Controlling State Advertisements of Non-negotiated LDP Applications
RFC 7473

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Internet Engineering Task Force (IETF)                           K. Raza
Request for Comments: 7473                                    S. Boutros
Category: Standards Track                            Cisco Systems, Inc.
ISSN: 2070-1721                                               March 2015

  Controlling State Advertisements of Non-negotiated LDP Applications

Abstract

   There is no capability negotiation done for Label Distribution
   Protocol (LDP) applications that set up Label Switched Paths (LSPs)
   for IP prefixes or that signal point-to-point (P2P) Pseudowires (PWs)
   for Layer 2 Virtual Private Networks (L2VPNs).  When an LDP session
   comes up, an LDP speaker may unnecessarily advertise its local state
   for such LDP applications even when the peer session is established
   for some other applications like Multipoint LDP (mLDP) or the Inter-
   Chassis Communication Protocol (ICCP).  This document defines a
   solution by which an LDP speaker announces to its peer its
   disinterest in such non-negotiated applications, thus disabling the
   unnecessary advertisement of corresponding application state, which
   would have otherwise been advertised over the established LDP
   session.

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/rfc7473.

Raza & Boutros               Standards Track                    [Page 1]
RFC 7473        State Adv. Control of Non-negotiated Apps     March 2015

Copyright Notice

   Copyright (c) 2015 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
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   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 ....................................................3
   2. Conventions Used in This Document ...............................4
   3. Non-negotiated LDP Applications .................................4
      3.1. Uninteresting State ........................................5
           3.1.1. Prefix-LSPs .........................................5
           3.1.2. P2P-PWs .............................................5
   4. Controlling State Advertisement .................................5
      4.1. State Advertisement Control Capability .....................6
      4.2. Capabilities Procedures ....................................8
           4.2.1. State Control Capability in an
                  Initialization Message ..............................9
           4.2.2. State Control Capability in a Capability Message ....9
   5. Applicability Statement .........................................9
   6. Operational Examples ...........................................11
      6.1. Disabling Prefix-LSPs and P2P-PWs on an ICCP Session ......11
      6.2. Disabling Prefix-LSPs on a L2VPN/PW tLDP Session ..........11
      6.3. Disabling Prefix-LSPs Dynamically on an
           Established LDP Session ...................................12
      6.4. Disabling Prefix-LSPs on an mLDP-only Session .............12
      6.5. Disabling IPv4 or IPv6 Prefix-LSPs on a Dual-Stack LSR ....12
   7. Security Considerations ........................................13
   8. IANA Considerations ............................................13
   9. References .....................................................14
      9.1. Normative References ......................................14
      9.2. Informative References ....................................14
   Acknowledgments ...................................................15
   Authors' Addresses ................................................15

Raza & Boutros               Standards Track                    [Page 2]
RFC 7473        State Adv. Control of Non-negotiated Apps     March 2015

1.  Introduction

   The LDP Capabilities specification [RFC5561] introduced a mechanism
   to negotiate LDP capabilities for a given feature between peer Label
   Switching Routers (LSRs).  The capability mechanism ensures that no
   unnecessary state is exchanged between peer LSRs unless the