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RFC 7358

Proposed STD
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Label Advertisement Discipline for LDP Forwarding Equivalence Classes (FECs)

Updates:    3212    4447    5036    5918    6388    7140


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Internet Engineering Task Force (IETF)                           K. Raza
Request for Comments: 7358                                    S. Boutros
Updates: 3212, 4447, 5036, 5918, 6388, 7140                   L. Martini
Category: Standards Track                            Cisco Systems, Inc.
ISSN: 2070-1721                                               N. Leymann
                                                        Deutsche Telekom
                                                            October 2014


                     Label Advertisement Discipline
             for LDP Forwarding Equivalence Classes (FECs)

Abstract

   The label advertising behavior of an LDP speaker for a given
   Forwarding Equivalence Class (FEC) is governed by the FEC type and
   not necessarily by the LDP session's negotiated label advertisement
   mode.  This document updates RFC 5036 to make that fact clear.  It
   also updates RFCs 3212, 4447, 5918, 6388, and 7140 by specifying the
   label advertisement mode for all currently defined LDP FEC types.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7358.

Page 2 
Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................2
   2. Label Advertisement Discipline ..................................3
      2.1. Update to RFC 5036 .........................................3
      2.2. Specification for LDP FECs .................................4
   3. Security Considerations .........................................4
   4. IANA Considerations .............................................4
   5. References ......................................................6
      5.1. Normative References .......................................6
      5.2. Informative References .....................................7
   Acknowledgments ....................................................8
   Authors' Addresses .................................................8

1.  Introduction

   The Label Distribution Protocol (LDP) [RFC5036] allows label
   advertisement mode negotiation at the time of session establishment.
   The LDP specification also dictates that only a single label
   advertisement mode be negotiated, agreed upon, and used for a given
   LDP session between two Label Switching Routers (LSRs).

   The negotiated label advertisement mode defined in RFC 5036 and
   carried in the LDP Initialization message is only indicative.  It
   indicates how the LDP speakers on a session will advertise labels for
   some Forwarding Equivalence Classes (FECs), but it is not a rule that
   restricts the speakers to behave in a specific way.  Furthermore, for
   some FEC types the advertising behavior of the LDP speaker is
   governed by the FEC type and not by the negotiated behavior.

   This document updates [RFC5036] to make that fact clear.  It also
   updates [RFC3212], [RFC4447], [RFC5918], [RFC6388], and [RFC7140] to
   indicate, for each FEC type that has already been defined, whether

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   the label binding advertisements for the FEC are constrained by the
   negotiated label advertisement mode or not.  Furthermore, this
   document specifies the label advertisement mode to be used for all
   currently defined FECs.

2.  Label Advertisement Discipline

   To remove any ambiguity and conflict regarding a label advertisement
   discipline among different FEC types sharing a common LDP session,
   this document specifies a label advertisement discipline for FEC
   types.

   This document introduces the following types for specifying a label
   advertisement discipline for a FEC type:

      -  DU (Downstream Unsolicited)
      -  DoD (Downstream on Demand)
      -  As negotiated (DU or DoD)
      -  Upstream ([RFC6389])
      -  Not applicable
      -  Unknown

2.1.  Update to RFC 5036

   Section 3.5.3 of [RFC5036] is updated to add the following two
   statements under the description of "A, Label Advertisement
   Discipline":

   -  Each document defining an LDP FEC must state the applicability of
      the negotiated label advertisement discipline for label binding
      advertisements for that FEC.  If the negotiated label
      advertisement discipline does not apply to the FEC, the document
      must also explicitly state the discipline to be used for the FEC.

   -  This document defines the label advertisement discipline for the
      following FEC types:

         +----------+----------+--------------------------------+
         | FEC Type | FEC Name | Label Advertisement Discipline |
         +----------+----------+--------------------------------+
         | 0x01     | Wildcard | Not applicable                 |
         | 0x02     | Prefix   | As negotiated (DU or DoD)      |
         +----------+----------+--------------------------------+

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2.2.  Specification for LDP FECs

   The label advertisement discipline for currently defined LDP FEC
   types is listed in Section 4.

   This document updates the respective RFCs in which these FECs are
   introduced and defined.

3.  Security Considerations

   This document only clarifies the applicability of an LDP session's
   label advertisement mode and hence does not add any LDP security
   mechanics and considerations to those already defined in the LDP
   specification [RFC5036].

4.  IANA Considerations

   This document mandates the specification of a label advertisement
   discipline for each defined FEC type and hence IANA's "Forwarding
   Equivalence Class (FEC) Type Name Space" registry under IANA's "Label
   Distribution Protocol (LDP) Parameters" registry has been extended as
   follows:

   -  Added a new column titled "Label Advertisement Discipline" with
      the following possible values:

         o  DU
         o  DoD
         o  As negotiated (DU or DoD)
         o  Upstream
         o  Not applicable
         o  Unknown

   -  Made this document an additional reference for the registry itself
      and for all affected registrations.

   -  Kept other columns of the registry in place and populated as they
      were.

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   For the currently assigned FEC types, the updated registry looks
   like:

   +=====+====+===============+==============+===========+============+
   |Value|Hex | Name          |Label         | Reference |Notes/      |
   |     |    |               |Advertisement |           |Registration|
   |     |    |               |Discipline    |           |Date        |
   +=====+====+===============+==============+===========+============+
   | 0   |0x00|Reserved       |              |           |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 1   |0x01|Wildcard       |Not applicable| [RFC5036] |            |
   |     |    |               |              | [RFC7358] |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 2   |0x02|Prefix         |As negotiated | [RFC5036] |            |
   |     |    |               |(DU or DoD)   | [RFC7358] |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 4   |0x04|CR-LSP         |DoD           | [RFC3212] |            |
   |     |    |               |              | [RFC7358] |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 5   |0x05|Typed Wildcard |Not applicable| [RFC5918] |            |
   |     |    |FEC Element    |              | [RFC7358] |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 6   |0x06|P2MP           |DU            | [RFC6388] |            |
   |     |    |               |              | [RFC7358] |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 7   |0x07|MP2MP-up       |DU            | [RFC6388] |            |
   |     |    |               |              | [RFC7358] |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 8   |0x08|MP2MP-down     |DU            | [RFC6388] |            |
   |     |    |               |              | [RFC7358] |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 9   |0x09|HSMP-upstream  |DU            | [RFC7140] | 2014-01-09 |
   |     |    |               |              | [RFC7358] |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 10  |0x0A|HSMP-downstream|DU, Upstream  | [RFC7140] | 2014-01-09 |
   |     |    |               |              | [RFC7358] |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 128 |0x80|PWid           |DU            | [RFC4447] |            |
   |     |    |FEC Element    |              | [RFC7358] |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 129 |0x81|Generalized    |DU            | [RFC4447] |            |
   |     |    |PWid           |              | [RFC7358] |            |
   |     |    |FEC Element    |              |           |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 130 |0x82|P2MP PW        |Upstream      | [P2MP-PW] | 2009-06-03 |
   |     |    |Upstream       |              | [RFC7358] |            |
   |     |    |FEC Element    |              |           |            |
   +-----+----+---------------+--------------+-----------+------------+

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   +-----+----+---------------+--------------+-----------+------------+
   | 131 |0x83|Protection     |DU            |[FAST-PROT]| 2010-02-26 |
   |     |    |FEC Element    |              | [RFC7358] |            |
   +-----+----+---------------+--------------+-----------+------------+
   | 132 |0x84|P2MP PW        |DU            | [P2MP-PW] | 2014-04-04 |
   |     |    |Downstream     |              | [RFC7358] |            |
   |     |    |FEC Element    |              |           |            |
   +-----+----+---------------+--------------+-----------+------------+

5.  References

5.1.  Normative References

   [RFC3212]   Jamoussi, B., Ed., Andersson, L., Callon, R., Dantu, R.,
               Wu, L., Doolan, P., Worster, T., Feldman, N., Fredette,
               A., Girish, M., Gray, E., Heinanen, J., Kilty, T., and A.
               Malis, "Constraint-Based LSP Setup using LDP", RFC 3212,
               January 2002, <http://www.rfc-editor.org/info/rfc3212>.

   [RFC4447]   Martini, L., Ed., Rosen, E., El-Aawar, N., Smith, T., and
               G. Heron, "Pseudowire Setup and Maintenance Using the
               Label Distribution Protocol (LDP)", RFC 4447, April 2006,
               <http://www.rfc-editor.org/info/rfc4447>.

   [RFC5036]   Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
               "LDP Specification", RFC 5036, October 2007,
               <http://www.rfc-editor.org/info/rfc5036>.

   [RFC5918]   Asati, R., Minei, I., and B. Thomas, "Label Distribution
               Protocol (LDP) 'Typed Wildcard' Forward Equivalence Class
               (FEC)", RFC 5918, August 2010,
               <http://www.rfc-editor.org/info/rfc5918>.

   [RFC6388]   Wijnands, IJ., Ed., Minei, I., Ed., Kompella, K., and B.
               Thomas, "Label Distribution Protocol Extensions for
               Point-to-Multipoint and Multipoint-to-Multipoint Label
               Switched Paths", RFC 6388, November 2011,
               <http://www.rfc-editor.org/info/rfc6388>.

   [RFC6389]   Aggarwal, R. and JL. Le Roux, "MPLS Upstream Label
               Assignment for LDP", RFC 6389, November 2011,
               <http://www.rfc-editor.org/info/rfc6389>.

   [RFC7140]   Jin, L., Jounay, F., Wijnands, IJ., and N. Leymann, "LDP
               Extensions for Hub and Spoke Multipoint Label Switched
               Path", RFC 7140, March 2014,
               <http://www.rfc-editor.org/info/rfc7140>.

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5.2.  Informative References

   [FAST-PROT] Shen, Y., Aggarwal, R., Henderickx, W., and Y. Jiang,
               "PW Endpoint Fast Failure Protection", Work in Progress,
               draft-ietf-pwe3-endpoint-fast-protection-01, July 2014.

   [P2MP-PW]   Sivabalan, S., Ed., Boutros, S., Ed., Martini, L.,
               Konstantynowicz, M., Del Vecchio, G., Nadeau, T., Jounay,
               F., Niger, P., Kamite, Y., Jin, L., Vigoureux, M.,
               Ciavaglia, L., Delord, S., and K. Raza, "Signaling
               Root-Initiated Point-to-Multipoint Pseudowire using LDP",
               Work in Progress, draft-ietf-pwe3-p2mp-pw-04, March 2012.

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Acknowledgments

   We acknowledge Eric Rosen and Rajiv Asati for their initial review
   and input on the document.

Authors' Addresses

   Kamran Raza
   Cisco Systems, Inc.
   2000 Innovation Drive
   Ottawa, ON K2K-3E8
   Canada

   EMail: skraza@cisco.com


   Sami Boutros
   Cisco Systems, Inc.
   3750 Cisco Way
   San Jose, CA  95134
   United States

   EMail: sboutros@cisco.com


   Luca Martini
   Cisco Systems, Inc.
   9155 East Nichols Avenue, Suite 400
   Englewood, CO  80112
   United States

   EMail: lmartini@cisco.com


   Nicolai Leymann
   Deutsche Telekom AG
   Winterfeldtstrasse 21
   Berlin 10781
   Germany

   EMail: N.Leymann@telekom.de