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RE: [mpls] Last Call: <draft-ietf-mpls-tp-cc-cv-rdi-05.txt>(Proactive Connectivity Verification, Continuity Check and Remote Defectindication for MPLS Transport Profile) to Proposed Standard

2011-07-14 12:51:10
Rui,
I kindly propose not to refer in this context to the Feb2011 WP3 and
SG15 plenary meetings....
Very unfortunately, it was far away from being a technical
discussion.....or technical poll. 
Therefore it cannot be a reference to any argument in this context.  
Regards,
Nurit


-----Original Message-----
From: ietf-bounces(_at_)ietf(_dot_)org 
[mailto:ietf-bounces(_at_)ietf(_dot_)org] On Behalf Of
ext Rui Costa
Sent: Thursday, July 14, 2011 8:33 PM
To: David Allan I
Cc: mpls(_at_)ietf(_dot_)org; ietf(_at_)ietf(_dot_)org; IETF-Announce
Subject: RE: [mpls] Last Call:
<draft-ietf-mpls-tp-cc-cv-rdi-05.txt>(Proactive Connectivity
Verification, Continuity Check and Remote Defectindication for MPLS
Transport Profile) to Proposed Standard

David,

T-MPLS rose from MPLS/IP's OAM blanks. Our main interest on it is the
simple/reliable OAM we had in SDH but lost in MPLS/IP. Otherwise, the
work in T-MPLS or MPLS-TP would be rather pointless.
ITU-T was historically the right place to define such OAM. So, our
interest started with ITU-T's work in T-MPLS and not when IETF joined.


We value IETF's work, and in 2008, when the IETF rose doubts about
future interoperability between T-MPLS and MPLS/IP (and the "danger to
the internet"), even though all T-MPLS Recommendations were approved and
the OAM one was ready for approval, a decision was made to listen
carefully to MPLS/IP's top experts' input.


IETF's unilateral decision to select BFD was IMHO a surprise: being a
primary goal in T-MPLS, i'd assume OAM definition was ITU-T's
responsibility/expertise or at least a compromise between the 2 SDOs.
ITU-T's not just a boilerplate stamper.
Hearing that "the decision was expressed in mpls-tp-analysis draft" was
another surprise: among the possible ways, the document showed, IMHO,
1731 as the closest one to requirements.


We don't need a requirement to agree on reusing as most as possible MPLS
and PW: it's common sense. However, it can't distract us from primary
goals.


"The issue is not code point, which is the trivial part. It is reuse of
the majority of the implementation. Again, pretty basic."
In other words, the problem is not backwards compatibility, (ergo the
"danger to the internet" problem never really existed) but maintaining
particular deployed platforms. If we had to convert cars into planes, we
couldn't say "to reuse the implementation, we can't add wings": they
wouldn't fly.
I'm used to FW/HW development and i don't share your cost/simplicity
view. (Please check other LC responses on this particular point.) I know
field network support and think you'd change your opinion if you had to
work on 24h field network support.



I agree with you that other opinions exist, counting not only
manufacturers but also operators. On the operators that don't agree with
you are certainly clients of yours. It's none of my business that you
view their opinions as "grumblings", but that's far from describing the
polls' results in the Feb2011 WG3 and SG15 plenaries, showing a minority
sharing your view, and that, although those not subscribing it tolerate
its evolution, you don't theirs.
Operators and their clients are the ones that, at the end of the day,
pay for networks. From the above, it'll be IMHO impossible to understand
if these Recommendations don't take into account these "grumblers'"
view, other than the obsession of those insisting to sell swiss knifes
to those who just want sharp scalpels. Why don't we call that also "not
constructive"?
"[R:] IMHO, between your MPLS-TP view and MPLS/IP, it becomes more and
more difficult to tell which is which.
[D:]That is because MPLS-TP is not a new techology, it is an addition to
the entire MPLS protocol suite."
Yes, i understand your view, David, but i'm sure you and i don't
subscribe this one:
"The creatures outside looked from pig to man, and from man to pig, and
from pig to man again; but already it was impossible to say which was
which".

Hope this helps. My comrade cents,
Rui



-----Original Message-----
From: David Allan I [mailto:david(_dot_)i(_dot_)allan(_at_)ericsson(_dot_)com]
Sent: sexta-feira, 8 de Julho de 2011 17:13
To: Rui Costa; Stewart Bryant
Cc: erminio(_dot_)ottone_69(_at_)libero(_dot_)it; mpls(_at_)ietf(_dot_)org; 
ietf(_at_)ietf(_dot_)org;
IETF-Announce
Subject: RE: [mpls] Last Call: <draft-ietf-mpls-tp-cc-cv-rdi-05.txt>
(Proactive Connectivity Verification, Continuity Check and Remote Defect
indication for MPLS Transport Profile) to Proposed Standard

Rui:

You wrote:

Reading something, keeping it on record, without effect in the draft
and "ignoring comments" have IMHO similar outcomes. As author of the
draft you are free to do it. These standards have a great impact
in our work, so i'm also free to write what i did.

Numerous comments did have effect on the draft and those that didn't
were either simply not actionable, were rhetorical or not constructive,
and a few had to be balanced against comments coming from the MPLS & BFD
WGs. I would translate "ingored" or "without effect" to "did not get
one'e way". In the standards process it happens.

My technical concerns regarding this draft were expressed...
...in the (ITU-T -> IETF, Feb/2011) liaison regarding it (LS281, i
believe);
...in operators' meetings' that took place during ITU-T's Feb/2011
plenary meeting;

I and the WG don't really have access to private grumblings.

Lots of other opinions were expressed as well, and they did not all
agree with you.

Some:
CC/CV
I don't understand the need for 2 types of packets: a single type
allows CC; mismatching identifiers in the same CC packets allow CV.
Besides adding complexity, we whether always activate both or
potentiate undetected mismerges.

OK, lets walk through this.

We want CV all the time so that any misconectivity can be detected, but
on the list it was expressed that the group did not want the overhead of
processing the source MEP TLV in every packet in order to achieve this.
We could carry it in every packet and have the receiver simply ignore
most of them, but then that would make the defect entry criteria
compeltely random and the exit criteria unreliable as well, not really a
good design. Hence they are separated using different ACH code points
and the receiver is obliged to process every source MEP TLV it receives.
I hope this is clear.

(BTW: can't understand how we propose one ACH codepoint to CC, another
for CV, [counting other drafts, another for frame loss ...] but don't
consider assigning 1 single ACH protocol identifier codepoint >as
requested by ITU-T)

Because that puts you into two protocol ID demultiplexing steps per OAM
PDU recevied to determine the intended function. Hence COSTS MORE. That
is pretty basic...

Uni P2P / P2MP
I can't see how BFD will support unidir and hence P2MP other than...
...eliminating the session "state variable" (down, init, up), aiming
just the state variables we really need, bringing us to something
similar to 1731, eventually with other bits on the wire or...
...using IP to create the reverse way, which we cannot assume per
requirements;
Will we create a complete different tool for that?
(BFD's B="bidirectional")

I would not go so far as to say "similar to 1731", there is actually a
lot of difference under the hood. As for uni-directional BFD, that is a
BFD WG problem at the moment.

Provisioning list
This is an MPLS profile/subset (and i heard) achievable through a
particular configuration. So, i expect each draft-ietf-mpls-TP-* to
focus on that profile/configuration. However, i keep seeing
references f.i. to IP encapsulations unexpected under TP's OAM.
I don't thus understand what the aim is: do we expect this in TP, are
we talking about MPLS in general?... The TP profile is never quite
delimited.
Does chapter 4 contain ALL the configurable parameters list agreed to
provide in the comparison session?

It should. As for encapsulations, unless TP is in a complete island not
connected to anything (which as a network is rather useless) it will be
expected to interoperate with the rest of the MPLS architecture, and the
stated intention of tool development was that what resulted was
applicable to the broader MPLS architecture. Which means backwards
compatiblity and procedures for interoperation.

Backwards compatibility
This was the main argument risen to ground MPLS-TP OAM on BFD. It's
not a better argument than grounding MPLS-TP OAM on 1731 due to its ETH
deployment plus coherence with SDH, OTN, as defended by ITU-T.
For reasons like the above, however, MPLS-TP BFD won't be backwards
compatible with previous BFD (even considering just CC/CV). They don't
even share the same codepoint.

The issue is not code point, which is the trivial part. It is reuse of
the majority of the implementation. Again, pretty basic.

Simplicity
Whether we look to PDH, SDH, OTN or ETH, ITU-T's approach to CC is
simpler: in each flow, a standard defined nr of constant heartbeat
signals (with standard constant or provisioned period - no
auto/negotiated -) means OK. A standard defined number of misses means
lost Rx connection. An RDI, the only articulation between Rx and Tx
flows, meaningful in bidirectional applications, allows each
pear to identify Tx problems.
This OAM simplicity is the key for reliable fail finger pointing,
performance reports and protection. Also to allow scaling, more
implementation opportunities/manufacturers, which is valuable for
operators.

Well IMO there was not a lot of interest in T-MPLS until the IETF was
going to re-define it and make it compatible with IP/MPLS. So there was
an industry wide "design intent" implied here.

IMHO, between your MPLS-TP view and MPLS/IP, it becomes more and more
difficult to tell which is which.

That is because MPLS-TP is not a new techology, it is an addition to the
entire MPLS protocol suite.

Hope this helps
D









-----Original Message-----
From: David Allan I [mailto:david(_dot_)i(_dot_)allan(_at_)ericsson(_dot_)com]
Sent: quarta-feira, 6 de Julho de 2011 19:25
To: erminio(_dot_)ottone_69(_at_)libero(_dot_)it; Rui Costa; 
ietf(_at_)ietf(_dot_)org; IETF-Announce
Cc: mpls(_at_)ietf(_dot_)org
Subject: RE: [mpls] R: Re: Last Call:
<draft-ietf-mpls-tp-cc-cv-rdi-05.txt> (Proactive Connectivity
Verification, Continuity Check and Remote Defect indication for MPLS
Transport Profile) to Proposed Standard

Hi Erminio:

<snipped>
Several service providers regarded this draft as not meeting their
transport networks' needs.

E> This is a true statement: the solution in this draft is useless for
many MPLS- TP deployments.

The two statements do not necessarily follow.

What we established during discussions at the SG15 plenary in February
was that the issue some service providers had was that the IETF BFD
solution exceeded their requirements in that there was additional
functionality they did not see a need for, and that they considered any
additional functionality parasitic.

However this is a consequence of adapting an existing technology to a
new application. I do not see any way around that. And the entire joint
project was based on the premise of engineering re-use not greenfield
design. That is what it said on the tin up front, and IMO why when the
IETF started down this path packet transport transitioned from being a
minority sport to mainstream, so it is a bit late to cry foul....

My 2 cents
Dave




-----Original Message-----
From: David Allan I [mailto:david(_dot_)i(_dot_)allan(_at_)ericsson(_dot_)com]
Sent: quarta-feira, 6 de Julho de 2011 18:36
To: erminio(_dot_)ottone_69(_at_)libero(_dot_)it; loa(_at_)pi(_dot_)nu; Rui 
Costa
Cc: mpls(_at_)ietf(_dot_)org; ietf(_at_)ietf(_dot_)org; IETF-Announce
Subject: RE: [mpls] R: Re: Last Call:
<draft-ietf-mpls-tp-cc-cv-rdi-05.txt> (Proactive Connectivity
Verification, Continuity Check and Remote Defect indication for MPLS
Transport Profile) to Proposed Standard

Hi Erminio:

Two of the three document editors were present at SG15 plenary in
February where the comments originated. The revised meeting schedule
resulted in a day spent going through the document with the editors. IMO
there were lots of discussion and legitimate issues with the document
identified and corrected so it was a useful session. The liaison of same
was in many ways *after the fact*.

Cheers
Dave




-----Original Message-----
From: erminio(_dot_)ottone_69(_at_)libero(_dot_)it 
[mailto:erminio(_dot_)ottone_69(_at_)libero(_dot_)it]
Sent: quarta-feira, 6 de Julho de 2011 18:34
To: Rui Costa; ietf(_at_)ietf(_dot_)org; IETF-Announce
Cc: mpls(_at_)ietf(_dot_)org
Subject: R: Re: [mpls] Last Call: <draft-ietf-mpls-tp-cc-cv-rdi-05.txt>
(Proactive Connectivity Verification, Continuity Check and Remote Defect
indication for MPLS Transport Profile) to Proposed Standard

The way this draft has been developed is a bit strange.

The poll for its adoption as a WG document was halted by the MPLS WG
chair because "it is not possible to judge consensus":

http://www.ietf.org/mail-archive/web/mpls/current/msg04502.html

The lack of consensus was motivated by serious technical concerns raised
by several transport experts during the poll.

Nevertheless the MPLS WG chair decided to adopt the draft as a WG
document:

http://www.ietf.org/mail-archive/web/mpls/current/msg04512.html

After several WG revisions and WG LCs, the technical issues have not
been resolved.

Several service providers regarded this draft as not meeting their
transport
networks' needs.

This is a true statement: the solution in this draft is useless for many
MPLS- TP deployments.


-----Original Message-----
From: erminio(_dot_)ottone_69(_at_)libero(_dot_)it 
[mailto:erminio(_dot_)ottone_69(_at_)libero(_dot_)it]
Sent: quarta-feira, 6 de Julho de 2011 18:26
To: loa(_at_)pi(_dot_)nu; Rui Costa
Cc: mpls(_at_)ietf(_dot_)org; ietf(_at_)ietf(_dot_)org; IETF-Announce
Subject: R: Re: [mpls] Last Call: <draft-ietf-mpls-tp-cc-cv-rdi-05.txt>
(Proactive Connectivity Verification, Continuity Check and Remote Defect
indication for MPLS Transport Profile) to Proposed Standard

 Version -04 of the document was published June 28th.

 The publication request for draft-ietf-mpls-tp-cc-cv-rdi was  sent
June 29th.


So when the WG LC to confirm the LC comment resolution has been
launched?

The proto write-up says:

            It has also passed a working roup call to verify that LC
comments were correctly with minor comments.

It also says:

            The comments has been
            carefully discussed between the authors and people making
the comments and
            has been resolved.

But it seems that some comments have not been discussed with the authors
of the comments. When ITU-T Q10/15 has been involved in discussing its
comments?




-----Original Message-----
From: Loa Andersson [mailto:loa(_at_)pi(_dot_)nu]
Sent: quarta-feira, 6 de Julho de 2011 16:44
To: Rui Costa
Cc: ietf(_at_)ietf(_dot_)org; IETF-Announce; mpls(_at_)ietf(_dot_)org
Subject: Re: [mpls] Last Call: <draft-ietf-mpls-tp-cc-cv-rdi-05.txt>
(Proactive Connectivity Verification, Continuity Check and Remote Defect
indication for MPLS Transport Profile) to Proposed Standard

All,

Since someone has commented about the process used for resolving
questions on
draft-ietf-mpls-tp-cc-cv-rdi I am supplying some details below.

The history of draft-ietf-mpls-tp-cc-cv-rdi working group review
process is:

On February 3rd 2011 the working group last call was issued
on version -03

      This was copied to the the Ad Hoc Team List
      and liaised to SG15 also on February 3rd

      This working group last call ended om Feb 28


      On Feb 28 we also received a liaison with comments from SG15


The authors compiled a list of all comments received  as part the MPLS
working group last call; these  comments - and the intended resolution -
is included in the meeting minutes from the Prague meeting:


      http://www.ietf.org/proceedings/80/slides/mpls-9.pdf


  During the IETF meeting in Prague, we agreed with the BFD working
  group to do a separate working group last callfor the BFD working
  group

The (BFD) working group last call was started on March 30th and ran
for 13 days. The last call ended on April 11th.

  The authors have since worked hard to resolve comments, some
  issue has been brought to the working group mailing list for
  resolution.

  Version -04 of the document was published June 28th.

  The publication request for draft-ietf-mpls-tp-cc-cv-rdi was  sent
  June 29th.

  The AD review resulted in a "New ID needed" due to mostly editorial
  comments. Version -05 was published on June 29 and the IETF last call
  started as soon as the new ID was avaialbe.

  The current list of Last Call Comments resoltion is also avaiable at:
  http://www.pi.nu/~loa/cc-cv-rdi-Last-Call-Comments.xls

  The list of issues that the authors kept very carefully, shows without
doubt
  that no comments been ignored.

  Loa
  mpls wg document shepherd







-----Original Message-----
From: David Allan I [mailto:david(_dot_)i(_dot_)allan(_at_)ericsson(_dot_)com]
Sent: quarta-feira, 6 de Julho de 2011 14:58
To: Rui Costa; ietf(_at_)ietf(_dot_)org; IETF-Announce
Cc: mpls(_at_)ietf(_dot_)org
Subject: RE: [mpls] Last Call: <draft-ietf-mpls-tp-cc-cv-rdi-05.txt>
(Proactive Connectivity Verification, Continuity Check and Remote Defect
indication for MPLS Transport Profile) to Proposed Standard

Hi Rui:

The comments were not ignored, the resolution of the Q10 comments as
well as those collected from the MPLS WG was presented at the last IETF.
My spreadsheet from which that report was generated and has been
augmented to include the BFD WG comments is available at
http://www.pi.nu/~loa/cc-cv-rdi-Last-Call-Comments.xls

So you know...
Dave


-----Original Message-----
From: ietf-bounces(_at_)ietf(_dot_)org 
[mailto:ietf-bounces(_at_)ietf(_dot_)org] On Behalf Of
Rui Costa
Sent: segunda-feira, 4 de Julho de 2011 23:03
To: ietf(_at_)ietf(_dot_)org; IETF-Announce
Cc: mpls(_at_)ietf(_dot_)org
Subject: RE: [mpls] Last Call: <draft-ietf-mpls-tp-cc-cv-rdi-05.txt>
(Proactive Connectivity Verification, Continuity Check and Remote Defect
indication for MPLS Transport Profile) to Proposed Standard

IMHO and for the record:

ITU-T comments regarding this draft haven't been discussed with ITU-T
but were simply ignored. No LS describing these comments' resolution was
sent.

Several service providers regarded this draft as not meeting their
transport networks' needs.

[The v03 draft was published in Feb and went to WG LC.
The v04 draft addressing WG LC comments was published on the 28th June
(same date as the proto write-up).
When was the WG LC launched, to verify LC comments resolution?]

Regards,
Rui


-----Original Message-----
From: mpls-bounces(_at_)ietf(_dot_)org 
[mailto:mpls-bounces(_at_)ietf(_dot_)org] On Behalf Of
The IESG
Sent: quinta-feira, 30 de Junho de 2011 14:47
To: IETF-Announce
Cc: mpls(_at_)ietf(_dot_)org
Subject: [mpls] Last Call: <draft-ietf-mpls-tp-cc-cv-rdi-05.txt>
(Proactive Connectivity Verification, Continuity Check and Remote Defect
indication for MPLS Transport Profile) to Proposed Standard


The IESG has received a request from the Multiprotocol Label Switching
WG
(mpls) to consider the following document:
- 'Proactive Connectivity Verification, Continuity Check and Remote
   Defect indication for MPLS Transport Profile'
  <draft-ietf-mpls-tp-cc-cv-rdi-05.txt> as a 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(_at_)ietf(_dot_)org mailing lists by 2011-07-14. Exceptionally, comments 
may
be
sent to iesg(_at_)ietf(_dot_)org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract

   Continuity Check, Proactive Connectivity Verification and Remote
   Defect Indication functionalities are required for MPLS-TP OAM.

   Continuity Check monitors the integrity of the continuity of the
   label switched path for any loss of continuity defect. Connectivity
   verification monitors the integrity of the routing of the label
   switched path between sink and source for any connectivity issues.
   Remote defect indication enables an End Point to report, to its
   associated End Point, a fault or defect condition that it detects on
   a pseudo wire, label switched path or Section.

   This document specifies methods for proactive continuity check,
   continuity verification, and remote defect indication for MPLS-TP
   label switched paths, pseudo wires and Sections using Bidirectional
   Forwarding Detection.


The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-mpls-tp-cc-cv-rdi/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-mpls-tp-cc-cv-rdi/


No IPR declarations have been submitted directly on this I-D.
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