Re: [alto] Opsdir early review of draft-ietf-alto-oam-yang-06

Dan Romascanu <> Wed, 26 April 2023 07:25 UTC

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From: Dan Romascanu <>
Date: Wed, 26 Apr 2023 10:25:24 +0300
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To: Jensen Zhang <>
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Subject: Re: [alto] Opsdir early review of draft-ietf-alto-oam-yang-06
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Hi Jensen,

Thank you for your email and for addressing my comments.

See in-line.



On Tue, Apr 25, 2023 at 4:01 PM Jensen Zhang <>

> Hi Dan,
> Sorry for the delay. Many thanks for your review. Please see our response
> inline below.
> On Fri, Apr 21, 2023 at 4:00 PM Dan Romascanu via Datatracker <
>> wrote:
>> Reviewer: Dan Romascanu
>> Review result: Has Nits
>> Ready with Nits
>> This document defines YANG data models for Operations, Administration, and
>> Maintenance (OAM) & Management of ALTO. The operator can use these data
>> models
>> to set up an ALTO server, create, update and remove ALTO information
>> resources,
>> manage the access control, configure server discovery, and collect
>> statistical
>> data.
>> I like this document. It is clearly written and very well structured. I
>> liked
>> the description of requirements, the information model corresponding to
>> the
>> requirements, and the extension example modules in the Appendices. These
>> are
>> all very useful for operators who need to understand and use the YANG
>> modules.
>> Understanding and using this document requires a good knowledge of ALTO.
>> My review is focused on the design and data modelling issues relevant for
>> operations and manageability. I did not perform a YANG review, I assume
>> that
>> YANG Doctors review is performed separately.
>> This document is Ready with a couple of editorial comments.
>> Editorial & Nits:
>> 1. There are many more acronyms not included in Section 3 or expanded at
>> first
>> occurrence. Maybe the respective acronyms sections in the ALTO documents
>> should
>> be mentioned / referred
> Thanks for pointing out this issue. We have included all the acronyms that
> occur in the document in Sec 3. You can check the changes in our early edit
> [1].
> [1]:
> But we are not sure if the acronyms that only occur in the YANG modules
> should also be included.

I believe that the answer is yes. There is no other separate abbreviations
section for the YANG modules.

>> 2. In Section
>> > In practice, multiple ALTO servers can be deployed for scalability.
>>    That may require communication among different ALTO servers.
>>    The "ietf-alto" module does not contain any configuration for the
>>    communication between peer ALTO servers.  Instead, it provides the
>>    configuration for how an ALTO server can be discovered by another
>>    ALTO server on demand (Figure 6).
>> I understand that the communication between ALTO servers is out of scope.
>> However, I do not understand how is the scalability requirement met. Is
>> there /
>> Will there be another YANG module to define this data model? Something
>> else
>> than YANG? Maybe this is described in another ALTO document that I did
>> not find.
> The scalability requirement is not explicitly defined in this document. It
> looks like a part of R1 but is not mandatory.
> And I am not quite sure what is the scalability requirement that you
> mentioned here. There can be two kinds of scalability issues:
> 1. The scalability of a large number of network domains and elements. This
> issue requires the deployment of multiple ALTO server instances in
> different domains and communications among different ALTO servers in
> different domains. WG is still discussing the related topic [2]. The
> solution is not mature. So we consider it to be out of the scope of this
> document.
> [2]:
> 2. The scalability of a large number of client connections. i.e., the load
> balance issue. This may need some autoscaling or load-balancing
> configuration parameters. Is this what you want to add?

I was referring to the scalability issue mentioned in the document in the
sentence 'In practice, multiple ALTO servers can be deployed for
scalability.'. This seems to be related to issue #1 in your answer. If the
solution is considered not mature at this stage, maybe you should mention
just that in the document, to explain why it is out of scope.

> Thanks,
> Jensen