One document matched: draft-andersson-mpls-sig-decision-03.txt-19768.txt
Differences from 03.txt-02.txt
MPLS Working Group Loa Andersson
Internet-Draft
Informational George Swallow
Expiration Date: April 2003 Cisco Systems
26 November, 2002
The MPLS Working Group decision on MPLS signaling protocols
<draft-andersson-mpls-sig-decision-03.txt>
Status of this Memo
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026 [RFC2026].
Internet-Drafts are working documents of the Internet Engineering Task
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Abstract
This document documents the consensus reached by the MPLS Working Group
within the IETF to focus its efforts on "RSVP-TE: Extensions to RSVP
for LSP Tunnels" (RFC3209) as the MPLS signalling protocol for traffic
engineering applications and to undertake no new efforts relating to
"Constraint-Based LSP Setup using LDP" (RFC3212).
-When this document has been approved by the IESG, the following note
will be added to the abstract: "The recommendations of chapter 6 have
been accepted by the IESG"
Conventions used in this document
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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].
Contents
1. Introduction ...................................................... 2
1.1 Objectives of document ........................................ 2
1.2 Nomenclature .................................................. 3
2. Background ........................................................ 3
3. CCAMP implementation study ........................................ 4
4. MPLS Working Group discussion ..................................... 4
4.1 Phase 1 ....................................................... 4
4.2 IETF process .................................................. 5
4.3 Relationship to other standards organizations ................. 5
4.4 Phase 2 ....................................................... 6
5. MPLS Working Group consensus ...................................... 7
6. Recommendation to the IESG ........................................ 8
7. Security considerations ........................................... 8
8. IANA considerations ............................................... 8
9. References ........................................................ 9
9.1 Normative ..................................................... 9
9.2 Non-normative ................................................. 9
1. Introduction
1.1 Objectives of document
This document documents the MPLS Working group consensus to continue to
develop RFC3209 [RFC3209] as the signalling protocol for MPLS signaling
for Traffic Engineering applications.
This document also documents the MPLS working group consensus to not
undertake any new work related to RFC3212 [RFC3212], e.g. there are no
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plans to progress RFC 3212 beyond proposed standard. No other actions
are taken relative the document status of RFC3212 [RFC3212] or RFCs that
specify extensions to RFC3212.
In section 6 we put forward the decision we believe the IESG should take
based on the consensus in MPLS working group on this issue. All other
sections is a documentation of the consensus process.
1.2 Nomenclature
This document uses the term "CR-LDP related working group drafts" to
refer to a group of Internet Drafts that specify changes or extensions
to [RFC3212] and the term "CR-LDP related RFCs" to discuss the group of
RFCs that specify the protocol and the applicability of [RFC3212].
The CR-LDP related working group drafts are:
"Multi Protocol Label Switching Label Distribution Protocol Query
Message Description" [QUERY]
"Improving Topology Data Base Accuracy with Label Switched Path
Feedback in Constraint Based Label Distribution Protocol [FEED]
"Signalling Unnumbered Links in CR-LDP" [UNNUM]
"Fault Tolerance for the Label Distribution Protocol (LDP)" [FT]
"Generalized MPLS Signaling - CR-LDP Extensions" [GEN]
"Generalized Multi-Protocol Label Switching Extensions for SONET
and SDH Control" [SONET]
"Generalized MPLS Signalling Extensions for G.709 Optical
Transport Networks Control" [G709]
"Generalized Multiprotocol Label Switching Extensions to Control
Non-Standard SONET and SDH Features" [SDH]
CR-LDP related RFCs
The CR-LDP related RFCs are:
RFC3212, "Constraint-Based LSP Setup using LDP"
RFC3213, "Applicability Statement for CR-LDP"
RFC3214, "LSP Modification Using CR-LDP"
No further updates of the CR-LDP related RFCs, beyond their current
statuses are planned within the MPLS Working Group.
2. Background
Very early (1997) in the MPLS standardization it was clear that a
protocol would be needed that would enable providers to setup LSPs that
took other information (e.g. various QoS parameters) into account.
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Development of this type of signalling protocol took two different
tracks:
- extensions to RSVP for setting up MPLS tunnels [RFC3209]
- extensions to LDP for setting constraint based LSPs [RFC3212]
The motivation for the choice of protocol in both cases was
straightforward. Extending RSVP-TE to do in an MPLS environment what it
already was doing (handling QoS information and reserving resources) in
an IP environment is comprehensible; you only have to add the label
distribution capability. Extending a native MPLS protocol like LDP,
which was designed to do label distribution, to handle some extra TLVs
with QoS information is also not revolutionary.
The MPLS group never reached a consensus on which way to go. Both
protocols were progressed to proposed standard.
3. CCAMP implementation study
An implementation survey of GMPLS implementations was published in June
2002 [GMPLS]. The survey includes responses from 22 different
implementers. Twenty-one of 22 implementations include the GMPLS
signalling based on [RFC3209], while only 3 include signalling based on
[RFC3212].
4. MPLS Working Group discussion
4.1 Phase 1
The GMPLS implementation report prompted questions asking if it was
reasonable to have two different protocols for the same thing. The
discussion was brought to the MPLS Working Group at the meeting in
Yokohama in July 2002. After discussion at the meeting it was decided to
"bring this to the list" and also invite comments from the other Sub-IP
Area Working Groups.
The following question sent to the mailing lists:
"As there are issues with having two similar standards (potentially
diverging), and it generates duplicate work in several IETF working
groups, the question was asked whether we should make CR-LDP
informational (which still make it available and possible to work with)
and progress only RSVP-TE on the standards track."
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The response to this question was largely positive, but some problems
were immediately pointed out:
- there are non-IETF standards which reference RFC3212. Taking CR-LDP
off the standards track would cause un-necessary problems for those
organisations and should be done only after co-ordinating with
those organizations
- there is, e.g. in RFC2026 [RFC2026], no documented process
according to which a document on the standards track may be move to
a status that is non-standards track
Each of these arguments is by themselves strong and would have led to
some reformulation of the proposal to move CR-LDP to informational.
Moreover, in combination it was clear that the original proposal was not
viable.
On the other hand the support for doing additional development of CR-LDP
as an IETF standards track alternative to RSVP-TE was extremely small.
4.2 IETF process
The current IETF process for managing changes in RFC status does not
include any information on how to move an existing standard track RFC to
a non-standard track status, nor does it include a prohibition of such
an action. It has been shown that such actions have been previously
taken e.g. RFCs 2673 and 2874 were moved from Proposed Standard to
Experimental. Though the cases are not exactly parallel to the MPLS
signalling case it shows that the IETF and IESG are prepared to take
such decisions given that the arguments are sufficiently strong.
4.3 Relationship to other standards organizations
The relationship with other standard organizations is an important part
IETF work. We are dependent on their work and they make use of our
technology; each organization has their own area of expertise. It is
therefore necessary that both sides handle their standards documentation
in such a way that no unnecessary updates or revisions are introduced
simply by sloppy handling of documents.
Consequently we need to keep CR-LDP referenceable, i.e. on the standards
track, for the foreseeable future. The implication of this is not that
we need to progress it further, or need to undertake further work in the
area. One implication however is that standards organizations which
reference the document, need to be notified of our decision so that they
(at their own pace) can change their references to more appropriate
documents. It is also expected that they will notify us when they no
longer have a need to normative reference to CR-LDP.
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4.4 Phase 2
Based on the feed back from this first discussion the question to the
working group were reformulated as:
"Should the MPLS WG focus its efforts on a signalling protocol
for traffic engineering applications on RSVP-TE, and hence the WG effort
with CR-LDP be discontinued? This would not involve any change in
document status for CR-LDP, nor would it hinder continued
individual contributions in the CR-LDP space. It would involve
a change in the MPLS WG charter to reflect this."
It was pointed out that "nor would it hinder continued individual
contributions" is too weak. We actually discourage, while it is not
prohibited, continued work in the CR-LDP area. That is the whole point
with taking this decision.
It was also pointed out that while it is quite acceptable to not accept
further working group documents, it would also be appropriate to take
the existing CR-LDP related working group Internet Drafts through the
process to proposed standard or informational as intended. This is
applicable to the following documents, since much of the work has
already been completed on them:
- in MPLS WG
-- Multi Protocol Label Switching Label Distribution Protocol Query
Message Description
-- Improving Topology Data Base Accuracy with Label Switched Path
-- Feedback in Constraint Based Label Distribution Protocol
-- Signalling Unnumbered Links in CR-LDP
-- Fault Tolerance for the Label Distribution Protocol (LDP)
- in CCAMP WG
-- Generalized MPLS Signaling - CR-LDP Extensions
-- Generalized Multi-Protocol Label Switching Extensions for SONET
and SDH Control
-- Generalized MPLS Signalling Extensions for G.709 Optical
Transport Networks Control
-- Generalized Multiprotocol Label Switching Extensions to Control
Non-Standard SONET and SDH Features
Some of the documents listed above are not in themselves extensions to
CR-LDP, but in one way or another are deemed to be "equally applicable
to CR-LDP". For those documents it will be fully appropriate to progress
them beyond proposed standard in the future if they meet the
requirements.
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RFCs that are extensions to CR-LDP, e.g., RFCs 3213 and 3214, will
remain proposed standard documents.
After this compromise was proposed a good consensus quickly formed
supporting the proposal. Close to 90% of the people participating
discussion said that they support or at least accept this outcome of the
working group discussion.
5. MPLS Working Group consensus
In a message to the working group (date) the working groups chairs
stated that consensus had been reached on:
- that the MPLS WG needs to focus its efforts on RSVP-TE (RFC 3209)
as protocol for traffic engineering signalling.
- that the Working Group will undertake no new work r5elated to CR-
LDP.
- that the WG charter should be updated to reflect this.
- that the WG will recommend that CR-LDP (RFC 3212) remain a proposed
standard.
- that the WG will recommend that RFCs 3213 and 3214, which are
closely related to CR-LDP, remain proposed standard.
- that existing Working Group drafts related to or updating/changing
CR-LDP will be progressed through the standards process to
proposed standard or informational RFCs as appropriate.
- that "the existing cr-ldp working group documents" are:
-- Multi Protocol Label Switching Label Distribution Protocol
Query Message Description
-- Improving Topology Data Base Accuracy with Label Switched Path
Feedback in Constraint Based Label Distribution Protocol
Signalling Unnumbered Links in CR-LDP
-- Fault Tolerance for the Label Distribution Protocol (LDP)
-- Generalized MPLS Signaling - CR-LDP Extensions
-- Generalized Multi-Protocol Label Switching Extensions for
SONET and SDH Control
-- Generalized MPLS Signalling Extensions for G.709 Optical
Transport Networks Control
-- Generalized Multiprotocol Label Switching Extensions to
Control Non-Standard SONET and SDH Features
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- that the MPLS working group will take on no new Working Group
documents related to CR-LDP.
- that the MPLS working group will entertain no efforts to promote
CR-LDP beyond proposed standard.
- that individual contributions related to CR-LDP area are not
prohibited, but discouraged.
- that a message will be sent to the relevant standards organizations
notifying them of this change of focus on MPLS signalling
protocols.
6. Recommendation to the IESG
Based on the consensus in the MPLS working group we recommend the IESG
to:
- confirm the MPLS Working Group consensus to undertake no new work
on CR-LDP and focus on RSVP-TE as signalling protocol for traffic
engineering applications for MPLS, as described in this document
- adopt as an IETF policy to refrain from entertaining work that
intends to progress RFC-3212 or related RFCs beyond proposed
standard
- adopt as an IETF policy to refrain from entertaining new working
group documents that are extensions to RFC3212
- review the IETF process with respect to management of documents
that needs to be moved from standards track to any other status
- publish this document as Informational RFC
7. Security considerations
This document only discusses a refocusing of the MPLS Working Group work
and consequently brings no new security considerations.
8. IANA considerations
This document brings no IANA considerations.
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9. References
9.1 Normative
[RFC2026]
Bradner, S. "The Internet Standards Process -- Revision 3", RFC 2026,
October 1996.
[RFC2119]
Bradner, S. "Key words for use in RFCs to Indicate Requirement
Levels", RFC 2119, March 1997.
[RFC3212]
Jamoussi, B. et.al., "Constraint-Based LSP Setup using LDP" RFC3212,
January 2002.
[RFC3209]
Awduche, D. et.al., "RSVP-TE: Extensions to RSVP for LSP Tunnels",
RFC3209, December 2001.
9.2 Non-normative
[RFC3213]
Jamoussi, B. et.al., "Applicability Statement for CR-LDP", RFC3213,
Jan 2002
[RFC3214]
Jamoussi, B. et.al., "LSP Modification Using CR-LDP" RFC3213, Jan
2002
[GMPLS]
Rekhther,Y and Berger,L, "Generalized MPLS Signaling - Implementation
Survey" http://www.ietf.org/IESG/Implementations/MPLS-SIGNALING-
Implementation.txt , June 2002.
[QUERY]
Ashwood-Smith P. and A. Paraschiv, "Multi Protocol Label Switching
Label Distribution Protocol Query MessageDescription" Work in
Progress, May 2002.
[FEED]
Jamoussi, B. et.al., "Improving Topology Data Base Accuracy with LSP
Feedback in CR-LDP", Work in progress, May 2002.
[UNNUM]
Rekhter, Y., et.al., "Signalling Unnumbered Links in CR-LDP", Work
in Progress, July 2002.
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[FT]
Farrel, A., et.al., "Fault Tolerance for the Label Distribution
Protocol (LDP)", Work in Progress, Sep 2002.
[GEN]
Ashwood-Smith, P. and Berger, L. (eds) "Generalized MPLS Signaling -
CR-LDP Extensions", Work in Progress, Aug 2002.
[SONET]
Mannie, E and Papadimitriou, D., "Generalized Multiprotocol Label
Switching Extensions forSONET and SDH Control" Work in Progress, Aug
2002.
[G709]
Papadimitriou, D. (ed), "Generalized MPLS Signalling Extensionsfor
G.709 Optical Transport Networks Control" Work in Progress, June
2002.
[SDH]
"Generalized Multiprotocol Label Switching Extensions to Control Non-
Standard SONET and SDH Features" Work in Progress, June 2002
Authors contacts:
Loa Andersson
email: loa@pi.se
George Swallow
Cisco Systems, Inc.
250 Apollo Drive
Chelmsford, MA 01824
Voice: +1 978 244 8143
email: swallow@cisco.com
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