Applicability of the Babel Routing Protocol
draft-ietf-babel-applicability-10

[Ballot comment]
I agree with several of my co-ADs that this document reads a lot like marketing but I don’t feel strongly enough about it to ask for specific changes.

[Ballot comment]
I agree with several other ADs that the document tries too hard to be a marketing brochure.  I do not find that sufficiently objectionable to interfere, but it would be nice to tone it down a bit.

[Ballot comment]
When a use case calls for all nodes to participate in the IGP (as
opposed to just connecting to a local point of access and letting that
router run the IGP, there may be privacy considerations regarding the
mobility/connectivity of individual nodes in the information conveyed
over the routing protocol.  It would be good to acknowledge that such
use cases may exist (or disclaim applicability to them) in this
document.

Section 1.1

It's probably worth expanding DSDV on first use.

Section 2.2

(side note: this is probably just me coming from an abstract
math/topology background and not a routing background, but the term
"non-transitive link" puzzles me a little bit.  My understanding of the
non-transitivity property is that if A has a link to B, and B has a link
to C, then it's not necessarily the case that A can get traffic to/from
C via B.  But that seems like more of a property of the node policy or
other constraints on B than of any particular link.  I can live with
being puzzled, here, but if there's a quick explanation, I'd be
interested in hearing it.)

Section 2.3

  All of the extensions designed to date interoperate with the base
  protocol and with each other.  This, again, is a consequence of the
  protocol design: in order to check that two extensions to the Babel
  protocol are interoperable, it is enough to verify that the
  interaction of the two does not violate the base protocol's
  assumptions.

As another reviewer noted, "interoperable" doesn't seem like quite the
right word; "compatible" seems potentially more appropriate, or perhaps
"usable with each other".

Section 2.4.3

  Babel's loop-avoidance mechanism relies on making a route unreachable
  after a retraction until all neighbours have been guaranteed to have
  acted upon the retraction, even in the presence of packet loss.
  Unless the optional algorithm described in Section 3.5.5 of
  [RFC6126bis] is implemented, this entails that a node is unreachable
  for a few minutes after the most specific route to it has been
  retracted.  [...]

Section 3.5.5 of draft-ietf-babel-rfc6126bis-07 seems to discuss two
different mechanismis to guarantee that no neighbor is using the current
node as next-hop for prefix P.  (1) is that the operation being referred
to here, and (2) if so, should this be "one of the mechanisms"?
Basically, I'm not sure I'm chasing the reference in the way intended.

Section 5

I think we need to couch the "most deployments" language with something
like "at the time of this writing" -- there's no guarantee that it will
remain true in perpetuity.

Given, e.g., https://www.krackattacks.com/, it's unclear to me that it's
reasonable to continue to claim that WPA2 provides a way to secure a
link layer.  (WPA3 is not shaping up to do much better, given https://www.schneier.com/blog/archives/2019/04/vulnerabilities_7.html .)

[Ballot comment]
(1) Section 2.1. This section makes a number strong claims that I would recommend be tempered:

-- Per the sentence, “Given a sufficiently friendly audience, the principles behind Babel can be explained in 15 minutes, and a full description of the protocol can be done in 52 minutes (one microcentury)”, what does this mean?  If this is to suggest to the reader that they too can learn Babel in 15 minutes, it is unconvincing and reads like a marketing statement.

-- Per the phrase, “…including one that was reportedly written and debugged in just two nights“, this statement is not convincing without context.

-- Per the sentence, “In addition to the above, our implementation experience indicates that Babel tends to be robust with respect to bugs: more often than not, an implementation bug …”, this text is an improvement over -07 (thank you), but I still view this as a high risk, anecdotal claim.  I strongly recommend it be removed.

(2) Section 2.2.  This section uses the designation of “strong” vs. a “weak” property.  Where are those defined?

(3) Section 2.2.  Per the sub-bullets of “These weak requirements make Babel a robust protocol …”, what assurance does the phrase “does most likely not” suggest?  Furthermore, the claim that implementation bugs won’t collapse the network based on an uncited “extensive” experience seems too strong of claim.

(4) Per Section 3.1.  How big is a “medium-sized hybrid network”?

(5) Per Section 3.1.  What are “meshy wireless bits”?

(6) Section 3.2.  Is there a citation for the successful deployment in “large scale overlay networks, built out of thousands of tunnels spanning continents”?

(7) Section 3.4. The utility of Babel in small and home offices surprised me as I wasn't expecting such networks to mix IPv4 and v6; and use an IGP.

(8) Section 5.  Per the sentence “Due to its simplicity, Babel-HMAC  …”, I’m not sure that simplicity should be driving the choice of the security properties.  It seems like it should be the security requirements.

[Ballot comment]
No blocking comment: 

Given the different environments where Babel can be used, it would be ideal if Operational Guidance for future deployments was provided.  For context, please see my ballot for draft-ietf-babel-applicability: https://mailarchive.ietf.org/arch/msg/babel/o-yj5D9vXa2Th9orObWDh-heEU8

[Ballot comment]
Thanks for writing this document and the recent updates. While it is an easy read, I agree with others that there might still be some case where maybe benefits are overstated, e.g. sec 2.1 is not very objective and only provides basically two anecdotes. Other examples are these sentences:

"In addition to the above, our implementation experience indicates
  that Babel tends to be robust with respect to bugs: more often than
  not, an implementation bug does not violate the properties on which
  Babel relies, and therefore slows down convergence or causes sub-
  optimal routing rather than causing the network to collapse."

or

"No other routing protocol known to us is similarly robust and
  efficient in this particular kind of topology."
(also still one "us" here)

[Ballot comment]
Juliusz,

Thank you for addressing my previous DISCUSS. I have edited my position to "no objection".

-éric

== (previous) DISCUSS ==

-- Section 2.2 --

The 'bug resistance' property of Babel was perhaps learned during the implementation, but, I wonder whether the document may simply state 'robust with respect to bugs', this is quite a strong statement that needs to be backed by facts or proof.

== COMMENTS ==

The title of the document is about 'applicability'; but, should it also include 'use cases' in the title ?

-- Section 3.1 --

The 2nd paragraph is too dense: should explain why Babel is a good fit.

-- Section 5 --

Comparison between HMAC & DTLS variants is probably irrelevant in this document. Though, a use case with security in mind would be benefitial.

Also, the comparison should include all aspects including confidentiality and anti-reply for both HMAC & DTLS.

== NITS ==

-- Section 2.2 --

As I am not a native English speaker, I wonder whether 'light' should not be preferred to 'weak' in "These weak requirements make Babel a robust protocol"

-- Section 3.1 --

Suggest to change the section name into "Diverse networks" or "heterogenous networks".

[Ballot comment]
Thanks for writing this.

I find the use of "we" and "our" odd for a consensus document. I think the document would be improved if these used the document itself as the subject (e.g., "this document describes" instead of "we describe").

I think the claims made in the bulleted list at the end of Section 2.2 need citations.

[Ballot comment]
Agree with Eric, I think the document is a bit over zealous in it's claims and phrasing, e.g. "where traditional routing protocols
give up." One could say "where traditional routing protocols do not perform as well." As there are always tweaks to be made for the "traditional" to meet application needs and so avoid the fork lift of a new protocol.

[Ballot discuss]
Julius,

Thank you for the work put into this document. I have one DISCUSS and a couple of COMMENTs.

One generic comment: is there a need to describe (even in a short format) Babel again?

Regards,

-éric

== DISCUSS ==

-- Section 2.2 --

The 'bug resistance' property of Babel was perhaps learned during the implementation, but, I wonder whether the document may simply state 'robust with respect to bugs', this is quite a strong statement that needs to be backed by facts or proof.

[Ballot comment]
== COMMENTS ==

The title of the document is about 'applicability'; but, should it also include 'use cases' in the title ?

-- Section 3.1 --

The 2nd paragraph is too dense: should explain why Babel is a good fit.

-- Section 5 --

Comparison between HMAC & DTLS variants is probably irrelevant in this document. Though, a use case with security in mind would be benefitial.

Also, the comparison should include all aspects including confidentiality and anti-reply for both HMAC & DTLS.

== NITS ==

-- Section 2.2 --

As I am not a native English speaker, I wonder whether 'light' should not be preferred to 'weak' in "These weak requirements make Babel a robust protocol"

-- Section 3.1 --

Suggest to change the section name into "Diverse networks" or "heterogenous networks".

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

The IANA Functions Operator has reviewed draft-ietf-babel-applicability-06, 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 2019-07-04):

From: The IESG
To: IETF-Announce
CC: babel-chairs@ietf.org, babel@ietf.org, draft-ietf-babel-applicability@ietf.org, Donald Eastlake , d3e3e3@gmail.com, martin.vigoureux@nokia.com
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Applicability of the Babel routing protocol) to Informational RFC


The IESG has received a request from the Babel routing protocol WG (babel) to
consider the following document: - 'Applicability of the Babel routing
protocol'
  as Informational RFC

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 2019-07-04. 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


  Babel is a routing protocol based on the distance-vector algorithm
  augmented with mechanisms for loop avoidance and starvation
  avoidance.  In this document, we argue that there exist niches where
  Babel is useful and that are not adequately served by more mature
  protocols.




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

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-babel-applicability/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?

Informational as indicated on the title page.

(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:

Babel is a routing protocol based on the distance-vector algorithm
augmented with mechanisms for loop avoidance and starvation avoidance.
This applicability document argues that there exist niches where Babel
is useful and that are not adequately served by other protocols.

  Working Group Summary:

This was not a particularly controversial draft in the WG. There was
substantial suport and no objection on the mailing list and consensus
was declared during the WG meeting at IETF-102.

  Document Quality:

This is a brief applicability document. There are multiple independent
interoperable implementation of the routing protocol which is its
subject. A Shepherd's review found only one minor typo that has been
fixed.

  Personnel:
    Document Shepherd:  Donald Eastlake
    Responsible Area Director:  Martin Vigoureux

(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.

This is a short document that has had a routing review. See
https://www.ietf.org/mail-archive/web/babel/current/msg00531.html
Ths Shepherd looked it over and found a typo introduced by the update
to version -04 which has been fixed in -05. See
https://www.ietf.org/mail-archive/web/babel/current/msg01563.html

(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 such special review required. A rotuing QA review was done 31
January 2017.

(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?

No special concerns.

(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. Here is the IPR staement of the one author:
https://www.ietf.org/mail-archive/web/babel/current/msg01424.html

(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 disclosures.

(9) How solid is the WG consensus behind this document?

There is adequate consensus for the document. There was significant
discussion at WG Last Call time.

(10) Has anyone threatened an appeal or otherwise indicated extreme
    discontent?

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).

Didn't find any nits.

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

No such formal review required.

(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?

The only normative reference is draft-ietf-babel-rfc6126bis which is
expected to be advanced soon.

(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 downward normative references.

(16) Will publication of this document change the status of any
    existing RFCs?

This document does not change the status of any other RFCs.

(17) Describe the Document Shepherd's review of the IANA
    considerations section, especially with regard to its consistency
    with the body of the document.

This document requires no IANA actions.

(18) List any new IANA registries that require Expert Review for
    future allocations.

No IANA registries created.

(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.

No such formal language is used in this document.

(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?

Informational as indicated on the title page.

(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:

Babel is a routing protocol based on the distance-vector algorithm
augmented with mechanisms for loop avoidance and starvation avoidance.
This applicability document argues that there exist niches where Babel
is useful and that are not adequately served by other protocols.

  Working Group Summary:

This was not a particularly controversial draft in the WG. There was
substantial suport and no objection on the mailing list and consensus
was declared during the WG meeting at IETF-102.

  Document Quality:

This is a brief applicability document. There are multiple independent
interoperable implementation of the routing protocol which is its
subject. A Shepherd's review found only one minor typo that has been
fixed.

  Personnel:
    Document Shepherd:  Donald Eastlake
    Responsible Area Director:  Martin Vigoureux

(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.

This is a short document that has had a routing review. See
https://www.ietf.org/mail-archive/web/babel/current/msg00531.html
Ths Shepherd looked it over and found a typo introduced by the update
to version -04 which has been fixed in -05. See
https://www.ietf.org/mail-archive/web/babel/current/msg01563.html

(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 such special review required. A rotuing QA review was done 31
January 2017.

(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?

No special concerns.

(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. Here is the IPR staement of the one author:
https://www.ietf.org/mail-archive/web/babel/current/msg01424.html

(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 disclosures.

(9) How solid is the WG consensus behind this document?

There is adequate consensus for the document. There was significant
discussion at WG Last Call time.

(10) Has anyone threatened an appeal or otherwise indicated extreme
    discontent?

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).

Didn't find any nits.

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

No such formal review required.

(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?

The only normative reference is draft-ietf-babel-rfc6126bis which is
expected to be advanced soon.

(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 downward normative references.

(16) Will publication of this document change the status of any
    existing RFCs?

This document does not change the status of any other RFCs.

(17) Describe the Document Shepherd's review of the IANA
    considerations section, especially with regard to its consistency
    with the body of the document.

This document requires no IANA actions.

(18) List any new IANA registries that require Expert Review for
    future allocations.

No IANA registries created.

(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.

No such formal language is used in this document.