Re: [mpls] [PWE3] draft-ietf-pwe3-rfc4447bis-00.txt Notes

Luca (and all),
I fully support the idea of progressing RFC 4447 to Internet Standard. 

Looking up the draft, I have found the following difference with the current text:

RFC 4447, Section 3:
       LDP MUST be used in its  "downstream unsolicited" mode.
which is quite unambiguous.

draft-ietf-pwe3-rfc4447bis-00, Section 3, changes this to:
       LDP MUST exchange PW FEC label bindings in downstream unsolicited manner, independent of the
       negotiated label advertisement mode of the LDP session. 

I assume that this is the change you've had in mind when you said:
""Added text to specify that downstream unsolicited bit does not apply to PW application..."
even if the actual text states that it does apply.

But, what is more serious, this seems to contradict the following statement in RFC 5036, Section 2.6:
      However, for any given LDP session, each LSR must be aware of the label distribution method used by its peer
      in order to avoid situations where one peer using Downstream  Unsolicited label distribution assumes its peer is also. 

and further in Section 2.6.3:
   Each interface on an LSR is configured to operate in either
   Downstream Unsolicited or Downstream on Demand advertisement mode.
   LSRs exchange advertisement modes during initialization. 

I am not sure that the proposed change in 4447 complies with the quoted statements in 5036.

A reference (in the notes only, not in the draft) to draft-raza (which has not yet been posted as a WG document) does not justify such a deviation IMHO. It could also put 4447bis on hold if an explicit dependency is created. At the very least we should hear what the MPLS WG has to say on that.

And, speaking about references, I see that RFC 4448 is marked as "Work in Progress" in the draft.

Is it just a typo, or do you imply that it is going to undergo a revision soon?

Hopefully these notes will be useful.

Regards,
     Sasha

________________________________________
From: pwe3-bounces@ietf.org [pwe3-bounces@ietf.org] on behalf of Luca Martini [lmartini@cisco.com]
Sent: Tuesday, July 10, 2012 8:35 PM
To: pwe3
Subject: [PWE3] draft-ietf-pwe3-rfc4447bis-00.txt Notes

WG,

At the request of the chairs, I have posted the initial version of an
update to rfc4447.

This is the next step in the process defined by rfc6410 to progress this
document to "Internet Standard".
Quoting rfc6410:

"   A specification may be, and indeed, is likely to be, revised as it
    advances from Proposed Standard to Internet Standard.  When a revised
    specification is proposed for advancement to Internet Standard, the
    IESG shall determine the scope and significance of the changes to the
    specification, and, if necessary and appropriate, modify the
    recommended action.  Minor revisions and the removal of unused
    features are expected, but a significant revision may require that
    the specification accumulate more experience at Proposed Standard
    before progressing."

According to the above guidelines, I have revised the rfc4447 document
to incorporate all erratas , and a WG discussions about the PW
encapsulation being symmetric in both direction of traffic. I also added
a clarification about the LDP mode bit as per MPLS WG discussion.
Let me know what else I might have missed.

Here is a list of changes from my log:
--------------------------------------------------------------------------------------------------------------------------------
- Updated all references - published v00 of bis rfc draft
- Added clarification about PW always being symmetrical in both
direction of traffic.
- Changed Generalized ID FEC element, and  Generalized PWid FEC element
to >> Generalized PWid FEC element to be consistent with IANA allocation
and within the document ( this was noted in errata, but IMHO incorrectly
rejected )
- Errata ID: 1530 - accepted
- Errata ID: 3112 - accepted
- Errata ID: 3114 - accepted
- Errata ID: 3115 - removed table
- Errata ID: 86 - accepted
- Errata ID: 938  - accepted
- Added text to specify that downstream unsolicited bit does not apply
to pw application according to
draft-raza-mpls-ldp-applicability-label-adv-02.txt (WG document of MPLS WG)
- made source identical , to rfc

--------------------------------------------------------------------------------------------------------------------------------

Thanks.
Luca
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