Filename: draft-ohta-mpls-label-value-00.txt

ITU-T Study Group 13                                             H. Ohta
Request for Comments:                                                NTT
Obsoletes:                                                   August 2001
Category: INFORMATIONAL                                   


    Use of a reserved label value defined in RFC 3032 for MPLS 
    OAM functions

Status of this Memo

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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 a proposed use of a label value in a draft
   ITU-T Recommendation and requests allocation of this value by IANA.




Ohta                                                            [Page 1]

RFC          Use of a reserved label value defined in         April 2001
             RFC 3032 for MPLS OAM functions  

1. ITU-T Study Group 13, Question 3/13 are progressing work on MPLS OAM
functions and are working on the following two Draft Recommendations:

(1) Draft Recommendation Y.1710 (Requirements for OAM functionality for
MPLS networks)
(2) Draft Recommendation Y.1711 (OAM mechanisms for MPLS networks)

Document (1) is currently being approved and the intention is to apply 
the other Draft Recommendation (2) to the approval process at the next 
Study Group 13 meeting in January 2002.
 
Concerning (2), Study Group 13 would like to draw attention to Section 
6.1 as quoted below.  This is regarding the identification of OAM packets 
from normal user-plane traffic packets.  Study Group 13 has tentatively 
decided that a special 'OAM Alert Label' be used for this purpose.  This 
label is defined by using one of the reserved label values defined in 
RFC 3032 (MPLS label stack encoding). A value of 14 has tentatively been 
used for this purpose and IANA is requested to consider if the use of
this value is acceptable. If a different value should be used instead 
of 14 Study Group 13 is ready to change the value.  

If there is any problem with this proposal please let the author know 
before the end of September 2001. 

Extracts from draft Recommendation Y.1711 follow:

"1. Scope
This Recommendation provides mechanisms for user-plane OAM (Operation 
and Maintenance) functionality in MPLS networks according to the 
requirements and principles given in Draft 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."


"6.1 Identification of OAM packets from normal user plane traffic using 
special MPLS label values

The label structure defined in RFC 3031 indicates a single label field 
of 20 bits. Label field values 0-4 have already been reserved for special 
functions. This recommendation introduces a new label value, herein 
referred to as the 'OAM Alert Label'. The recommended numerical value the 
OAM Alert Label is 14, and yet to be officially confirmed by IANA whether 
the use of this value causes any problem. This label value indicates that
the first octet following the OAM Alert Labelled header in the OAM payload 
is an OAM Function Type field whose value defines the type of defect 
handling OAM function (i.e. CV, P, FDI or BDI) which follows in the 
payload area."

Further information can be obtained from the author.

2. Author's Address
   
   Mr. H. OHTA
   NTT
   Network Service Systems Laboratories
   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