Re: [Pce] Alvaro Retana's No Objection on draft-ietf-pce-stateful-pce-lsp-scheduling-19: (with COMMENT)
Dhruv Dhody <dd@dhruvdhody.com> Wed, 22 July 2020 04:25 UTC
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From: Dhruv Dhody <dd@dhruvdhody.com>
Date: Wed, 22 Jul 2020 09:54:48 +0530
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To: Alvaro Retana <aretana.ietf@gmail.com>
Cc: Alvaro Retana via Datatracker <noreply@ietf.org>, The IESG <iesg@ietf.org>, pce-chairs <pce-chairs@ietf.org>, draft-ietf-pce-stateful-pce-lsp-scheduling@ietf.org, pce@ietf.org
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Subject: Re: [Pce] Alvaro Retana's No Objection on draft-ietf-pce-stateful-pce-lsp-scheduling-19: (with COMMENT)
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Hi Huaimo, Alvaro, <snip> > > > (2) §4.1: "a PCE MUST synchronize to other PCEs within the network...Which > > way is used to achieve this is out of scope for this document." If the > > synchronization mechanism is out of scope, how can an implementation be > > compliant with this specification? IOW, if there's nothing to normatively > > refer to, then normative language shouldn't be used, or a mechanism should > > be mandated. In either case, because synchronization between the PCEs seems > > important for this specification, I would like to also see a discussion > > about the specific effects on LSP scheduling instead of the generic pointer > > to rfc7399. > > > > [HC]: The description related seems too broad. We have rephrased > > the related text to focus on the state of a scheduled LSP > > crossing multiple domains from an ingress domain to an egress domain. > ... > > > As mentioned separately...I think that changing the scenario is not a > good idea at this point. It also leaves the single domain case > unaddressed. > > I suggested making these changes in section 4.1 - In case of multiple PCEs within a single domain, the PCE would need to synchronize their scheduling information with other PCEs within the domain. This could be achieved by proprietary database synchronization techniques or via a possible PCEP extension [I-D.litkowski-pce-state-sync]. The technique used to synchronize SLSP-DB is out of scope for this document. Also, update section 4.3 with - o The stateful PCE MUST update its local scheduled LSP-DB and scheduled TED with the scheduled LSP and synchronize the scheduling information with other PCEs in the domain. > > > §4.3 says that the "stateful PCE...shall send a PCRpt message with the > > scheduled LSP to other PCEs...to achieve...synchronization." Even though > > normative language is not used, the intent seems to specifically point at > > using PCRpt messages for synchronization... > > > > Besides the confusing use of language, rfc8231 defines PCRpt as a "message > > sent by a PCC to a PCE to report the current state of an LSP", but I didn't > > see where the use if defined between PCEs -- maybe I missed it. §6.1 does > > reinforce that the "Path Computation State Report (PCRpt) is a PCEP message > > sent by a PCC to a PCE to report the status of one or more LSPs as per > > [RFC8231]....This message is also used to synchronize the scheduled LSPs to > > other PCE as described in [RFC8231]". But this last point is what I can't > > find in rfc8231. > > > > [HC]: We have updated/cleaned the text related. > > The Path Computation State Report (PCRpt) is a PCEP message sent by > > a PCC to a PCE as per [RFC8231]. A PCE can act as a PCC to send a PCRpt > > message to another PCE. > > The "as described in [RFC8231]" text is still not accurate -- that > document doesn't talk about using the PCRpt message between PCEs. > > I don't think that the "PCE can act as a PCC" part is well defined. > Is it specified somewhere else? > In this case, the right reference is draft-litkowski-pce-state-sync to synchronize between PCEs using PCRpt/PCUpd. My suggestion would be to change the text in Section 6.1 (version -19) OLD: This message is also used to synchronize the scheduled LSPs to other PCE as described in [RFC8231] NEW: This message could also be used to synchronize the scheduled LSPs to other PCE as described in [I-D.litkowski-pce-state-sync]. END I can even live with removing the text completely. BTW, just for information - PCE acting as PCC and using PCReq message towards other PCEs goes back to RFC 5441. RFC 8751 has a child PCE acting as PCC and sending PCRpt messages to parent PCE. But that has no bearing on the fate of the above text. Thanks, Dhruv
- [Pce] Alvaro Retana's No Objection on draft-ietf-… Alvaro Retana via Datatracker
- Re: [Pce] Alvaro Retana's No Objection on draft-i… Huaimo Chen
- Re: [Pce] Alvaro Retana's No Objection on draft-i… Alvaro Retana
- Re: [Pce] Alvaro Retana's No Objection on draft-i… Dhruv Dhody
- Re: [Pce] Alvaro Retana's No Objection on draft-i… Alvaro Retana
- Re: [Pce] Alvaro Retana's No Objection on draft-i… Huaimo Chen
- Re: [Pce] Alvaro Retana's No Objection on draft-i… Huaimo Chen