Hi Mike, Olivier,

Speaking as a WG member...

On Mon, Mar 29, 2021 at 2:42 PM Mike Koldychev (mkoldych)
<[email protected]> wrote:
>
> Hi Olivier,
>
>
>
> I would not recommend using the BSID TLV for #2 (Signal the presence of a 
> Stitching Label in the path of a Tunnel/Policy). ERO/SR-ERO is the object 
> that encodes the label-stack/path, and the SL is part of the label-stack/path 
> of the previous Policy/Tunnel that uses it, so it belongs to the ERO/SR-ERO.

I agree.

> BTW I don’t believe there is currently a way in PCEP to represent a BSID ERO 
> sub-object, it would be useful to define it in some common way with the 
> Stitching Label.
>

For SR we can use the existing SR-ERO subobject itself as per the
binding label/SID draft, and we also have a Label subobject that can
be made to use for non-SR cases.


>
>
> I agree about using flag(s) instead of allocating a new PST to represent the 
> SL in the BSID TLV.
>
>

We should describe a clear relationship between binding and stitching
labels. Then, TE-PATH-BINDING TLV could be used to report/request a
stitching label with a flag set in this TLV.

Thanks!
Dhruv

>
> *IF* RSVP-TE RECORD_ROUTE is used, then RRO object is appropriate.
>
>
>
> Thanks,
>
> Mike.
>
>
>
> From: [email protected] <[email protected]>
> Sent: Tuesday, March 23, 2021 2:11 PM
> To: Mike Koldychev (mkoldych) <[email protected]>; Stone, Andrew (Nokia - 
> CA/Ottawa) <[email protected]>; Dhruv Dhody <[email protected]>
> Cc: [email protected]
> Subject: Re: [Pce] Implementation option of 
> draft-ietf-pce-stateful-interdomain-01.txt
>
>
>
> Hi Mike,
>
> Le 22/03/2021 à 21:03, Mike Koldychev (mkoldych) a écrit :
>
> Hi Olivier,
>
>
>
> I believe what you are trying to achieve is:
>
> Attach a Stitching Label to a Tunnel/Policy, similar to how a Binding Label 
> points to a Tunnel/Policy.
>
> [OD] Yes. Exactly
>
>
> Signal the presence of a Stitching Label in the path of a Tunnel/Policy.
>
> [OD] Yes by using PCE to PCE exchange through PCEP to convey this information
>
>
>
>
>
> I believe that #1 can be achieved using the Binding Label TLV, by perhaps 
> defining another Binding Type. And #2 can be achieved by adding another 
> ERO/SR-ERO sub-object.
>
> [OD] I think that both #1 & #2 could be achieved using the TE-PATH-BINDING 
> TLV minus the addition of new flag to mention that the TE-PATH-BINDING TLV 
> transport a Stitching Label. I would not define a new Binding Type as we 
> could re-use which have been already define in the pce-binding-sid draft and 
> we would not go back to the same problem as with the multiple PST code point. 
> So, a dedicated flag to mention that it is a Binding Label for inter-domain 
> would be better.
>
>
>
> I do not think it’s a good idea to use the RRO unless there is an actual RSVP 
> RECORD_ROUTE being used.
>
> [OD] I tend to be agree after analysis all potential inconvenient, in 
> particular in term of management. But, in another hand, the Stitching label 
> is part of the Tunnel path reported by the Record Route Object.
>
> Regards
>
> Olivier
>
>
>
> Thanks,
>
> Mike.
>
>
>
> From: Pce <[email protected]> On Behalf Of Stone, Andrew (Nokia - 
> CA/Ottawa)
> Sent: Thursday, March 11, 2021 11:11 AM
> To: [email protected]; Dhruv Dhody <[email protected]>
> Cc: [email protected]
> Subject: Re: [Pce] Implementation option of 
> draft-ietf-pce-stateful-interdomain-01.txt
>
>
>
> Hi Olivier,
>
>
>
> Thanks for pointing this out. I think the presentation slide wording might 
> have been a bit stronger than what is currently written in the posted draft, 
> as the text does not prohibit the use of RRO but rather acknowledge and 
> document that there are implementations which skip inclusion of SR-RRO (Nokia 
> implementation does send SR-RRO), so it documents how to handle this scenario 
> on the PCE. The text indicates that SR-RRO may or may not be included, and if 
> omitted the PCE is to fallback to treating the ERO “like” it was an RRO.
>
>
>
> https://datatracker.ietf.org/doc/html/draft-koldychev-pce-operational-03#section-6
>
>
>
>    A PCC MUST send an (possibly empty) ERO/SR-ERO/SRv6-ERO in the PCRpt
>
>    message for every LSP.  A PCC MAY send an SR-RRO/SRv6-RRO for an SR-
>
>    TE/SRv6-TE LSP (respectively).  A PCE SHOULD interpret the RRO/SR-
>
>    RRO/SRv6-RRO as the actual path the LSP is taking but MAY interpret
>
>    only the ERO/SR-ERO/SRv6-ERO as the actual path.  In the absence of
>
>    an RRO/SR-RRO/SRv6-RRO a PCE SHOULD interpret the ERO/SR-ERO/SRv6-ERO
>
>    (respectively) as the actual path for the LSP.
>
>
>
>
>
> I think the potential interdomain stitching label case you point out and the 
> S-Flag defined in RFC8664 mentioned by Dhruv during the meeting seem to be 
> valid use cases where an SR-RRO would need to be included.
>
>
>
> Thanks!
>
> Andrew
>
>
>
> From: Pce <[email protected]> on behalf of "[email protected]" 
> <[email protected]>
> Organization: Orange Labs
> Date: Thursday, March 11, 2021 at 5:17 AM
> To: Dhruv Dhody <[email protected]>
> Cc: "[email protected]" <[email protected]>
> Subject: Re: [Pce] Implementation option of 
> draft-ietf-pce-stateful-interdomain-01.txt
>
>
>
> Hello Dhruv, all,
>
> Following the presentation done during the IETF meeting, please find the link 
> to the presentation: 
> https://datatracker.ietf.org/meeting/110/materials/slides-110-pce-32-inter-domain-00
>
> I also not a major point to take into account following the presentation of 
> draft PCEP Operational Clarification (draft-koldychev-pce-operational) see 
> https://datatracker.ietf.org/doc/draft-koldychev-pce-operational/ and 
> https://datatracker.ietf.org/meeting/110/materials/slides-110-pce-34-operational-clarification-00:
>
>  => In this draft, authors propose to use SR-ERO/SRv6-ERO and to NOT use 
> SR-RRO/SR-v6-RRO for Segment Routing.
>
> As a consequence for the stateful inter-domain draft, proposed option d1, d2 
> and d3 become invalid as it uses the RRO to convey the Stiching Label. Thus, 
> only option d4 with a specific new sub-Object to convey the Stitching Label 
> remains valid.
>
> As usual, comments are welcome.
>
> Regards
>
> Olivier
>
> Le 26/02/2021 à 05:35, Dhruv Dhody a écrit :
>
> Hi Olivier,
>
> Thanks for starting this thread.
>
> As a WG participant...
>
>
>
> On Tue, Feb 23, 2021 at 12:05 AM <[email protected]> wrote:
>
> Dear all,
>
> According to the remark about implementation we got during the WG call
> for adoption, we would start a new thread to discuss this point.
> The goal isto prepare the discussion for next IETF meeting and reach a
> consensusin order to edit revision 2 of the draft.
>
> The stitching label principle requires at least a certain number of
> modifications in the current PCEP version:
>
>  a) A new PCE Capability to announce the inter-domain behaviour
>  b) A new PCE Association Group to associate the local paths identifier
>     to the inter-domain identifier
>  c) new PCEP Errors to manage the Stitching Label exchange
>  d) A mechanism to convey the Stitching Label
>
> If there is no other choice than to reuse existing PCEP Objects by
> allocating new code points for modifications a-c,there is several
> options for point d, which we have tried to list below:
>
>  d1) Use ERO and RRO in conjunction to new Path Setup code points as
>      described in version 01 of the draft. It is the simplest
>      implementation but as mention by Dhruv, each time a new path
>      enforcement appear, a new PST code point must be allocated.
>      For example, when Segment Routing v6 will be standardized, we must
>      allocate a new Stitching label PST code point for SRv6.
>  d2) Use ERO and ERO in conjunction to a new flag in LSP. Simple as for d1,
>      but need to use the LSP Extended Flag draft as all LSP flags have been
>      already allocated.
>  d3) Same as d2 but find another place for the flag e.g. SRP or LSPA Object.
>  d4) Define a new PCEP sub-Objet TLV within the LSP Object to convey the
>      stitching label. This is more independent but need extra parsing from
>      an implementation point of view.
>
>
> My preference would for d2 or d3 (in that order).
> LSP Extended Flag is adopted by the WG and is ready for prime-time use -- 
> let's use it :)
> Authors of LSP Extended Flag are waiting for the draft blockade to be lifted 
> to post the -00 WG I-D.
>
> Thanks!
> Dhruv
>
>
>
> Please, give us your opinion about these different options and don't hesitate
> to propose others.
>
> Regards
>
> Olivier on be-half of co-author's
>
>
>
>
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>
>
> Olivier Dugeon
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> Ce message et ses pieces jointes peuvent contenir des informations 
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>
> a l'expediteur et le detruire ainsi que les pieces jointes. Les messages 
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> --
>
>
>
> Olivier Dugeon
> Orange Expert, Future Networks
> Open Source Referent
> Orange/IMT/OLN/WTC/IEE/iTeQ
>
>
>
> fixe : +33 2 96 07 28 80
> mobile : +33 6 82 90 37 85
> [email protected]
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> _________________________________________________________________________________________________________________________
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>
>
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> ce message par erreur, veuillez le signaler
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> a l'expediteur et le detruire ainsi que les pieces jointes. Les messages 
> electroniques etant susceptibles d'alteration,
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> Orange decline toute responsabilite si ce message a ete altere, deforme ou 
> falsifie. Merci.
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>
>
> This message and its attachments may contain confidential or privileged 
> information that may be protected by law;
>
> they should not be distributed, used or copied without authorisation.
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> If you have received this email in error, please notify the sender and delete 
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