Network Working Group                                          B. Thomas
Request for Comments: 5038                           Cisco Systems, Inc.
Category: Informational                                     L. Andersson
                                                                Acreo AB
                                                            October 2007

The Label Distribution Protocol (LDP) Implementation Survey Results

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

   Multiprotocol Label Switching (MPLS), described in RFC 3031, is a
   method for forwarding packets that uses short, fixed-length values
   carried by packets, called labels, to determine packet next hops.  A
   fundamental concept in MPLS is that two Label Switching Routers
   (LSRs) must agree on the meaning of the labels used to forward
   traffic between and through them.  This common understanding is
   achieved by using a set of procedures, called a Label Distribution
   Protocol (as described in RFC 3036) , by which one LSR informs
   another of label bindings it has made.  One such protocol, called
   LDP, is used by LSRs to distribute labels to support MPLS forwarding
   along normally routed paths.  This document reports on a survey of
   LDP implementations conducted in August 2002 as part of the process
   of advancing LDP from Proposed to Draft Standard.

   1. Introduction ....................................................2
      1.1. The LDP Survey Form ........................................2
      1.2. LDP Survey Highlights ......................................3
   2. Survey Results for LDP Features .................................4
   3. Security Considerations .........................................7
   4. References ......................................................7
   Appendix A. Full LDP Survey Results ................................8
   Appendix B. LDP Implementation Survey Form ........................13

1. Introduction

   Multiprotocol Label Switching (MPLS) is a method for forwarding
   packets that uses short fixed-length values carried by packets,
   called labels, to determine packet next hops [RFC3031].  A
   fundamental MPLS concept is that two Label Switching Routers (LSRs)
   must agree on the meaning of the labels used to forward traffic
   between and through them.  This common understanding is achieved by
   using a set of procedures by which one LSR informs another of label
   bindings it has made.

   Label Distribution Protocol (LDP) specifies a set of procedures LSRs
   use to distribute labels to support MPLS forwarding along normally
   routed paths.  LDP was specified originally by [RFC3036].  The
   current LDP specification is [RFC5036], which obsoletes [RFC3036].
   [RFC3037] describes the applicability of LDP.

   This document reports on a survey of LDP implementations conducted in
   August 2002 as part of the process of advancing LDP from Proposed to
   Draft standard.

   This section highlights some of the survey results.  Section 2
   presents the survey results for LDP features, and Appendix A presents
   the survey results in full.  Appendix B contains a copy of the survey
   form.

1.1. The LDP Survey Form

   The LDP implementation survey requested the following information
   about LDP implementation:

   -  Responding organization.  Provisions were made to accommodate
      organizations that wished to respond anonymously.

   -  The status, availability, and origin of the LDP implementation.

   -  The LDP features implemented and for each whether it was tested
      against an independent implementation.  The survey form listed
      each LDP feature defined by [RFC3036] and requested one of the
      following as the status of the feature:

         t: Tested against another independent implementation
         y: Implemented but not tested against independent
            implementation
         n: Not implemented
         x: Not applicable to this type of implementation

      In addition, for the 'n' status, the responder could optionally
      provide the following additional information:

         s: RFC specification inadequate, unclear, or confusing
         u: Utility of feature unclear
         r: Feature not required for feature set implemented

   This document uses the following conventions for reporting survey
   results for a feature:

      At By Cn indicates:

      -  A responders implemented the feature and tested it against
         another independent implementation (t)
      -  B responders implemented the feature but have not tested it
         against an independent implemented (y)
      -  C responders did not implement the feature (n)

      (Ds Eu Fr) indicates optional responses:

      -  D responders thought the RFC 3036 specification of the feature
         inadequate, unclear, or confusing (s).
      -  E responders thought the utility of the feature unclear (u).
      -  F responders considered the feature not required for the
         feature set implemented (combines x and r).

1.2. LDP Survey Highlights

   This section presents some highlights from the implementation survey.

      -  There were 12 responses to the survey, 2 of which were
         anonymous.  At the time of the survey, 10 of the implementation
         were available as products and 2 were in beta test.  Eleven of
         the implementations were available for sale; the remaining
         implementation had been done by a company no longer in
         business.

      -  Seven implementations were independently written from the RFC
         3036 specification.  Four implementations combined purchased or
         free code with code written by the responder.

         One of the implementations was fully purchased code ported to
         the vendor's platform.

      -  Every LDP feature in the survey questionnaire was implemented
         by at least 2 respondents.

      -  Each of the 8 LDP Label Distribution Modes implemented and
         tested:

            8t 2y 2n   DU,  Ord Cntl, Lib reten
            7t 1y 4n   DU,  Ind Cntl, Lib reten
            7t 1y 4n   DoD  Ord Cntl, Cons reten
            6t 1y 5n   DoD, Ind Cntl, Cons reten
            6t 1y 5n   DU,  Ord Cntl, Cons reten
            6t 0y 6n   DU,  Ind Cntl, Cons reten
            4t 3y 5n   DoD, Ord Cntl, Lib reten
            4t 2y 6n   DoD, Ind Cntl, Lib reten

      -  Platform and Interface Label Spaces were both widely supported.

            12t 0y 0n  Per platform
             7t 1y 4n  Per interface

      -  LDP Basic and Targeted Sessions were both widely supported.

            12t 0y 0n  Basic/Directly Connected
            11t 1y 0n  Targeted

      -  The TCP MD5 Option for LDP session TCP connections was not
         widely implemented.

            3t 1y 8n

2. Survey Results for LDP Features

   This section presents the survey results for LDP features using the
   notational convention described in Section 1.2.  It omits the
   optional status responses (s, u, r); complete results may be found in
   Appendix A.

      Feature
         Survey Result

      Interface types
         12t 0y 0n      Packet
         2t 3y 7n       Frame Relay
         6t 2y 4n       ATM
      Label Spaces
         12t 0y 0n      Per platform
         7t 1y 4n       Per interface
      LDP Discovery
         12t 0y 0n      Basic
         11t 1y 0n      Targeted

      LDP Sessions
         12t 0y 0n      Directly Connected
         11t 1y 0n      Targeted
      LDP Modes
         7t 1y 4n       DU, Ind Cntl, Lib reten
         8t 2y 2n       DU, Ord Cntl, Lib reten
         6t 0y 6n       DU, Ind Cntl, Cons reten
         6t 1y 5n       DU, Ord Cntl Cons reten
         4t 2y 6n       DoD, Ind Cntl, Lib reten
         4t 3y 5n       DoD, Ord Cntl, Lib reten
         6t 1y 5n       DoD, Ind Cntl, Cons reten
         7t 1y 4n       DoD, Ord Cntl, Cons reten
      Loop Detection
         9t 2y 1n
      TCP MD5 Option
         3t 1y 8n
      LDP TLVs
         7t 4y 0n       U-bit
         7t 4y 0n       F-bit
         12t 0y 0n      FEC TLV
         6t 5y 1n         Wildcard
         12t 0y 0n        Prefix
         10t 0y 2n        Host
         12t 0y 0n      Address List TLV
         10t 1y 1n      Hop Count TLV
         9t 2y 1n       Path Vector TLV
         12t 0y 0n      Generic Label TLV
         6t 2y 4n       ATM Label TLV
         2t 3y 7n       Frame Relay Label TLV
         12t 0y 0n      Status TLV
         9t 3y 0n       Extended Status TLV
         6t 4y 2n       Returned PDU TLV
         6t 4y 2n       Returned Message TLV
         12t 0y 0n      Common Hello Param TLV
         12t 0y 0n        T-bit
         11t 0y 1n        R-bit
         11t 1y 0n        Hold Time
         12t 0y 0n      IPv4 Transport Addr TLV
         7t 2y 3n       Config Sequence Num TLV
         1t 1y 1n       IPv6 Transport Addr TLV
         12t 0y 0n      Common Session Param TLV
         12t 0y 0n        KeepAlive Time
         11t 0y 1n        PVLim
         11t 1y 0n        PDU Max Length
         6t 2y 2n       ATM Session Param TLV
                          M values
         5t 3y 4n           0 No Merge
         3t 3y 6n           1 VP Merge

         5t 3y 4n           2 VC Merge
         3t 3y 6n           3 VP & VC Merge
         6t 2y 4n         D-bit
         6t 2y 4n         ATM Label Range Component
         2t 3y 7n       FR Session Param TLV
                          M values
         2t 3y 7n           0 No Merge
         2t 3y 7n           1 Merge
         2t 3y 7n         D-bit
         2t 3y 7n         FR Label Range Component
         10t 0y 2n      Label Request Msg ID TLV
         2t 5y 5n       Vendor-Private TLV
         1t 5y 6n       Experimental TLV
      LDP Messages
         12t 0y 0n      Notification Msg
         12t 0y 0n      Hello Msg
         12t 0y 0n      Initialization Msg
         12t 0y 0n      KeepAlive Msg
         12t 0y 0n      Address Msg
         12t 0y 0n      Address Withdraw Msg
         12t 0y 0n      Label Mapping Msg
         10t 0y 2n        Label Request Msg Id TLV
         10t 1y 1n        Hop Count TLV
         10t 1y 1n        Path Vect TLV
         9t 0y 3n       Label Request Msg
         9t 0y 3n         Hop Count TLV
         9t 0y 3n         Path Vect TLV
         12t 0y 0n      Label Withdraw Msg
         12t 0y 0n        Label TLV
         11t 0y 1n      Label Release Msg
         10t 1y 1n        Label TLV
         9t 2y 1n       Label Abort Req Msg
         2t 5y 5n       Vendor-Private Msg
         1t 5y 6n       Experimental Msg
      LDP Status Codes
         9t 3y 0n       Success
         8t 4y 0n       Bad LDP Id
         7t 5y 0n       Bad Ptcl Version
         7t 5y 0n       Bad PDU Length
         7t 5y 0n       Unknown Message Type
         7t 5y 0n       Bad Message Length
         7t 4y 0n       Unknown TLV
         7t 5y 0n       Bad TLV length
         7t 5y 0n       Malformed TLV Value
         11t 1y 0n      Hold Timer Expired
         11t 1y 0n      Shutdown
         10t 1y 1n      Loop Detected
         7t 5y 0n       Unknown FEC

         11t 1y 0n      No Route
         9t 3y 0n       No Label Resources
         8t 3y 1n       Label Resources Available
                        Session Rejected
         7t 5y 0n         No Hello
         9t 2y 1n         Param Advert Mode
         9t 2y 1n         Param PDUMax Len
         8t 3y 1n         Param Label Range
         7t 5y 0n         Bad KA Time
         11t 1y 0n      KeepAlive Timer Expired
         9t 1y 2n       Label Request Aborted
         6t 5y 1n       Missing Message Params
         7t 5y 0n       Unsupported Addr Family
         7t 5y 0n       Internal Error

3. Security Considerations

   This document is a survey of existing LDP implementations; it does
   not specify any protocol behavior.  Thus, security issues introduced
   by the document are not discussed.

4. Informative References

   [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
             Label Switching Architecture", RFC 3031, January 2001.

   [RFC3036] Andersson, L., Doolan, P., Feldman, N., Fredette, A., and
             B. Thomas, "LDP Specification", RFC 3036, January 2001.

   [RFC3037] Thomas, B. and E. Gray, "LDP Applicability", RFC 3037,
             January 2001.

   [RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
             "LDP Specification", RFC 5036, October 2007.

Appendix A. Full LDP Survey Results

LDP Implementation Survey Form (V 1.0)

=======================================================================
A. General Information

Responders:

  Anonymous:   2
  Public:      10

    Agilent Technologies
    Celox Networks, Inc.
    Cisco Systems, Inc.
    Data Connection Ltd.
    NetPlane Systems, Inc
    Redback Networks
    Riverstone Networks
    Trillium, An Intel Company
    Vivace Networks, Inc.
    Wipro Technologies

=======================================================================
B. LDP Implementation Status, Availability, Origin

Status:
     [  ]  Development
     [  ]  Alpha
     [ 2]  Beta
     [10]  Product
     [  ]  Other (describe):

Availability:
     [  ]  Public and free
     [  ]  Only to selected organizations/companies but free
     [11]  On sale
     [  ]  For internal company use only
     [ 1]  Other:

Implementation based on:  (check all that apply)
     [ 1]  Purchased code
          (please list source if possible)
     [  ]  Free code
          (please list source if possible)
     [ 7]  Internal implementation
          (no outside code, just from specs)
     [ 4]  Internal implementation on top of purchased
          or free code

=======================================================================
C. LDP Feature Survey

For each feature listed, please indicate the status of the
implementation using one of the following:

    't'   tested against another independent implementation
    'y'   implemented but not tested against independent
          implementation
    'n'   not implemented
    'x'   not applicable to this type of implementation

  Optional: For 'n' status, indicate reason for not implementing
            using one of the following:

            's'  RFC specification inadequate, unclear, or confusing
            'u'  utility of feature unclear
            'r'  feature not required for feature set implemented

  Feature                                           RFC 3036 Section(s)
    Survey Result

  Interface types                                   2.2.1, 2.5.3,
                                                    2.8.2, 3.4.2
    12t 0y 0n            Packet
    2t 3y 7n(3r 1x)      Frame Relay
    6t 2y 4n(3r)         ATM
  Label Spaces                                      2.2.1, 2.2.2
    12t 0y 0n            Per platform
    7t 1y 4n(4r)         Per interface
  LDP Discovery                                     2.4
    12t 0y 0n            Basic                      2.4.1
    11t 1y 0n            Targeted                   2.4.2
  LDP Sessions                                      2.2.3
    12t 0y 0n            Directly Connected         --
    11t 1y 0n            Targeted                   2.3
  LDP Modes                                         2.6
    7t 1y 4n(2u 1r)      DU, Ind cntl, Lib reten    2.6
    8t 2y 2n(1r)         DU, Ord cntl, Lib reten    2.6
    6t 0y 6n(2u 2r)      DU, Ind cntl, Cons reten   2.6
    6t 1y 5n(1u 2r)      DU, Ord cntl, Cons reten   2.6
    4t 2y 6n(2u 2r)      DoD, Ind cntl, Lib reten   2.6
    4t 3y 5n(2r)         DoD, Ord cntl, Lib reten   2.6
    6t 1y 5n(2u 2r)      DoD, Ind cntl, Cons reten  2.6
    7t  1y 4n(1u 2r)     DoD, Ord cntl, Cons reten  2.6
  Loop Detection                                    2.8
    9t 2y 1n

  TCP MD5 Option                                    2.9
    3t 1y 8n(1u 1r 1x)
  LDP TLVs                                          3.3, 3.4, throughout
    7t 4y 0n(1 noreply)  U-bit                      3.3
    7t 4y 0n(1 noreply)  F-bit                      3.3
                         FEC TLV                    1, 2.1, 3.4.1
    6t 5y 1n(1r)           Wildcard                 3.4.1
    12t 0y 0n              Prefix                   3.4.1
    10t 0y 2n(s1 1u 1r)    Host                     2.1, 3.4.1
    12t 0y 0n            Address List TLV           3.4.3
    10t 1y 1n            Hop Count TLV              3.4.4
    9t 2y 1n             Path Vector TLV            3.4.5
    12t 0y 0n            Generic Label TLV          3.4.2.1
    6t 2y 4n(2r)         ATM Label TLV              3.4.2.2
    2t 3y 7n(1u 2r 1x)   Frame Relay Label TLV      3.4.2.3
    12t 0y 0n            Status TLV                 3.4.6
    9t 3y 0n             Extended Status TLV        3.5.1
    6t 4y 2n             Returned PDU TLV           3.5.1
    6t 4y 2n             Returned Message TLV       3.5.1
    12t 0y 0n            Common Hello Param TLV     3.5.2
    12t 0y 0n                T-bit                  3.5.2
    11t 0y 1n                R-bit                  3.5.2
    11t 1y 0n                Hold Time              3.5.2
    12t 0y 0n            IPv4 Transport Addr TLV    3.5.2
    7t 2y 3n             Config Sequence Num TLV    3.5.2
    1t 1y 1n(1u 4r 1x)   IPv6 Transport Addr TLV    3.5.2
    12t 0y 0n            Common Session Param TLV   3.5.3
    12t 0y 0n              KeepAlive Time           3.5.3
    11t 0y 1n              PVLim                    3.5.3
    11t 1y 0n              PDU Max Length           3.5.3
    6t 2y 2n(1r 1x)      ATM Session Param TLV      3.5.3
                           M values
    5t 3y 4n(1r 1x)          0 No Merge             3.5.3
    3t 3y 6n(s 1 1r 1x)      1 VP Merge             3.5.3
    5t 3y 4n(1r 1x)          2 VC Merge             3.5.3
    3t 3y 6n(s1 1r 1x)       3 VP & VC Merge        3.5.3
    6t 2y 4n(1r 1x)        D-bit                    3.5.3
    6t 2y 4n(1r 1x)        ATM Label Range          3.5.3
                             Component
    2t 3y 7n(1u 1r 2x)   FR Session Param TLV       3.5.3
                           M values
    2t 3y 7n(1u 1r 2x)       0 No Merge             3.5.3
    2t 3y 7n                 1 Merge                3.5.3
    2t 3y 7n(1u 1r 2x)     D-bit                    3.5.3
    2t 3y 7n(1u 1r 2x)     FR Label Range           3.5.3
                             Component
    10t 0y 2n            Label Request Msg Id TLV   3.5.7
    2t 5y 5n(1u 1r)      Vendor-Private TLV         3.6.1.1

    1t 5y 6n(2r)         Experimental TLV           3.6.2
  LDP Messages                                      3.5, throughout
    12t 0y 0n            Notification Msg           3.5.1
    12t 0y 0n            Hello Msg                  3.5.2
    12t 0y 0n            Initialization Msg         3.5.3
    12t 0y 0n            KeepAlive Msg              3.5.4
    12t 0y 0n            Address Msg                3.5.5
    12t 0y 0n            Address Withdraw Msg       3.5.6
    12t 0y 0n            Label Mapping Msg          3.5.7
    10t 0y 2n(1r)          Label Request Msg Id TLV 3.5.7
    10t 1y 1n              Hop Count TLV            3.5.7
    10t 1y 1n              Path Vect TLV             3.5.7
    9t 0y 3n(1x)         Label Request Msg          3.5.8
    9t 0y 3n(1x)           Hop Count TLV            3.5.8
    9t 0y 3n(1x)           Path Vect TLV            3.5.8
    12t 0y 0n            Label Withdraw Msg         3.5.10
    12t 0y 0n              Label TLV                3.5.10
    11t 0y 1n            Label Release Msg          3.5.11
    10t 1y 1n              Label TLV                3.5.11
    9t 2y 1n             Label Abort Req Msg        3.5.9
    2t 5y 5n(1u 1r)      Vendor-Private Msg         3.6.1.2
    1t 5y 6n(2r)         Experimental Msg           3.6.2
  LDP Status Codes                                  3.4.6
    9t 3y 0n             Success                    3.4.6, 3.9
    8t 4y 0n             Bad LDP Id                 3.5.1.2.1
    7t 5y 0n             Bad Ptcl Version           3.5.1.2.1
    7t 5y 0n             Bad PDU Length             3.5.1.2.1
    7t 5y 0n             Unknown Message Type       3.5.1.2.1
    7t 5y 0n             Bad Message Length         3.5.1.2.1
    7t 4y 0n(1 noreply)  Unknown TLV                3.5.1.2.2
    7t 5y 0n             Bad TLV Length             3.5.1.2.2
    7t 5y 0n             Malformed TLV Value        3.5.1.2.2
    11t 1y 0n            Hold Timer Expired         3.5.1.2.3
    11t 1y 0n            Shutdown                   3.5.1.2.4
    10t 1y 1n            Loop Detected              3.4.5.1.2, 3.5.8.1
    7t 5y 0n             Unknown FEC                3.4.1.1
    11t 1y 0n            No Route                   3.5.8.1
    9t 3y 0n             No Label Resources         3.5.8.1
    8t 3y 1n             Label Resources Available  3.5.8.1
                         Session Rejected           2.5.3, 3.5.3
    7t 5y 0n               No Hello                 2.5.3, 3.5.3
    9t 2y 1n               Param Advert Mode        2.5.3, 3.5.3
    9t 2y 1n               Param PDU Max Len        2.5.3, 3.5.3
    8t 3y 1n               Param Label Range        2.5.3, 3.5.3
    7t 5y 0n               Bad KA Time              3.5.1.2.5, 3.5.3
    11t 1y 0n            KeepAlive Timer Expired    2.5.6, 3.5.1.2.3
    9t 1y 2n             Label Request Aborted      3.5.9.1
    6t 5y 1n             Missing Message Params     3.5.1.2.1

7t 5y 0n Unsupported Addr Family 3.4.1.1, 3.5.5.1
7t 5y 0n Internal Error 3.5.1.2.7

Appendix B. LDP Implementation Survey Form

LDP Implementation Survey Form (V 1.0)

The purpose of this form is to gather information about implementations
of LDP as defined by RFC 3036.  The information is being requested as
part of the process of advancing LDP from Proposed to Draft Standard.

The form is patterned after the implementation report form used for
HTTP/1.1; see:

http://www.ietf.org/IESG/Implementations/http1.1-implementations.txt

=======================================================================
A. General Information

Please provide the following information.
----------------------------------------------------------------

Organization:

Organization url(s):

----------------------------------------------------------------

Product title(s):

Brief description(s):

----------------------------------------------------------------

Contact for LDP information
   Name:
   Title:
   E-mail:
   Organization/department:
   Postal address:
   Phone:
   Fax:

=======================================================================
B. LDP Implementation Status, Availability, Origin

Please check [x] the boxes that apply.
----------------------------------------------------------------

Status:
     [ ]  Development
     [ ]  Alpha
     [ ]  Beta
     [ ]  Product
     [ ]  Other (describe):

Availability
     [ ]  Public and free
     [ ]  Only to selected organizations/companies but free
     [ ]  On sale.
     [ ]  For internal company use only
     [ ]  Other:

Implementation based on:  (check all that apply)
     [ ]  Purchased code
          (please list source if possible)
     [ ]  Free code
          (please list source if possible)
     [ ]  Internal implementation
          (no outside code, just from specs)
     [ ]  Internal implementation on top of purchased
          or free code
          List portions from external source:
          List portions developed internally:

=======================================================================
C. LDP Feature Survey

For each feature listed, please indicate the status of the
implementation using one of the following:

    't'   tested against another independent implementation
    'y'   implemented but not tested against independent implementation
    'n'   not implemented
    '-'   not applicable to this type of implementation

  Optional: For 'n' status, indicate reason for not implementing using
            one of the following:

            's'  RFC specification inadequate, unclear, or confusing
            'u'  utility of feature unclear
            'r'  feature not required for feature set implemented

------------------+-----------------------------+-----------------------
                  |                             | Status
                  |                             | (one of t, y, n, -;
                  |                             | if n, optionally
Feature           | RFC 3036 Section(s)         | one of s, u, r)
==================+=============================+=======================
Interface types   | 2.2.1, 2.5.3, 2.8.2, 3.4.2
  ----------------+-----------------------------+-----------------------
  Packet          |                             |
  ----------------+-----------------------------+-----------------------
  Frame Relay     |                             |
  ----------------+-----------------------------+-----------------------
  ATM             |                             |
==================+=============================+=======================
Label Spaces      | 2.2.1, 2.2.2
  ----------------+-----------------------------+-----------------------
  Per platform    |                             |
  ----------------+-----------------------------+-----------------------
  Per interface   |                             |
==================+=============================+=======================
LDP Discovery     | 2.4
  ----------------+-----------------------------+-----------------------
  Basic           | 2.4.1                       |
  ----------------+-----------------------------+-----------------------
  Targeted        | 2.4.2                       |

  ----------------+-----------------------------+-----------------------
    Wildcard      | 3.4.1                       |
  ----------------+-----------------------------+-----------------------
    Prefix        | 2.1, 3.4.1                  |
  ----------------+-----------------------------+-----------------------
    Host          | 2.1, 3.4.1                  |
------------------+-----------------------------+-----------------------
  Address List    | 3.4.3                       |
------------------+-----------------------------+-----------------------
  Hop Count       | 3.4.4                       |
------------------+-----------------------------+-----------------------
  Path Vector     | 3.4.5                       |
------------------+-----------------------------+-----------------------
  Generic Label   | 3.4.2.1                     |
------------------+-----------------------------+-----------------------
  ATM Label       | 3.4.2.2                     |
------------------+-----------------------------+-----------------------
  Frame Relay     | 3.4.2.3                     |
  Label           |                             |
------------------+-----------------------------+-----------------------
  Status          | 3.4.6                       |
------------------+-----------------------------+-----------------------
  Extended Status | 3.5.1                       |
------------------+-----------------------------+-----------------------
  Returned PDU    | 3.5.1                       |
------------------+-----------------------------+-----------------------
  Returned Message| 3.5.1                       |
------------------+-----------------------------+-----------------------
  Common Hello    | 3.5.2                       |
  Parameters      |                             |
  ----------------+-----------------------------+-----------------------
    T-bit         | 3.5.2                       |
  ----------------+-----------------------------+-----------------------
    R-bit         | 3.5.2                       |
  ----------------+-----------------------------+-----------------------
    Hold Time     | 3.5.2                       |
------------------+-----------------------------+-----------------------
  IPv4 Transport  | 3.5.2                       |
  Address         |                             |
------------------+-----------------------------+-----------------------
  Configuration   | 3.5.2                       |
  Sequence Number |                             |
------------------+-----------------------------+-----------------------
  IPv6 Transport  | 3.5.2                       |
  Address         |                             |
------------------+-----------------------------+-----------------------
  Common Session  | 3.5.3                       |
  Parameters      |                             |

  ----------------+-----------------------------+-----------------------
    KeepAlive Time| 3.5.3                       |
  ----------------+-----------------------------+-----------------------
    PVLim         | 3.5.3                       |
  ----------------+-----------------------------+-----------------------
    Max PDU Length| 3.5.3                       |
------------------+-----------------------------+-----------------------
  ATM Session     | 3.5.3                       |
  Parameters      |                             |
  ----------------+-----------------------------+-----------------------
    M values      |                             |
      0 No Merge  | 3.5.3                       |
      ------------+-----------------------------+-----------------------
      1 VP Merge  | 3.5.3                       |
      ------------+-----------------------------+-----------------------
      2 VC Merge  | 3.5.3                       |
      ------------+-----------------------------+-----------------------
      3 VP &      | 3.5.3                       |
        VC Merge  |                             |
  ----------------+-----------------------------+-----------------------
    D-bit         | 3.5.3                       |
  ----------------+-----------------------------+-----------------------
    ATM Label     | 3.5.3                       |
    Range         |                             |
    Component     |                             |
------------------+-----------------------------+-----------------------
  Frame Relay     | 3.5.3                       |
  Session         |                             |
  Parameters      |                             |
------------------+-----------------------------+-----------------------
    M values      |                             |
      0 No Merge  | 3.5.3                       |
      ------------+-----------------------------+-----------------------
      1 Merge     | 3.5.3                       |
  ----------------+-----------------------------+-----------------------
    D-bit         | 3.5.3                       |
  ----------------+-----------------------------+-----------------------
    Frame Relay   | 3.5.3                       |
    Label Range   |                             |
    Component     |                             |
  ----------------+-----------------------------+-----------------------
  Label Request   | 3.5.7                       |
  Message Id      |                             |
------------------+-----------------------------+-----------------------
  Vendor-Private  | 3.6.1.1                     |
------------------+-----------------------------+-----------------------
  Experimental    | 3.6.2                       |

==================+=============================+=======================
LDP Messages      | 3.5, throughout
------------------+-----------------------------+-----------------------
  Notification    | 3.5.1                       |
------------------+-----------------------------+-----------------------
  Hello           | 3.5.2                       |
------------------+-----------------------------+-----------------------
  Initialization  | 3.5.3                       |
------------------+-----------------------------+-----------------------
  KeepAlive       | 3.5.4                       |
------------------+-----------------------------+-----------------------
  Address         | 3.5.5                       |
------------------+-----------------------------+-----------------------
  Address Withdraw| 3.5.6                       |
------------------+-----------------------------+-----------------------
  Label Mapping   | 3.5.7                       |
  ----------------+-----------------------------+-----------------------
    Label Request | 3.5.7                       |
    Message Id TLV|                             |
  ----------------+-----------------------------+-----------------------
    Hop Count TLV | 3.5.7                       |
  ----------------+-----------------------------+-----------------------
    Path Vect TLV | 3.5.7                       |
------------------+-----------------------------+-----------------------
  Label Request   | 3.5.8                       |
  ----------------+-----------------------------+-----------------------
    Hop Count TLV | 3.5.8                       |
  ----------------+-----------------------------+-----------------------
    Path Vect TLV | 3.5.8                       |
------------------+-----------------------------+-----------------------
  Label Withdraw  | 3.5.10                      |
  ----------------+-----------------------------+-----------------------
    Label TLV     | 3.5.10                      |
------------------+-----------------------------+-----------------------
  Label Release   | 3.5.11                      |
  ----------------+-----------------------------+-----------------------
    Label TLV     | 3.5.11                      |
------------------+-----------------------------+-----------------------
  Label Abort Req | 3.5.9                       |
------------------+-----------------------------+-----------------------
  Vendor-Private  | 3.6.1.2                     |
------------------+-----------------------------+-----------------------
  Experimental    | 3.6.2                       |

==================+=============================+=======================
LDP Status Codes  | 3.4.6
------------------+-----------------------------+-----------------------
  Success         | 3.4.6, 3.9                  |
------------------+-----------------------------+-----------------------
  Bad LDP Id      | 3.5.1.2.1                   |
------------------+-----------------------------+-----------------------
  Bad Ptcl Version| 3.5.1.2.1                   |
------------------+-----------------------------+-----------------------
  Bad PDU Length  | 3.5.1.2.1                   |
------------------+-----------------------------+-----------------------
  Unknown Message | 3.5.1.2.1                   |
  Type            |                             |
------------------+-----------------------------+-----------------------
  Bad Message     | 3.5.1.2.1                   |
  Length          |                             |
------------------+-----------------------------+-----------------------
  Unknown TLV     | 3.5.1.2.2                   |
------------------+-----------------------------+-----------------------
  Bad TLV length  | 3.5.1.2.2                   |
------------------+-----------------------------+-----------------------
  Malformed TLV   | 3.5.1.2.2                   |
  Value           |                             |
------------------+-----------------------------+-----------------------
  Hold Timer      | 3.5.1.2.3                   |
  Expired         |                             |
------------------+-----------------------------+-----------------------
  Shutdown        | 3.5.1.2.4                   |
------------------+-----------------------------+-----------------------
  Loop Detected   | 3.4.5.1.2, 3.5.8.1          |
------------------+-----------------------------+-----------------------
  Unknown FEC     | 3.4.1.1                     |
------------------+-----------------------------+-----------------------
  No Route        | 3.5.8.1                     |
------------------+-----------------------------+-----------------------
  No Label        | 3.5.8.1                     |
  Resources       |                             |
------------------+-----------------------------+-----------------------
  Label Resources | 3.5.8.1                     |
  Available       |                             |
------------------+-----------------------------+-----------------------
  Session Rejected| 2.5.3, 3.5.3                |
  No Hello        |                             |

Author's Addresses

   Bob Thomas
   Cisco Systems, Inc.
   1414 Massachusetts Ave.
   Boxborough MA 01719

   EMail: rhthomas@cisco.com

   Loa Andersson
   Acreo AB
   Isafjordsgatan 22
   Kista, Sweden

   EMail: loa.andersson@acreo.se
          loa@pi.se

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