A Cost Mode Registry for the Application-Layer Traffic Optimization (ALTO) Protocol
RFC 9274

Received changes through RFC Editor sync (created alias RFC 9274, changed abstract to 'This document creates a new IANA registry for tracking cost modes supported by the Application-Layer Traffic Optimization (ALTO) Protocol. Also, this document relaxes a constraint that was imposed by the ALTO specification on allowed cost mode values.

This document updates RFC 7285.', changed pages to 7, changed standardization level to Proposed Standard, changed state to RFC, added RFC published event at 2022-07-26, changed IESG state to RFC Published, created updates relation between draft-ietf-alto-cost-mode and RFC 7285)

[Ballot comment]
Old DISCUSS:

Probably an easily answered issue, but I am not too familiar with ALTO.

    The string MUST be no more than 32 characters, and it MUST NOT contain characters other than [...]

Are there implementations that already deployed a cost string with more than 32 characters or characters not in this newly imposed set of characters? What should happen if that is in use? That is, is this protocol modification potentially breaking interoperability with older implementations?

[previously all values were numerical or ordinal, which would not exceed 32 chars, nor allow non-ascii digit characters, so this string restriction is orthogonal to old types and not a new restriction on old types. Also, generic error handling is defined on how to deal with strings that are too long or have wrong characters.]

While no fan of "patch RFCs", thank you for at least putting the OLD and NEW text in one document, so an implementer and reviewer doesn't have to switch between documents and get confused about what was read was the old doc or new doc.

That said, patching in the text "This document" feels a little weird. What RFC does "This document" then refer to?
Perhaps change "This document defines two cost modes" to "Two cost modes are defined".

    Future documents that define a new cost mode SHOULD indicate

I think that SHOULD can be a MUST. Although one could question the 2119 usage as it seems to be a directive to a document author and not a protocol action. So I would also be okay with lowercasing this.

[Ballot comment]
Thanks for addressing my DISCUSS position.

A minor suggestion: In Section 5, include the table of initial values after you've defined the required fields.

[Ballot discuss]
Paul said:

> I think that SHOULD can be a MUST. Although one could question the 2119 usage as it seems to be a directive to a document author and not a protocol action. So I would also be okay with lowercasing this.

I'm ambivalent about the first sentence, but I concur strongly with the second; use of BCP 14 language to establish a requirement against some future document seems quite unconventional to me.  Can we talk about why this is necessary and/or appropriate?

[Ballot discuss]
Probably an easily answered issue, but I am not too familiar with ALTO.

    The string MUST be no more than 32 characters, and it MUST NOT contain characters other than [...]

Are there implementations that already deployed a cost string with more than 32 characters or characters not in this newly imposed set of characters? What should happen if that is in use? That is, is this protocol modification potentially breaking interoperability with older implementations?

[Ballot comment]
While no fan of "patch RFCs", thank you for at least putting the OLD and NEW text in one document, so an implementer and reviewer doesn't have to switch between documents and get confused about what was read was the old doc or new doc.

That said, patching in the text "This document" feels a little weird. What RFC does "This document" then refer to?
Perhaps change "This document defines two cost modes" to "Two cost modes are defined".

    Future documents that define a new cost mode SHOULD indicate

I think that SHOULD can be a MUST. Although one could question the 2119 usage as it seems to be a directive to a document author and not a protocol action. So I would also be okay with lowercasing this.

[Ballot comment]
Thank you to Stephen Farrell for the SECDIR review.

Section 4 specifies an assignment policy of “IETF Review.”  To double-check, you also do not want a designated expert too?

[Ballot comment]
# ART AD Review of draft-ietf-alto-cost-mode-03

cc @fpalombini

Thank you for the work on this document.

Many thanks to Jaime Jimenez for his ART ART review: https://mailarchive.ietf.org/arch/msg/art/AdWmf0LOQ2JPGOZRQWVqTczvlwA/, and thanks to the authors for addressing his comment.

I only have one comment about the IANA section - I do not believe it rises as a DISCUSS, but I strongly think it should be addressed before publication.

Francesca

## Comments

### IANA considerations

Section 4:
>  This document requests IANA to create a new subregistry entitled
>  "ALTO Cost Modes" under the "Application-Layer Traffic Optimization
>  (ALTO) Protocol" registry available at [ALTO].

Please add a paragraph going over the different fields in the registry, listing them and providing a short description.

In the definition for the "Identifier" field you should either repeat or point to the constraints defined in Section 3.2, including the fact that identifiers prefixed with "priv:" are reserved for Private Use (Section 4.1 of [RFC8126]) (which I believe is more precise than just saying "_Cost modes_ prefixed with "priv" are reserved ..." at the end of the section).


## Notes

This review is in the ["IETF Comments" Markdown format][ICMF], You can use the
[`ietf-comments` tool][ICT] to automatically convert this review into
individual GitHub issues.

[ICMF]: https://github.com/mnot/ietf-comments/blob/main/format.md
[ICT]: https://github.com/mnot/ietf-comments

[Ballot comment]
# GEN AD review of draft-ietf-alto-cost-mode-03

CC @larseggert

Thanks to Roni Even for the General Area Review Team (Gen-ART) review
(https://mailarchive.ietf.org/arch/msg/gen-art/xlaIzXHKY1NzjJRJpuXpzKwP4rc).

## Comments

### Section 1, paragraph 4
```
    Additional cost modes are required for specific ALTO deployment cases
    (e.g., [I-D.ietf-alto-path-vector]).  In order to allow for such use
    cases, this document relaxes the constraint imposed by the base ALTO
    specification on allowed cost modes (Section 3) and creates a new
    ALTO registry to track new cost modes (Section 4).
```
I second Rob's DISCUSS, i.e., it's not clear at all that current ALTO
implementations will handle this protocol parameter now taking on
values other than "numerical" or "ordinal" without explicit
negotiation.

I will let Rob hold the DISCUSS, but will monitor the discussion to
see if this issue will be addressed.

## Notes

This review is in the ["IETF Comments" Markdown format][ICMF], You can use the
[`ietf-comments` tool][ICT] to automatically convert this review into
individual GitHub issues. Review generated by the [`ietf-reviewtool`][IRT].

[ICMF]: https://github.com/mnot/ietf-comments/blob/main/format.md
[ICT]: https://github.com/mnot/ietf-comments
[IRT]: https://github.com/larseggert/ietf-reviewtool

[Ballot discuss]
Hi,

This is a "discuss" discuss, as in I'm not sure the document is wrong, but I thought that it would be helpful to flag this for further discussion.

In RFC 7285, cost-mode is defined as a field that MUST take one of two string values, either "numerical" or "ordinal".  I'm not really familiar with RFC 7285, and in particular, whether a receiver is required to explicitly check that the received data must take one of these two values, or whether a reasonable implementation could check for a single value, and if doesn't match that value assume that it must be the other value (since there are only two allowed values).  Obviously, moving to more than two values could then cause this assumption to break in existing implementations.  Was this issue considered and discussed by the WG?  It looks like alto does support a versioning mechanism (i.e., by defining new media types) that might allow the definition of this field to be upgraded in a safer way.  Was that approach considered?

Regards,
Rob

(BEGIN IANA COMMENTS)

IESG/Authors/WG Chairs:

The IANA Functions Operator has completed its review of draft-ietf-alto-cost-mode-02. If any part of this review is inaccurate, please let us know.

The IANA Functions Operator has a question about one of the actions requested in the IANA Considerations section of this document.

The IANA Functions Operator understands that, upon approval of this document, there is a single action which we must complete.

A new registry is to be created called the ALTO Cost Modes registry. The new registry will be created on the Application-Layer Traffic Optimization (ALTO) Protocol registry page located at:

https://www.iana.org/assignments/alto-protocol/

The new registry will be managed via IETF Review as defined in RFC8126 with one exception:

Cost modes prefixed with "priv:" are reserved for Private Use.

There are initial registrations in the new registry as follows:

+===========-+=============================+====================+
| Identifier | Description | Intended Semantics |
+============+=============================+====================+
| numerical | Indicates that numerical | Section 6.1.2.1 |
| | operations can be performed | of RFC7285 |
| | on the returned costs | |
+------------+-----------------------------+--------------------+
| ordinal | Indicates that the cost | Section 6.1.2.2 |
| | values in a cost map | of RFC7285 |
| | represent ranking | |
+------------+-----------------------------+--------------------+

IANA Question --> Should the References for these registrations be the same as the Intended Semantics? If not, what should the references be?

The IANA Functions Operator understands that this is the only action required to be completed upon approval of this document.

Note: The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is meant only to confirm the list of actions that will be performed.

For definitions of IANA review states, please see:

https://datatracker.ietf.org/help/state/draft/iana-review

Thank you,

Michelle Thangtamsatid
IANA Services Specialist

(END IANA COMMENTS)

The following Last Call announcement was sent out (ends 2022-05-13):

From: The IESG
To: IETF-Announce
CC: alto-chairs@ietf.org, alto@ietf.org, draft-ietf-alto-cost-mode@ietf.org, kaigao@scu.edu.cn, martin.h.duke@gmail.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (A Cost Mode Registry for the Application-Layer Traffic Optimization (ALTO) Protocol) to Proposed Standard


The IESG has received a request from the Application-Layer Traffic
Optimization WG (alto) to consider the following document: - 'A Cost Mode
Registry for the Application-Layer Traffic Optimization
  (ALTO) Protocol'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
last-call@ietf.org mailing lists by 2022-05-13. Exceptionally, comments may
be sent to iesg@ietf.org instead. In either case, please retain the beginning
of the Subject line to allow automated sorting.

Abstract


  This document creates a new IANA registry for tracking cost modes
  supported by the Application-Layer Traffic Optimization (ALTO)
  protocol.  Also, this document relaxes a constraint that was imposed
  by the ALTO specification on allowed cost mode values.

  This document updates RFC 7285.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-alto-cost-mode/



No IPR declarations have been submitted directly on this I-D.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
Standard, Informational, Experimental, or Historic)? Why is this the proper type
of RFC? Is this type of RFC indicated in the title page header?

Proposed Standard.  This is appropriate because this document
updates RFC 7285 (published as Proposed Standard), specifying a mechanism to
define new cost mode values. The type of RFC is indicated in the title page
header.

(2) The IESG approval announcement includes a Document Announcement Write-Up.
Please provide such a Document Announcement Write-Up. Recent examples can be
found in the "Action" announcements for approved documents. The approval
announcement contains the following sections:

Technical Summary:

This document creates a new IANA registry for tracking cost modes supported by
the Application-Layer Traffic Optimization (ALTO) protocol. Also, this document
relaxes a constraint that was imposed by the ALTO specification on allowed cost
mode values.

Working Group Summary:

This document was first proposed on March 4, 2022, as a solution to move forward
the path vector document [1], where a new cost mode is required but RFC 7285
does not provide such extensibility. It was adopted as a WG document on March
17, after a Call for Adoption on the mailing list.

During Call for Adoption [2], Adrian [2.1] suggested to add a "description"
attribute for the new IANA registry. The suggestion is adopted in the WG
revision. Dhruv suggested to follow the format of other ALTO registry types
defined in RFC 7285 [2.2] and initiated the discussion on the use of "priv:".

Some editorial comments were made but no controversy was raised during the Call
for Adoption [2] and Working Group Last Call [3].

Document Quality:

The document has been discussed on the mailing list and there is clear consensus
to standardize the document. A WGLC [3] was issued on March 25, 2022. It
received 3 reviews where editorial comments were produced by Peng Liu, Jordi
Ros-Giralt and Qiao Xiang. The comments have been addressed in the -01 version
(April 11). A shepherd review was posted to the mailing list [4] on April 16 and
the -02 version has been submitted to address the review comments.

Personnel:

Kai Gao was appointed as the Document Shepherd and Martin Duke is the
Responsible Area Director.

(3) Briefly describe the review of this document that was performed by the
Document Shepherd. If this version of the document is not ready for publication,
please explain why the document is being forwarded to the IESG.

The document is well written: the motivation is clear and the proposed mechanism
is clean. Comments raised in Call for Adoption and WGLC are already addressed in
the latest revision. During the shepherd review, the following comments were
proposed and address in -02. Given that we have sufficient reviews (6 individual
reviewers from the WG) for the document, I think the draft is ready for
publication.

Comments in Shepherd Review:

Section 3.1, last paragraph: The document uses BCP 14 keyword "SHOULD" but does
not specify how to handle the case when the behavior is not specified. Either
the "SHOULD" keyword is replaced by "MUST" or an additional sentence is
required, e.g.,

NEW:
    Otherwise, the new cost mode applies to all cost metrics.

Section 4:

I also agree with Dhruv's comment that the contents of the "ALTO Cost Modes"
registry should be better specified. While the initial entries set good examples
of how to register a new cost mode, it can still be helpful if the format and
content of each field are specified in more details, e.g., using similar
specifications in Sections 14.2 and 14.3 of RFC 7285 (as suggested by Dhruv).

I would also suggest the "Specification" field be renamed to "Intended
Semantics", to be consistent with other ALTO registries (in RFC 7285 and in the
unified property draft).

(4) Does the document Shepherd have any concerns about the depth or breadth of
the reviews that have been performed?

No.

(5) Do portions of the document need review from a particular or from broader
perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or
internationalization? If so, describe the review that took place.

No.

(6) Describe any specific concerns or issues that the Document Shepherd has with
this document that the Responsible Area Director and/or the IESG should be aware
of? For example, perhaps he or she is uncomfortable with certain parts of the
document, or has concerns whether there really is a need for it. In any event,
if the WG has discussed those issues and has indicated that it still wishes to
advance the document, detail those concerns here.

The shepherd does not raise any concerns or issues.

(7) Has each author confirmed that any and all appropriate IPR disclosures
required for full conformance with the provisions of BCP 78 and BCP 79 have
already been filed. If not, explain why?

No known IPR is related to the document.

(8) Has an IPR disclosure been filed that references this document? If so,
summarize any WG discussion and conclusion regarding the IPR disclosures.

The authors have confirmed that they are not aware of any IPR related to the
document. See [5].

(9) How solid is the WG consensus behind this document? Does it represent the
strong concurrence of a few individuals, with others being silent, or does the
WG as a whole understand and agree with it?

The document has received strong consensus from the working group.

(10) Has anyone threatened an appeal or otherwise indicated extreme discontent?
If so, please summarise the areas of conflict in separate email messages to the
Responsible Area Director. (It should be in a separate email because this
questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this document. (See
http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist).
Boilerplate checks are not enough; this check needs to be thorough.

No nits are raised by the ID nits tool.

(12) Describe how the document meets any required formal review criteria, such
as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

Do not apply.

(13) Have all references within this document been identified as either
normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative references
exist, what is the plan for their completion?

No.

(15) Are there downward normative references (see RFC 3967)? If so, list these
downward references to support the Area Director in the Last Call procedure.

No.

(16) Will publication of this document change the status of any existing RFCs?
Are those RFCs listed on the title page header, listed in the abstract, and
discussed in the introduction? If the RFCs are not listed in the Abstract and
Introduction, explain why, and point to the part of the document where the
relationship of this document to the other RFCs is discussed. If this
information is not in the document, explain why the WG considers it unnecessary.

This document updates RFC 7285. The updated RFC is listed on
the title page header, in the abstract and discussed in the introduction.

(17) Describe the Document Shepherd's review of the IANA considerations section,
especially with regard to its consistency with the body of the document. Confirm
that all protocol extensions that the document makes are associated with the
appropriate reservations in IANA registries. Confirm that any referenced IANA
registries have been clearly identified. Confirm that newly created IANA
registries include a detailed specification of the initial contents for the
registry, that allocations procedures for future registrations are defined, and
a reasonable name for the new registry has been suggested (see RFC 8126).

The document requires a new IANA subregistry to be created under the
"Application-Layer Traffic Optimization (ALTO) Protocol Registry" [6]. It is
consistent with Section 3 of the document, which updates RFC 7285 by relaxing
the constraints on cost mode values and providing a mechanism to specify new
cost modes. The newly created IANA subregistry is entitled "ALTO Cost
Modes", which precisely describe the meaning of entries in this registry.
Detailed specifications of two initial entries, namely "numerical" and
"ordinal", are included, which is backward compatible with RFC 7285. The
registration procedure is defined: a new entry will be assigned after approved
by IETF Review.

Editorial comments on the IANA considerations section are as mentioned in (3).

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find useful in
selecting the IANA Experts for these new registries.

Do not apply. (The new IANA registry does not require Expert Review.)

(19) Describe reviews and automated checks performed by the Document Shepherd to
validate sections of the document written in a formal language, such as XML
code, BNF rules, MIB definitions, YANG modules, etc.

Do not apply.

(20) If the document contains a YANG module, has the module been checked with
any of the recommended validation tools
(https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module comply
with the Network Management Datastore Architecture (NMDA) as specified in
RFC8342?

This document does not contain a YANG module.

[1] https://mailarchive.ietf.org/arch/msg/alto/BFM6fDzbgPuJGa8GyzrdJLWtHWo/
[2] https://mailarchive.ietf.org/arch/msg/alto/O6qbsk6FojHmTdh7Xw8qrKpBQ4w/#
[2.1] https://mailarchive.ietf.org/arch/msg/alto/QOfcu8W1OFQAt2OHjgxbOy9D38w/
[2.2] https://mailarchive.ietf.org/arch/msg/alto/B1agkfVtdu7tsad2-MzErQXMk44/
[3] https://mailarchive.ietf.org/arch/msg/alto/8phstZdfJzZDhFzV7WSneM-qhf0/
[4] https://mailarchive.ietf.org/arch/msg/alto/nnMN4OFND-ICa0t3cMXxEzZ-JoQ/
[5] https://mailarchive.ietf.org/arch/msg/alto/7mO9AqLUvN6CxHxxutyJgozJHb4/
[6] https://www.iana.org/assignments/alto-protocol/alto-protocol.xhtml

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
Standard, Informational, Experimental, or Historic)? Why is this the proper type
of RFC? Is this type of RFC indicated in the title page header?

Proposed Standard.  This is appropriate because this document
updates RFC 7285 (published as Proposed Standard), specifying a mechanism to
define new cost mode values. The type of RFC is indicated in the title page
header.

(2) The IESG approval announcement includes a Document Announcement Write-Up.
Please provide such a Document Announcement Write-Up. Recent examples can be
found in the "Action" announcements for approved documents. The approval
announcement contains the following sections:

Technical Summary:

This document creates a new IANA registry for tracking cost modes supported by
the Application-Layer Traffic Optimization (ALTO) protocol. Also, this document
relaxes a constraint that was imposed by the ALTO specification on allowed cost
mode values.

Working Group Summary:

This document was first proposed on March 4, 2022, as a solution to move forward
the path vector document [1], where a new cost mode is required but RFC 7285
does not provide such extensibility. It was adopted as a WG document on March
17, after a Call for Adoption on the mailing list.

During Call for Adoption [2], Adrian [2.1] suggested to add a "description"
attribute for the new IANA registry. The suggestion is adopted in the WG
revision. Dhruv suggested to follow the format of other ALTO registry types
defined in RFC 7285 [2.2] and initiated the discussion on the use of "priv:".

Some editorial comments were made but no controversy was raised during the Call
for Adoption [2] and Working Group Last Call [3].

Document Quality:

The document has been discussed on the mailing list and there is clear consensus
to standardize the document. A WGLC [3] was issued on March 25, 2022. It
received 3 reviews where editorial comments were produced by Peng Liu, Jordi
Ros-Giralt and Qiao Xiang. The comments have been addressed in the -01 version
(April 11). A shepherd review was posted to the mailing list [4] on April 16 and
the -02 version has been submitted to address the review comments.

Personnel:

Kai Gao was appointed as the Document Shepherd and Martin Duke is the
Responsible Area Director.

(3) Briefly describe the review of this document that was performed by the
Document Shepherd. If this version of the document is not ready for publication,
please explain why the document is being forwarded to the IESG.

The document is well written: the motivation is clear and the proposed mechanism
is clean. Comments raised in Call for Adoption and WGLC are already addressed in
the latest revision. During the shepherd review, the following comments were
proposed and address in -02. Given that we have sufficient reviews (6 individual
reviewers from the WG) for the document, I think the draft is ready for
publication.

Comments in Shepherd Review:

Section 3.1, last paragraph: The document uses BCP 14 keyword "SHOULD" but does
not specify how to handle the case when the behavior is not specified. Either
the "SHOULD" keyword is replaced by "MUST" or an additional sentence is
required, e.g.,

NEW:
    Otherwise, the new cost mode applies to all cost metrics.

Section 4:

I also agree with Dhruv's comment that the contents of the "ALTO Cost Modes"
registry should be better specified. While the initial entries set good examples
of how to register a new cost mode, it can still be helpful if the format and
content of each field are specified in more details, e.g., using similar
specifications in Sections 14.2 and 14.3 of RFC 7285 (as suggested by Dhruv).

I would also suggest the "Specification" field be renamed to "Intended
Semantics", to be consistent with other ALTO registries (in RFC 7285 and in the
unified property draft).

(4) Does the document Shepherd have any concerns about the depth or breadth of
the reviews that have been performed?

No.

(5) Do portions of the document need review from a particular or from broader
perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or
internationalization? If so, describe the review that took place.

No.

(6) Describe any specific concerns or issues that the Document Shepherd has with
this document that the Responsible Area Director and/or the IESG should be aware
of? For example, perhaps he or she is uncomfortable with certain parts of the
document, or has concerns whether there really is a need for it. In any event,
if the WG has discussed those issues and has indicated that it still wishes to
advance the document, detail those concerns here.

The shepherd does not raise any concerns or issues.

(7) Has each author confirmed that any and all appropriate IPR disclosures
required for full conformance with the provisions of BCP 78 and BCP 79 have
already been filed. If not, explain why?

No known IPR is related to the document.

(8) Has an IPR disclosure been filed that references this document? If so,
summarize any WG discussion and conclusion regarding the IPR disclosures.

The authors have confirmed that they are not aware of any IPR related to the
document. See [5].

(9) How solid is the WG consensus behind this document? Does it represent the
strong concurrence of a few individuals, with others being silent, or does the
WG as a whole understand and agree with it?

The document has received strong consensus from the working group.

(10) Has anyone threatened an appeal or otherwise indicated extreme discontent?
If so, please summarise the areas of conflict in separate email messages to the
Responsible Area Director. (It should be in a separate email because this
questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this document. (See
http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist).
Boilerplate checks are not enough; this check needs to be thorough.

No nits are raised by the ID nits tool.

(12) Describe how the document meets any required formal review criteria, such
as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

Do not apply.

(13) Have all references within this document been identified as either
normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative references
exist, what is the plan for their completion?

No.

(15) Are there downward normative references (see RFC 3967)? If so, list these
downward references to support the Area Director in the Last Call procedure.

No.

(16) Will publication of this document change the status of any existing RFCs?
Are those RFCs listed on the title page header, listed in the abstract, and
discussed in the introduction? If the RFCs are not listed in the Abstract and
Introduction, explain why, and point to the part of the document where the
relationship of this document to the other RFCs is discussed. If this
information is not in the document, explain why the WG considers it unnecessary.

This document updates RFC 7285. The updated RFC is listed on
the title page header, in the abstract and discussed in the introduction.

(17) Describe the Document Shepherd's review of the IANA considerations section,
especially with regard to its consistency with the body of the document. Confirm
that all protocol extensions that the document makes are associated with the
appropriate reservations in IANA registries. Confirm that any referenced IANA
registries have been clearly identified. Confirm that newly created IANA
registries include a detailed specification of the initial contents for the
registry, that allocations procedures for future registrations are defined, and
a reasonable name for the new registry has been suggested (see RFC 8126).

The document requires a new IANA subregistry to be created under the
"Application-Layer Traffic Optimization (ALTO) Protocol Registry" [6]. It is
consistent with Section 3 of the document, which updates RFC 7285 by relaxing
the constraints on cost mode values and providing a mechanism to specify new
cost modes. The newly created IANA subregistry is entitled "ALTO Cost
Modes", which precisely describe the meaning of entries in this registry.
Detailed specifications of two initial entries, namely "numerical" and
"ordinal", are included, which is backward compatible with RFC 7285. The
registration procedure is defined: a new entry will be assigned after approved
by IETF Review.

Editorial comments on the IANA considerations section are as mentioned in (3).

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find useful in
selecting the IANA Experts for these new registries.

Do not apply. (The new IANA registry does not require Expert Review.)

(19) Describe reviews and automated checks performed by the Document Shepherd to
validate sections of the document written in a formal language, such as XML
code, BNF rules, MIB definitions, YANG modules, etc.

Do not apply.

(20) If the document contains a YANG module, has the module been checked with
any of the recommended validation tools
(https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module comply
with the Network Management Datastore Architecture (NMDA) as specified in
RFC8342?

This document does not contain a YANG module.

[1] https://mailarchive.ietf.org/arch/msg/alto/BFM6fDzbgPuJGa8GyzrdJLWtHWo/
[2] https://mailarchive.ietf.org/arch/msg/alto/O6qbsk6FojHmTdh7Xw8qrKpBQ4w/#
[2.1] https://mailarchive.ietf.org/arch/msg/alto/QOfcu8W1OFQAt2OHjgxbOy9D38w/
[2.2] https://mailarchive.ietf.org/arch/msg/alto/B1agkfVtdu7tsad2-MzErQXMk44/
[3] https://mailarchive.ietf.org/arch/msg/alto/8phstZdfJzZDhFzV7WSneM-qhf0/
[4] https://mailarchive.ietf.org/arch/msg/alto/nnMN4OFND-ICa0t3cMXxEzZ-JoQ/
[5] https://mailarchive.ietf.org/arch/msg/alto/7mO9AqLUvN6CxHxxutyJgozJHb4/
[6] https://www.iana.org/assignments/alto-protocol/alto-protocol.xhtml

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
Standard, Informational, Experimental, or Historic)? Why is this the proper type
of RFC? Is this type of RFC indicated in the title page header?

Proposed Standard.  This is appropriate because this document
updates the Internet standard RFC 7285, specifying a mechanism to
define new cost mode values. The type of RFC is indicated in the title page
header.

(2) The IESG approval announcement includes a Document Announcement Write-Up.
Please provide such a Document Announcement Write-Up. Recent examples can be
found in the "Action" announcements for approved documents. The approval
announcement contains the following sections:

Technical Summary:

This document creates a new IANA registry for tracking cost modes supported by
the Application-Layer Traffic Optimization (ALTO) protocol. Also, this document
relaxes a constraint that was imposed by the ALTO specification on allowed cost
mode values.

Working Group Summary:

This document was first proposed on March 4, 2022, as a solution to move forward
the path vector document [1], where a new cost mode is required but RFC 7285
does not provide such extensibility. It was adopted as a WG document on March
17, after a Call for Adoption on the mailing list.

During Call for Adoption [2], Adrian [2.1] suggested to add a "description"
attribute for the new IANA registry. The suggestion is adopted in the WG
revision. Dhruv suggested to follow the format of other ALTO registry types
defined in RFC 7285 [2.2] and initiated the discussion on the use of "priv:".

Some editorial comments were made but no controversy was raised during the Call
for Adoption [2] and Working Group Last Call [3].

Document Quality:

The document has been discussed on the mailing list and there is clear consensus
to standardize the document. A WGLC [3] was issued on March 25, 2022. It
received 3 reviews where editorial comments were produced by Peng Liu, Jordi
Ros-Giralt and Qiao Xiang. The comments have been addressed in the -01 version
(April 11). A shepherd review was posted to the mailing list [4] on April 16 and
the -02 version has been submitted to address the review comments.

Personnel:

Kai Gao was appointed as the Document Shepherd and Martin Duke is the
Responsible Area Director.

(3) Briefly describe the review of this document that was performed by the
Document Shepherd. If this version of the document is not ready for publication,
please explain why the document is being forwarded to the IESG.

The document is well written: the motivation is clear and the proposed mechanism
is clean. Comments raised in Call for Adoption and WGLC are already addressed in
the latest revision. During the shepherd review, the following comments were
proposed and address in -02. Given that we have sufficient reviews (6 individual
reviewers from the WG) for the document, I think the draft is ready for
publication.

Comments in Shepherd Review:

Section 3.1, last paragraph: The document uses BCP 14 keyword "SHOULD" but does
not specify how to handle the case when the behavior is not specified. Either
the "SHOULD" keyword is replaced by "MUST" or an additional sentence is
required, e.g.,

NEW:
    Otherwise, the new cost mode applies to all cost metrics.

Section 4:

I also agree with Dhruv's comment that the contents of the "ALTO Cost Modes"
registry should be better specified. While the initial entries set good examples
of how to register a new cost mode, it can still be helpful if the format and
content of each field are specified in more details, e.g., using similar
specifications in Sections 14.2 and 14.3 of RFC 7285 (as suggested by Dhruv).

I would also suggest the "Specification" field be renamed to "Intended
Semantics", to be consistent with other ALTO registries (in RFC 7285 and in the
unified property draft).

(4) Does the document Shepherd have any concerns about the depth or breadth of
the reviews that have been performed?

No.

(5) Do portions of the document need review from a particular or from broader
perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or
internationalization? If so, describe the review that took place.

No.

(6) Describe any specific concerns or issues that the Document Shepherd has with
this document that the Responsible Area Director and/or the IESG should be aware
of? For example, perhaps he or she is uncomfortable with certain parts of the
document, or has concerns whether there really is a need for it. In any event,
if the WG has discussed those issues and has indicated that it still wishes to
advance the document, detail those concerns here.

The shepherd does not raise any concerns or issues.

(7) Has each author confirmed that any and all appropriate IPR disclosures
required for full conformance with the provisions of BCP 78 and BCP 79 have
already been filed. If not, explain why?

No known IPR is related to the document.

(8) Has an IPR disclosure been filed that references this document? If so,
summarize any WG discussion and conclusion regarding the IPR disclosures.

The authors have confirmed that they are not aware of any IPR related to the
document. See [5].

(9) How solid is the WG consensus behind this document? Does it represent the
strong concurrence of a few individuals, with others being silent, or does the
WG as a whole understand and agree with it?

The document has received strong consensus from the working group.

(10) Has anyone threatened an appeal or otherwise indicated extreme discontent?
If so, please summarise the areas of conflict in separate email messages to the
Responsible Area Director. (It should be in a separate email because this
questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this document. (See
http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist).
Boilerplate checks are not enough; this check needs to be thorough.

No nits are raised by the ID nits tool.

(12) Describe how the document meets any required formal review criteria, such
as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

Do not apply.

(13) Have all references within this document been identified as either
normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative references
exist, what is the plan for their completion?

No.

(15) Are there downward normative references (see RFC 3967)? If so, list these
downward references to support the Area Director in the Last Call procedure.

No.

(16) Will publication of this document change the status of any existing RFCs?
Are those RFCs listed on the title page header, listed in the abstract, and
discussed in the introduction? If the RFCs are not listed in the Abstract and
Introduction, explain why, and point to the part of the document where the
relationship of this document to the other RFCs is discussed. If this
information is not in the document, explain why the WG considers it unnecessary.

This document updates RFC 7285. The updated RFC is listed on
the title page header, in the abstract and discussed in the introduction.

(17) Describe the Document Shepherd's review of the IANA considerations section,
especially with regard to its consistency with the body of the document. Confirm
that all protocol extensions that the document makes are associated with the
appropriate reservations in IANA registries. Confirm that any referenced IANA
registries have been clearly identified. Confirm that newly created IANA
registries include a detailed specification of the initial contents for the
registry, that allocations procedures for future registrations are defined, and
a reasonable name for the new registry has been suggested (see RFC 8126).

The document requires a new IANA subregistry to be created under the
"Application-Layer Traffic Optimization (ALTO) Protocol Registry" [6]. It is
consistent with Section 3 of the document, which updates RFC 7285 by relaxing
the constraints on cost mode values and providing a mechanism to specify new
cost modes. The newly created IANA subregistry is entitled "ALTO Cost
Modes", which precisely describe the meaning of entries in this registry.
Detailed specifications of two initial entries, namely "numerical" and
"ordinal", are included, which is backward compatible with RFC 7285. The
registration procedure is defined: a new entry will be assigned after approved
by IETF Review.

Editorial comments on the IANA considerations section are as mentioned in (3).

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find useful in
selecting the IANA Experts for these new registries.

Do not apply. (The new IANA registry does not require Expert Review.)

(19) Describe reviews and automated checks performed by the Document Shepherd to
validate sections of the document written in a formal language, such as XML
code, BNF rules, MIB definitions, YANG modules, etc.

Do not apply.

(20) If the document contains a YANG module, has the module been checked with
any of the recommended validation tools
(https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module comply
with the Network Management Datastore Architecture (NMDA) as specified in
RFC8342?

This document does not contain a YANG module.

[1] https://mailarchive.ietf.org/arch/msg/alto/BFM6fDzbgPuJGa8GyzrdJLWtHWo/
[2] https://mailarchive.ietf.org/arch/msg/alto/O6qbsk6FojHmTdh7Xw8qrKpBQ4w/#
[2.1] https://mailarchive.ietf.org/arch/msg/alto/QOfcu8W1OFQAt2OHjgxbOy9D38w/
[2.2] https://mailarchive.ietf.org/arch/msg/alto/B1agkfVtdu7tsad2-MzErQXMk44/
[3] https://mailarchive.ietf.org/arch/msg/alto/8phstZdfJzZDhFzV7WSneM-qhf0/
[4] https://mailarchive.ietf.org/arch/msg/alto/nnMN4OFND-ICa0t3cMXxEzZ-JoQ/
[5] https://mailarchive.ietf.org/arch/msg/alto/7mO9AqLUvN6CxHxxutyJgozJHb4/
[6] https://www.iana.org/assignments/alto-protocol/alto-protocol.xhtml

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
Standard, Informational, Experimental, or Historic)? Why is this the proper type
of RFC? Is this type of RFC indicated in the title page header?

The working group is requesting a Proposed Standard. This is appropriate because
this document updates the Internet standard RFC 7285, specifying a mechanism to
define new cost mode values. The type of RFC is indicated in the title page
header.

(2) The IESG approval announcement includes a Document Announcement Write-Up.
Please provide such a Document Announcement Write-Up. Recent examples can be
found in the "Action" announcements for approved documents. The approval
announcement contains the following sections:

Technical Summary:

This document creates a new IANA registry for tracking cost modes supported by
the Application-Layer Traffic Optimization (ALTO) protocol. Also, this document
relaxes a constraint that was imposed by the ALTO specification on allowed cost
mode values.

Working Group Summary:

This document was first proposed on March 4, 2022, as a solution to move forward
the path vector document [1], where a new cost mode is required but RFC 7285
does not provide such extensibility. It was adopted as a WG document on March
17, after a Call for Adoption on the mailing list.

During Call for Adoption [2], Adrian [2.1] suggested to add a "description"
attribute for the new IANA registry. The suggestion is adopted in the WG
revision. Dhruv suggested to follow the format of other ALTO registry types
defined in RFC 7285 [2.2] and initiated the discussion on the use of "priv:".

Some editorial comments were made but no controversy was raised during the Call
for Adoption [2] and Working Group Last Call [3].

Document Quality:

The document has been discussed on the mailing list and there is clear consensus
to standardize the document. A WGLC [3] was issued on March 25, 2022. It
received 3 reviews where editorial comments were produced by Peng Liu, Jordi
Ros-Giralt and Qiao Xiang. The comments have been addressed in the -01 version
(April 11). A shepherd review was posted to the mailing list [4] on April 16 and
the -02 version has been submitted to address the review comments.

Personnel:

Kai Gao was appointed as the Document Shepherd and Martin Duke is the
Responsible Area Director.

(3) Briefly describe the review of this document that was performed by the
Document Shepherd. If this version of the document is not ready for publication,
please explain why the document is being forwarded to the IESG.

The document is well written: the motivation is clear and the proposed mechanism
is clean. Comments raised in Call for Adoption and WGLC are already addressed in
the latest revision. During the shepherd review, the following comments were
proposed and address in -02. Given that we have sufficient reviews (6 individual
reviewers from the WG) for the document, I think the draft is ready for
publication.

Comments in Shepherd Review:

Section 3.1, last paragraph: The document uses BCP 14 keyword "SHOULD" but does
not specify how to handle the case when the behavior is not specified. Either
the "SHOULD" keyword is replaced by "MUST" or an additional sentence is
required, e.g.,

NEW:
    Otherwise, the new cost mode applies to all cost metrics.

Section 4:

I also agree with Dhruv's comment that the contents of the "ALTO Cost Modes"
registry should be better specified. While the initial entries set good examples
of how to register a new cost mode, it can still be helpful if the format and
content of each field are specified in more details, e.g., using similar
specifications in Sections 14.2 and 14.3 of RFC 7285 (as suggested by Dhruv).

I would also suggest the "Specification" field be renamed to "Intended
Semantics", to be consistent with other ALTO registries (in RFC 7285 and in the
unified property draft).

(4) Does the document Shepherd have any concerns about the depth or breadth of
the reviews that have been performed?

No.

(5) Do portions of the document need review from a particular or from broader
perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or
internationalization? If so, describe the review that took place.

No.

(6) Describe any specific concerns or issues that the Document Shepherd has with
this document that the Responsible Area Director and/or the IESG should be aware
of? For example, perhaps he or she is uncomfortable with certain parts of the
document, or has concerns whether there really is a need for it. In any event,
if the WG has discussed those issues and has indicated that it still wishes to
advance the document, detail those concerns here.

The shepherd does not raise any concerns or issues.

(7) Has each author confirmed that any and all appropriate IPR disclosures
required for full conformance with the provisions of BCP 78 and BCP 79 have
already been filed. If not, explain why?

No known IPR is related to the document.

(8) Has an IPR disclosure been filed that references this document? If so,
summarize any WG discussion and conclusion regarding the IPR disclosures.

The authors have confirmed that they are not aware of any IPR related to the
document. See [5].

(9) How solid is the WG consensus behind this document? Does it represent the
strong concurrence of a few individuals, with others being silent, or does the
WG as a whole understand and agree with it?

The document has received strong consensus from the working group.

(10) Has anyone threatened an appeal or otherwise indicated extreme discontent?
If so, please summarise the areas of conflict in separate email messages to the
Responsible Area Director. (It should be in a separate email because this
questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this document. (See
http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist).
Boilerplate checks are not enough; this check needs to be thorough.

No nits are raised by the ID nits tool.

(12) Describe how the document meets any required formal review criteria, such
as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

Do not apply.

(13) Have all references within this document been identified as either
normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative references
exist, what is the plan for their completion?

No.

(15) Are there downward normative references (see RFC 3967)? If so, list these
downward references to support the Area Director in the Last Call procedure.

No.

(16) Will publication of this document change the status of any existing RFCs?
Are those RFCs listed on the title page header, listed in the abstract, and
discussed in the introduction? If the RFCs are not listed in the Abstract and
Introduction, explain why, and point to the part of the document where the
relationship of this document to the other RFCs is discussed. If this
information is not in the document, explain why the WG considers it unnecessary.

This document will change the status of RFC 7285. The updated RFC is listed on
the title page header, in the abstract and discussed in the introduction.

(17) Describe the Document Shepherd's review of the IANA considerations section,
especially with regard to its consistency with the body of the document. Confirm
that all protocol extensions that the document makes are associated with the
appropriate reservations in IANA registries. Confirm that any referenced IANA
registries have been clearly identified. Confirm that newly created IANA
registries include a detailed specification of the initial contents for the
registry, that allocations procedures for future registrations are defined, and
a reasonable name for the new registry has been suggested (see RFC 8126).

The document requires a new IANA subregistry to be created under the
"Application-Layer Traffic Optimization (ALTO) Protocol Registry" [6]. It is
consistent with Section 3 of the document, which updates RFC 7285 by relaxing
the constraints on cost mode values and providing a mechanism to specify new
cost modes. The newly created IANA subregistry is entitled "ALTO Cost
Modes", which precisely describe the meaning of entries in this registry.
Detailed specifications of two initial entries, namely "numerical" and
"ordinal", are included, which is backward compatible with RFC 7285. The
registration procedure is defined: a new entry will be assigned after approved
by IETF Review.

Editorial comments on the IANA considerations section are as mentioned in (3).

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find useful in
selecting the IANA Experts for these new registries.

Do not apply. (The new IANA registry does not require Expert Review.)

(19) Describe reviews and automated checks performed by the Document Shepherd to
validate sections of the document written in a formal language, such as XML
code, BNF rules, MIB definitions, YANG modules, etc.

Do not apply.

(20) If the document contains a YANG module, has the module been checked with
any of the recommended validation tools
(https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module comply
with the Network Management Datastore Architecture (NMDA) as specified in
RFC8342?

This document does not contain a YANG module.

[1] https://mailarchive.ietf.org/arch/msg/alto/BFM6fDzbgPuJGa8GyzrdJLWtHWo/
[2] https://mailarchive.ietf.org/arch/msg/alto/O6qbsk6FojHmTdh7Xw8qrKpBQ4w/#
[2.1] https://mailarchive.ietf.org/arch/msg/alto/QOfcu8W1OFQAt2OHjgxbOy9D38w/
[2.2] https://mailarchive.ietf.org/arch/msg/alto/B1agkfVtdu7tsad2-MzErQXMk44/
[3] https://mailarchive.ietf.org/arch/msg/alto/8phstZdfJzZDhFzV7WSneM-qhf0/
[4] https://mailarchive.ietf.org/arch/msg/alto/nnMN4OFND-ICa0t3cMXxEzZ-JoQ/
[5] https://mailarchive.ietf.org/arch/msg/alto/7mO9AqLUvN6CxHxxutyJgozJHb4/
[6] https://www.iana.org/assignments/alto-protocol/alto-protocol.xhtml