Subject: [homenet] Genart last call review of draft-ietf-homenet-babel-profile-05

From: Stewart Bryant <[email-masked]>
Date: Tue, 20 Feb 2018 09:46:57 -0800

Reviewer: Stewart Bryant
Review result: Ready with Issues

I am the assigned Gen-ART reviewer for this draft. The General Area
Review Team (Gen-ART) reviews all IETF documents being processed
by the IESG for the IETF Chair.  Please treat these comments just
like any other last call comments.

For more information, please see the FAQ at

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Document: draft-ietf-homenet-babel-profile-05
Reviewer: Stewart Bryant
Review Date: 2018-02-20
IETF LC End Date: 2018-02-26
IESG Telechat date: Not scheduled for a telechat

Summary: This is understandable, and close to completion. There are a few minor
points that need attention, and couple of major points that may just need
clarification.

Major issues:

 In addition,
      if implementations use conflicting route selection policies,
      persistent oscillations might occur.
SB> Is this consistent with the statement earlier in the para that
SB> " Distinct
SB>   implementations of RFC 6126bis Babel will interoperate, in the
SB>   sense that they will maintain a set of loop-free forwarding paths"?

=======

 Since IPv6 has some
      features that make implementations somewhat simpler and more
      reliable (notably link-local addresses), we require carrying
      control data over IPv6.
SB> Earlier you said that IPv4 also had Link Local addresses, so how
SB> can link local addresses be the deciding selection criteria? Is there
SB> something technically better about IPv6 LL?

Minor issues:

      Rationale: support for wireless transit links is a "killer
      feature" of Homenet, something that is requested by our users and
      easy to explain to our bosses.  In the absence of dynamically

SB> Not sure explicability to your boss counts for much as a basis for
SB> a feature an international standard.

======

Nits/editorial comments:

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.

SB> HNCP needs to be expanded
SB> Both need a reference, but the reference needs to be expanded
SB> i.e. RFC7788 not [RFC7788]

=====

   The core of the Homenet protocol suite consists of HNCP [RFC7788], a
SB> HNCP needs to be expanded on first use

=====

---

From: Juliusz Chroboczek <[email-masked]>
Date: Wed, 21 Feb 2018 01:42:05 +0100

> I am the assigned Gen-ART reviewer for this draft.

Thanks for your comments, Stewart.

Yes, it is consistent.  Please see Section 3.6 of rfc6126bis.

In short, Babel guarantees that the forwarding graph remains loop-free
at all times (which is somewhat weaker than what you'd expect -- in
particular, it does not entail that a packet will never pass the same
router more than once).  It does not make any guarantees about the
stability of the forwarding graph if the route selection policy is
completely crazy.

As far as I am aware, the problem of defining the class of non-crazy route
selection policies is an open research problem.  The best we can do, to
the best of my knowledge, is give examples of policies that do not cause
oscillations.

This is not unlike BGP, which does an excellent job avoiding loops, but
does not prevent persisten oscillations in the presence of crazy policies.
Interestingly enough, a numbre of papers indicate that this is not
a problem in the Internet, and that router operators are pretty good at
defining reasonable BGP policies.  I believe the same is true of Babel.

No, I didn't -- I'm trying to be consistent, and use LL to mean fe80::/64.
I believe the issue is in Section 1, where I say

   traffic is carried over either link-local IPv6 or IPv4

where what I mean is

   either link-local IPv6 carries traffic, or IPv4 carries traffic.

I'm not a native speaker, and I'll be grateful if you can suggest a better
formulation.

I think this paragraph is helpful for implementors -- it helps people
explain to their bosses why we're bothering with link-quality estimation
when we've done routing protocols with no link-quality estimation for the
last fifty years or so.  (The Fuzzball LSI-11 router had link-quality
estimation, but that was in the 1980s.)  Still, if you find the tone too
informal, I'm open to reformulating.

>    interactions between HNCP and Babel.

SB> HNCP needs to be expanded Both need a reference, but the reference
SB> needs to be expanded i.e. RFC7788 not [RFC7788]

Is this consistent with the last sentence of RFC 7322 Section 4.3?

-- Juliusz

---

From: Jeff <[email-masked]>
Date: Wed, 21 Feb 2018 08:21:32 -0600

> informal, I'm open to reformulating.
I too think the rationale is important but the phrasing may be 
confusing.  Being a native speaker of U.S. English (and almost fluent in 
Southern Californiaese ;-)  I found the colloquialisms confusing. 
Perhaps I could suggest something in the vein of "very important" or 
"much desired feature" etc for "killer".  I found the term "bosses" 
leaving much to interpretation and would prefer to see something more 
like "management" or "decision maker", or perhaps even "Corporate" used 
instead.

Jeff Bowden

---

From: Juliusz Chroboczek <[email-masked]>
Date: Wed, 21 Feb 2018 20:09:30 +0100

> I too think the rationale is important but the phrasing may be confusing. Being
> a native speaker of U.S. English (and almost fluent in Southern Californiaese
> ;-) I found the colloquialisms confusing.

Being myself a native speaker of an Eastern-European dialect with way too
many postalveolar fricatives, I will be grateful for additional guidance.

> "much desired feature"

This is not the notion that I tried to express, probably badly.  It's not
necessarily the important feature, it's the one that will make people
implement and deploy the protocol stack in the first place.

Long-term, the important feature of Homenet is having a clean architecture
for multi-link IPv6 networks.  From the point of view of the end-user,
however, multiple layers of NAT work just as well, so it's not a "killer"
feature.

Short-term, the two visible features are support for multiple uplinks and
support for wireless transit.  No other protocol stack can do either of
these without manual intervention, so these are Homenet's "killer"
features.

I agree that the term might not be familiar to everyone, and I would be
sincerely grateful for help with expressing this notion concisely and
without undue colloquialisms.

> I found the term "bosses" leaving much to interpretation

This happens to be deliberate.  I am trying to avoid implying too much
about the organisational structure to which the reader belongs -- the
"boss" here could be the CIO, but it could be the leader of an Academic
project, it could be the supervisor of the intern who's implementing
Homenet, or it could be the Benevolent Dictator for Life of a Free
Software project.

If you find a sufficiently stately term that covers all of the above, I'll
take it.  (My thesaurus suggests "chieftain", but I tend to favour "foreman".)

> or perhaps even "Corporate" used instead.

Now you're trying to pick a fight ;-)

-- Juliusz

---

From: "STARK, BARBARA H" <[email-masked]>
Date: Wed, 21 Feb 2018 20:19:31 +0000

> implement and deploy the protocol stack in the first place.

Suggestion for '"killer feature" of Homenet': driver for using Homenet

> This happens to be deliberate.  I am trying to avoid implying too much about
> the organisational structure to which the reader belongs -- the "boss" here
> could be the CIO, but it could be the leader of an Academic project, it could
> be the supervisor of the intern who's implementing Homenet, or it could be
> the Benevolent Dictator for Life of a Free Software project.
> 
> If you find a sufficiently stately term that covers all of the above, I'll take it.
> (My thesaurus suggests "chieftain", but I tend to favour "foreman".)

Suggestion for "our bosses": decision makers
Which applies to all of the example people mentioned, but also spouses, significant others, and spoiled children -- who may be more relevant in the context of homenet.

Barbara

---

From: Juliusz Chroboczek <[email-masked]>
Date: Thu, 22 Feb 2018 01:30:04 +0100

> Suggestion for '"killer feature" of Homenet': driver for using Homenet

That's good.

>> If you find a sufficiently stately term that covers all of the above,
>> I'll take it.  (My thesaurus suggests "chieftain", but I tend to favour
>> "foreman".)

> Suggestion for "our bosses": decision makers

"easy to explain to the decision makers"?  It's okay, but sounds somewhat
cold and corporate to my (admittedly foreign) ears.  I'll wait a little
while in case somebody has a better idea.

(Since we all seem to be in a chatty mood -- on Tuesday last, I was
teaching virtual memory allocation techniques, and needed a translation
for "eager allocation" as opposed to "lazy".  One student proposed
"allocation zélée".  I'm loving it.)

-- Juliusz

---

From: Toke Høiland-Jørgensen <[email-masked]>
Date: Thu, 22 Feb 2018 11:30:33 +0100

> while in case somebody has a better idea.

"masters"
"liege lords"
"jarls"
"overseers"
"(robot) overlords"
"decision-making units"
"callers of shots"
"head honchos"

(As you can see, I tried and failed to come up with something better;
I'd tend to agree that "decision makers" is a bit cold and corporate,
but then we are writing a standards document, not a 19th century romance
novel...)

-Toke

---

From: Juliusz Chroboczek <[email-masked]>
Date: Thu, 22 Feb 2018 14:04:39 +0100

> we are writing a standards document, not a 19th century romance novel

It is a truth generally acknowledged that a single man in possession of
a good fortune must be in want of a home network.

---

From: Toke Høiland-Jørgensen <[email-masked]>
Date: Thu, 22 Feb 2018 14:31:26 +0100

> a good fortune must be in want of a home network.

Ah yes, much better. I for one believe it prudent to adopt this style
for all homenet documents, lest we risk being relegated to the obscurity
of the cold and corporate world of yesteryear ;)

-Toke

---

From: Juliusz Chroboczek <[email-masked]>
Date: Fri, 23 Feb 2018 00:31:30 +0100

After much thought, I have settled on the following:

      Rationale: support for wireless transit links is a distinguishing
      feature of Homenet, and one that is requested by our users.  In
      the absence of dynamically computed metrics, the routing protocol
      attempts to minimise the number of links crossed by a route, and
      therefore prefers long, lossy links to shorter, lossless ones.  In
      wireless networks, "hop-count routing is worst-path routing".

I find the previous version clearer and more informative, but I've read
ISO/IEC 10589, and therefore understand that the author of a Standard
should aim to sound professional rather than indulging in such amateurish
endeavours as being clear or informative.

-- Juliusz