Homenet Profile of the Babel Routing Protocol
draft-ietf-homenet-babel-profile-07

[Ballot comment]
A nit comment on the metrics of the similar magnitude - there may be lessons learned from ISIS and wide style metrics as the current metric name space is quite narrow.

[Ballot comment]
Thanks for addressing my DISCUSS!  For reference, the discussion is here: https://mailarchive.ietf.org/arch/msg/homenet/A2PbWoYvxDbK0oqHFa_yPb80H9k


I do have some non-blocking comments:

(1) I think that this document walks a fine line when Normatively referring to Appendix A in rfc6126bis given that it is an informative appendix.  In general, it does a good job at it -- I do, however, have one nit: "The algorithm described in Appendix A of RFC 6126bis MAY be used."  I think that changing that to something non-normative would be good, perhaps something like "Appendix A provides an example of an algorithm..." or simply s/MAY/may

(2) This reminds me; please use rfc8174 template (for Normative language).

(3) The Non-requirements sections (2.2/3.2) are confusing to me.  Maybe it's the "negative logic"...

(3.1) What do these non-requirements represent?  Are they requirements that were considered at some point, but discarded?  Using rfc2119 language adds to the confusion -- consider describing these non-requirements not using it.

NR2, for example, is worded as a requirement that was considered, and the rationale explains why not: an "implementation of Babel MAY include support for other extensions"...this is not a requirement because "with the exception of source-specific routing, no extensions are required".  Ok.

(3.2) Are implementers to interpret that the converse is true/expected?  In the case of NR2, is a true interpretation that implementations SHOULD NOT include support for other extensions?  IOW, while the option of other extensions is not a requirement, is not having them one?

(3.3) The non-requirements in §3.2 seem a lot more confusing to me:

(3.3.1) NR3 -- The text says that the requirement not considered (non-requirement) is such that "an HNCP node that receives a DHCPv6 prefix delegation MAY announce a non-specific IPv6 default route", but the rationale says that "announcing an additional non-specific route is allowed".  I'm confused.  Is announcing the additional route ok, or not?  Is it ok to assume that optionally advertising the additional route is ok?  If it's allowed, then why is this a non-requirement?

(3.3.2) For NR4, is the non-requirement, i.e. one that was not considered, that the source-specific route SHOULD NOT be announced?  This piece is also confusing to me because the rationale says (at least the way I read it) that it may be ok to advertise.  It seems to me that the text is saying that in fact the route SHOULD NOT (or even MUST NOT be announced)...which brings me to the question: what is the requirement that was not considered?  What am I missing?

[Ballot comment]
Some very minor comments:

Substantive Comments

§2.1, REQ5: I agree with Benjamin Kaduk that " MUST use metrics that are of
  a similar magnitude" is a bit vague to be used with a MUST.

Editorial Comments:

§1.1: Please consider using the 8174 boilerplate. There is at least one instance of a lower case keyword.

§2.2 and others: I find the term "non-requirements" confusing here. Please consider "Optional Requirements".

§3, first paragraph: "separates between configuration, which is done by HNCP, and routing, which is done by Babel": The word "between" does not belong.

[Ballot discuss]
I would like to DISCUSS about the Intended Status of this document -- with the Chairs and AD.

I have to confess that I haven't been following the homenet WG as closely as I probably should have.  Hopefully that means that the topic below has been discussed and documented already, making this DISCUSS easy to resolve.

Back in 2015, the then-Chairs and the AD posted a note titled "Routing Design Team outcome and next steps"[1]; in it, they declared "rough consensus that Babel[*] shall be the “mandatory to implement” routing protocol for Homenet routers, albeit only on an Experimental basis at this time...we solicit Experimental Internet Drafts to document Homenet-specific profiles of any applicable routing solution and to report results of any relevant experimentation and implementation.  We expect that this decision will be revisited in a future Standards Track document based on specifications and running code available at that time."

My interpretation of the above text is that Babel is MTI, but that the work (documents) will be Experimental...and that this decision could change in the future (most likely towards confirming and moving to the Standards Track).  This document was originally adopted as Experimental.  I didn't find an explicit discussion on the list about changing that original overall direction, nor another declaration by the Chairs/AD.  I did find find a thread in which one of the Chairs (Barbara) asked about the status for this document (and this document only)[2]; the initial question was framed around the references being Standards Track documents (HNCP and rfc6126bis) -- just one answer came back (from the author of this document)...

I'm treating this point as a DISCUSS because I think that the WG consensus may have not been determined to change the original declaration from the Chairs/AD (from 2015).  In my interpretation of that original declaration, moving Babel to the Standards Track means a recognition that it will be *the* protocol going forward (which changes that initial "only on an Experimental basis at this time" phrase), is something that should be discussed explicitly, and not just in light of this one document.  That is the part that I haven't seen.

I note that in the conclusion of the thread about the status of this document [3] Barbara does include reasoning that may result in changing the original declaration (as does the Shepherd writeup), for example: "there exist multiple, interoperable implementations" and "no drafts proposing other homenet routing protocol profiles have been submitted"...but those points don't seem to have been considered/discussed by the WG (they were not in the original message and I didn't find another thread -- I also looked at the minutes of the last couple of IETF meetings).

To be clear, I have no objection with Babel being used in homenet applications, or with it being the Standard protocol.  My point here is that it is not clear to me that the WG explicitly reached consensus to change the declaration from the Chairs/AD.  I will be happy to clear this DISCUSS when the Chairs/AD point me to the discussion that I missed, or simply tell me that the declaration from 2015 is no longer valid and that the WG knows, or that they believe that the thread discussing this document is enough to call consensus...or something to that effect.


[1] https://mailarchive.ietf.org/arch/msg/homenet/kiI7pIYfpgT2Qrfx1VBAwng7_QY
[2] https://mailarchive.ietf.org/arch/msg/homenet/5L5WYN14gDCamP7qlknJmWkeU5M
[3] https://mailarchive.ietf.org/arch/msg/homenet/35EU8oBr8hunvvSRYUStypZIPVU

[Ballot comment]
(1) I think that this document walks a fine line when Normatively referring to Appendix A in rfc6126bis given that it is an informative appendix.  In general, it does a good job at it -- I do, however, have one nit: "The algorithm described in Appendix A of RFC 6126bis MAY be used."  I think that changing that to something non-normative would be good, perhaps something like "Appendix A provides an example of an algorithm..." or simply s/MAY/may

(2) This reminds me; please use rfc8174 template (for Normative language).

(3) The Non-requirements sections (2.2/3.2) are confusing to me.  Maybe it's the "negative logic"...

(3.1) What do these non-requirements represent?  Are they requirements that were considered at some point, but discarded?  Using rfc2119 language adds to the confusion -- consider describing these non-requirements not using it.

NR2, for example, is worded as a requirement that was considered, and the rationale explains why not: an "implementation of Babel MAY include support for other extensions"...this is not a requirement because "with the exception of source-specific routing, no extensions are required".  Ok.

(3.2) Are implementers to interpret that the converse is true/expected?  In the case of NR2, is a true interpretation that implementations SHOULD NOT include support for other extensions?  IOW, while the option of other extensions is not a requirement, is not having them one?

(3.3) The non-requirements in §3.2 seem a lot more confusing to me:

(3.3.1) NR3 -- The text says that the requirement not considered (non-requirement) is such that "an HNCP node that receives a DHCPv6 prefix delegation MAY announce a non-specific IPv6 default route", but the rationale says that "announcing an additional non-specific route is allowed".  I'm confused.  Is announcing the additional route ok, or not?  Is it ok to assume that optionally advertising the additional route is ok?  If it's allowed, then why is this a non-requirement?

(3.3.2) For NR4, is the non-requirement, i.e. one that was not considered, that the source-specific route SHOULD NOT be announced?  This piece is also confusing to me because the rationale says (at least the way I read it) that it may be ok to advertise.  It seems to me that the text is saying that in fact the route SHOULD NOT (or even MUST NOT be announced)...which brings me to the question: what is the requirement that was not considered?  What am I missing?

[Ballot comment]
Section 2.1

  REQ5: a Homenet implementation of Babel MUST use metrics that are of
  a similar magnitude to the values suggested in Appendix A of
  RFC 6126bis.

"MUST" and "similar magnitude" are not a great pairing.

I agree with the secdir reviewer that the link classification is
important, and would suggest a that SHOULD become MUST for "if it is
unable to determine whether a link is wired or wireless, it MUST
make the worst-case hypothesis".

Section 4

I always worry a little bit about the ability to classify links as
"trusted", but there are probably cases where it's valid to do so.
(Whether there are enough cases where it's valid to do so that would
provide enough use cases for this document perhaps will need to wait
for deployment experience.)

I do wonder whether it's worth enumerating the "upper-layer security
protocol"s that HNCP and Babel support, as there are tradeoffs among
the PSK/PKI/TOFU options that the implementor may need to consider.

[Ballot comment]
Just as a side note, you need to make sure that all occurances of RFC 6126bis will be replaced with the new RFC by the RFC Editor before publication.

[Ballot comment]
Just as a side note, you need to make sure that all occurances of RFC 6126bis will be replaced with the new RFC on publication by the RFC Editor before publication.

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

The IANA Services Operator has reviewed draft-ietf-homenet-babel-profile-05, which is currently in Last Call, and has the following comments:

We understand that this document doesn't require any registry actions.

While it's often helpful for a document's IANA Considerations section to remain in place upon publication even if there are no actions, if the authors strongly prefer to remove it, we do not object.

If this assessment is not accurate, please respond as soon as possible.

Thank you,

Sabrina Tanamal
Senior IANA Services Specialist

The following Last Call announcement was sent out (ends 2018-02-26):

From: The IESG
To: IETF-Announce
CC: homenet-chairs@ietf.org, draft-ietf-homenet-babel-profile@ietf.org, Barbara Stark , homenet@ietf.org, bs7652@att.com, terry.manderson@icann.org
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Homenet profile of the Babel routing protocol) to Proposed Standard


The IESG has received a request from the Home Networking WG (homenet) to
consider the following document: - 'Homenet profile of the Babel routing
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
ietf@ietf.org mailing lists by 2018-02-26. 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 defines the subset of the Babel routing protocol and
  its extensions that a Homenet router must implement, as well as the
  interactions between HNCP and Babel.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-homenet-babel-profile/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-homenet-babel-profile/ballot/


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 is requested and indicated in the title page header. It is proper because all required elements of this profile are Proposed Standard with multiple interoperable implementations, there are no competing proposals, and no WG member objected at end of 2017 when asked if this should be changed to Proposed Standard.

(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 defines the subset of the Babel routing protocol [RFC6126bis] and its extensions that a Homenet router must implement, as well as the interactions between HNCP [RFC7788] and Babel.

Working Group Summary:

When this draft was adopted by the WG in 2015, there was extremely contentious debate regarding what protocol to select as the recommended homenet routing protocol. It was agreed at that time that this draft would be adopted as Experimental. Over the past 2 years, no other homenet routing protocol profiles have been proposed. The Babel protocol has completed WG Last Call as a Proposed Standard in babel WG.

There has also been considerable debate related to recommendations for securing the Babel protocol and HNCP [RFC7788]. There appears to be general agreement that it is acceptable to allow these protocols to operate without encryption or signatures in the homenet environment. This is not meant to preclude further work on cryptographically securing both protocols; the homenet and babel WGs are continuing work on this.

Document Quality:

Are there existing implementations of the protocol? Have a significant number of vendors indicated their plan to implement the specification? Are there any reviewers that merit special mention as having done a thorough review, e.g., one that resulted in important changes or a conclusion that the document had no substantive issues? If there was a MIB Doctor, Media Type or other expert review, what was its course (briefly)? In the case of a Media Type review, on what date was the request posted?

This document specifies a profile of the Babel protocol and Babel-specific HNCP protocol elements, and not a protocol itself. There are multiple, interoperable implementations of the Babel protocol (including the Babel source-specific routing extension) and HNCP protocol and of the profile defined in this draft. The number of requirements needed to specify the profile are minimal, and there have been no major changes to the profile defined in this draft. Several people have reviewed and provided comments, including one early security review (Leif Johansson). The review of the base protocol definition is being done in the babel WG.

Personnel:

Who is the Document Shepherd? Who is the Responsible Area Director?
Document Shepherd is Barbara Stark. Responsible AD is Terry Manderson.

(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 entire draft was reviewed.

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

No concerns.

(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.

Security has been of particular concern. An early security review was done by Leif Johansson.

(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.

No specific 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?

Yes.

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

No IPR has been filed.

(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?

There has been strong WG consensus that a routing protocol is needed for homenet, and that a profile definition is needed to achieve zero-configuration. Initially, the WG was very split as to which routing protocol to select. Those who had wanted another protocol (IS-IS) have been largely silent on this Babel profile. However, they also have not proposed a homenet profile for IS-IS (note that it was initially agreed to have this babel profile draft be Experimental, to allow for competing proposals). The WG as a whole does understand this document and agrees that a profile is needed to ensure zero-configuration interoperability. There is also agreement that this document describes a reasonable zero-configuration profile for Babel.

(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.)

There have been no appeal threats. No extreme discontent has been expressed since the adoption of this draft.

(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 issues or nits were found by the idnits tool or by the document shepherd.

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

Not applicable.

(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. The normative specifications are advancing normally. Of the works in progress, draft-ietf-babel-rfc6126bis is in WG Last Call and draft-ietf-babel-source-specific is an active WG draft.

(15) Are there downward normative references 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.

No.

(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 5226).

There are no IANA considerations.

(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.

None.

(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, etc.

Not applicable.

The basis of this document (draft-ietf-babel-rfc6126bis) is a Proposed Standard. There exist multiple, interoperable, open source implementations of the Babel protocol. No homenet profile for another routing protocol has been proposed. When the homenet list was asked at end of 2017 whether this document should be changed to a Proposed Standard, there were no objections raised (though there was mention of the original discussion from 2 years prior that started this document as Informational).

status set to "Experimental" to reflect the WG Chair decision to adopt Babel as the "mandatory to implement" routing protocol for Homenet networks on an experimental basis.