RE: [Teas] Yangdoctors last call review of draft-ietf-teas-yang-te-topo-08

[Xufeng Liu <[e-mail]>]

Hi Rob,

While the tooling is very nice to have, especially for writing new models or converting models, we do not have to use it for every model. It seems not necessary to use the tooling on this model for now. We already know that we can manually convert it to NMDA style if needed.

Thanks,
- Xufeng

> -----Original Message-----
> From: Robert Wilton [mailto:[e-mail]]
> Sent: Wednesday, June 21, 2017 5:34 AM
> To: Xufeng Liu <[e-mail]>; Mahesh Jethanandani
> <[e-mail]>; [e-mail]
> Cc: [e-mail]; [e-mail]; [e-mail]
> Subject: Re: [Teas] Yangdoctors last call review of draft-ietf-teas-yang-te-topo-
> 08
> 
> Hi Xufeng,
> 
> On 12/06/2017 22:28, Xufeng Liu wrote:
> > Hi Mahesh,
> >
> > Thank you much for the review. We have submitted an updated draft
> (https://tools.ietf.org/html/draft-ietf-teas-yang-te-topo-09) to address these
> issues. More detailed explanations are put below inline.
> >
> > If the responses and updates are satisfactory, we are ready for the last call.
> >
> > Best regards,
> > - Xufeng
> >
> >> -----Original Message-----
> >> From: Mahesh Jethanandani [mailto:[e-mail]]
> >> Sent: Wednesday, May 24, 2017 11:44 AM
> >> To: [e-mail]
> >> Cc: [e-mail]; [e-mail];
> >> [e-mail]
> >> Subject: Yangdoctors last call review of
> >> draft-ietf-teas-yang-te-topo-08
> >>
> >> Reviewer: Mahesh Jethanandani
> >> Review result: Ready with Issues
> >>
> >> Document reviewed: draft-ietf-teas-yang-te-topo-08
> >>
> >> Status: Ready with Issues
> >>
> >> I am not an expert in Traffic Engineering. This review is looking at
> >> the draft from a YANG perspective. With that said, I have marked it as “Ready
> with Issues”
> >> because of some of the points discussed below.
> >>
> >> Summary:
> >>
> >> This document defines a YANG data model for representing, retrieving
> >> and manipulating TE Topologies. The model serves as a base model that
> >> other technology specific TE Topology models can augment.
> >>
> >> Comments:
> >>
> >> Almost all the containers in the model are presence containers. Is
> >> there a reason why they have to be presence containers? Note, that
> >> presence containers are containers whose existence itself represents
> >> configuration data. What particular configuration data is each container
> representing in itself?
> > [Xufeng] Containers that use “presence” are:
> > 	- Container “underlay”
> > 	  o  We have changed 13 occurrences of such containers to be not
> presence container.
> > 	- Container “te” under augmentation
> > 	  o  To indicate that “TE” is enabled (configuration data)
> > 	  o  Also used to do augmentation. The “presence” statement can
> prevent the mandatory child from affecting augmented base model.
> > 	- /nw:networks/nw:network/nw:network-types/te-topology!
> > 	  o  A mechanism required by I2RS topology model to specify the
> topology type.
> >
> >> It is difficult to co-relate the diagram with the model itself
> >> because of different terms being used to define different parts of the model.
> >> There is “TE Topology Model” and then there is “Generic TE Topology
> Model”.
> >> Are these one and the same models? If so, a common term for both of
> >> them would be helpful.
> > [Xufeng] Yes. These two terms are the same. Figure 12, Figure 13, and relevant
> descriptions have been updated to make the document consistent.
> >
> >> There is extensive use of groupings in the document. However, not all
> >> instances of groupings are used multiple number of times. Where they
> >> are not being repeated, it would be better to move the grouping
> >> directly where the uses statement resides. Case in point the grouping
> connectivity-label-restriction-list.
> > [Xufeng] We have removed the following groupings
> >      te-link-augment
> >      te-node-augment
> >      te-termination-point-augment
> >      te-topologies-augment
> >      te-topology-augment
> >      te-link-state-underlay-attributes
> >      te-node-state-derived-notification
> >      te-topology-type
> >
> > The remaining groupings have been kept so that we can:
> > 	- Share the groupings in this model
> > 	- Prepare to be shared by a model augmenting this model
> > 	- Prevent a grouping or configuration section from being too long
> > 	- Improve readability
> >
> >> The split between config and state containers does not seem to follow
> >> any particular pattern.
> > [Xufeng] The pattern is clear:
> > For each manageable entity (object), there is a config container and state
> container. The configurable properties go into the config container and state
> properties go into the state container. Such objects are identified by a list item
> or a presence container so that the “create”, “delete”, and “modify” operations
> can be performed on them. The non-presence containers do not represent
> configuration data so they do not introduce such objects.
> >
> >> It is neither a top level split, as is the case with existing IETF
> >> models,
> > [Xufeng] We could not do top level split because the base I2RS network
> topology model (https://tools.ietf.org/html/draft-ietf-i2rs-yang-network-topo-
> 12) that we augment does not have the top-level split (for its own reasons).
> >
> >> nor do they follow the OpenConfig style of splitting config and state
> >> under each relevant leaf,
> > [Xufeng] The pattern is consistent with this style in principle, with some
> adjustments to fit to our multiple levels of hierarchy.
> This is effectively a new forth style of YANG models that is not consistent with
> any of the three existing styles, i.e.:
>   - Current IETF config/state split model style
>   - NMDA combined config/state tree
>   - OpenConfig split config/state containers immediately above the config true
> leaves.
> 
> Tooling that it designed to work with OpenConfig models will need
> customization to work with these TE models because the config/state
> containers will not be where the tooling expects them to be.
> 
> Thanks,
> Rob