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rfc:rfc6923

Internet Engineering Task Force (IETF) R. Winter Request for Comments: 6923 NEC Category: Standards Track E. Gray ISSN: 2070-1721 Ericsson

                                                       H. van Helvoort
                                         Huawei Technologies Co., Ltd.
                                                              M. Betts
                                                                   ZTE
                                                              May 2013
            MPLS Transport Profile (MPLS-TP) Identifiers
                    Following ITU-T Conventions

Abstract

 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 Operations, Administration, and Maintenance (OAM)
 functions to include identifier information in a format typically
 used by the International Telecommunication Union Telecommunication
 Standardization Sector (ITU-T).

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/rfc6923.

Winter, et al. Standards Track [Page 1] RFC 6923 MPLS-TP ITU-T IDs May 2013

Copyright Notice

 Copyright (c) 2013 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
    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 ..................................7
 5. MPLS-TP Tunnel and LSP Identifiers ..............................7
    5.1. MPLS-TP Point-to-Point Tunnel Identifiers ..................7
    5.2. MPLS-TP LSP Identifiers ....................................8
         5.2.1. MPLS-TP Co-Routed Bidirectional LSP Identifiers .....8
         5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers ....9
 6. Pseudowire Path Identifiers .....................................9
 7. Maintenance Identifiers .........................................9
    7.1. MEG Identifiers ...........................................10
    7.2. MEP Identifiers ...........................................10
    7.3. MIP Identifiers ...........................................10
 8. Security Considerations ........................................11
 9. References .....................................................11
    9.1. Normative References ......................................11
    9.2. Informative References ....................................12

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] by adding new identifiers based on ITU-T
 conventions.  It is not intended that both types of identifiers will
 be used at the same time in the same domain.

Winter, et al. Standards Track [Page 2] RFC 6923 MPLS-TP ITU-T IDs May 2013

 [RFC6370] defines a set of MPLS-TP transport and management entity
 identifiers to support bidirectional (co-routed and associated)
 point-to-point MPLS-TP Label Switched Paths (LSPs), including
 Pseudowires (PWs) and Sections that follow the IP/MPLS conventions.
 This document specifies an alternative way to generate unambiguous
 identifiers for operators/service providers based on ITU-T
 conventions and specifies how these operator/service provider
 identifiers can be used to generate unambiguous identifiers for the
 existing set of identifiable MPLS-TP entities described in [RFC6370].
 This document solely defines those identifiers.  Their use and
 possible protocol extensions to carry them are out of the scope of
 this document.
 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
 ISO: International Organization for Standardization
 ITU: International Telecommunication Union
 ITU-T: ITU Telecommunication Standardization Sector
 LSP: Label Switched Path
 MEG: Maintenance Entity Group
 MEP: Maintenance Entity Group End Point
 MIP: Maintenance Entity Group Intermediate Point
 MPLS: Multiprotocol Label Switching
 PW: Pseudowire
 TSB: (ITU-T) Telecommunication Standardization Bureau
 UMC: Unique MEG ID Code

Winter, et al. Standards Track [Page 3] RFC 6923 MPLS-TP ITU-T IDs May 2013

1.2. Requirements Notation

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in [RFC2119].

1.3. Notational Conventions

 This document uses the notational conventions laid out in [RFC6370]:
    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 objects.

2. Named Entities

 This document provides additional identifiers supplementing those
 defined in [RFC6370].  The identifiers in [RFC6370] are composed of a
 set of atomic identifiers, and this document defines some new atomic
 identifiers that can be substituted for some of those that have
 already been defined, to create new identifiers.  The set of
 identifiers defined in [RFC6370] is:
 o  Global_ID
 o  Node

Winter, et al. Standards Track [Page 4] RFC 6923 MPLS-TP ITU-T IDs May 2013

 o  Interface
 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 Autonomous System (AS) number of the operator.
 The ITU-T, however, traditionally identifies operators and service
 providers based on the ITU 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, all of which are
 referenced at [ICC-list], can be assigned to ITU-T members as well as
 non-members.  The national regulatory authorities act as an
 intermediary between the ITU/TSB and operators/service providers.
 One of 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.  This uniqueness assumption is
 the basis for creating a globally unique ICC-based operator ID.
 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 uppercase
 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 uppercase letters (i.e., A-Z).

Winter, et al. Standards Track [Page 5] RFC 6923 MPLS-TP ITU-T IDs May 2013

 The International Organization for Standardization (ISO) establishes
 internationally recognized codes for the representation of names of
 countries, territories or areas of geographical interest, and their
 subdivisions, published as a list of CCs [CC-list] in ISO Standard
 3166-1 [ISO3166-1].
 The ICC and CC characters are coded according to ITU-T Recommendation
 T.50 [T.50].
 Together, the CC and the ICC form the ICC_Operator_ID as:
    CC::ICC

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 that, just like the Global_ID, is prefixed to the
 IF_ID.  Using the notation from RFC 6370 [RFC6370]:
    Global_ID::Node_ID::IF_Num
 is functionally equivalent to:
    ICC_Operator_ID::Node_ID::IF_Num
 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
 Sections 7.1, 7.2, and 7.3, respectively).

Winter, et al. Standards Track [Page 6] RFC 6923 MPLS-TP ITU-T IDs May 2013

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 document 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 that 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.
 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 Sections 5.1 and 5.2.

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

Winter, et al. Standards Track [Page 7] RFC 6923 MPLS-TP ITU-T IDs May 2013

 Where global uniqueness is required, using ITU-T conventions, the
 ICC_Operator_ID is prefixed to the Tunnel_ID.  Thus, a globally
 unique Tunnel_ID becomes:
    A1-{ICC_Operator_ID::Node_ID::Tunnel_Num}::
    Z9-{ICC_Operator_ID::Node_ID::Tunnel_Num}
 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 subsections 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
 the Tunnel ID.  Consequently, the format of an MPLS-TP co-routed
 bidirectional LSP_ID is:
    A1-{Node_ID::Tunnel_Num}::Z9-{Node_ID::Tunnel_Num}::LSP_Num
 [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:
    A1-{ICC_Operator_ID::Node_ID::Tunnel_Num}::
    Z9-{ICC_Operator_ID::Node_ID::Tunnel_Num}::LSP_Num

Winter, et al. Standards Track [Page 8] RFC 6923 MPLS-TP ITU-T IDs May 2013

5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers

 An associated bidirectional LSP needs a separate LSP_Num for both of
 its unidirectional LSPs.  The LSP number is again a 16-bit unsigned
 integer that needs to be unique within the scope of the ingress's
 Tunnel_Num.  Consequently, the format of an MPLS-TP associated
 bidirectional LSP_ID is:
    A1-{Node_ID::Tunnel_Num::LSP_Num}::
    Z9-{Node_ID::Tunnel_Num::LSP_Num}
 Each of the unidirectional LSPs of which the associated bidirectional
 LSP is composed may be referenced by one of the following
 identifiers:
    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:
    A1-{ICC_Operator_ID::Node_ID::Tunnel_Num::LSP_Num}::
    Z9-{ICC_Operator_ID::Node_ID::Tunnel_Num::LSP_Num}

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].  Instead 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:
    A1-{ICC_Operator_ID::Node_ID::AC_ID}::
    Z9-{ICC_Operator_ID::Node_ID::AC_ID}

7. Maintenance Identifiers

 The following subsections define the identifiers for the various
 maintenance-related groups and entities as defined in [RFC6371].  In
 contrast to the IDs defined in [RFC6370], this document does not
 define separate maintenance identifiers for Sections, PWs, and LSPs.

Winter, et al. Standards Track [Page 9] RFC 6923 MPLS-TP ITU-T IDs May 2013

7.1. MEG Identifiers

 MEG_IDs for MPLS-TP Sections, LSPs, and PWs 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) and
 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 [Y.1731_cor1].
 The resulting MEG_ID is:
    CC::ICC::UMC
 To avoid the potential for the concatenation of a short (i.e., less
 than 6 characters) 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.
 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.  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:
    MEG_ID::MEP_Index
 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 on which the MIP resides

Winter, et al. Standards Track [Page 10] RFC 6923 MPLS-TP ITU-T IDs May 2013

 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 used.
 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 naming scheme and does not
 introduce new security concerns.  However, as mentioned in the
 Security Considerations section of [RFC6370], protocol specifications
 that describe the use of this naming scheme 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. References

9.1. Normative References

 [ISO3166-1]   "Codes for the representation of names of countries and
               their subdivisions -- Part 1: Country codes", ISO
               3166-1, 2006.
 [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.
 [T.50]        "International Reference Alphabet (IRA) (Formerly
               International Alphabet No. 5 or IA5) - Information
               technology - 7-bit coded character set for information
               exchange", ITU-T Recommendation T.50, September 1992.
 [Y.1731_cor1] "OAM functions and mechanisms for Ethernet based
               networks - Corrigendum 1", ITU-T Recommendation
               G.8013/Y.1731 Corrigendum 1, October 2011.

Winter, et al. Standards Track [Page 11] RFC 6923 MPLS-TP ITU-T IDs May 2013

9.2. Informative References

 [CC-list]     "List of Country Codes - ISO 3166 (CCs)",
               <http://www.iso.org/iso/country_codes.htm>.
 [ICC-list]    "List of ITU Carrier Codes (ICCs)",
               <http://www.itu.int/oth/T0201>.
 [RFC6371]     Busi, I., Ed., and D. Allan, Ed., "Operations,
               Administration, and Maintenance Framework for MPLS-
               Based Transport Networks", RFC 6371, September 2011.

Authors' Addresses

 Rolf Winter
 NEC
 EMail: rolf.winter@neclab.eu
 Eric Gray
 Ericsson
 EMail: eric.gray@ericsson.com
 Huub van Helvoort
 Huawei Technologies Co., Ltd.
 EMail: huub.van.helvoort@huawei.com
 Malcolm Betts
 ZTE
 EMail: malcolm.betts@zte.com.cn

Winter, et al. Standards Track [Page 12]

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