Re: [Gen-art] Gen-ART LC/Telechat Review of draft-ietf-isis-genapp-03.txt

["Les Ginsberg (ginsberg)" <[e-mail]>]

Ben -

> -----Original Message-----
> From: Ben Campbell [mailto:[e-mail]]
> Sent: Wednesday, October 06, 2010 7:10 AM
> To: Les Ginsberg (ginsberg)
> Cc: [e-mail]; General Area Review
> Team; The IETF
> Subject: Re: Gen-ART LC/Telechat Review of draft-ietf-isis-genapp-
> 03.txt
> 
> Thanks for the quick response. Comments inline:
> 
> On Oct 6, 2010, at 7:55 AM, Les Ginsberg (ginsberg) wrote:
> 
> > Ben -
> >
> > Thanx for the review.
> > Inline.
> >
> >> -----Original Message-----
> >> From: Ben Campbell [mailto:[e-mail]]
> >> Sent: Tuesday, October 05, 2010 12:06 PM
> >> To: [e-mail]; General Area Review
> > Team
> >> Cc: The IETF
> >> Subject: Gen-ART LC/Telechat Review of
draft-ietf-isis-genapp-03.txt
> >>
> >> I am the assigned Gen-ART reviewer for this draft. For background
on
> >> Gen-ART, please see the FAQ at
> >> < http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
> >>
> >> Please wait for direction from your document shepherd
> >> or AD before posting a new version of the draft.
> >>
> >> Document: draft-ietf-isis-genapp-03.txt
> >> Reviewer: Ben Campbell
> >> Review Date: 05 Oct 2010
> >> IESG Telechat date: 07 Oct 2010
> >>
> >> Summary:
> >>
> >> The draft is almost ready for publication as a proposed standard,
> but
> > I
> >> have some concerns that I think should be addressed first.
> >>
> >>
> >> Major issues:
> >>
> >> -- This draft creates an "expansion" code point in an IANA
registry,
> >> where the expansion registration requirements are weaker than those
> of
> >> the parent registry. This always makes me nervous, as it opens the
> >> window for end-runs around the registration requirements of the
> > parent.
> >>
> >> In this particular instance, the parent registry policy is "expert
> >> review" while the proposed expansion registry policy is
> "specification
> >> required". This draft puts normative requirements on the content of
> > the
> >> required specifications, and makes additional non-normative
> statements
> >> about the intended use of the GENINFO code point. This implies to
me
> >> that the review process needs to do more than determine that
> > sufficient
> >> specification exists. Rather, it needs to determine that the
> criteria
> >> in this draft are met by that specification. Therefore, I think
that
> > it
> >> would be appropriate for the GENINFO registry to use the "expert
> >> review" policy.
> >
> > From RFC 5226:
> >
> > "Specification Required - Values and their meanings must be
> >            documented in a permanent and readily available public
> >            specification, in sufficient detail so that
> interoperability
> >            between independent implementations is possible.  When
> used,
> >            Specification Required also implies use of a Designated
> >            Expert, who will review the public specification..."
> >
> > We deliberately chose "Specification Required" because:
> >
> > a)It requires a public specification
> > b)It allows the public specification to be other than an RFC
> > c)It requires expert review
> 
> Completing the sentence in your quote: "who will review the public
> specification and evaluate whether it is sufficiently clear to allow
> interoperable implementations."
> 
> My understanding of "Specification Required" is that the expert review
> is merely to ensure that the documentation is sufficiently complete
and
> readable to implement in an interoperable way. That review is not
> intended to ensure compliance to other criteria specified in the
draft.
> 
> However, the draft includes some specific criteria for GENINFO
> applications. If you want the reviewer to enforce those criteria, then
> I think you need at least "Expert Review". OTOH, in RFC5226, the
> "expert review" policy has less to say about the required level of
> documentation, so the draft might require some more meat in that area.
> 

This is a bit distressing - because you are suggesting that RFC 5226
doesn't define a category which is appropriate for our usage - which
means we have to try to define a unique policy. I am not quite sure how
to do that with sufficient authority and minimal controversy.

My understanding is that RFC 5226 is specific to IANA considerations -
so we have attempted to define a clear policy as to how the review of
code point assignments is done.

Beyond that, it seems clear that a given Application specification could
specify behavior that might be seen as undesirable e.g. it could specify
some extremely high rate of updates. Given that we allow application
specification to be defined in public documents from a variety of
sources, I don't see how we could define an enforceable review policy
for the application specifications. It is at the IANA codepoint
allocation that we have control - and certainly it seems within the
purview of an expert to say "I think your specification is flawed and I
won't approve the allocation of codepoints until the issues of concern
are addressed".


> I note that while RFC3563, which established the IS-IS TLV Codepoint
> registry, says "Expert Review", the review criteria is pretty much
> equivalent to "standards action". I'm guessing the only reason it was
> not "standards action" was to allow ISO/IEC JTC1/SC6 to submit
> specifications, which are to be held to the same standard as a
> standards-track RFC, but do not actually get published as such. So for
> practical purposes, the proposed policy for GENINFO is significantly
> weaker than for the parent registry--more so than one might think from
> just looking at the registry itself.

I am not clear on why "Expert Review" is seen as a stronger review
criteria than "Specification Required" - which includes expert review as
well as a requirement for a public specification.

> 
> 
> >
> >>
> >> Minor issues:
> >>
> >> -- section 4.2, 2nd paragraph: "Where this is not possible, the two
> >> affected LSPs SHOULD be flooded as an atomic action"
> >>
> >> Any reason that this is not a MUST, since it seems like the safety-
> net
> >> behavior for when the aforementioned SHOULD is not  possible to
> > follow?
> >>
> >
> > It is a recommended behavior. If an implementation does not do this
> it
> > does not create an interoperability issue - but it may create
> > sub-optimal behavior.
> 
> Okay.
> 
> >
> >> -- Section 4.3: "When information in the two GENINFO TLVs conflicts
> > i.e
> >> there are different settings for a given attribute, the procedure
> used
> >> to choose which copy shall be used is undefined."
> >>
> >> Should their be normative requirement not to create this undefined
> >> condition in the first place?
> >
> > If the revised version of a GENINFO TLV is sent in an LSP with a
> > different number from the previous version there can be transient
> > windows where other systems have two copies of information regarding
> the
> > same application. This may be unavoidable. For completeness we
> specify
> > that the choice of what to do in such transient situations is
> > implementation specific (undefined). This section does specify ways
> to
> > minimize the occurrence/duration of such transient periods.
> 
> Does leaving this undefined cause interop issues? If not, then no
> problem.

There is no alternative. It is not possible to determine in a reliable
way which copy is "newer".

> 
> >
> >>
> >>
> >>
> >> -- Security Considerations:
> >>
> >> This seems too lightweight. Is it impossible for GENINFO
> applications
> >> to include sensitive information? Are there no security guidelines
> > that
> >> should apply to GENINFO application specifications?
> >
> > We have no way of knowing what type of information might be
> advertised
> > by a given application - and we are not limiting what may be
> advertised.
> > Clearly the public document which specifies the application would
> need
> > to address the security issues it introduces. We cannot do that
here.
> 
> Since the registration policy is not at least "RFC Required", there's
> no explicit requirement that the public document actually do this. If
> you wish to require them to do it, you will need to state something to
> that effect. (See previous comment about whether the registration
> policy actually enforces that sort of criteria.)

I appreciate your point - but I don't see how we have the authority to
place a requirement on a document developed in another standards body.

> 
> 
> >
> >>
> >> Even if the answer is that the underlying IS-IS protocol provides
> >> sufficient security for any reasonable use of the GENINFO code
> point,
> >> it would be worth saying that explicitly.
> >>
> >> Nits/editorial comments:
> >>
> >> -- section 2
> >>
> >> Please expand IS-IS and PDU on first mention.
> >
> > OK
> >
> >>
> >> -- section 6, last paragraph:
> >>
> >> Expected/desired by whom?
> >
> > Well, at least by the authors. :-)
> 
> Okay :-) I guess, I meant to say that, if this expectation was a
matter
> of WG concensus, you could state it more strongly, as in "The IS-IS
> working group expected..."

I don't think we currently have WG consensus on this point.

   Les

> 
> >
> >>
> >> -- Outdated reference for draft-ietf-isis-mi
> >
> > It was current at the time the draft was written.
> >
> >
> >   Les
> >