Jeff,

IMHO, the MSD or the MSD(type 1) just indicates a certain label imposition 
capability which should be signaling-agnostic. More specially, the MSD or 
MSD(type1) capability could be signaled via IGP, BGP or PCEP. 

If the semantic of MSD (type 1) as defined in your IGP-MSD draft equals the 
semantics of MSD as defined in PCEP-SR draft, I believe it'd better to iron out 
such terminology inconsistency ASAP.

Best regards,
Xiaohu

> -----邮件原件-----
> 发件人: Jeff Tantsura [mailto:[email protected]]
> 发送时间: 2017年12月22日 5:22
> 收件人: Xuxiaohu; Les Ginsberg (ginsberg); Ketan Talaulikar (ketant); Christian
> Hopps; [email protected]
> 抄送: [email protected]; [email protected]
> 主题: Re: 答复: [Isis-wg] WG Last Call for draft-ietf-isis-segment-routing-msd-07
> 
> Xuxiaohu,
> 
> To clarify:
> The concept had been developed in both, in parallel, however PCEP
> implementation is limited (node only, PCC in question has to have PCEP 
> sessions
> with the PCE), and this is clearly stated in the draft – if MSD is known from 
> both
> sources (PCEP and IGP/BGP-LS) the later takes precedence. IGP drafts are the
> source of truth when it comes to semantics definitions.



> Personally, I don’t see any confusion wrt name, all drafts have been around 
> for
> quite some time, reviewed by many people, presented in academia and
> networking events, noone was ever confused…
> 
> I’m not sure about value of your proposal either, and I’d leave the decision
> what to use to people who are the consumers of the technology, those who are
> going to implement it (at least 3 MSD implementations are on their ways).
> 
> As the last point – we are not “considering” expanding, the draft is clear 
> about
> the future extensions to come and encoding is done in a way to facilitate such
> extensions.
> This is the working group last call for the draft, not a discussion whether we
> should proceed with the technology:
> If you see any technical problems with the solution proposed – I’d be the 
> first
> to listen to you and address them!
> 
> Happy holidays!
> 
> Cheers,
> Jeff
> 
> -----Original Message-----
> From: Xuxiaohu <[email protected]>
> Date: Wednesday, December 20, 2017 at 18:40
> To: "Les Ginsberg (ginsberg)" <[email protected]>, "Ketan Talaulikar 
> (ketant)"
> <[email protected]>, Christian Hopps <[email protected]>, "[email protected]"
> <[email protected]>
> Cc: "[email protected]" <[email protected]>,
> "[email protected]"
> <[email protected]>
> Subject: 答复: [Isis-wg] WG Last Call for draft-ietf-isis-segment-routing-msd-07
> Resent-From: <[email protected]>
> Resent-To: <[email protected]>, <[email protected]>,
> <[email protected]>, <[email protected]>
> Resent-Date: Wed, 20 Dec 2017 18:40:16 -0800 (PST)
> 
>     Hi Les,
> 
>     If I understand it correctly, the MSD concept was originated from
> (https://tools.ietf.org/html/draft-ietf-pce-segment-routing-11#page-7) as
> described below:
> 
>     "The "Maximum SID Depth" (1
>        octet) field (MSD) specifies the maximum number of SIDs (MPLS label
>        stack depth in the context of this document) that a PCC is capable of
>        imposing on a packet."
> 
>     Before considering expanding the semantics of the MSD concept as defined
> in the above PCE-SR draft, how about first considering renaming the capability
> of imposing the maximum number of labels so as to eliminate possible
> confusions, e.g., Writable Label-stack Depth (WLD) as opposed to the Readable
> Label-stack Depth (RLD) as defined in
> (https://tools.ietf.org/html/draft-ietf-ospf-mpls-elc) and
> (https://tools.ietf.org/html/draft-ietf-isis-mpls-elc) ?
> 
>     Best regards,
>     Xiaohu
> 
>     > -----邮件原件-----
>     > 发件人: Isis-wg [mailto:[email protected]] 代表 Les Ginsberg
> (ginsberg)
>     > 发送时间: 2017年12月21日 4:02
>     > 收件人: Ketan Talaulikar (ketant); Christian Hopps; [email protected]
>     > 抄送: [email protected]; [email protected]
>     > 主题: Re: [Isis-wg] WG Last Call for 
> draft-ietf-isis-segment-routing-msd-07
>     >
>     > Ketan -
>     >
>     > Thanx for the comments.
>     > I think we do want to allow MSD support for values other than imposition
>     > values. We will revise the text so we are not restricted to only 
> imposition
> cases.
>     >
>     >   Les
>     >
>     >
>     > > -----Original Message-----
>     > > From: Ketan Talaulikar (ketant)
>     > > Sent: Wednesday, December 20, 2017 1:51 AM
>     > > To: Christian Hopps <[email protected]>; [email protected]
>     > > Cc: [email protected]; [email protected]
>     > > Subject: RE: [Isis-wg] WG Last Call for
>     > > draft-ietf-isis-segment-routing-msd-07
>     > >
>     > > Hello,
>     > >
>     > > I support this document and would like to ask the authors and WG to
>     > > consider if we can expand the scope of this draft to not just
>     > > "imposition" of the SID stack but also other similar limits related to
> other
>     > actions (e.g.
>     > > reading, processing, etc.). With Segment Routing, we are coming across
>     > > various actions that nodes need to do with the SID stack for different
>     > > purposes and IMHO it would be useful to extend the MSD ability to
>     > > cover those as they arise.
>     > >
>     > > Thanks,
>     > > Ketan
>     > >
>     > > -----Original Message-----
>     > > From: Isis-wg [mailto:[email protected]] On Behalf Of Christian
>     > > Hopps
>     > > Sent: 20 December 2017 14:03
>     > > To: [email protected]
>     > > Cc: [email protected]; [email protected]
>     > > Subject: [Isis-wg] WG Last Call for
>     > > draft-ietf-isis-segment-routing-msd-07
>     > >
>     > >
>     > > The authors have asked for and we are starting a WG Last Call on
>     > >
>     > >  https://datatracker.ietf.org/doc/draft-ietf-isis-segment-routing-msd/
>     > >
>     > > which will last an extended 4 weeks to allow for year-end PTO 
> patterns.
>     > >
>     > > An IPR statement exists:
>     > >
>     > >
>     > > https://datatracker.ietf.org/ipr/search/?submit=draft&id=draft-ietf-is
>     > > is-
>     > > segment-routing-msd
>     > >
>     > > Authors please reply to the list indicating whether you are aware of
>     > > any
>     > > *new* IPR.
>     > >
>     > > Thanks,
>     > > Chris.
>     > >
>     > > _______________________________________________
>     > > Isis-wg mailing list
>     > > [email protected]
>     > > https://www.ietf.org/mailman/listinfo/isis-wg
>     >
>     > _______________________________________________
>     > Isis-wg mailing list
>     > [email protected]
>     > https://www.ietf.org/mailman/listinfo/isis-wg
> 
> 

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