Thank you very much Dhruv, the text you proposed has been included.

Best regards,
Haoyu

From: Dhruv Dhody <[email protected]>
Sent: Sunday, November 21, 2021 8:22 PM
To: Haoyu Song <[email protected]>
Cc: [email protected]; [email protected]; [email protected]; 
[email protected]; [email protected]; opsawg <[email protected]>
Subject: Re: RtgDir Last Call review: draft-ietf-opsawg-ntf-10

Hi Haoyu,

Thanks for taking my comments into consideration. Focusing on the open points...


o   Something that I find missing in the document is that the network 
controller could be a valuable source of network telemetry as well. Consider a 
PCE, the controller could be a source of network-wide data, such as the 
association between network paths, cumulative network metrics, global network 
utilization, etc. The document is currently very network-device-specific (as a 
data source). My suggestion would be to handle the centralized controller 
either as a separate section or part of the control plane and management plane 
telemetry.
[HS] We hold a view on a telemetry system that it collects data from different 
network planes, in which a centralized controller, if exists,  is the host for 
the telemetry  applications and a consumer for the data. In a sense, a 
controller acquires the original data from various network planes and it might 
further process the data and even generate new data based on telemetry data for 
applications. We summarize this process as "network operation applications" in 
the framework. Is this an acceptable view?

Dhruv: In most cases that could be true. I do find it limiting to assume all 
such applications are hosted at a single central controller. Looking at figure 
3 in RFC 8309 - 
https://www.rfc-editor.org/rfc/rfc8309.html#section-4<https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.rfc-editor.org%2Frfc%2Frfc8309.html%23section-4&data=04%7C01%7Chaoyu.song%40futurewei.com%7Cf87d7c629ea14c2188ee08d9ad6fbced%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637731517699454988%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=phgAdnLv9stOKAz5kQq0Kxq5Ga30Ik5cVd1V9rh5fV8%3D&reserved=0>,
 it is possible that the bottom controller does the telemetry handling but the 
analysis and application happen at the orchestrator level.

Anyways, maybe you could add some version of the below text -

Note that in some cases the controller itself may be the source of telemetry 
data that is unique to it or derived from the telemetry data collected from the 
network elements. Some of the principles and taxonomy specific to the control 
plane and management plane telemetry could also be applied to the controller 
when it is required to provide the telemetry data to Network Operation 
Applications hosted outside. The scope of the document is focused on the 
network elements telemetry and further details related to controllers are thus 
out of scope.

o   Something else that I find missing is the multi-domain aspects. You could 
mark it as out of scope or better yet do talk about it how there could possibly 
be a hierarchy and recursive nature in your framework to handle multi-domain. 
Currently, it is mentioned in passing while describing data fusion in section 
3.4.
[HS] Multi-domain has many particular issues we think we should leave out of 
scope, although the general framework would still fit. We will make it clear in 
the new revision.

Dhruv: Looking forward to the text!


* Query
o   Section 4.1
*  In figure 2, why MIB is mentioned in the management plane only, why not 
control plane when various control plane protocols have MIBs? Similarly, there 
are forwarding statistics MIB that might work in the forwarding plane? Also, 
add SNMP and ASN.1(?) in the table corresponding to MIB.
[HS] In the text we "note that the  selected techniques [in the figure] just 
reflect the de facto state of the art and are by no means exhaustive." Here we 
only mean to provide some representatives in each category.

Dhruv: I understand that, it stood out to me because YANG was mentioned in 
other planes but not MIB.

Thanks!
Dhruv


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