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:[email protected]]
Sent: Thursday, December 21, 2017 3:27 PM
To: Paul Mattes <[email protected]>; Xuxiaohu <[email protected]>; Les
Ginsberg (ginsberg) <[email protected]>; Ketan Talaulikar (ketant)
<[email protected]>; Christian Hopps <[email protected]>; [email protected]
Cc: [email protected]; [email protected]
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 <[email protected]>
Date: Thursday, December 21, 2017 at 11:59
To: Xuxiaohu <[email protected]>, "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: RE: [Isis-wg] 答复: 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: 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:[email protected]] On Behalf Of Xuxiaohu
Sent: Wednesday, December 20, 2017 8:40 PM
To: Les Ginsberg (ginsberg) <[email protected]>; Ketan Talaulikar (ketant)
<[email protected]>; Christian Hopps <[email protected]>; [email protected]
Cc: [email protected]; [email protected]
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:[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://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
> > [email protected]
> > https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww
> > .ietf.org%2Fmailman%2Flistinfo%2Fisis-wg&data=02%7C01%7Cpamattes%40m
> > icrosoft.com%7C757ccfb23bad4b5e33bf08d5481c2f29%7C72f988bf86f141af91
> > ab2d7cd011db47%7C1%7C0%7C636494208255322142&sdata=LLhn%2B5j%2BWIqR0R
> > PknF9Nh0dBgJm9sItDxGDkCmCDYCM%3D&reserved=0
>
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