Re: [Isis-wg] =?UTF-8?B?562U5aSN?=: WG Last Call for draft-ietf-isis-segment-routing-msd-07

Jeff Tantsura <jefftant.ietf@gmail.com> Fri, 22 December 2017 19:09 UTC

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Date: Fri, 22 Dec 2017 11:09:19 -0800
From: Jeff Tantsura <jefftant.ietf@gmail.com>
To: Paul Mattes <pamattes@microsoft.com>, Xuxiaohu <xuxiaohu@huawei.com>, "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>, "Ketan Talaulikar (ketant)" <ketant@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>
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Thread-Topic: [Isis-wg] =?UTF-8?B?562U5aSN?=: WG Last Call for draft-ietf-isis-segment-routing-msd-07
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Subject: Re: [Isis-wg] =?UTF-8?B?562U5aSN?=: WG Last Call for draft-ietf-isis-segment-routing-msd-07
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Hi Paul,

Thanks for your comments!

I do see your point, at his point in time “MSD” is a common term in the industry and changing would create more confusion than good.

IETF documents provide formal definition of the terms defined in it, so for all practical reasons, a person who’s unsure about the meaning of a term, rather than trying to guess its meaning, should read the draft/RFC that defines the term and use that definition.

I understand, my explanation doesn’t quite address your comment, I do hope, if such frustrating discussion happens again, you could point to the above paragraph.

If you feel – Terminology section need more/better definitions, I’d be very grateful for your suggestions. 

Cheers,
Jeff

-----Original Message-----
From: Paul Mattes <pamattes@microsoft.com>
Date: Thursday, December 21, 2017 at 14:27
To: Jeff Tantsura <jefftant.ietf@gmail.com>om>, Xuxiaohu <xuxiaohu@huawei.com>om>, "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>om>, "Ketan Talaulikar (ketant)" <ketant@cisco.com>om>, Christian Hopps <chopps@chopps.org>rg>, "isis-wg@ietf.org" <isis-wg@ietf.org>
Cc: "isis-ads@ietf.org" <isis-ads@ietf.org>rg>, "draft-ietf-isis-segment-routing-msd@ietf.org" <draft-ietf-isis-segment-routing-msd@ietf.org>
Subject: RE: [Isis-wg] 答复:  WG Last Call for draft-ietf-isis-segment-routing-msd-07

    This is a nit about terminology, not about the underlying concepts or specific definitions, which are quite clear.
    
    I've been part of a number of frustrating discussions about the "maximum number of labels", where people seem to automatically assume that it is just one number. Sometimes they assume it is the imposition limit, and sometimes they assume it is the read depth. Calling the standardized maximum number of labels imposed "Maximum SID Depth" only spreads the confusion, since (just looking at the name) it could refer to imposition, reading or both. If I could turn back the clock, I would call MSD something like "Maximum label imposition depth" to make the distinction more obvious.
    
    This is similar to the use of the term "traffic engineering" often implying "RSVP traffic engineering", which was harmless when RSVP was the only way to do it, but now is confusing.
    
            pdm
    
    -----Original Message-----
    From: Jeff Tantsura [mailto:jefftant.ietf@gmail.com] 
    Sent: Thursday, December 21, 2017 3:27 PM
    To: Paul Mattes <pamattes@microsoft.com>om>; Xuxiaohu <xuxiaohu@huawei.com>om>; 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: Re: [Isis-wg] 答复: WG Last Call for draft-ietf-isis-segment-routing-msd-07
    
    Paul,
    
    Where is the ambiguity? MSD (type 1) is about imposition indeed, while RLD is about ability to read at a particular depth, very different concepts, used differently by the path computation logic. Please elaborate?
    
    Thanks!   
    
    Cheers,
    Jeff
    
    -----Original Message-----
    From: Paul Mattes <pamattes@microsoft.com>
    Date: Thursday, December 21, 2017 at 11:59
    To: Xuxiaohu <xuxiaohu@huawei.com>om>, "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>om>, "Ketan Talaulikar (ketant)" <ketant@cisco.com>om>, Christian Hopps <chopps@chopps.org>rg>, "isis-wg@ietf.org" <isis-wg@ietf.org>
    Cc: "isis-ads@ietf.org" <isis-ads@ietf.org>rg>, "draft-ietf-isis-segment-routing-msd@ietf.org" <draft-ietf-isis-segment-routing-msd@ietf.org>
    Subject: RE: [Isis-wg] 答复:  WG Last Call for draft-ietf-isis-segment-routing-msd-07
    Resent-From: <alias-bounces@ietf.org>
    Resent-To: <jefftant.ietf@gmail.com>om>, <uma.chunduri@huawei.com>om>, <aldrin.ietf@gmail.com>om>, <ginsberg@cisco.com>
    Resent-Date: Thu, 21 Dec 2017 11:59:34 -0800 (PST)
    
        I agree. The term "Maximum SID Depth" is ambiguous, and that it represents the maximum label-imposition depth rather than the maximum label-read depth is a historical artifact rather than an indication of its relative importance. Better that the names and acronyms should directly reflect these two distinct concepts.
        
                pdm
        
        -----Original Message-----
        From: Isis-wg [mailto:isis-wg-bounces@ietf.org] On Behalf Of Xuxiaohu
        Sent: Wednesday, December 20, 2017 8:40 PM
        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: [Isis-wg] 答复: 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://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-ietf-pce-segment-routing-11%23page-7&data=02%7C01%7Cpamattes%40microsoft.com%7C757ccfb23bad4b5e33bf08d5481c2f29%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636494208255322142&sdata=v7qCqA3gbbQSpEzlxNEVco0c9nHl1Cu6OelBNKnrTDA%3D&reserved=0) 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://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-ietf-ospf-mpls-elc&data=02%7C01%7Cpamattes%40microsoft.com%7C757ccfb23bad4b5e33bf08d5481c2f29%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636494208255322142&sdata=ejx66Ba86eQyHLwEu6m13swIFqRsWGY%2BEBqCbjNtSI8%3D&reserved=0) and (https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-ietf-isis-mpls-elc&data=02%7C01%7Cpamattes%40microsoft.com%7C757ccfb23bad4b5e33bf08d5481c2f29%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636494208255322142&sdata=JLWqLM9dZp7A5j6iDguRulWZVuHWMIUZpBDIBC81zfo%3D&reserved=0) ?
        
        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://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdat
        > > atracker.ietf.org%2Fdoc%2Fdraft-ietf-isis-segment-routing-msd%2F&dat
        > > a=02%7C01%7Cpamattes%40microsoft.com%7C757ccfb23bad4b5e33bf08d5481c2
        > > f29%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636494208255322142&
        > > sdata=jAe9BGh48%2BW7M%2B54r%2FSS3YGDvoTtfpFroVNUx4fH4AE%3D&reserved=
        > > 0
        > >
        > > which will last an extended 4 weeks to allow for year-end PTO patterns.
        > >
        > > An IPR statement exists:
        > >
        > >
        > > https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdat
        > > atracker.ietf.org%2Fipr%2Fsearch%2F%3Fsubmit%3Ddraft%26id%3Ddraft-ie
        > > tf-is&data=02%7C01%7Cpamattes%40microsoft.com%7C757ccfb23bad4b5e33bf
        > > 08d5481c2f29%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C6364942082
        > > 55322142&sdata=1cpNKOYIByZn1tpR6%2FkoNtY3SuPQT01tM%2Bkd56x51lM%3D&re
        > > served=0
        > > 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://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww
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        > > PknF9Nh0dBgJm9sItDxGDkCmCDYCM%3D&reserved=0
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