifications on PST handling in > > draft-ietf-pce-lsp-setup-type & draft-ietf-pce-segment-routing > > > > > > > > Hi WG, > > > > > > > > I'm facing an interop issue between two PCEP implementations. > > > > PCE from vendor1 sends the PCInitiate for an SRTE LSP using the PST=1 > > in the SRP Object. > > > > PCC from vendor2 handles it correctly and delegates the LSP to the PCE > > using PST=1. > > > > When the PCE sends a PCUpdate message, it does not set the PST TLV in > > the SRP Object. > > > > The PCC rejects the PCUpdate because of a bad ERO subobject type. It > > reads the PCUpdate as having PST type=0. > > > > > > > > Based on my reading of draft-ietf-pce-lsp-setup-type & > > draft-ietf-pce-segment-routing. > > > > PST draft tells that for the PCE Initiation case, the PCE MAY include > > the PST if the message does not ave any other means of indicating the > > path setup type. SR draft tells "In order to setup an SR-TE LSP using > > SR, RP or SRP object MUST include PATH-SETUP-TYPE TLV". Unfortunately > > it does not specify explicitly in which message. From a reading > > perspective, we can understand from "In order to setup" that it > > applies to the PCInitiate message. But nothing tells about the > > PCUpdate message. > > > > However draft-ietf-pce-lsp-setup-type tells for the stateful PCE case > > that: "if the path setup type cannot be unambiguously inferred from > > ERO or any other object or TLV, PATH-SETUP-TYPE TLV MAY be used in > > PCRpt and PCUpd messages." > > > > In our case (PCE initiated) as the LSP has initially been setup > > through a PCInitiate message having the PST TLV, the PCC can infer > > that futher updates will use EROs associated with the same PST. > > > > > > > > Or do we allow to change the PST through PCUpdate messages which may > > require to always set the PST ? (moving from RSVP-TE to SR or the > > other way for a particular LSP) > > > > > > > > I would like to hear opinions of the WG on that problem ? > > > > > > > > Thanks, > > > > > > > > Brgds, > > > > > > > > > > > > Orange logo <http://www.orange.com/> > > > > > > > > *Stephane Litkowski * > > Network Architect > > Orange/SCE/EQUANT/OINIS/NET > > > > Orange Expert Future Networks > > > > phone: +33 2 23 *06* 49 83 > > > <https://monsi.sso.francetelecom.fr/index.asp?target=http%3A%2F%2Fclicvoice.s > so.francetelecom.fr%2FClicvoiceV2%2FToolBar.do%3Faction%3Ddefault%26root > service%3DSIGNATURE%26to%3D+33%202%2023%2028%2049%2083%20> NE > W ! > > mobile: +33 6 71 63 27 50 > > > <https://monsi.sso.francetelecom.fr/index.asp?target=http%3A%2F%2Fclicvoice.s > so.francetelecom.fr%2FClicvoiceV2%2FToolBar.do%3Faction%3Ddefault%26root > service%3DSIGNATURE%26to%3D+33%206%2037%2086%2097%2052%20> NE > W ! > > [email protected] <mailto:[email protected]> > > > > > > > > > ______________________________________________________________________ > > ___________________________________________________ > > > > Ce message et ses pieces jointes peuvent contenir des informations > > confidentielles ou privilegiees et ne doivent donc pas etre diffuses, > > exploites ou copies sans autorisation. 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