Re: [yang-doctors] Common rules for TE-related YANG modules prefixes (was Yangdoctors last call review of draft-ietf-ccamp-otn-topo-yang-11)

tom petch <> Wed, 21 October 2020 09:32 UTC

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From: tom petch <>
To: Italo Busi <>, "''" <>, "" <>
CC: "" <>, "" <>, "" <>
Thread-Topic: Common rules for TE-related YANG modules prefixes (was Yangdoctors last call review of draft-ietf-ccamp-otn-topo-yang-11)
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Date: Wed, 21 Oct 2020 09:32:38 +0000
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Subject: Re: [yang-doctors] Common rules for TE-related YANG modules prefixes (was Yangdoctors last call review of draft-ietf-ccamp-otn-topo-yang-11)
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From: CCAMP <> on behalf of Italo Busi <>
Sent: 21 October 2020 09:26
To: ''org';

Hi all,

We have got a YANG doctor review comment on OTN topology YANG model advocating that "modules from a common group could use some common and obvious rules for prefixes" (see mail below).

While the comment seems reasonable to us, we have noted that, up to now, there are no such rules, as summarized in this table:

There are no such rules, as in YANG Guidelines, but it is a good idea, probably taken as read by those who have been around the block a few times and have had to live with the (lack of) naming conventions in older management software, and incorporated automatically by such; and it has been regularly commented on by those reviewing YANG modules.  I have made such comments recently on BGP and on NSF modules.

But it should be noted that this is a multidimensional issue whereas the suggested changes below only take traffic engineering into account, as if that was the only attribute that matters.  I think this  wrong.  Thus which matters more, that modules have traffic engineering in common or that they have e.g. WSON in common?  I think that latter matters more in making it easier for users to understand so no, nothing else should start with te.   Note too that there is often a separate types module and many such use a suffix of the letter 't'  for this so having 'tet' somewhere in the string I also think likely to confuse.

Tom Petch

TE      OTN     WSON    Flexi-Grid      ETH-TE  MPLS-TE
Topology        tet     otntopo wson    flexi-grid      ethtetopo       tet-mpls
Tunnel  te      otn-tunnel      wson-tunnel     flexi-grid-media-channel        eth-tunnel      te-mpls
Path Computation        te-pc

In order to have such common rules, the prefixes could be changed as:

TE      OTN     WSON    Flexi-Grid      ETH-TE  MPLS-TE
Topology        tet     tet-otn tet-wson        tet-flexig      tet-eth tet-mpls
Tunnel  te      te-otn  te-wson te-flexig       te-eth  te-mpls
Path Computation        tep     tep-otn tep-wson        tep-flexig      tep-eth tep-mpls

It is worth noting that

  *   the prefix used by TE topology cannot be changed since it has been already published as RFC8795
  *   we do not know whether we can change the prefix for the WSON topology since the draft has already passed IETF Last Call (our assumption is that this would still be possible)

We would like to gather CCAMP and TEAS WGs opinion about whether:

  1.  Having common rules for TE YANG modules is valuable
  2.  The proposed prefixes are acceptable

Aihua, Haomian and Italo (on behalf of co-authors)

-----Original Message-----
From: Radek Krejčí via Datatracker []
Sent: venerdì 16 ottobre 2020 15:33
Subject: Yangdoctors last call review of draft-ietf-ccamp-otn-topo-yang-11

Reviewer: Radek Krejčí
Review result: Ready with Issues

This is my yang doctor review of draft draft-ietf-ccamp-otn-topo-yang-11 with the ietf-otn-topology@2020-09-21 YANG module.

Despite the size of the module, its structure is very simple repeatedly following a pattern of augmenting ietf-te-topology by groupings defined in ietf-layer1-types module.

Datatracker's validation with yanglint reports a number of warnings, but they are false positive (fixed in yanglint 1.9.16 - the fixed version still reports warnings, but they are all from the imported ietf-layer1-type module).

My only note to the module itself is about the two defined groupings - I'm not sure about the reusability of the groupings in other modules. If the reusability is not the concern, I don't see any reason to define them.

Regarding the draft, as a reader, I would appreciate a more targeted description in section 3. Instead of just dumping the tree diagram in section 3.2, it would be useful to split it into several areas with some brief descriptions and examples.

The list of paths is introduced in Section 6 as "the subtrees and data nodes and their sensitivity/vulnerability", but I don't see explained/described the mentioned sensitivity/vulnerability of those paths.

The prefix of the YANG module (also referred to in Section 7 ) - 'otntopo' - seems inconsistent to me. The relevant ietf-te-topology has 'tet' (so I would expect 'otnt' here), on the other hand, the ietf-otn-tunnel has 'otn-tunnel'
prefix (then I would expect 'otn-topo' prefix here). The 'otntopo' seems to introduce just another format. As a reader/user, I would prefer if the modules from a common group could use some common and obvious rules for prefixes.