Re: [Isis-wg] WG Last Call for draft-ietf-isis-segment-routing-msd-07

"Ketan Talaulikar (ketant)" <ketant@cisco.com> Thu, 21 December 2017 04:15 UTC

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From: "Ketan Talaulikar (ketant)" <ketant@cisco.com>
To: Xuxiaohu <xuxiaohu@huawei.com>, "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>, Christian Hopps <chopps@chopps.org>, "isis-wg@ietf.org" <isis-wg@ietf.org>
CC: "isis-ads@ietf.org" <isis-ads@ietf.org>, "draft-ietf-isis-segment-routing-msd@ietf.org" <draft-ietf-isis-segment-routing-msd@ietf.org>
Thread-Topic: [Isis-wg] WG Last Call for draft-ietf-isis-segment-routing-msd-07
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Date: Thu, 21 Dec 2017 04:15:36 +0000
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Subject: Re: [Isis-wg] WG Last Call for draft-ietf-isis-segment-routing-msd-07
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Hi Xu,

I am arguing the exact opposite of what you are saying. 

Let us leave ELC/ERLD aside since it is very limited to entropy label use-case and the proposed IGP/BGP-LS encoding is very specific to that. I am not sure if this is the time anymore to revisit that.

The MSD proposal came later and I support is since I've found its use to be much more widespread and the proposed IGP/BGP-LS protocol encoding to be very efficient as an implementer of these protocols. Hence the request to not restrict it to "writable" or "imposition" cases solely. It is also not just about "readability" - which by itself is pretty meaningless. Even ERLD is about "reading" and then "doing *something specific* about it" as discussed in ietf-spring-segment-routing-mpls. 

There is no second thoughts about the IGP ELC drafts and they are very useful and necessary. Just to be clear there is *no functional or operational change* that I am arguing for here. The discussion is purely on the way to handle these encodings and whether we can use the MSD mechanism in a generalized manner. 

Thanks,
Ketan

-----Original Message-----
From: Xuxiaohu [mailto:xuxiaohu@huawei.com] 
Sent: 21 December 2017 08:10
To: Les Ginsberg (ginsberg) <ginsberg@cisco.com>om>; Ketan Talaulikar (ketant) <ketant@cisco.com>om>; Christian Hopps <chopps@chopps.org>rg>; isis-wg@ietf.org
Cc: isis-ads@ietf.org; draft-ietf-isis-segment-routing-msd@ietf.org
Subject: 答复: [Isis-wg] WG Last Call for draft-ietf-isis-segment-routing-msd-07

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:isis-wg-bounces@ietf.org] 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; isis-wg@ietf.org
> 抄送: isis-ads@ietf.org; draft-ietf-isis-segment-routing-msd@ietf.org
> 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 <chopps@chopps.org>rg>; isis-wg@ietf.org
> > Cc: isis-ads@ietf.org; draft-ietf-isis-segment-routing-msd@ietf.org
> > 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:isis-wg-bounces@ietf.org] On Behalf Of 
> > Christian Hopps
> > Sent: 20 December 2017 14:03
> > To: isis-wg@ietf.org
> > Cc: isis-ads@ietf.org; draft-ietf-isis-segment-routing-msd@ietf.org
> > 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
> > Isis-wg@ietf.org
> > https://www.ietf.org/mailman/listinfo/isis-wg
> 
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