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MPLS-TP Identifiers Following ITU-T Conventions

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 6923.
Authors Rolf Winter , Eric Gray , Huub van Helvoort , Malcolm Betts
Last updated 2013-01-05 (Latest revision 2012-11-07)
Replaces draft-win-mpls-tp-itu-t-identifiers
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IESG IESG state Became RFC 6923 (Proposed Standard)
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Responsible AD Adrian Farrel
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Network Working Group                                     R. Winter, Ed.
Internet-Draft                                                       NEC
Intended status: Standards Track                            E. Gray, Ed.
Expires: May 11, 2013                                           Ericsson
                                                         H. van Helvoort
                                           Huawei Technologies Co., Ltd.
                                                                M. Betts
                                                        November 7, 2012

            MPLS-TP Identifiers Following ITU-T Conventions


   This document specifies an extension to the identifiers to be used in
   the Transport Profile of Multiprotocol Label Switching (MPLS-TP).
   Identifiers that follow IP/MPLS conventions have already been
   defined.  This memo augments that set of identifiers for MPLS-TP
   management and OAM functions to include identifier information in a
   format typically used by the ITU-T.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 11, 2013.

Copyright Notice

   Copyright (c) 2012 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
   ( in effect on the date of

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   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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
     1.2.  Requirements notation  . . . . . . . . . . . . . . . . . .  4
     1.3.  Notational Conventions . . . . . . . . . . . . . . . . . .  4
   2.  Named Entities . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Uniquely Identifying an Operator - the ICC_Operator_ID . . . .  5
     3.1.  Use of the ICC_Operator_ID . . . . . . . . . . . . . . . .  6
   4.  Node and Interface Identifiers . . . . . . . . . . . . . . . .  6
   5.  MPLS-TP Tunnel and LSP Identifiers . . . . . . . . . . . . . .  7
     5.1.  MPLS-TP Point-to-Point Tunnel Identifiers  . . . . . . . .  7
     5.2.  MPLS-TP LSP Identifiers  . . . . . . . . . . . . . . . . .  7
       5.2.1.  MPLS-TP Co-Routed Bidirectional LSP Identifiers  . . .  7
       5.2.2.  MPLS-TP Associated Bidirectional LSP  Identifiers  . .  8
   6.  Pseudowire Path Identifiers  . . . . . . . . . . . . . . . . .  9
   7.  Maintenance Identifiers  . . . . . . . . . . . . . . . . . . .  9
     7.1.  MEG Identifiers  . . . . . . . . . . . . . . . . . . . . .  9
     7.2.  MEP Identifiers  . . . . . . . . . . . . . . . . . . . . . 10
     7.3.  MIP Identifiers  . . . . . . . . . . . . . . . . . . . . . 10
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 11
     10.2. Informative References . . . . . . . . . . . . . . . . . . 11
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11

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1.  Introduction

   This document augments the initial set of identifiers to be used in
   the Transport Profile of Multiprotocol Label Switching (MPLS-TP)
   defined in [RFC6370].

   [RFC6370] defines a set of MPLS-TP transport and management entity
   identifiers to support bidirectional (co-routed and associated)
   point-to-point MPLS-TP LSPs, including PWs and Sections which follow
   the IP/MPLS conventions.

   This document specifies an alternative way to uniquely identify an
   operator/service provider based on ITU-T conventions and specifies
   how this operator/service provider identifier can be used to make the
   existing set of MPLS-TP transport and management entity identifiers,
   defined by [RFC6370], globally unique.

   This document solely defines those identifiers.  Their use and
   possible protocols extensions to carry them is out of scope in this

   In this document, we follow the notational convention laid out in
   [RFC6370], which is included in this document for convenience in
   Section 1.3.

1.1.  Terminology

   CC: Country Code

   ICC: ITU Carrier Code

   ITU-T: International Telecommunication Union Telecommunication
   Standardization Sector

   LSP: Label Switched Path

   MEG: Maintenance Entity Group

   MEP: Maintenance Entity Group End Point

   MIP: Maintenance Entity Group Intermediate Point

   MPLS: Multi-Protocol Label Switching

   PW: Pseudowire

   TSB: (ITU-T) Telecommunication Standardization Bureau

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   UMC: Unique MEG ID Code

1.2.  Requirements notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

1.3.  Notational Conventions

   All multiple-word atomic identifiers use underscores (_) between the
   words to join the words.  Many of the identifiers are composed of a
   set of other identifiers.  These are expressed by listing the latter
   identifiers joined with double-colon "::" notation.

   Where the same identifier type is used multiple times in a
   concatenation, they are qualified by a prefix joined to the
   identifier by a dash (-).  For example, A1-Node_ID is the Node_ID of
   a node referred to as A1.

   The notation defines a preferred ordering of the fields.
   Specifically, the designation A1 is used to indicate the lower sort
   order of a field or set of fields and Z9 is used to indicate the
   higher sort order of the same.  The sort is either alphanumeric or
   numeric depending on the field's definition.  Where the sort applies
   to a group of fields, those fields are grouped with {...}.

   Note, however, that the uniqueness of an identifier does not depend
   on the ordering, but rather, upon the uniqueness and scoping of the
   fields that compose the identifier.  Further, the preferred ordering
   is not intended to constrain protocol designs by dictating a
   particular field sequence or even what fields appear in which

2.  Named Entities

   This document makes modest changes to the set of identifiers defined
   in [RFC6370].  Most changes replace certain parts in the already
   defined identifiers that are themselves composed of a set of atomic
   identifiers.  The set of identifiers defined in [RFC6370] are:

   o  Global_ID

   o  Node

   o  Interface

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   o  Tunnel

   o  LSP

   o  PW

   o  MEG

   o  MEP

   o  MIP

   The following sections go through this list of identifiers one by
   one.  The structure of this document is loosely aligned with the
   structure of [RFC6370].

3.  Uniquely Identifying an Operator - the ICC_Operator_ID

   In [RFC6370] an operator is uniquely identified by the Global_ID
   which is based on the AS number of the operator.  The ITU-T however
   traditionally identifies operators/service providers based on the
   ITU-T Carrier Code (ICC) as specified in [M1400].

   The ITU-T Telecommunication Standardization Bureau (TSB) maintains a
   list of assigned ICCs [ICC-list].  Note that ICCs can be assigned to
   both, ITU-T members as well as non-members, all of which are
   referenced at [ICC-list].  The national regulatory authorities act as
   an intermediary between the ITU/TSB and operators/service providers.
   Amongst the things that the national authorities are responsible for
   in the process of assigning an ICC is to ensure that the Carrier
   Codes are unique within their country.

   The ICC itself is a string of one to six characters, each character
   being either alphabetic (i.e.  A-Z) or numeric (i.e. 0-9).
   Alphabetic characters in the ICC SHOULD be represented with upper
   case letters.

   Global uniqueness is assured by concatenating the ICC with a Country
   Code (CC).  The Country Code (alpha-2) is a string of two alphabetic
   characters represented with upper case letters (i.e., A-Z).  The
   Country Code format is defined in ISO 3166-1 [ISO3166-1].  Together,
   the CC and the ICC form the ICC_Operator_ID as:


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3.1.  Use of the ICC_Operator_ID

   The ICC_Operator_ID is used as a replacement for the Global_ID as
   specified in [RFC6370], i.e. its purpose is to provide a globally
   unique context for other MPLS-TP identifiers.

   As an example, an Interface Identifier (IF_ID) in [RFC6370] is
   specified as the concatenation of the Node_ID (a unique 32-bit value
   assigned by the operator) and the Interface Number (IF_Num, a 32-bit
   unsigned integer assigned by the operator that is unique within the
   scope of a Node_ID).  To make this IF_ID globally unique the
   Global_ID is prefixed.  This memo specifies the ICC_Operator_ID as an
   alternative format which, just like the Global_ID, is prefixed to the
   IF_ID.  Using the notation from RFC 6370 [RFC6370]:


   is functionally equivalent to:


   The same substitution procedure applies to all identifiers specified
   in [RFC6370] with the exception of the MEG ID, MEP ID and MIP ID.
   MEG, MEP and MIP identifiers are redefined in this document (see
   Section 7.1, Section 7.2 and Section 7.3 respectively).

4.  Node and Interface Identifiers

   The format of the node and interface identifiers are not changed by
   this memo except for the case when global uniqueness is required.

   [RFC6370] defines the node identifier (Node_ID) as a unique 32-bit
   value assigned by the operator within the scope of a Global_ID.  The
   structure of the Node_ID itself is not defined as it is left to the
   operator to choose an appropriate value.  The value zero however is
   reserved and MUST NOT be used.

   This draft does not change the above definition.  However, in case
   global uniqueness is required, the Node_ID is prefixed with the
   ICC_Operator_ID as defined in Section 3.

   [RFC6370] further defines interface numbers (IF_Num) as 32-bit
   unsigned integers which can be freely assigned by the operator and
   must be unique in the scope of the respective Node_ID.  The IF_Num
   value 0 has a special meaning and therefore it MUST NOT be used to
   identify an MPLS-TP interface.

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   An interface identifier (IF_ID) identifies an interface uniquely
   within the context of an ICC_Operator_ID.  It is formed by
   concatenating the Node_ID with the IF_Num to result in a 64-bit
   identifier formed as Node_ID::IF_Num.

   Global uniqueness of the IF_ID, if needed, can be assured by
   prefixing the identifier with the ICC_Operator_ID.

5.  MPLS-TP Tunnel and LSP Identifiers

   This document does not change the definition for local tunnel and LSP
   IDs.  When global uniqueness is needed, the format of these
   identifiers is as described in Section 5.1 and Section 5.2 below.

5.1.  MPLS-TP Point-to-Point Tunnel Identifiers

   Tunnel IDs (Tunnel_ID) are based on the end points' Node_IDs and
   locally assigned tunnel numbers (Tunnel_Num) which identify the
   tunnel at each end point.  The tunnel number is a 16-bit unsigned
   integer unique within the context of the Node_ID.  A full tunnel ID
   is represented by the concatenation of these two end point-specific
   identifiers.  Using the A1/Z9 convention, the format of a Tunnel_ID


   Where global uniqueness is required, using ITU-T conventions, the
   ICC_Operator_ID is prefixed to the Tunnel_IDs.  Thus, a globally
   unique Tunnel_ID becomes:

      A1-{ICC_Operator_ID::Node_ID::Tunnel_Num}:: Z9-

   As per [RFC6370], when an MPLS-TP Tunnel is configured, it MUST be
   assigned a unique IF_ID at each end point as defined in Section 4.

5.2.  MPLS-TP LSP Identifiers

   The following sub-sections define identifiers for MPLS-TP co-routed
   bidirectional and associated bidirectional LSPs.  Since MPLS-TP Sub-
   Path Maintenance Entities (SPMEs) are also LSPs, they use the same
   form of IDs.

5.2.1.  MPLS-TP Co-Routed Bidirectional LSP Identifiers

   The LSP identifier (LSP_ID) for a co-routed bidirectional LSP is
   formed by adding a 16-bit unsigned integer LSP number (LSP_Num) to

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   the tunnel ID.  Consequently, the format of an MPLS-TP co-routed
   bidirectional LSP_ID is:


   [RFC6370] notes that, the "uniqueness of identifiers does not depend
   on the A1/Z9 sort ordering".

   A co-routed bidirectional LSP is provisioned or signaled as a single
   entity and therefore a single LSP_Num is used for both unidirectional
   LSPs.  These can be referenced by the following identifiers:

      A1-Node_ID::A1-Tunnel_Num::LSP_Num::Z9-Node_ID and

      Z9-Node_ID::Z9-Tunnel_Num::LSP_Num::A1-Node_ID, respectively.

   Global uniqueness is accomplished by using globally unique Node_IDs.
   A globally unique LSP_ID consequently becomes:


5.2.2.  MPLS-TP Associated Bidirectional LSP  Identifiers

   Associated bidirectional LSPs need an LSP_Num for each unidirectional
   LSP it consists of.  The LSP number is again a 16-bit unsigned
   integer which needs to be unique within the scope of the ingress'
   Tunnel_Num. Consequently, the format of an MPLS-TP associated
   bidirectional LSP_ID is:


   Each of the unidirectional LSPs of which the associated bidirectional
   LSP consists of may be referenced by one of the following

      A1-Node_ID::A1-Tunnel_Num::A1-LSP_Num::Z9-Node_ID and

      Z9-Node_ID::Z9-Tunnel_Num::Z9-LSP_Num::A1-Node_ID, respectively.

   A globally unique LSP_ID is constructed using the globally unique
   Node_IDs as defined before.  Consequently, a globally unique LSP_ID
   is formulated as:


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6.  Pseudowire Path Identifiers

   The PW Path Identifier (PW_Path_ID) is structured in a similar manner
   as the PW_Path_ID described in section 6 of [RFC6370].  In stead of
   the Global_ID used in [RFC6370] this document uses the
   ICC_Operator_ID to make the PW-Path_ID globally unique.  In this
   document the Attachment Individual Identifier (AII) is composed of
   three fields.  These are the ICC_Operator_ID, the Node_ID and the
   AC_ID.  The AC-ID is as defined in [RFC5003].  The complete globally
   unique PW_Path_ID is formulated as:


7.  Maintenance Identifiers

   A Maintenance Entity Group (MEG) as defined by [RFC6371] is a
   collection of one or more maintenance enties that belong to the same
   transport path.  These maintenance entities can be e.g.  Maintenance
   Entity Group End Points (MEPs) or Maintenance Entity Group
   Intermediate Points (MIPs).  The following sub-sections define the
   identifiers for the various maintenance-related groups and entities.
   In contrast to the IDs defined in [RFC6370], this document does not
   define separate maintenance identifiers for sections, PWs and LSPs.

7.1.  MEG Identifiers

   MEG_IDs for MPLS-TP Sections, LSPs and Pseudowires following ITU-T
   conventions are based on the globally unique ICC_Operator_ID.  In
   this case, the MEG_ID is a string of up to 15 characters and consists
   of three subfields: the Country Code (as described in Section 3), the
   ICC (as described in Section 3) which together form the
   ICC_Operator_ID, followed by a Unique MEG ID Code (UMC) as defined in

   The resulting MEG_ID is:


   To avoid the potential for the concatenation of a short (i.e. less
   than 6 Character) ICC with a UMC not being unique the UMC MUST start
   with the "/" character which is not allowed in the ICC itself.  This
   way, the MEG_ID can also be easily decomposed into its individual
   components by a receiver.

   The UMC MUST be unique within the organization identified by the
   combination of CC and ICC.

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   The ICC_Operator_ID-based MEG_ID may be applied equally to a single
   MPLS-TP Section, LSP or Pseudowire.

7.2.  MEP Identifiers

   ICC_Operator_ID-based MEP_IDs for MPLS-TP Sections, LSPs and
   Pseudowires are formed by appending a 16-bit index to the MEG_ID
   defined in Section 7.1 above.  Within the context of a particular
   MEG, we call the identifier associated with a MEP the MEP Index
   (MEP_Index).  The MEP_Index is administratively assigned.  It is
   encoded as a 16-bit unsigned integer and MUST be unique within the
   MEG.  An ICC_Operator_ID-based MEP_ID is structured as:


   An ICC_Operator_ID-based MEP ID is globally unique by construction
   given the ICC_Operator_ID-based MEG_ID's global uniqueness.

7.3.  MIP Identifiers

   ICC_Operator_ID-based MIP_IDs for MPLS-TP Sections, LSPs and
   Pseudowires are formed by a global IF_ID that is obtained by
   prefixing the identifier of the interface the MIP resides with the
   ICC_Operator_ID as described in Section 3.1.  This allows MIPs to be
   independently identified in nodes where a per-interface MIP model is

   If only a per-node MIP model is used, one MIP is configured.  In this
   case, the MIP_ID is formed by using the Node_ID and an IF_Num of 0.

8.  Security Considerations

   This document extends an existing information model and does not
   introduce new security concerns.  But, as mentioned in the security
   considerations section of [RFC6370] protocol specifications that
   describe use of this information model may introduce security risks
   and concerns about authentication of participants.  For this reason,
   these protocol specifications need to describe security and
   authentication concerns that may be raised by the particular
   mechanisms defined and how those concerns may be addressed.

9.  IANA Considerations

   There are no IANA actions resulting from this document.

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10.  References

10.1.  Normative References

              "Codes for the representation of names of countries and
              their subdivisions -- Part 1: Country codes", ISO 3166-1.

   [M1400]    "Designations for interconnections among operators'
              networks", ITU-T Recommendation M.1400, July 2006,

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5003]  Metz, C., Martini, L., Balus, F., and J. Sugimoto,
              "Attachment Individual Identifier (AII) Types for
              Aggregation", RFC 5003, September 2007.

   [RFC6370]  Bocci, M., Swallow, G., and E. Gray, "MPLS Transport
              Profile (MPLS-TP) Identifiers", RFC 6370, September 2011.

              "OAM functions and mechanisms for Ethernet based networks
              - Corrigendum 1", ITU-T Recommendation ITU-T G.8013/Y.1731
              (2011) Corrigendum 1.

10.2.  Informative References

              "List of ITU Carrier Codes (ICCs)",

   [RFC6371]  Busi, I. and D. Allan, "Operations, Administration, and
              Maintenance Framework for MPLS-Based Transport Networks",
              RFC 6371, September 2011.

Authors' Addresses

   Rolf Winter (editor)


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   Eric Gray (editor)


   Huub van Helvoort
   Huawei Technologies Co., Ltd.


   Malcolm Betts


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