Hi, Deepak,

Thanks a lot for bring this to IETF, I’d like to comment on the #3 requirement 
you mentioned below, regarding the use of templates, I believe this is related 
to your slides from #11 to #14.

First, I think the default and mandatory statements defined in the YANG modules 
should follow the way it is supposed to be, it doesn’t make a lot of sense to 
me to remove them simply because we have issues when using them in template 
mechanism. Slide #13 (e.g., “Hence solving these issues requires new modules 
without mandatories and defaults”) seems to indicate that you’re finding ways 
to remove the default and mandatory statements in published modules, but I feel 
this should not be right way to go.

I guess I don’t really understand the issues you are describing here, I fully 
agree that the results should be a merge of the template and values explicitly 
provided, with the latter ones taking precedence over the template. But for the 
default configuration, the slides mentioned “A default statement will (silently 
!) overrule a different value coming from the template if not explicitly 
configured to repeat the template value.” To me, this is not the always the 
case, and it would probably depend on the with-defaults basic mode defined in 
RFC 6243 which defines how a server handles the default data. For example, if 
it is “report-all” basic mode, the server would consider every data node with a 
schedule default value to exist, and then it would probably override a template 
value silently; but if the server uses a “explicit” basic mode,  it won’t 
consider the default data to exist until it is explicitly provided by the 
client, so it feels to me that what is configured in the template should become 
the final merged result.

For mandatory node, could you please clarify a little bit on why “A mandatory 
statement forces an ONU instance to repeat a data node already configured in 
the template”? For validation purpose? But I think it is the merged results 
that should be subject to validation.

I am sorry if I have any misunderstandings, I would wait for your I-D and see 
if that helps understand it better. Thanks.

Best Regards,
Qiufang
From: Deepak Rajaram (Nokia) <[email protected]>
Sent: Tuesday, July 23, 2024 4:52 PM
To: [email protected]
Subject: [netmod] Yang Scalability

Dear all

Thanks for the opportunity to present on yang scalability, this is a follow-up 
after having briefly introduced the real-life YANG scalability and performance 
challenges layed out in the Broadband Forum liaison.

I would encourage NETMOD participants to go over the slides in the meeting 
materials section of ietf-120/netmod. 
slides-120-netmod-10-bbf-liaison-on-management-at-scale-projects<https://datatracker.ietf.org/meeting/120/materials/slides-120-netmod-10-bbf-liaison-on-management-at-scale-projects>

Short summary:

Based on studies conducted by several Broadband Forum meeting participants, it 
is found that existing standard YANG implementations do not scale up to 
configurations that contain a very high number of interfaces; for instance in a 
Passive Optical Network, a single Optical Line Termination (OLT) can easily 
surpass 30.000 interfaces (i.e. a few per Optical Network Unit). This is a real 
challenge for network deployments. We are seeing scaling challenges in terms of 
datastore sizes and datastore manipulations (slow configuration, slow data 
retrieval).

While a PON network is taken as an example, it’s more than likely this scaling 
challenge will find its way to other parts of networks as products and industry 
evolves.

We believe this is something NETMOD needs to address with urgency.

As a result of the study, to address such scalability issues, few salient 
points were analyzed and translated into following requirements:


  1.  “Clustering” data nodes
  2.  Reducing datastore size by using shared profiles
  3.  Reducing datastore size by using “templates”

Existing ietf-schema-mount (RFC8528<https://www.rfc-editor.org/rfc/rfc8528>) 
and the new draft of full: 
embed<https://datatracker.ietf.org/doc/draft-jouqui-netmod-yang-full-include/> 
definitely prove to be useful for certain aspects, including reusability of 
modules as-is. Still, in their current form they fall short for overcoming the 
scalability issues, which we believe can be mitigated using “templates” and 
profiles.

I expect a more detailed ID will be brought forward explaining the proposal of 
templates/profiles. In anticipation of this ID, I would welcome the group to go 
over the slides for more details on the concepts. Any feedback/suggestions are 
more than welcome 😊

Regards
Deepak

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