2.5.8 Multiprotocol Label Switching (mpls)

NOTE: This charter is a snapshot of the 63rd IETF Meeting in Paris, France. It may now be out-of-date.

Last Modified: 2005-06-27


George Swallow <swallow@cisco.com>
Loa Andersson <loa@pi.se>

Routing Area Director(s):

Bill Fenner <fenner@research.att.com>
Alex Zinin <zinin@psg.com>

Routing Area Advisor:

Alex Zinin <zinin@psg.com>

Mailing Lists:

General Discussion: mpls@lists.ietf.org
To Subscribe: https://www1.ietf.org/mailman/listinfo/mpls
Archive: http://cell.onecall.net/cell-relay/archives/mpls/mpls.index.html

Description of Working Group:

The MPLS working group is responsible for standardizing a base
technology for using label switching and for the implementation of
label-switched paths over various packet based link-level
technologies, such as Packet-over-Sonet, Frame Relay, ATM, and
LAN technologies (e.g. all forms of Ethernet, Token Ring, etc.).
This includes procedures and protocols for the distribution of
labels between routers and encapsulation.

The working group is also responsible for specifying the necessary
MIBs for the functionality specified in the base MPLS technology.

The first generation of the MPLS standards are largely complete,
and the current WG work items are:

- procedures and protocols for multicast protocol extensions for
  point-to-multipoint TE, including soft-preemption

- Define requirements and mechanisms for MPLS OAM

- Define an overall OAM framework for MPLS applications

- MPLS-specific aspects of traffic engineering for multi-areas/multi-AS
  in cooperation with the CCAMP WG

- Determine (with CCAMP) what procedures are appropriate for evaluating
  proposals to extend the MPLS and GMPLS protocols, and document these

- Document current implementation practices for MPLS load sharing

The Working Group chairs tracking of the working group documents can be
viewed at http://www.tla-group.com/~mpls/mpls-wg-docs.htm

Goals and Milestones:

Done  Submit documents from original MPLS effort to IESG
Done  Framework for IP multicast over label-switched paths ready for advancement.
Done  LDP fault tolerance specification ready for advancement to Proposed Standard.
Done  Submit Definitions of Managed Objects for MultoiProtocol Label Switching, Label Distribution Protocol (LDP) to the IESG for publication as Proposed Standards
Done  Specification for MPLS-specific recovery ready for advancement.
Done  Submit Multiprotocol Label Switching (MPLS) Forward Equivalency Class-To-Next Hop Label Forwarding Entry Management Information Base to the IESG for publication as Proposed Standards
Done  Submit Multiprotocol Label Switching (MPLS) Label Switching Router (LSR), Management Information Base to the IESG for publication as Proposed Standards
Done  Submit Multiprotocol Label Switching (MPLS) Management Overview to the IESG for publication as Proposed Standards
Done  Submit Definitions of Textual Conventions for Multiprotocol Label Switching (MPLS) Management to the IESG for publication as Proposed Standards
Done  Submit Multiprotocol Label Switching (MPLS) Traffic Engineering Management Information Base to the IESG for publication as Proposed Standards
Done  Submit the Traffic Engineering Link MIB to the IESG for as a Proposed Standard
Done  Submit a specification on Encapsulations to carry MPLS over IP and GRE to the IESG for as a Proposed Standard
Nov 03  Together with CCAMP complete and establish the (G)MPLS change process
Apr 04  Advance MPLS Architecture and MPLS encapsulation to Draft Standard
Apr 04  Submit a specification on Soft Pre-emption of LSP Tunnels to the IESG for publication as a Proposed Standard
Apr 04  Submit specification on LSR Self Test to the IESG for publication as a Proposed Standard
Jul 04  Submit specification on LSP Ping to the IESG for publication as a Proposed Standard
Jul 04  Submit a document defining the scope, requirements, and issues to resolve for setup of P2MP TE LSPs (MPLS and GMPLS)
Aug 04  Submit an OAM Framework Document to the IESG for publication as an Informational RFC
Oct 04  Advance 'Extension to RSVP for LSP Tunnels' to Draft Standard
Nov 04  Submit document(s) specifying protocol extensions, enhancements and mechanisms for setup of P2MP TE LSPs
Nov 04  Submit a BCP on MPLS load sharing to the IESG


  • draft-ietf-mpls-icmp-02.txt
  • draft-ietf-mpls-lsp-hierarchy-08.txt
  • draft-ietf-mpls-bundle-06.txt
  • draft-ietf-mpls-mgmt-overview-09.txt
  • draft-ietf-mpls-bgp-mpls-restart-04.txt
  • draft-ietf-mpls-lsp-ping-09.txt
  • draft-ietf-mpls-lc-if-mib-06.txt
  • draft-ietf-mpls-nodeid-subobject-06.txt
  • draft-ietf-mpls-oam-requirements-06.txt
  • draft-ietf-mpls-soft-preemption-06.txt
  • draft-ietf-mpls-telink-mib-07.txt
  • draft-ietf-mpls-lsr-self-test-05.txt
  • draft-ietf-mpls-rsvpte-attributes-05.txt
  • draft-ietf-mpls-explicit-null-02.txt
  • draft-ietf-mpls-ecmp-bcp-01.txt
  • draft-ietf-mpls-oam-frmwk-03.txt
  • draft-ietf-mpls-rsvp-te-p2mp-02.txt
  • draft-ietf-mpls-p2mp-sig-requirement-03.txt
  • draft-ietf-mpls-over-l2tpv3-00.txt

    Request For Comments:

    RFC2702 I Requirements for Traffic Engineering Over MPLS
    RFC3031 PS Multiprotocol Label Switching Architecture
    RFC3032 PS MPLS Label Stack Encoding
    RFC3033 PS The Assignment of the Information Field and Protocol Identifier in the Q.2941 Generic Identifier and Q.2957 User-to-user Signaling for the Internet Protocol
    RFC3034 PS Use of Label Switching on Frame Relay Networks Specification
    RFC3035 PS MPLS using LDP and ATM VC Switching
    RFC3036 PS LDP Specification
    RFC3037 PS LDP Applicability
    RFC3038 PS VCID Notification over ATM link for LDP
    RFC3063 E MPLS Loop Prevention Mechanism
    RFC3107 PS Carrying Label Information in BGP-4
    RFC3209 PS RSVP-TE: Extensions to RSVP for LSP Tunnels
    RFC3210 I Applicability Statement for Extensions to RSVP for LSP-Tunnels
    RFC3212 PS Constraint-Based LSP Setup using LDP
    RFC3213 I Applicability Statement for CR-LDP
    RFC3214 PS LSP Modification Using CR-LDP
    RFC3215 I LDP State Machine
    RFC3270 PS MPLS Support of Differentiated Services
    RFC3353 I Framework for IP Multicast in MPLS
    RFC3443 PS Time to Live (TTL) Processing in MPLS Networks (Updates RFC 3032)
    RFC3469 I Framework for MPLS-based Recovery
    RFC3477 PS Signalling Unnumbered Links in Resource ReSerVation Protocol - Traffic Engineering (RSVP-TE)
    RFC3478 PS Graceful Restart Mechanism for Label Distribution Protocol
    RFC3479 PS Fault Tolerance for the Label Distribution Protocol (LDP)
    RFC3480 PS Signalling Unnumbered Links in CR-LDP (Constraint-Routing Label Distribution Protocol)
    RFC3612 I Applicability Statement for Restart Mechanisms for the Label Distribution Protocol (LDP)
    RFC3811 Standard Definitions of Textual Conventions for Multiprotocol Label Switching (MPLS) Management
    RFC3812 Standard Multiprotocol Label Switching (MPLS) Traffic Engineering Management Information Base
    RFC3813 Standard Multiprotocol Label Switching (MPLS) Label Switching Router (LSR)Management Information Base
    RFC3814 Standard Multiprotocol Label Switching (MPLS) Forwarding Equivalence Class To Next Hop Label Forwarding Entry (FEC-To-NHLFE)Management Information Base
    RFC3815 Standard Definitions of Managed Objects for the Multiprotocol Label Switching, Label Distribution Protocol (LDP)
    RFC3988 E Maximum Transmission Unit Signalling Extensions for the Label Distribution Protocol
    RFC4023 Standard Encapsulating MPLS in IP or Generic Routing Encapsulation (GRE)
    RFC4090 Standard Fast Reroute Extensions to RSVP-TE for LSP Tunnels

    Current Meeting Report

    Multi-Protocol Label Switching WG (mpls)

    MONDAY, August 1 at 10:30 - 12:30
    CHAIRS: Loa Andersson <loa@pi.se>
            George Swallow <swallow@cisco.com>


    1. ICMP interactions with MPLS

    Ron gave a short background; ICMP as specified in RFC792, does not have a mechanism to report MPLS header information when a router fails to deliver a packet. The MPLS WG processed a draft on MPLS extensions (an object to report the MPLS header) for ICMP and requested that the draft should be published as an RFC on the Standards track. The IESG decided not to publish it because of "layer violation". However the draft has been widely implemented and is an integrated part of most MPLS implementations.
    The draft has now been resurrected <draft-ietf-mpls-icmp-03>, and the discussion is what work we need to undertake get it published.
    It was pointed out that we can't change anything in the technical details. This needs to be coordinated with the Internet Area, and one
    Suggestion is to move the parts that are not MPLS specific into a draft that the Internet Area will progress, while the MPLS specific parts goes through the MPLS working group.
    Ron will discuss this in the Internet Area meeting and we will await the outcome of this discussion.

    Slides: http://www.tla-group.com/~mpls/MPLS-Extensions-to-ICMP.ppt

    2. Agenda bashing
    Apart from moving the discussion on MPLS ICMP, to the top of the agenda to make possible for Ron to present the same topic in the Internet Area meeting (taking place at the same time), there were no other changes in agenda.

    Slides: http://www.tla-group.com/~mpls/mpls-agenda-paris.htm

    3. Working group status
    Working group chairs reported on the status of working group documents:

    Parking Place
    We have a new "parking place", i.e. a web site that lists all documents that IESG have approved to be published as RFCs. The parking place is located at:


    New RFCs from the MPLS working group since last meeting:
    RFC 4090 Fast Reroute Extensions for RSVP-TE for LSP Tunnels

    Working group documents in RFC-ed queue:
    draft-ietf-mpls-lsp-hierarchy-08.txt (2002-04-11!)

    We have documents that have been stuck in the RFC-editors queue for some time. Actually the oldest document in the queue comes from the MPLS working group.

    Working group documents in parking place:

    Working group documents in IESG review:
    draft-ietf-mpls-ecmp-bcp-01.txt (publication requested)
    draft-ietf-mpls-lc-if-mib-06.txt (new ID needed)
    draft-ietf-mpls-lsp-ping-09.txt (new ID needed)
    draft-ietf-mpls-nodeid-subobject-05.txt (ietf last call)
    draft-ietf-mpls-bgp-mpls-restart (IESG evaluation)
    draft-ietf-mpls-rsvpte-attributes (IESG evaluation)

    MPLS working group drafts:
    draft-ietf-mpls-oam-requirements-06.txt (dated)
    draft-ietf-mpls-rfc3036bis-01.txt (dated)

    4. LDP to Draft Standards

    draft-ietf-mpls-rfc3036bis-01.txt has gone through minor editing and is ready for WG last call.

    draft-minei-ldp-operational-experience-01.txt has been refreshed, it is a required informational reference for advancing the BIS draft. Please provide this draft with in depth review.

    One additional draft - protocol analysis - is also required (RFC 1264) to take LDP to draft standard to receive in depth review.
    The packages we need to prepare for taking LDP to Draft Standard also include <draft-thomas-mpls-ldp-survey2002-00.txt>.

    Working group chairs will start the Working Last Call on the LDP document and poll the list for making the implementation survey and the operational experiences working group documents.

    Slides: http://www.tla-group.com/~mpls/ldp_to_standard_63.ppt

    5. MPLS OAM

    LSR Self Test

    This draft has been waiting for the LSP Ping to clear working last call. This has now happened and after minor changes it is ready go to working group last call.

    Slides: None

    P2MP LSP Ping

    Since the meeting in Minneapolis a new work from Bill Fenner (new co-author) has been added and the objectives have been made more precise. Currently it is possible to ping one specific leaf or the whole tree.
    There was a good support for making it a working group document. Working group chairs will confirm this based on input on the working group mailing list.

    Slides: http://www.tla-group.com/~mpls/p2mp-lsp-ping-02-MPLS-WG.ppt


    The draft addresses issues for using the base LSP Ping in Inter AS contexts. Although there is a need to complete some sections of the draft the authors ask for feedback. One problem with using base LSP Ping is that the IP address found in the packet need not be routable if the forwarding failure occurs in an AS to which the AS where the packet originates does not announce the address that is found "under" the MPLS label. The indicated solution is to record the ASBR that the LSP Ping packet passes through, and if a failure occurs return the packet to the ASBR. The author will continue working on the document and fill in the un-finished sections. Authors request feedback from the working group.

    Slides: http://www.tla-group.com/~mpls/draft-nadeau-mpls-interas-lspping.ppt

    P2MP OAM requirements

    The document addresses issues on how to detect and report data plane failures. Tom thinks that the document is a little rough; it needs a clarification and additional review. The P2MP OAM requirements should go into a document of its own and needs to address both diagnostic and periodic OAM. Input from Service Providers and careful review is important.

    Loa asked who has read and who supported this to become a working group document. Among those who have read the document there is a good support for making it a working group document. Needs to be confirmed on the list.

    Slides: http://www.tla-group.com/~mpls/P2MP-Req-v0.2.ppt

    6. MPLS Multicast and MPLS P2MP

    Rahul said that version -02 was recently published, according the authors it is not entirely ready for last called and a version -03 is planned. The working group should take the opportunity to read and comment.

    The background is that there is some inconsistency between what RFC3032 says about multicast and unicast, and the actual requirements. The three drafts discuss separate aspects of this and propose mechanisms solutions to some of the problems.
    One of the mechanisms that are introduced is upstream label allocation (UAL). The drafts also concluded that it is not necessary to have one code point allocated for unicast and one for multicast, since this is given by context in the NHLFE.
    Conclusion is that there is some need to revisit how code points have been assigned. Instead of assigning one code point for unicast (8847) and one for multicast (8848), the draft suggests that the code points are used for downstream allocated (8847) and upstream allocated (8848).
    The concept of "Neighbor specific labels" is introduced since this is required for support of upstream assigned labels. With UAL - the context of a label is derived from the neighbor from whom the labeled packet was sent.

    The chairs asked how many had read the drafts and who thought they need to become working group drafts. Neither the amount of people who have read the drafts nor the support for making them working group drafts was conclusive.

    The working group chairs will take steps to initiate a discussion on the mailing list. Adrian pointed out that the LDP and RSVP-TE aspects are split out in separate drafts. The working group co-chairs strongly supported this. Authors agreed to this.
    Slides: http://www.tla-group.com/~mpls/ietf-63-mpls-upstream.ppt

    MPLS Multicast

    Jean-Louis discussed the multicast requirements that are emerging
    in MPLS VPN applications. Extending LDP is a fairly low complexity route to support P2MP LSP setup requirements.

    The discussion brought up issues like why it is appropriate to have a
    leaf-initiated protocol in the p2mp case when this was not the case in the TE case. The benefits of shared trees vs. source based trees were discussed.

    George pointed out that some of the requirements are on the IGP routing rather than MPLS or LDP.

    Since this work is not captured in the working group milestones we need to ask the ADs if we can update the working group charter. Only after that we can accept this as a working group document.

    George asked for a sense of how many people were interested
    in doing this work in this WG. Many hands were raised. The working group chairs will bring this to the ADs.

    Slides: http://www.tla-group.com/~mpls/P2MP-LDP-REQ-06.ppt


    To extend LDP for p2mp is an attractive option since LDP is widely deployed. In these networks there might be a need for p2mp LSPs, but deploying RSVP-TE might be considered too much of a cost.

    Slides: http://www.tla-group.com/~mpls/ldp-p2mp.ppt

    This draft also proposes extensions to LDP for multicast, there seems to be enough overlap between two drafts to look into if there is a possibility to merge them into one. The author agreed to this.

    Slides: http://www.tla-group.com/~mpls/mldp-ietf-paris.ppt


    Due to lack of time it was not possible to make this presentation.

    BGP Point to Multipoint LSP
    Satoru Matsushima

    Due to lack of time it was not possible to make this presentation.

    6. Inter-Area LDP

    Due to lack of time it was not possible to make this presentation.

    7. End of meeting


    MPLS Extensions to ICMP
    Progressing LDP to draft-standard status
    Detecting P2MP Data Plane Failures
    Detecting MPLS Data Plane Failures in Inter-AS and inter-provider Scenarios
    Update on: draft-yasukawa-mpls-p2mp-oam-reqs-00.txt
    MPLS Multicast Encapsulations
    MPLS Upstream Label Assignment for RSVP-TE and LDP
    LDP Extensions for Point to Multipoint LSPs