Re: [alto] Another review for draft-ietf-alto-oam-yang-07

Jensen Zhang <> Sat, 20 May 2023 15:30 UTC

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From: Jensen Zhang <>
Date: Sat, 20 May 2023 23:30:19 +0800
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To: Shenshen Chen <>
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Subject: Re: [alto] Another review for draft-ietf-alto-oam-yang-07
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Hi Shenshen,

Many thanks for your review comments. Please see my response inline.


On Sat, May 20, 2023 at 6:05 PM Shenshen Chen <>

> Hi, all
> I wrote a review for draft-ietf-alto-oam-yang-07, following the call for
> volunteers from Jordi.
> Since I am not confident with my comments, please feel free to ignore
> them. The following comments are started with the related part of the draft.
> 1. The whole draft
> It confuses me if this draft claims "a single data model" or "multiple
> models".
>     Some sentences take a single model:
>     * defines a YANG data model (Introduction)
>     * Scope of data model (title of Sec 4.1.)
>     * The data model (Table 2)
>     Some assume multiple models:
>     * YANG Data Models (title of this document)
>     * The following items are in the scope of the data models (Sec 4.1.)
> I prefer a single model (with multiple modules). By the way, there are
> some more
> "singular and plural" issues, e.g., titles of A.3. and A.5.

Thanks for catching the inconsistent words. We will go through the whole
document and fix them.

> 2. Figure 1
> The description of Figure 1 seems to be ambiguous - it presents
>     * Both the server manager and information resource manager will
>       report statistics data to performance monitor and logging and
>       fault manager.
> But Figure 1 shows that Information Resource Manager only reports to
> Logging and Fault Manager, rather than both two Managers.

Maybe the "report" label is confusing. We want to label "report" on all
four arrows from server manager and information resource manager to
performance monitor and logging & fault manager. We will refine Figure 1 to
make it clear.

> Also, the 2nd paragraph of the description presents
>     * The algorithm plugins will register callbacks to the corresponding
>       ALTO information resources upon the configuration; ...
> But I cannot find the corresponding components in Figure 1
> (I assume the "plugin" shown in Figure 1 refers to the 5th paragraph).

Not sure which components are missing here. Algorithm plugins or ALTO
information resources?

> 3. Sec 5.4.1.
> It presents
>     * If poll-interval is zero, the ALTO server will not fetch the data
> source.
> I wonder whether the poll-interval should be allowed to be zero since it
> seems cannot work.
> If it should, should we define such a mode differently from
> proactive/reactive modes?

Although I don't understand why it cannot work, I agree that it is a good
idea to move it to a different mode.

> 5. Some relationships/structures are not clear to me
> a) The R3 seems to be overlapped with R6 and R7.
> And the 'meta' defined in Sec 5.3.3. seems to be overlapped with Sec 6.2.

R3 focuses on the writable data nodes. R6 and R7 focus on the read-only
data nodes.

> b) Sec 5.3. presents "Server-level Operation and Management" and
> Sec 5.4. presents "Server Configuration Management".
> Does it mean the Management (the "M" in "O&M") consists of
> server-level management and configuration management?

Management ("M" in "O&M") is not limited to server-level management and
configuration management. RFC 6291 has more concrete descriptions of this
term. For ALTO, RFC 7285 (Sec 16) suggests 6 pieces of management
components. The server-level management in this document defines an
aggregation of multiple management components. I guess this makes you
confused. We will add a paragraph at the beginning of Sec 5.3 to clarify

> Clarifying their relationships explicitly would be helpful to me.
> And there are some minor comments:
> 1. Sec 5.1.
>     * The container 'alto-server' contains both configuration and
> operational data
> Use "configurational" to be consistent with "operational".
> 2. Figure 4
>     * IETF ALTO Server Level Subtree Structure (title)
> Use "Server-Level" to be consistent with other parts.
> 3. Sec 5.3.
>     * The ALTO server instance contains a set of data nodes server-level
> operation
>       and management for ALTO that are shown in Figure 4.
> It seems a word (e.g. "for") is missing between "nodes" and "server-level
> operation".
> 4. Sec 5.4.3.
>     * They declare the Capabilities of the ALTO information resource ...
> Use "Capabilities (Section 9.1.3 of [RFC7285])" to make it clear.
> 5. Sec 5.3.4.
>     * All the related configurations are covered by the server listen
> stack.
> Use "ALTO Server Listen Stack" to make it clear.
> 6. Sec 5.4.2.
>     * Each resource entry provides configurations defining how to create
> or update an ALTO information resource.
> This topic sentence does not mention "remove". Maybe use expressions like
> "One can create, update or remove an ALTO information resource by adding,
> updating, or removing a resource entry" or some other expressions.

Many thanks for the editing suggestions. We will consider them.

> In the end, here is a random thought: is there any concern about the
> shutdown, or just assume the ALTO server would never be deliberately shut
> down?

That's a very good point. The operation of server shutdown is not in the
scope. But the server crash should be considered. Right now, the data model
does not include any healthcheck-related data nodes explicitly. The syslog
may be used to handle this.

> Best Regards,
> Shenshen
> Shenshen Chen
> PhD student
> Tongji University
> _______________________________________________
> Email