Re: [Teas] Status update on draft-ietf-teas-yang-l3-te-topo

Xufeng Liu <xufeng.liu.ietf@gmail.com> Wed, 24 February 2021 16:54 UTC

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From: Xufeng Liu <xufeng.liu.ietf@gmail.com>
Date: Wed, 24 Feb 2021 11:54:33 -0500
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To: tom petch <ietfa@btconnect.com>
Cc: TEAS WG <teas@ietf.org>
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Subject: Re: [Teas] Status update on draft-ietf-teas-yang-l3-te-topo
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Hi Tom,

Thanks for the additional thoughts. We have posted an updated version
https://tools.ietf.org/html/draft-ietf-teas-yang-l3-te-topo-10, which
hopefully addresses these comments.

Best,
- Xufeng

On Wed, Nov 25, 2020 at 7:37 AM tom petch <ietfa@btconnect.com> wrote:

> From: Xufeng Liu <xufeng.liu.ietf@gmail.com>
> Sent: 20 November 2020 23:02
>
> Hi Tom,
> Thank you much for your further comments. We have posted
> https://datatracker.ietf.org/doc/html/draft-ietf-teas-yang-l3-te-topo-09,
> hoping to address some of your comments below.
>
> <tp>
> I have had a second go at -09 and have some more thoughts.
>
> Figure 3 I like, especially as you have achieved it in ASCII.
>
> s.2.2.3
> Can a termination point be reference with tp-id or do you have to use
> node+link as here?
>
[Xufeng]: tp-id is unique within a node, a node-ref is unique within a
network (i.e. topology), so we have to use the tuple {tip-id, node-ref,
network-id} to uniquely identify a tp-id.

>
> s.2 talks of two YANG modules when there are four; ok two are PSC but I
> think that that might be spelt out here in this section.
>
[Xufeng]: Added a paragraph.

>
> congruent is 'with' something not 'to' something, I believe
>
[Xufeng]: Changed.

>
> between the one modeling element in the layer 3 unicast topology /to/and/
>
[Xufeng]: Fixed.

>
> This YANG data model /allows/supports/ both cases.
>
[Xufeng]: Fixed.

>
> associated /to/with/ the objects in one /corresponding/corresponding
> [corresponding is what adulterers do!]
>
[Xufeng]: Fixed.

>
> Tom Petch
>
>
>
>
>
>
>
> Thanks,
> - Xufeng
>
> On Tue, Jul 14, 2020 at 7:34 AM tom petch <ietfa@btconnect.com<mailtomailto:
> ietfa@btconnect.com>> wrote:
> From: Xufeng Liu <xufeng.liu.ietf@gmail.com<mailtomailto:
> xufeng.liu.ietf@gmail.com>>
> Sent: 13 July 2020 15:29
>
> Hi Tom,
>
> Thanks for further reviewing. We have posted an updated version
> https://datatracker.ietf.org/doc/html/draft-ietf-teas-yang-l3-te-topo-08.
> Some rewording has been made, with the hope of making the document more
> comprehensible. Please let us know for anything that is still confusing
> (for such an unconventional modeling approach).
>
> <tp>
> I still find some of the terminology in this a challenge.
>
> 2.1   o  The multiplicity of such an association is: 0..1 to 0..1.
> the following sentence suggests it is '1 to 0..1'
>
> [Xufeng]: The next sentence describes the relation on an object, but such
> a description is relevant only if such an object exists. When such an
> object has not been created in the ietf-l3-te-topology, the corresponding
> layer 3 TE topology may already contain an object that can be potentially
> associated with the to-be-created object. In this case, 0 in
> ietf-l3-te-topology, and 1 in ietf-te-topology. Therefore, I’d say that
> multiplicity is still 0..1 to 0..1.
>
>
>
> 'associated to the objects in a coresponding TE topology'
> 'a' suggests there can be more than one which the YANG does not seem to
> and 2.2.1 has 'the' not 'a'
>
> [Xufeng]: Changed ‘a’ to ‘one’, hoping that “associated to the objects in
> one corresponding TE topology" would avoid the possibility of “more than
> one”.
>
> in passing 'associated with' and 'corresponding'
>
> '   Since ietf-te-topology augments ietf-network-topology defined in
> [RFC8345] [I-D.ietf-teas-yang-te-topo], the referenced leaf
>    /nw:networks/network/network-id identifies an instance of TE topology
>    by inheritance. '
> No and no!  ietf-network-topology is in one document so there should be
> only one reference or else the module name is wrong or ....
> And the referenced leaf does not identify an instance of TE Topology -
> it identifies a network of any type.  As the next sentence makes clear,
> this module has to ensure it is of the correct type and does so.
>
> [Xufeng]: Reworded the section, trying to clarify the leafref
> relationship. Please let us know if it is better.
>
> '   If the TE topology is congruent to the layer 3 unicast topology, the
>    above reference can still be used to specified TE parameters defined
>    in the TE topology model.
> I do not understand.  What parameters? I do not see any and if they were
> to be defined in TE Topology then they should not be specified here or
> anywhere else.
>
> [Xufeng]: One example of the TE parameters is te-delay-metric. Such
> parameters are defined in the TE Topology model. They are not specified in
> l3-te-topology, but they can be configured in the corresponding te-topology
> instance.
>
>
> s.2.2.2
> 'a node in the layer 3 TE topology may have a reference to the
> corresponding TE node.'
> perhaps clearer as
> 'a node in the layer  3 TE topology may have a reference to the
> corresponding node in the TE Topology.'
>
> [Xufeng]: Yes. Reworded as suggested.
>
> s.2.2.3 s.2.2.4 ditto mutatis mutandi
>
> [Xufeng]: Fixed too.
>
> More technically this I-D seems confused about prefix and inconsistent
> elsewhere
> .
> module
>      namespace "urn:ietf:params:xml:ns:yang:ietf-l3-te-topology";
>      prefix "l3tet";
> IANA
>    name:         ietf-l3-te-topology
>    namespace:    urn:ietf:params:xml:ns:yang:ietf-l3-te-topology
>    prefix:       l3te
>
> [Xufeng]: Fixed the IANA section.
>
> YANG
>        container l3-te {
>          presence "Indicates L3 TE Topology";
>
>    augment /nw:networks/nw:network/nw:network-types
>              /l3t:l3-unicast-topology:
>      +--rw l3-te!
>
> [Xufeng]: Is there anything wrong here? l3-te is the name of a container
> and is not the prefix.
>
> In passing, 'congruent with' in many places (at least in English
> English)
>
> [Xufeng]: Is it not correct? Or “congruent to” is preferred? Did a brief
> search, it seems that “congruent with” is more popular.
>
>
>
> s.3
> The YANG data  model defined in this document ...
> This document specifies two YANG modules ..
> actually three!
>
> [Xufeng]: Is the above paragraph in Sec 2: “Modeling Considerations for L3
> TE Topologies”? If so, the the description is intended to be scoped to Sec
> 2. We have two modules for L3 TE Topologies, and the other two modules are
> for Packet Switching Technology Extensions.
>
>
>
> Tom Petch
>
>
> Best regards,
> - Xufeng
>
> On Fri, May 8, 2020 at 6:06 AM tom petch <ietfa@btconnect.com<mailtomailto:
> ietfa@btconnect.com><mailto:ietfa@btconnect.com<mailto:ietfa@btconnect.com>>>
> wrote:
> From: Xufeng Liu <xufeng.liu.ietf@gmail.com<mailtomailto:
> xufeng.liu.ietf@gmail.com><mailto:xufeng.liu.ietf@gmail.com<mailto:
> xufeng.liu.ietf@gmail.com>>>
> Sent: 07 May 2020 00:22
>
> Hi Tom,
>
> Thanks for reviewing and sorry about the errors. We have posted an updated
> version https://tools.ietf.org/html/draft-ietf-teas-yang-l3-te-topo-07,
> to fix the errors about the augmentation description and to rephrase a
> couple of sections to explain the relations between the related models and
> their objects. Please let us know for anything that is not clear enough.
>
> <tp>
> Thanks for the update.  I now find s.2 s.2.1 clear but still struggle
> thereafter.  When you use layer 3 topology I find it ambiguous.  Is it
> layer 3 unicast topology or layer 3 te topology?  Thus in s.2.2.1
> "When TE is enabled on a layer 3 topology .. " implies unicast
> "congruent to the layer 3 topology .."
> implies unicast
> " the layer 3 topology will have a reference.."
>  ah, no, must be layer 3 te topology
> and this is the case throughout the rest of s.2.  I would like to see
> those references to layer 3 topology clarified, unicast or te.  You may
> want to say that layer 3 topology means ... while layer 3 ... topology will
> be spelt out in full or some such, I am easy, but do think that you need to
> use two distinct terms.
> [Xufeng]: Reworded. Please let us know if anything is confusing.
>
> As you may infer, I like to work top down, start with Abstract, then
> Introduction, then s.2 s.3 making sense of them before seeing if the module
> does what these sections say, so when I get stuck in s.2, I do not make it
> to details of the YANG module.
> [Xufeng]: Thank you much for looking at it. We are striving to get your
> review unstuck.
>
> Tom Petch
>
> Thanks,
> - Xufeng
>
> On Fri, May 1, 2020 at 6:56 AM tom petch <ietfa@btconnect.com<mailtomailto:
> ietfa@btconnect.com><mailto:ietfa@btconnect.com<mailto:ietfa@btconnect.com
> >><mailto:ietfa@btconnect.com<mailto:ietfa@btconnect.com><mailto:
> ietfa@btconnect.com<mailto:ietfa@btconnect.com>>>> wrote:
> From: Teas <teas-bounces@ietf.org<mailto:teas-bounces@ietf.org><mailto:
> teas-bounces@ietf.org<mailto:teas-bounces@ietf.org>><mailto:
> teas-bounces@ietf.org<mailto:teas-bounces@ietf.org><mailto:
> teas-bounces@ietf.org<mailto:teas-bounces@ietf.org>>>> on behalf of
> Xufeng Liu <xufeng.liu.ietf@gmail.com<mailto:xufeng.liu.ietf@gmail.com
> ><mailto:xufeng.liu.ietf@gmail.com<mailto:xufeng.liu.ietf@gmail.com
> >><mailto:xufeng.liu.ietf@gmail.com<mailto:xufeng.liu.ietf@gmail.com
> ><mailto:xufeng.liu.ietf@gmail.com<mailto:xufeng.liu.ietf@gmail.com>>>>
> Sent: 21 April 2020 21:09
>
>
> Status update on draft-ietf-teas-yang-l3-te-topo
>
> Current Status:
>
>   *  The updated revision -06 was posted on March 8, 2020:
>      - Editorial changes.
>   *  Corordinated with ietf-eth-te-topology and ietf-te-mpls-tp-topo
>      for the augmentation of ietf-te-topology
>      - ietf-te-topology does not need to be changed.
>   *  Answered YANG doctor's review comments.
>
> Open Issues:
>
>   *   None.
>
> <tp>
>
> I started  to review this and have given up,  I cannot make sense of
> section 2, which I see as fundamental to understanding the I-D.
>  Thus
> The YANG modulues  ietf-l3-te-topology ...
> These two modules augment ietf-l3-te topology
> No they don't!  This augments
> ietf-l3-unicast-topology
> which is quite different and I find this confusion elsewhere in section
> two. Thus
> Relationship  between Layer 3 Topology and TE Topology
> Is that Layer 3 TE Topology or ietf-network-topology?  I think that many
> if not most  references to TE Topology are ambiguous and need clarifying -
> is the reference to Layer 3 TE Topology to  ietf-network-topology?
>
> Some of the words are quirky and this website is determined not to let me
> put them into an e-mail but here goes.
>
> modulues
> topoology
> moducment
> Local ink
>
> Tom Petch
> Next Steps:
>
>
>   *  Update the model to sync with the referenced models like
> draft-ietf-teas-yang-te-types if there are any changes.
>   *  Welcome further reviews and suggestions.
>   *  Working Group Last Call after completing the above.
>
> Thanks,
> - Xufeng
>