H. Ohta
   Internet Draft                                                   NTT
   Document: draft-ohta-mpls-label-value-01.txt
   Expires: August 2002                                   February 2002
   
   
   
           Use of a reserved label value defined in RFC 3032 for
                            MPLS OAM functions
   
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      This document requests IANA to allocate a label value.
      Distribution of this memo is unlimited.
   
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   Abstract
   
      This document describes use of an MPLS reserved label value for
   identification of user-plane MPLS OAM packets as described in the
   ITU-T draft Recommendation Y.1711, and makes a request to IANA for
   allocation of a reserved label for this purpose.
   
   
   
   
   
   
   
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          Use of a reserved label value defined in RFC 3032  Feb 2002
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   1. Introduction
   This document describes use of an MPLS reserved label value for
   identification of user-plane MPLS OAM packets as described in the
   ITU-T draft Recommendation Y.1711 (on MPLS OAM functions) and makes a
   request to IANA for allocation of a reserved label for this purpose.
   
   
   2. OAM functions
   MPLS OAM (Operation and Maintenance) provide necessary tools for
   network operators to operate and maintain the networks.  MPLS OAM
   functionality is required at the MPLS layer, and more specifically at
   each MPLS level, independent of OAM functionality provided by the
   lower layers (SONET/SDH, etc.).  The objectives of the OAM functions
   include the followings:
   
   - Defect and failure detection:
   Defect/failures affecting the transport of user information are
   detected by continuous or periodic checking. As a result,
   maintenance event information or various alarms will be produced.
   
   - Reporting the defect/failure information:
   Defect information is given to other management entities (e.g.
   Operation Support System) in order to provide the appropriate
   indications to the maintenance staff for maintaining the Quality of
   Service (QoS) level offered to customers.
   
   - Defect/failure localization:
   Determination by internal or external test systems of a failed entity
   is performed if defect information is insufficient.
   
   - Performance monitoring:
   Performance (packet losses, transfer delay, bit errors, etc.) of
   the user information transport is measured in order to estimate
   the transport integrity.
   
   Related work in IETF can be found in [1], [2], [3].
   
   
   3. MPLS OAM work in ITU-T SG13
   ITU-T Study Group 13, Question 3/13 is progressing work on user-plane
   MPLS OAM and has produced the following documents:
   
   (1) Approved Recommendation Y.1710 (Requirements for OAM
   functionality for MPLS networks) [4]
   (2) Draft Recommendation Y.1711 (OAM mechanisms for MPLS networks)[5]
   (3) Draft Recommendation Y.1720 (MPLS Protection Switching)[6] which
   relies on OAM mechanisms in Y.1711.
   
   Please note that we are planning to put the document (2) above into
   the approval process in the middle of February.  The user-plane MPLS
   
   
   
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          Use of a reserved label value defined in RFC 3032  Feb 2002
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   OAM mechanisms[5] relies on the use of a special label called 'OAM
   Alert Label'.  Study Group 13 has tentatively decided to use one of
   the reserved label values defined in RFC 3032(MPLS label stack
   encoding)[7] to differentiate OAM packets from the normal user
   packets. A value of 14 has been proposed for this purpose. IANA is
   requested to consider if the use of this value is acceptable. Should
   the said value not be acceptable by IANA, Study Group 13 is ready to
   accept another reserved label value (as per IANA's recommendation).
   
   Study group 13 appreciates if IANA advises the author of any problem
   with the use of this value no later than April 30, 2002.
   Extracts from draft Recommendation Y.1711 follow:
   
   "1 Introduction
   This Recommendation provides mechanisms for user-plane OAM (Operation
   and Maintenance) functionality in MPLS networks according to the
   requirements and principles given in Recommendation Y.1710.  It is
   recognized that OAM functionality is important in public networks for
   ease of network operation, for verifying network performance and to
   reduce operational costs.  OAM functionality is especially important
   for networks, which are required to deliver (and hence be measurable
   against) QoS (Quality of Service) and availability performance
   parameters/objectives."
   
   
   " 5.1 Identification of OAM packets from normal user-plane traffic
   The label structure defined in [7] indicates a single label field of
   20 bits.  Some label field values have already been reserved for
   special functions[7].
   
   This Recommendation introduces a new globally reserved label value,
   herein referred to as the 'OAM Alert Label'.  The recommended
   numerical value of the OAM Alert Label is 14."
   
   Further information can be obtained from the author.
   
   
   4. IANA considerations
   
   It is requested that the IANA consider if the use of the MPLS
   reserved label value of 14 as the 'OAM Alert Label' is acceptable.
   If it is acceptable, it is requested that the use of this value is
   officially assigned. Study group 13 appreciates if IANA will advise
   the author of any problem with the use of this value, and if
   necessary recommends an alternative reserved label value no later
   than April 30, 2002.
   .
   
   
   
   
   
   
   
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          Use of a reserved label value defined in RFC 3032  Feb 2002
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   5. References
   
      [1]  Neil Harrison et. al. "Requirements for OAM in MPLS Networks",
      IETF Work in progress, draft-harrison-mpls-oam-req-01.txt,
      December 2001
   
      [2]  David Allan et. al. " A Framework for MPLS User Plane OAM",
      IETF Work in progress, draft-allan-mpls-oam-frmwk-01.txt, November
      2001
   
      [3]  Mina Azad et. al. " MPLS user-plane OAM messaging", IETF Work
      in progress, draft-azad-mpls-oam-messaging-01.txt, December 2001
   
      [4] ITU-T recommendation Y.1710, "Requirements for OAM
      functionality for MPLS networks" Caracas, Venezuela, May 2001
   
      [5] ITU-T draft recommendation Y.1711, "OAM mechanism for MPLS
      networks", Geneva, Switzerland, February 2002
   
      [6] ITU-T draft recommendation Y.1720, "Protection switching for
      MPLS networks", Caracas, Venezuela, May 2001
   
      [7] IETF, RFC 3032, MPLS label stack encoding, Category: Standards
      Track, January 2001.
   
   
   6. Author's Address
   
      Hiroshi OHTA
      NTT
      3-9-11 Midori-Cho, Musashino-Shi
      Tokyo 180-8585 Japan
   
      Tel: +81 422 59 3617
      Fax: +81 422 59 3782
      Email: ohta.hiroshi@lab.ntt.co.jp
   
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