Internet DRAFT - draft-andersson-mpls-sig-decision

draft-andersson-mpls-sig-decision



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 
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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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