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

Copyright Notice

Copyright © 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

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)      |
         +----------+----------+--------------------------------+

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.

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    |              |           |            |
   +-----+----+---------------+--------------+-----------+------------+
   
   +-----+----+---------------+--------------+-----------+------------+
   | 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>.

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.

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