Using Multipoint LDP When the Backbone Has No Route to the Root
RFC 6512

The IANA Actions for this document are dependent upon approval of a
separate Internet Draft ( draft-ietf-mpls-ldp-p2mp ).

Upon approval of this document, IANA understands that there is a single
action that needs to be completed.

In the registry named "The LDP MP Opaque Value Element Basic Type"
created by the approval of ( draft-ietf-mpls-ldp-p2mp ), two new values
are to be registered as follows:

Name: Recursive Opaque Value
Value: TBD (requested value: 6)
Description: An opaque value of this type is itself a TLV that encodes
an mLDP FEC type.
Reference: [ RFC-to-be ]

Name: VPN-Recursive Opaque Value
Value: Type TBD (requested value: 7)
Description: An opaque value of this type consists of an eight-octet
Route Distinguisher, followed by a TLV that encodes an mLDP FEC type.
Reference: [ RFC-to-be ]

IANA understands that this is the only action required upon approval of
this document.

State changed to In Last Call from Last Call Requested.

The following Last Call Announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Subject: Last Call:  (Using Multipoint LDP when the Backbone has no Route to the Root) to Proposed Standard


The IESG has received a request from the Multiprotocol Label Switching WG
(mpls) to consider the following document:
- 'Using Multipoint LDP when the Backbone has no Route to the Root'
  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@ietf.org mailing lists by 2011-07-11. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  The control protocol used for constructing Point-to-Multipoint and
  Multipoint-to-Multipoint Label Switched Paths ("MP LSPs") contains a
  field that identifies the address of a "root node".  Intermediate
  nodes are expected to be able to look up that address in their
  routing tables.  However, if the route to the root node is a BGP
  route, and the intermediate nodes are part of a BGP-free core, this
  is not possible.  This document specifies procedures which enable a
  MP LSP to be constructed through a BGP-free core.  In these
  procedures, the root node address is temporarily replaced by an
  address that is known to the intermediate nodes and is on the path to
  the true root node.





The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-mpls-mldp-recurs-fec/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-mpls-mldp-recurs-fec/


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

State changed to AD Evaluation::Revised ID Needed from AD Evaluation.
AD review...

Hi,

Don't panic!

I have carried out my usual AD review of your draft. The purpose of the
review is to iron out any wrinkles before the document goes to IETF last
call and IESG review, the better to ensure smooth passage through those
stages and rapid adoption as an RFC.

Thank you for a well-written and clear document. I have no technical
concerns with your work. There is one relatively important editorial
point I would like you to resolve, and while you are at it, there are
a few nits that can be mopped up.

I think this merits a new revision, if you don't mind. As soon as I see
it, I will kick off the IETF last call.

I have also asked the document shepherd to find out about the
implementation status for me. Implementation is not a requirement, but
the write-up needs to give the information. Obviously, at least an
intent to implement is strongly desirable.

Many thanks,
Adrian

---

I don't think including Figure 1 here actually adds to the readability
of the document. And, as usual, when there is a duplicated definition
we have to worry about cross-checking and stating which document
contains the normative definition. It would be better if you could delete
the figure and simply reference [mLDP].

---

Rather trivially, the text about Figure 2 does not state what R is.
Suggest...

s/route for R/route for R in the customer network/

---

Section 1

s/from CE1 address to R/from CE1 addressed to R/

---

The term "mLDP" turns up unexplained. Can you insert an expansion?

---

Section 2.2

It is not so important, but...

  PE1 therefore MUST create a new MP FEC element       

I don't think this is really a "MUST". I'd be happy with...

  PE1 creates a new MP FEC element

Similarly...
  PE1 then MUST send this FEC element to P1.
becomes...
  PE1 then sends this FEC element to P1.

This shows again in 3.2.2

---

Section 2.2

      PE2-FEC = , or

      PE2-FEC = >

With my small brain that is easily confused, I found "or" misleading.
Would "i.e." be more accurate?

---

Section 2.2

  This will result in CE1-FEC being sent on to CE2, and
  presumably further from CE2 to R.

Strike "presumably" because [mLDP] makes this clear.

---

Section 3.1

This is the second Figure 3!

The text about this figure doesn't match the figure itself. The figure
shows two explicit fields (RD and FEC), but the text talks about *the*
value field.

---

Section 5

It might be advisable to include an informational reference to RFC 5920

> (1.a) Who is the Document Shepherd for this document? Has the
>      Document Shepherd personally reviewed this version of the
>      document and, in particular, does he or she believe this
>      version is ready for forwarding to the IESG for publication?

Loa Andersson is the Document Shepherd.
He has reviewed the document and believes it is ready to be
forwarded to the IESG for publication.

> (1.b) Has the document had adequate review both from key WG members
>      and from key non-WG members? Does the Document Shepherd have
>      any concerns about the depth or breadth of the reviews that
>      have been performed?

The document has been reviewed in the MPLS working group. No concerns.

The shepherd is convinced that this is sufficient review for this
document.


> (1.c) Does the Document Shepherd have concerns that the document
>      needs more review from a particular or broader perspective,
>      e.g., security, operational complexity, someone familiar with
>      AAA, internationalization or XML?

No.

> (1.d) Does the Document Shepherd have any specific concerns or
>      issues with this document that the Responsible Area Director
>      and/or the IESG should be aware of? For example, perhaps he
>      or she is uncomfortable with certain parts of the document, or
>      has concerns whether there really is a need for it. In any
>      event, if the WG has discussed those issues and has indicated
>      that it still wishes to advance the document, detail those
>      concerns here. Has an IPR disclosure related to this document
>      been filed? If so, please include a reference to the
>      disclosure and summarize the WG discussion and conclusion on
>      this issue.

No such concerns. There is no IPR claim for this draft.


> (1.e) How solid is the WG consensus behind this document? Does it
>      represent the strong concurrence of a few individuals, with
>      others being silent, or does the WG as a whole understand and
>      agree with it?

The working group consensus is strong.


> (1.f) Has anyone threatened an appeal or otherwise indicated extreme
>      discontent? If so, please summarise the areas of conflict in
>      separate email messages to the Responsible Area Director. (It
>      should be in a separate email because this questionnaire is
>      entered into the ID Tracker.)

No threats or extreme discontent.

> (1.g) Has the Document Shepherd personally verified that the
>      document satisfies all ID nits? (See the Internet-Drafts Checklist
>      and http://tools.ietf.org/tools/idnits/). Boilerplate checks are
>      not enough; this check needs to be thorough. Has the document
>      met all formal review criteria it needs to, such as the MIB
>      Doctor, media type and URI type reviews?

The nits tool does not report any nits.


> (1.h) Has the document split its references into normative and
>      informative? Are there normative references to documents that
>      are not ready for advancement or are otherwise in an unclear
>      state? If such normative references exist, what is the
>      strategy for their completion? Are there normative references
>      that are downward references, as described in [RFC3967]? If
>      so, list these downward references to support the Area
>      Director in the Last Call procedure for them [RFC3967].

This document only has normative references.


> (1.i) Has the Document Shepherd verified that the document IANA
>      consideration section exists and is consistent with the body
>      of the document? If the document specifies protocol
>      extensions, are reservations requested in appropriate IANA
>      registries? Are the IANA registries clearly identified? If
>      the document creates a new registry, does it define the
>      proposed initial contents of the registry and an allocation
>      procedure for future registrations? Does it suggest a
>      reasonable name for the new registry? See [RFC5226]. If the
>      document describes an Expert Review process has Shepherd
>      conferred with the Responsible Area Director so that the IESG
>      can appoint the needed Expert during the IESG Evaluation?

There is well written IANA considerations section in this document
that request two code points from the new registry defined in the mLDP
draft for "The LDP MP Opaque Value Element Basic Type".
Values are requested for the "Recursive Opaque Value" and "VPN-Recursive
Opaque Value".


> (1.j) Has the Document Shepherd verified that sections of the
>      document that are written in a formal language, such as XML
>      code, BNF rules, MIB definitions, etc., validate correctly in
>      an automated checker?

No such formal language.

> (1.k) The IESG approval announcement includes a Document
>      Announcement Write-Up. Please provide such a Document
>      Announcement Write-Up? Recent examples can be found in the
>      "Action" announcements for approved documents. The approval
>      announcement contains the following sections:

Technical Summary

  When LPD is used as control protocol for constructing
  Point-to-Multipoint and    Multipoint-to-Multipoint Label Switched
  Paths ("MP LSPs") it contains a field that identifies the address
  of a "root node".
  Intermediate nodes are expected to be able to look up that address
  in their routing tables. However, if the route to the root node is
  a BGP route, and the intermediate nodes are part of a BGP-free
  core, this is not possible. 
  This document specifies procedures which enable a MP LSP to be
  constructed through a BGP-free core.  In these procedures, the root
  node address is temporarily replaced by an address that is known
  to the intermediate nodes and is on the path to the true root node.

Working Group Summary

  LPD is one of the MPLS core protocols that at the start were
  designed establish LSP connectivity that well reflected the
  topology as understood by the routing protocol. LDP has been
  extended for several different. This document addresses an issue
  that has been identified by the working group.

Document Quality

The document is well reviewed by the MPLS working group.