LDP Extensions to Support Maximally Redundant Trees
RFC 8320

Received changes through RFC Editor sync (changed abstract to 'This document specifies extensions to the Label Distribution Protocol (LDP) to support the creation of Label Switched Paths (LSPs) for Maximally Redundant Trees (MRTs). A prime use of MRTs is for unicast and multicast IP/LDP Fast Reroute, which we will refer to as "MRT-FRR".

The sole protocol extension to LDP is simply the ability to advertise an MRT Capability. This document describes that extension and the associated behavior expected for Label Switching Routers (LSRs) and Label Edge Routers (LERs) advertising the MRT Capability.

MRT-FRR uses LDP multi-topology extensions, so three multi-topology IDs have been allocated from the MPLS MT-ID space.')

Received changes through RFC Editor sync (created alias RFC 8320, changed abstract to 'This document specifies extensions to the Label Distribution Protocol (LDP) to support the creation of Label Switched Paths (LSPs) for Maximally Redundant Trees (MRTs). A prime use of MRTs is for unicast and multicast IP/LDP Fast Reroute, which we will refer to as "MRT-FRR".', changed pages to 21, changed standardization level to Proposed Standard, changed state to RFC, added RFC published event at 2018-02-22, changed IESG state to RFC Published)

[Ballot comment]
Editorial feedback (Tim Chown's OPS DIR review):

There are a number of typos in the document that I would expect the RFC Editor
to pick up, but it would be nice to correct these before pushing the document,
e.g., "Extension" singular on page 3, or "as foll If" on page 10.

[Ballot comment]
Section 4.1 defines some reserved bits in the new MRT capability TLV format. Typically, we specify that reserved bits are set to 0 on send and ignored on receive, to allow for future definition of a purpose for them.

[Ballot comment]
(1) I think that Section 4.4. (Interaction of MRT-related LDP advertisements with the MRT topology and computations) would benefit from a reference to rfc5443 (LDP IGP Synchronization).

(2) From Section 5: "The associated LSPs must be created before a failure occurs..."  Should that be a Normative MUST?

[Ballot comment]
I did notice a couple minor nits:

1) draft-ietf-mpls-mldp-node-protection is now RFC 7715.

2) In Terminology: "Island Border Router (IBR): A router that is not in the MRT Island
      but is adjacent to an IBR and in the same area/level as the IBR."
  This is the definition for an Island Neighbor.
The correct definition from
RFC 7812 is: " Island Border Router (IBR): A router in the MRT Island that is
      connected to a router not in the MRT Island, both of which are in
      a common area or level."

[Ballot comment]
1) I was just wondering if it was considered to just use one flag of the reserved field of the multi-topology extension in RFC7307 to advertise MRT support, given that MT must always advertised as well...?

2) Why would a node withdraw the MRT capability/ when would it send a MRT advertisement with S=0?

3) If you update the document, please also see the gen-art review: there are many small nits which will probably also be caught by the RFC editor but if you can fix them now, that's even better!

[Ballot comment]
Line 106
  familiar with the architecture in [RFC7812] to understand how and why
  the LDP extensions for behavior are needed.

It would actually be helpful to explain this here.


Line 430
  However, should this situation occur, the expected behavior of an LSR
  receiving these conflicting advertisements is defined as foll If an
  LSR receives a label mapping advertisement for a rainbow FEC from an

Nit: as follows.

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

The IANA Services Operator has completed its review of draft-ietf-mpls-ldp-mrt-06. If any part of this review is inaccurate, please let us know.

The IANA Services Operator understands that, upon approval of this document, there are four actions which we must complete. Please see our note about the fourth action.

First, in the TLV Type Name Space registry located on the Label Distribution Protocol (LDP) Parameters registry page located at:

https://www.iana.org/assignments/ldp-namespaces/

we'll remove the "temporary" label from the following early allocation:

Value: 0x050E
Description: MRT Capability TLV
Reference: [ RFC-to-be ]

Second, in the Status Code Name Space registry also on the Label Distribution Protocol (LDP) Parameters registry page located at:

https://www.iana.org/assignments/ldp-namespaces/

we'll remove the "temporary" label from the following early allocation:

Range/Value: 0x00000034
E: 0
Description: MRT Capability negotiated without MT Capability
Reference: [ RFC-to-be ]

Third, in the MPLS Multi-Topology Identifiers registry located at:

https://www.iana.org/assignments/mpls-multi-topology-parameters/

we'll remove the "temporary" label from the following early allocations:

Value: 3945
Purpose: Rainbow MRT MPLS MT-ID
Reference: [ RFC-to-be ]

Value: 3946
Purpose: Default Profile MRT-Red MPLS MT-ID
Reference: [ RFC-to-be ]

Value: 3947
Purpose: Default Profile MRT-Blue MPLS MT-ID
Reference: [ RFC-to-be ]


Fourth, also in the MPLS Multi-Topology Identifiers registry located at:

https://www.iana.org/assignments/mpls-multi-topology-parameters/

The purpose field of the MPLS Multi-Topology Identifiers Registry for MT-ID range 3948-3995 to "Unassigned (for future MRT-related values)", assuming the above suggested values are assigned. The Registration procedure for the entire registry remains "Standards Action".

NOTE: Rather than list a document as a reference for an unassigned range, our intention is to document the change to the 3948-3995 range by listing this as an additional reference for the registry itself, along with RFC 7307.

The IANA Services Operator understands that these four actions are the only ones required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is only to confirm what actions will be performed.

Thank you,

Amanda Baber
Lead IANA Services Specialist

The following Last Call announcement was sent out (ends 2017-09-01):

From: The IESG
To: IETF-Announce
CC: mpls@ietf.org, db3546@att.com, draft-ietf-mpls-ldp-mrt@ietf.org, mpls-chairs@ietf.org, tsaad@cisco.com, loa@pi.nu
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (LDP Extensions to Support Maximally Redundant Trees) to Proposed Standard


The IESG has received a request from the Multiprotocol Label Switching WG
(mpls) to consider the following document: - 'LDP Extensions to Support
Maximally Redundant Trees'
  as 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 2017-09-01. 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


  This document specifies extensions to the Label Distribution
  Protocol(LDP) to support the creation of label-switched paths for
  Maximally Redundant Trees (MRT).  A prime use of MRTs is for unicast
  and multicast IP/LDP Fast-Reroute, which we will refer to as MRT-FRR.

  The sole protocol extension to LDP is simply the ability to advertise
  an MRT Capability.  This document describes that extension and the
  associated behavior expected for LSRs (Label Switching Routers) and
  LERs (Label Edge Routers) advertising the MRT Capability.

  MRT-FRR uses LDP multi-topology extensions and requires three
  different multi-topology IDs to be allocated from the MPLS MT-ID
  space.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-mpls-ldp-mrt/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-mpls-ldp-mrt/ballot/


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

The MPLS Working Group request that

        LDP Extensions to Support Maximally Redundant Trees
                      draft-ietf-mpls-ldp-mrt

Is publsihed as an RFC on the Standards Track.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

  We request publication as a Proposed Standard, the document header says
  "Standards Track".
  The document specifies extensions and procedures for a Standard Track
  protocol (LDP) and Proposed Standard is the correct type of RFC.

(2) 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

  The document specify an extensions to the Label Distribution
  Protocol (LDP) that support the creation of label-switched paths
  for Maximally Redundant Trees (MRT).  The most obvious use of MRT
  is for Fast-Resoute for IP/LDP uni- and multicast. This is
  referred to as MRT-FRR.

  The document specifies this ability of LDP to advertise MRT
  Capability and the associated behavior expected for LSRs (Label
  Switching Routers) and LERs (Label Edge Routers) advertising the
  MRT Capability.

  MRT-FRR uses LDP multi-topology extensions and requires three
  different multi-topology IDs to be allocated from the MPLS MT-ID
  space.

Working Group Summary

  The working group support this document. The progress has been a
  bit slow, since we have been waiting for other MRT documents in
  other working groups.

Document Quality

  We are aware of two prototype implementations of this protocol
  specifiction. An implementation poll has been sent out to the
  working group, as soon as we have more information we will update
  the shepherd write-up.
 
  The document has been through the normal wg process, no other types
  are necessary.

Personnel

  Loa Andersson is the Document Shepherd
  Deborah Brungrard is the Responsible Area Director.

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

  The document shepherd has reviewed the document several times
  - when the document were first posted as an individual document
  - when preparing the adoption as a working group document
  - when the documents in other working groups were in such a state
    that it no longer blocked the progress of this document
  - at working group last call

  This document is ready for publication, save for a small nit on
  terminology on OSPF and IS-IS terminology on border routers. We
  have agreed to fold this update in with the comments from the
  RTG-DIR review.

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

  No such concerns.



(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.

  No such revieews needed.

(6) Describe any specific concerns or issues that the Document Shepherd
has 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.

  No such conserns.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

  All the authors have stated on the MPLS Working Group mailing list
  that they are unaware of any IPR that relates to this document.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

  There are no IPR disclosures against this document.

(9) 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?

  LDP FRR and  LDP based MRT FRR are corner stones in the MPLS
  protection architecture and has solid support in the working
  group.

(10) 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 publicly available.)

  No such threats.

(11) Identify any ID nits the Document Shepherd has found in this
document. (See https://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

  No nits identified, the nits tool points to two miscellaneous
  warnings:
  - a weird spacing in the table of content, it seems to me that
    cam await the final RFC Editor editing
  - the nits tool also calim that the RFC 2119 boilerplate is
    missing, it turns out the the boilerplate is there but that the
    text is not 100% what the boilerpalte is supposed to be. The
    authors has been told to change the bolier plate to:

    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
    "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
    document are to be interpreted as described in RFC 2119 [RFC2119].
                                                    ^^^^^^^^
    When the comments from the RTG-DIR is resolved.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

  No such formal reviews required.

(13) Have all references within this document been identified as
either normative or informative?

  The references are correctly split, with the the exception of the
  reference to RFC 2119 that I think should be a normative
  reference.

(14) 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 plan for their completion?

  All normative references are too existing RFCs.

(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

  No down references, all normative references are to Proposed
  Standard RFCs.

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

  There will be no status change for any other document when this is
  published.


(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

  The shepherd has reviewed the IANA section several times as the
  document developed. The IANA section is clear and well sritten.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.

  No new IANA registries created.

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.

  No such reviews necessary.