Label Advertisement Discipline for LDP Forwarding Equivalence Classes (FECs)
RFC 7358

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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.

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RFC 7358          Label Advert. Discipline for LDP FECs     October 2014

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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RFC 7358          Label Advert. Discipline for LDP FECs     October 2014

   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