Re: [mpls] MPLS-RT review on draft-cdh-mpls-tp-psc-non-revertive-00//RE: MPLS-RT review of mpls psc documents

Hi,

I have conducted a review of draft-cdh-mpls-tp-psc-non-revertive as
requested by the WG Chairs and have the following notes:

This draft purports to "update" RFC6378 to change non-revertive behavior of
the Linear Protection protocol. The method of updating the protocol is
through the addition of a Manual Switch to Working operator command to
affect the reversion of traffic to the working path. Along the way the
authors propose to change the name of the Manual Switch operator command
already defined in RFC6378 and also change the name of the Protecting
Administrative State to Switching Administrative State.

The format of the draft is in the form of an errata correction document,
indicating which paragraphs in the RFC should be replaced and what new text
should be substituted in its place.

This draft is part of a set of drafts that was discussed at the IETF87
meeting that will include an "overview" document that describes how to
incorporate the new functionality described in those drafts.

With this introduction I would like to make the following observations:
1. There are accepted methods used in the IETF to update a RFC by adding
new functionality to a protocol. Usually, this is done by writing a draft
that describes the new functionality on top of the existing functionality
rather than the method used here. This is especially strange considering
that they are not changing the behavior of the existing functionality but
just adding an additional command and describing its behavior.

2. Based on this observation and the fact that all of the suggested
"corrections" to the text involving "Manual Switch" are to change the name
but not the functionality, I do not see the justification in changing the
name of the existing Manual Switch command since its functionality is
essentially remaining as defined and there is no cause for confusion with
the new "Manual Switch to Working" command.

3. I see problems with the suggestion to change the
"Protecting Administrative State" to "Switching Administrative State" since
this requires the confusing statement (in Section 4.9) "the user traffic
SHALL be transported on either the protection path or the working path"
which is certainly always true for traffic that is being transported. Why
not create a new State? Or even better, since the MS-W is meant to return
the state to Normal why not just use Normal state?

4.An observation that I made to the psc-priority draft is applicable to
this draft as well - I do not understand the referencing of an LS from ITU
- this is not a standards document, just a contribution for discussion and
should not be referenced.

5.Section 4.8 of this document highlights a problem that is raised by this
set of drafts and their method of presentation. In this section, a
"correction" is proposed for text that appears in RFC6378 section 4.3.3.2.
This "corrects" the original text with new text. However, this text is also
"corrected" in the psc-priority draft! Now the question that needs to be
asked is which correction is the definitive correction - the one in this
draft or the one in the other draft? Is this dependent upon the order in
which the drafts will be published?

6. Section 4.6 of the draft presents a very lengthy description of an
"algorithm" for resolving the priority of inputs "having equal priority".
The case of inputs having the same priority are those in which the MS and
MS-W inputs are received. I believe that this set of rules are rather
confusing and the upshot of the explanation seems to be that either you use
the rule of "first-come first-served" or that MS-W has higher priority,
except in some very specific conditions. I am certain that this could be
more clearly stated or explained.

Bottom line, I do not think that this draft is ready for WG acceptance. I
would suggest that it be rewritten to update the new functionality that is
being proposed while leaving the existing non-changed functionality as is.
I also suggest that the format not be based on "corrections" to the
existing draft - this is not a contribution to a "living" document, but
rather a new document that updates the previous document.

Hope this helps,
yaacov weingarten

On Thu, Aug 22, 2013 at 12:05 PM, Mach Chen <mach.chen@huawei.com> wrote:

> Hi,
>
> I have done my MPLS-RT review on draft-cdh-mpls-tp-psc-non-revertive-00,
> here are my comments:
>
> I think that modification to Non-revertive mode, adding MS-W and renaming
> MS to MS-F are valid points. But I not sure whether there is a need to
> replace " Protecting administrative state" to "Switching administrative
> state".
>
> Read through the draft, it gives me the feeling that the draft just lists
> a set of erratas, I am not sure that this is the right way to progress the
> draft as it be. If the WG have the consensus on the content of the draft,
> IMHO, it's better to do a bis to RFC6378.
>
> Minor comment:
> It's better to expand the acronym when first use, for example the MS-F and
> MS-W, I have to guess the meaning of until I see the Acronyms section.
>
> Best regards,
> Mach
>
> > -----Original Message-----
> > From: Loa Andersson [mailto:loa@pi.nu]
> > Sent: Friday, August 09, 2013 8:01 PM
> > To: Eric Osborne (eosborne); Eric Gray; kenji.fujihira.dj@hitachi.com;
> Yaacov
> > Weingarten; Sam Aldrin; Mach Chen; Kamran Raza (skraza); Henderickx, Wim
> > (Wim); thomas.morin@orange.com; mjork@juniper.net
> > Cc: draft-osborne-mpls-psc-updates@tools.ietf.org;
> > draft-dj-mpls-tp-exer-psc@tools.ietf.org;
> > draft-rhd-mpls-tp-psc-sd@tools.ietf.org;
> > draft-cdh-mpls-tp-psc-non-revertive@tools.ietf.org;
> > draft-rhd-mpls-tp-psc-priority@tools.ietf.org;
> mpls-chairs@tools.ietf.org;
> > VIGOUREUX, MARTIN (MARTIN)
> > Subject: MPLS-RT review of mpls psc documents
> >
> > Eric, Eric, Kenji, Yacoov, Sam, Mach, Kamran, Wim, Thomas and Markus,
> >
> > You been selected as MPLS-RT reviewers for a set of psc document that we
> > will start progress through the mpls working group.
> >
> > The normal rules and question for an MPLS-RT apply:
> >
> > ---------- quote from a standard mail initiating MPLS-RT review -------
> >
> > Note to authors: You have been CC'd on this email so that you can know
> > that this review is going on. However, please do not review your own
> > document.
> >
> > Reviews should comment on whether the document is coherent, is it
> > useful (ie, is it likely to be actually useful in operational
> > networks), and is the document technically sound?  We are interested
> > in knowing whether the document is ready to be considered for WG
> > adoption (ie, it doesn't have to be perfect at this point, but should be
> > a good start).
> >
> > Reviews should be sent to the document authors, WG co-chairs and
> > WG secretary, and CC'd to the MPLS WG email list. If necessary, comments
> > may be sent privately to only the WG chairs.
> >
> > ---------------------- end quote -------------------------
> >
> > The only difference is that we take on more than one document and that
> > there are such inter-dependencies that we want to coordinate how they
> > are progressed through IETF.
> >
> > Please respond (at least) to the wg chairs and Martin that you are
> > willing/un-willing to undertake the reviews.
> >
> > Since we are starting MPLS-RT reviews of 5 documents, with 4 reviewers
> > for each document and each reviewer have two documents, you'll need
> > to send the review with the draft name in the subject line, i.e. do
> > not respond to this mail with your review comments.
> >
> > There is also a "PSC modes" document in the pipe, currently it is our
> > opinion that this document is necessary when we will start the wglc's
> > but is not necessary to make the other drafts wg documents.
> >
> > Can you please finish your reviews eob August 23, 2013.
> >
> > Here is the list of reviewers per document:
> >
> > draft-rhd-mpls-tp-psc-priority
> > ------------------------------
> > mach chen
> > thomas morin
> > yacoov weingarten
> > Wim Henderickx
> >
> > draft-cdh-mpls-tp-psc-non-revertive
> > -----------------------------------
> > mach chen
> > eric osborne
> > eric gray
> > yacoov weingarten
> >
> > draft-rhd-mpls-tp-psc-sd
> > ------------------------
> > eric osborne
> > sam aldrin
> > eric gray
> > kamran raza
> >
> > draft-dj-mpls-tp-exer-psc
> > -------------------------
> > sam aldrin
> > markus jork
> > kamran raza
> > kenji fuhira
> >
> > draft-osborne-mpls-psc-updates
> > ------------------------------
> > markus jork
> > thomas morin
> > kenji fuhira
> > Wim Henderickx
> >
> >
> > Authors,
> >
> > Please do not update the documents during the review period, we will
> > tell you when the review period has ended.
> >
> > When we close the review period you'll need to address the comments
> > from the reviewers and communicate with them (preferably on the mpls
> > wg mailing list) to make sure that they are comfortable with how the
> > comments has been addressed.
> >
> >
> > /Loa
> > for the mpls wg chairs
> >
> > --
> >
> >
> > Loa Andersson                        email: loa@mail01.huawei.com
> > Senior MPLS Expert                          loa@pi.nu
> > Huawei Technologies (consultant)     phone: +46 739 81 21 64
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-- 
Thanx and BR,
yaacov

*Still looking for new opportunity*