Experience with the Label Distribution Protocol (LDP)
RFC 5037

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Network Working Group                                  L. Andersson, Ed.
Request for Comments: 5037                                      Acreo AB
Category: Informational                                    I. Minei, Ed.
                                                        Juniper Networks
                                                          B. Thomas, Ed.
                                                     Cisco Systems, Inc.
                                                            October 2007

         Experience with the Label Distribution Protocol (LDP)

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Abstract

   The purpose of this memo is to document how some of the requirements
   specified in RFC 1264 for advancing protocols developed by working
   groups within the IETF Routing Area to Draft Standard have been
   satisfied by LDP (Label Distribution Protocol).  Specifically, this
   report documents operational experience with LDP, requirement 5 of
   section 5.0 in RFC 1264.

Table of Contents

   1. Introduction ....................................................2
   2. Operational Experience ..........................................2
      2.1. Environment and Duration ...................................2
      2.2. Applications and Motivation ................................3
      2.3. Protocol Features ..........................................3
      2.4. Security Concerns ..........................................4
      2.5. Implementations and Inter-Operability ......................4
      2.6. Operational Experience .....................................4
   3. Security Considerations .........................................5
   4. Acknowledgments .................................................5
   5. References ......................................................6
      5.1. Normative References .......................................6
      5.2. Informative References .....................................6

Andersson, et al.            Informational                      [Page 1]
RFC 5037            Experience with the LDP Protocol        October 2007

1.  Introduction

   The purpose of this memo is to document how some of the requirements
   specified in [RFC1264] for advancing protocols developed by working
   groups within the IETF Routing Area to Draft Standard have been
   satisfied by LDP.  Specifically, this report documents operational
   experience with LDP, requirement 5 of section 5.0 in RFC 1264.

   LDP was originally published as [RFC3036] in January 2001.  It was
   produced by the MPLS Working Group of the IETF and was jointly
   authored by Loa Andersson, Paul Doolan, Nancy Feldman, Andre
   Fredette, and Bob Thomas.  It has since been obsoleted by [RFC5036].

2.  Operational Experience

   This section discusses operational experience with the protocol.  The
   information is based on a survey sent to the MPLS Working Group in
   October 2004.  The questionnaire can be found in the MPLS Working
   Group mail archives for October 2004.

   11 responses were received, all but 2 requesting confidentiality.
   The survey results are summarized to maintain confidentiality.  The
   networks surveyed span different geographic locations: US, Europe,
   and Asia.  Both academic and commercial networks responded to the
   survey.

2.1.  Environment and Duration

   The size of the deployments ranges from less than 20 Label Switching
   Routers (LSRs) to over 1000 LSRs.  Eight out of the 11 deployments
   use LDP in the edge and the core, two on the edge only, and one in
   the core only.

   Sessions exist to peers discovered via both the basic and the
   extended discovery mechanisms.  In half the cases, more than one
   adjacency (and as many as four adjacencies) are maintained per
   session.  The average number of LDP sessions on an LSR ranges from
   under 10 to just over 80.  The responses are spread out as follows:
   under 10: 4 responses, 20-50: 4 responses, and over 80: 1 response.

   In the surveyed networks, the time LDP has been deployed ranges from
   under 1 year to over 4 years.  The responses are spread out as
   follows: under 1 year: 3 responses, 2 years: 2 responses, 3 years: 3
   responses, and over 4 years: 3 responses.

Andersson, et al.            Informational                      [Page 2]
RFC 5037            Experience with the LDP Protocol        October 2007

2.2.  Applications and Motivation

   Nine of the 11 responses list Layer 3 Virtual Private Networks
   (L3VPNs) as the application driving the LDP deployment in the
   network.

   The list of applications is as follows: L3VPNs: 9, pseudowires: 4
   current (and one planned deployment), L2VPNs: 4, forwarding based on
   labels: 2, and BGP-free core: 1.

   There are two major options for label distribution protocols, LDP and