MPLS Working Group                                              M. Bocci
Internet-Draft                                            Alcatel-Lucent
Intended status: Standards Track                              G. Swallow
Expires: September 9, 2010 January 13, 2011                                          Cisco
                                                           March 8,
                                                           July 12, 2010

                          MPLS-TP Identifiers


   This document specifies identifiers for MPLS-TP objects.  Included
   are identifiers conformant to existing ITU conventions and
   identifiers which are compatible with existing IP, MPLS, GMPLS, and
   Pseudowire definitions.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Named Entities . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Uniquely Identifying an Operator . . . . . . . . . . . . . . .  5
     3.1.  The Global ID  . . . . . . . . . . . . . . . . . . . . . .  5
     3.2.  ITU Carrier Code . . . . . . . . . . . . . . . . . . . . .  5
   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  8
     5.3.  Mapping to GMPLS Signalling  . . . . . . . . . . . . . . .  8
   6.  Pseudowire Path Identifiers  . . . . . . . . . . . . . . . . .  8  9
   7.  Maintenance Identifiers  . . . . . . . . . . . . . . . . . . .  9
     7.1.  Maintenance Entity Group Identifiers . . . . . . . . . . .  9 10
       7.1.1.  ICC based MEG_IDs  . . . . . . . . . . . . . . . . . .  9 10
       7.1.2.  IP Compatible MEG_IDs  . . . . . . . . . . . . . . . . 10  MPLS-TP Tunnel MEG_IDs . . . . . . . . . . . . . . 10  MPLS-TP LSP MEG_IDs  . . . . . . . . . . . . . . . 10  Pseudowire MEG_IDs . . . . . . . . . . . . . . . . 10
     7.2.  MEP_IDs  . . . . . . . . . . . . . . . . . . . . . . . . . 11
       7.2.1.  ICC based MEP_IDs  . . . . . . . . . . . . . . . . . . 11
       7.2.2.  IP based MEP_IDs . . . . . . . . . . . . . . . . . . . 11  MEP_IDs for  MPLS-TP LSPs and Tunnels LSP_MEP_ID . . . . . . . . . . . . . . . . 11  MEP_IDs for Pseudowires  . . . . . . . . . . . . . 12 11  MEP_IDs  Endpoint IDs for Pseudowire Segments . . . . . . . . . 12
     7.3.  MIP_IDs  . . . . . . . . . . . . . . . . . . . . . . . . . 13 12
   8.  Open issues  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 13
     10.2. Informative References . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14

1.  Introduction

   This document specifies identifiers to be used in within the
   Transport Profile of Multiprotocol Label Switching (MPLS-TP).  The
   MPLS-TP requirements [12] require that the elements and objects in an
   MPLS-TP environment are able to be configured and managed without a
   control plane.  In such an environment many conventions for defining
   identifiers are possible.  This document defines identifiers for
   MPLS-TP management and OAM functions suitable to ITU conventions and
   to IP/MPLS conventions.  Applicability of the different identifier
   schemas to different applications are outside the scope of this

1.1.  Terminology

   AII: Attachment Interface Identifier

   AP: Attachment Point

   ASN: Autonomous System Number

   FEC: Forwarding Equivalence Class

   GMPLS: Generalized Multi-Protocol Label Switching

   ICC: ITU Carrier Code

   LSP: Label Switched Path

   LSR: Label Switching Router

   ME: Maintenance Entity

   MEG: Maintenance Entity Group

   MEP: Maintenance Entity Group End Point

   MIP: Maintenance Entity Group Intermediate Point

   MPLS: Multi-Protocol Label Switching

   OAM: Operations, Administration and Maintenance

   P2MP: Point to Multi-Point

   P2P: Point to Point

   PSC: Protection State Coordination

   PW: Pseudowire
   RSVP: Resource Reservation Protocol

   RSVP-TE: RSVP Traffic Engineering

   S-PE: Switching Provider Edge

   T-PE: Terminating Provider Edge

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [1].

Notational Conventions in Backus-Naur Form

   All multiple-word atomic identifiers use underscores (_) between the
   words to join the words.  Many of the identifiers are composed of a
   concatenation of other identifiers, these are expressed using Backus-
   Naur Form.  Where the same identifier is used multiple times in a
   concatenation, they are qualified by a prefix joining it to the
   identifier by a dash (-).  For example Src-Node_ID is the Node_ID of
   a node referred to as Src (short for source).

2.  Named Entities

   In order to configure, operate and manage a transport network based
   on the MPLS Transport Profile, a number of entities require
   identification.  Identifiers for the follow entities are defined in
   this document:

   o  Operator

      *  ICC

      *  Global_ID

      *  ICC

   o  LSR

   o  LSP

   o  PW

   o  Interface

   o  MEG
   o  MEP

   o  MIP

   o  Tunnel

   Note that we have borrowed the term tunnel from RSVP-TE (RFC 3209)
   [2] where it is used to describe an entity that provides an LSP a connection
   between a source and destination LSR which LSR.  The tunnel in turn is
   instantiated by one or more LSPs, where the additional LSPs are used
   for protection or re-grooming of the tunnel.

3.  Uniquely Identifying an Operator

   Two forms of identification are defined, one that is compatible with
   IP operational practice called a Global_ID and one compatible with
   ITU practice, the ICC.  An Operator MAY be identified either by its
   Global_ID or by its ICC.

3.1.  The Global ID

   RFC 5003 [3] defines a globally unique Attachment Interface
   Identifier (AII).  That AII is composed of three parts, a Global ID Global_ID
   which uniquely identifies a operator, a prefix, and finally and
   attachment circuit identifier.  We have chosen to use that Global ID
   for MPLS-TP.  Quoting from RFC 5003, section 3.2, "The global ID can
   contain the 2-octet or 4-octet value of the operator's Autonomous
   System Number (ASN).  It is expected that the global ID will be
   derived from the globally unique ASN of the autonomous system hosting
   the PEs containing the actual AIIs.  The presence of a global ID
   based on the operator's ASN ensures that the AII will be globally

   When the Global_ID is derived from a 2-octet AS number, the two high-
   order octets of this 4-octet identifier MUST be set to zero.

   Note that this Global_ID is used solely to provide a globally unique
   context for other MPLS-TP identifiers.  It has nothing to do with the
   use of the ASN in protocols such as BGP.

3.2.  ITU Carrier Code

   M.1400 defines the ITU Carrier Code (ICC) assigned to a network
   operator/service provider and maintained by the ITU-T
   Telecommunication Standardization Bureau (TSB):

   ICCs can be assigned both to ITU-T and non-ITU-T members and the
   referenced local ICC website may contain ICCs of operators of both

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

4.  Node and Interface Identifiers

   An LSR requires identification of the node itself and of its
   interfaces.  An interface is the Access Point (AP) to a server layer
   MPLS-TP section or MPLS-TP tunnel.

   We call the identifier associated with a node a Node Identifier
   (Node_ID).  Within  The Node_ID is a unique 32-bit unsigned integer assigned
   by the context operator within the scope of a particular node, we
   call the identifier associated with an interface an Logical Interface
   Handle or LIH. Global_ID.  The combination of Node_ID::LIH we call value 0 (or in dotted decimal notation) is reserved MUST NOT be used.
   The Node_ID is not an Network
   Interface ID or IF_ID. IPv4 address.  However, it was chosen to be 32-
   bits to allow compatibility with existing MPLS deployments.  In
   existing MPLS deployments Node_IDs LSRs are IPv4 addresses.  Therefore
   we have chosen the Node_ID to be a 32-bit value assigned generally identified by the
   operator. an IPv4
   loopback address.  Where IPv4 addresses are in use the Node_ID can MAY be
   automatically mapped to the LSR's /32 IPv4 loopback address.  Note
   that, when IP reachability is not needed, the 32-bit Node_ID is not
   required to have any association with the IPv4 address space used in
   the operator's IGP or BGP, other that that they be uniquely chosen
   within the scope of that operator.

   GMPLS signaling [4] requires interface identification.  We have
   chosen BGP.

   In situations where a Node_ID needs to adopt the conventions of that RFC.  GMPLS allows three
   formats for the Interface_ID.  For IP numbered links, it be globally unique, this is simply
   accomplished by prefixing the IPv4 or IPv6 address associated identifier with the interface. operator's
   Global_ID.  The third
   format consists combination of an IPv4 Address plus a 32-bit unsigned integer for
   the specific interface.

   For MPLS-TP, we have adopted a format consistent with the third
   format above.  In MPLS-TP, each interface is assigned a 32-bit
   identifier which Global_ID::Node_ID we call a Logical Interface Handle (LIH).  The LIH
   MUST be unique within an Global
   Node ID or Global_Node_ID.

   Within the context of the Node_ID.  We map the Node_ID
   to the field the field which carries the IP address.  That is, an
   IF_ID is a 64-bit identifier consisting of the Node_ID followed by particular node, we call the LIH. identifier
   associated with an interface an Interface Number or IF_Num. The LIH in turn
   IF_Num is a 32-bit unsigned integer assigned by the operator and MUST
   be unique to within the
   node. scope of a Node_ID.  The LIH IF_Num value 0 has
   special meaning (see section Section 7.3 and must not be used as the LIH
   IF_Num in an MPLS-TP IF_ID.

   In situations where

   An Interface Identifier or IF_ID identifies an interface uniquely
   within the context of a Global_ID.  It is formed by concatenating the
   Node_ID or with the IF_Num. That is an IF_ID is a 64-bit identifier
   formed as Node_ID::IF_Num.

   This convention was chosen to allow compatibility with GMPLS.  GMPLS
   signaling [4] requires interface identification.  GMPLS allows three
   formats for the Interface_ID.  The third format consists of an IPv4
   Address plus a 32-bit unsigned integer for the specific interface.
   The format defined for MPLS-TP is consistent with this format, but
   uses the Node_ID instead of an IPv4 Address.

   An IF_ID needs to be globally unique, this is accomplished by
   prefixing the identifier with the operator's Global_ID.  The
   combination of Global_ID::Node_ID we call
   an Global Node ID or Global_Node_ID.  Likewise, the combination of
   Global_ID::Node_ID::LIH Global_ID::Node_ID::IF_Num we call an Global Interface
   ID or Global_IF_ID.

   The attachment point to an MPLS-TP Tunnels Tunnel (see section Section 5.1) 5.1
   also need needs an interface
   identifiers. identifier.  A procedure for automatically
   generating these is contained in that section.

5.  MPLS-TP Tunnel and LSP Identifiers

   A important construct within MPLS_TP is a connection which is
   provided across a working and a protection LSP.  Within this document
   we will use the term MPLS-TP Tunnel or simply tunnel for the
   connection provided by the working and protect LSPs.  This section
   defines an MPLS-TP Tunnel_ID to uniquely identify a tunnel and
   MPLS-TP LSP_IDs within the context of a tunnel.

5.1.  MPLS-TP Point to Point Tunnel Identifiers

   At each endpoint a tunnel is uniquely identified by the Source endpoint's
   Node_ID and a locally assigned tunnel number.  Specifically a
   Tunnel_Num is a 16-bit unsigned integer unique to within the context of
   the node.  The motivation for each endpoint having its own tunnel
   number is to allow a compact form for the MEP-ID.  See section

   Having two tunnel-ids also serves to simplify other signaling.  For
   instance an associated bi-directional tunnel could be setup using two
   unidirectional tunnels signaled via RSVP.

   The concatenation of the two endpoint identifier servers as the full
   identifier.  Thus  In a signaled situation, the node originating the
   signaling exchange is called the source and the target node is called
   the destination.  In a configured environment the endpoints could
   equally be called East and West.  Using the signaled convention and
   abbreviating the endpoint qualifiers to Src and Dst respectively, the
   format of the format of a Tunnel_ID is:


   Where the Tunnel_ID needs to be globally unique, this is accomplished
   by using globally unique Node_IDs as defined above.  Thus a globally
   unique Tunnel_ID becomes:

      Src-Global_ID::Src-Node_ID::Src-Tunnel_Num:: Dst-Global_ID::Dst-


   When an MPLS-TP Tunnel is configured, it MUST be assigned a unique
   IF_ID at both the source and destination endpoints.  As usual, the
   IF_ID is composed of the local NODE_ID concatenated with a 32-bit
   IF_Num. It is RECOMMENDED that the LIH IF_Num be auto-generated by adding
   2^31 to the local Tunnel_Num.

5.2.  MPLS-TP LSP Identifiers

   Within the scope of an MPLS-TP Tunnel_ID an LSP can be uniquely
   identified by a single LSP number.  Specifically an LSP_Num is a 16-
   bit unsigned integer unique within the Tunnel_ID.  Thus the format of
   a Tunnel_ID LSP_ID is:

      Src-Node_ID::Src-Tunnel_Num::Dst-Node_ID::Dst-Tunnel_Num:: LSP_Num


   Where the LSP_ID needs to be globally unique, this is accomplished by
   using globally unique Node_IDs as defined above.  Thus a globally
   unique Tunnel_ID becomes:

      Src-Global_ID::Src-Node_ID::Src-Tunnel_Num:: Dst-Global_ID::Dst-


5.3.  Mapping to GMPLS Signalling

   This section defines the mapping from an MPLS-TP LSP_ID to GMPLS.  At
   this time, GMPLS has yet to be extended to accommodate Global_IDs.
   Thus a mapping is only made for the network unique form of the

   GMPLS signaling [5] uses a 5-tuple to uniquely identify an LSP within
   a operator's network.  This tuple is composed of a Tunnel Endpoint
   Address, Tunnel_ID, Extended Tunnel ID, and Tunnel Sender Address and

   In situations where a mapping to the GMPLS 5-tuple is required, the
   following mapping is used.

   o  Tunnel Endpoint Address = Dst-Node_ID

   o  Tunnel_ID = Src-Tunnel_Num
   o  Extended Tunnel_ID = Src-Node_ID

   o  Tunnel Sender Address = Src-Node_ID

   o  LSP_ID = LSP_Num

6.  Pseudowire Path Identifiers

   Pseudowire signaling (RFC 4447 [6]) defines two FECs used to signal
   pseudowires.  Of these, FEC Type 129 along with AII Type 2 as defined
   in RFC 5003 [3] fits the identification requirements of MPLS-TP.

   In an MPLS-TP environment, a PW is identified by a set of identifiers
   which can be mapped directly to the elements required by FEC 129 and
   AII Type 2.  To distinguish this identifier from other Pseudowire
   Identifiers, we call this a Pseudowire Path Identifier or PW_Path_Id.

   The AII Type 2 is composed of three fields.  These are the Global_ID,
   the Prefix, and the AC_ID.  The Global_ID used in this document is
   identical to the Global_ID defined in RFC 5003.  The Node_ID is used
   as the Prefix.  The AC_ID is as defined in RFC 5003.

   To complete the FEC 129, all that is required is a Attachment Group
   Identifier (AGI).  That field is exactly as specified in RFC 4447.
   FEC 129 has a notion of Source AII (SAII) and Target AII (TAII).
   These terms are used relative to the direction of the signaling.  In
   a purely configured environment when referring to the entire PW, this
   distinction is not critical.  That is a FEC 129 of AGIa::AIIb::AIIc
   is equivalent to AGIa::AIIc::AIIb.  We note that in a signaled
   environment, the required convention in RFC 4447 is that at a
   particular endpoint, the AII associated with that endpoint comes
   first.  The complete PW_Path_Id is:

      AGI:Src-Global_ID::Src-Node_ID::Src-AC_ID:: Dst-Global_ID::Dst-


7.  Maintenance Identifiers

   [Note this section needs to reconciled with the MPLS-TP OAM

   In MPLS-TP a Maintenance Entity Group (MEG) represents an Entity that
   requires management and defines a relationship between a set of
   maintenance points.  A maintenance point is either Maintenance Entity
   Group End-point (MEP) or a Maintenance Entity Group Intermediate
   Point (MIP).  Maintenance points are uniquely associated with a MEG.
   Within the context of a MEG, MEPs and MIPs must be uniquely
   identified.  This section defines a means of uniquely identifying
   Maintenance Entity Groups, Maintenance Entities and uniquely defining
   MEPs and MIPs within the context of a Maintenance Entity Group.

   Note that depending on the requirements of a particular OAM
   interaction, the MPLS-TP maintenance entity context may be provided
   either explicitly using the MEG_IDs described above or implicitly by
   the label of the received OAM message.

7.1.  Maintenance Entity Group Identifiers

   Maintenance Entity Group Identifiers (MEG_IDs) are required for
   MPLS-TP Paths LSPs and Pseudowires.  Two classes of MEG_IDs are defined,
   one that follows the IP compatible identifier defined above as well
   as the ICC-format.

7.1.1.  ICC based MEG_IDs

   MEG_ID for MPLS-TP LSPs and Pseudowires MAY use the globally unique
   ICC-based format.

   In this case, the MEG_ID is a string of up to thirteen characters,
   each character being either alphabetic (i.e.  A-Z) or numeric (i.e.
   0-9) characters.  It consists of two subfields: the ICC (as defined
   in section 3) followed by a unique MEG code (UMC).  The UMC MUST be
   unique within the organization identified by the ICC.

   The ICC MEG_ID may be applied equally to MPLS-TP tunnels, a single
   MPLS-TP LSP, groups of single MPLS-TP LSPs, Pseudowires, and groups of LSP or
   Pseudowires.  Note that when encoded in a protocol such as in a TLV,
   a different type needs to be defined for LSP and PWs as the OAM
   capabilities may be different.

7.1.2.  IP Compatible MEG_IDs  MPLS-TP Tunnel LSP MEG_IDs

   Since a MEG pertains to a single MPLS-TP Tunnel, LSP, IP compatible MEG_IDs
   for MPLS-TP Tunnels LSPs are simply the corresponding Tunnel_IDs. LSP_IDs.  We note that
   while the two identifiers are syntactically identical, they have
   different semantics.  This semantic difference needs to be made
   clear.  For instance if both a MPLS-TP Tunnel_ID LSP_ID and MPLS-TP
   Tunnel LSP MEG_IDs
   are to be encoded in TLVs different types need to be assigned for
   these two identifiers.  MPLS-TP LSP MEG_IDs

   MEG_IDs for MPLS-TP LSPs may pertain to one or more LSPs.  Therefore
   the direct mapping used for tunnels is not possible.  However an
   indirect mapping which keeps the formats aligned is possible.  This
   is done by replacing the LSP_Num with a LSP_MEG_Num. Thus the format
   of a MPLS-TP LSP MEG_ID is:

      Src-Global_ID::Src-Node_ID::Src-Tunnel_Num:: Dst-Global_ID::Dst-

   When a MEG_ID is assigned to a single MPLS-TP LSP it is RECOMMENDED
   that the LSP_MEG_Num be assigned equal to the LSP_Num. When a MEG_ID
   is assigned to a group of MPLS-TP LSPs within a single MPLS-TP
   Tunnel, it is recommended that the MEG_ID be assigned equal to the
   LSP_Num of one member of the group of MPLS-TP LSPs.  In this
   situation if the chosen LSP is later deconfigured it is RECOMMENDED
   that this LSP_Num not be reused unless the new LSP in question will
   become a member of the same MEG.  Pseudowire MEG_IDs

   For Pseudowires a MEG pertains to a single PW.  The IP compatible
   MEG_ID for a PW is simply the corresponding PW_Path_ID.  We note that
   while the two identifiers are syntactically identical, they have
   different semantics.  This semantic difference needs to be made
   clear.  For instance if both a PW_Path_ID and a PW_MEG_ID is to be
   encoded in TLVs different types need to be assigned for these two

7.2.  MEP_IDs

7.2.1.  ICC based MEP_IDs

   ICC-based MEP_IDs for MPLS-TP LSPs and Pseudowires MAY be are formed by
   appending a unique number to the MEG_ID defined in section
   Section 7.1.1 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 and assigned.  It is encoded as a 16-bit
   unsigned integer. integer and MUST be unique within the MEG.  An ICC-based
   MEP_ID is:


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

7.2.2.  IP based MEP_IDs  MEP_IDs for  MPLS-TP LSPs and Tunnels LSP_MEP_ID

   In order to automatically generate MEP_IDs for MPLS-TP Tunnels and LSPs, we use
   the elements of identification that are unique to an endpoint.  This
   ensures that MEP_IDs are unique for all Tunnels and LSPs within a operator.  When
   Tunnels or LSPs cross operator boundaries, these are made unique by
   pre-pending them with the operator's Global_ID.  MPLS-TP Tunnel_MEP_ID


   The MPLS-TP Tunnel_MEP_ID is:


   In situations LSP_MEP_ID is


   where global uniqueness the Node_ID is required this becomes:

      Src-Global_ID::Src-Node_ID::Src-Tunnel_Num  MPLS-TP LSP_MEP_ID


      Src-Node_ID::Src-Tunnel_Num::LSP_Num the node in which the MEP is located and
   Tunnel_Num is the tunnel number unique to that node.

   In situations where global uniqueness is required this becomes:

      Src-Global_ID::Src-Node_ID::Src-Tunnel_Num::LSP_Num  MEP_IDs for Pseudowires

   Like MPLS-TP LSPs, Pseudowire endpoints (T-PEs) require MEP_IDs.  In
   order to automatically generate MEP_IDs for PWs, we simply use the
   AGI plus the AII associated with that end of the PW.  Thus a MEP_ID
   used in end-to-end for an Pseudowire T-PE takes the form:

      AGI:Src-Global_ID::Src-Node_ID::Src-AC_ID form

   where the Node_ID is the node in which the MEP is located and
   Tunnel_Num is the tunnel number unique to that node.  MEP_IDs  Endpoint IDs for Pseudowire Segments

   In some OAM communications, messages are originated by the node at
   one end of a PW segment and relayed to the other end by setting the
   TTL of the PW label to one.

   The MEP_ID Is Formed by a combination of a PW MEP_ID and the
   identification of the local node.  At an S-PE, there are two PW
   segments.  We distinguish the segments by using the MEP_ID which is
   upstream of the PW segment in question.  To complete the
   identification we suffix this with the identification of the local

      +-------+         +-------+         +-------+         +-------+
      |       |         |       |         |       |         |       |
      |      A|---------|B     C|---------|D     E|---------|F      |
      |       |         |       |         |       |         |       |
      +-------+         +-------+         +-------+         +-------+
        T-PE1             S-PE2             S-PE3             T-PE4

                       Pseudowire Maintenance Points

   For example, suppose that in the above figure all of the nodes have
   Global_ID GID1; the node are represented as named in the figure; and
   The identification for the Pseudowire is:

           AGI           = AGI1
           Src-Global_ID = GID1
           Src-Node_ID   = T-PE1
           Src-AC_ID     = AII1
           Dst-Global_ID = GID1
           Dst-Node_ID   = T-PE1
           Dst-AC_ID     = AII4

   The MEP_ID PW segment endpoint at point A would be AGI1::GID1:T-PE1::AII1.
   The MP_ID at point C would be AGI1::GID1:T-PE1::AII1::GID1:S-PE2.

   For interaction where the T-PE is acting as the segment endpoint, it
   too may use the Pseudowire Segment MEP_ID.

7.3.  MIP_IDs

   At a cross connect point, in order to automatically generate MIP_IDs
   for MPLS-TP, we simply use the IF_IDs of the two interfaces which are
   cross connected via the label bindings of the MPLS-TP LSP.  If only
   one MIP is configured, then the MIP_ID is formed using the Node_ID
   and an LIH IF_Num of 0.  In some contexts, such as LSP Ping[13], the
   Node_ID alone may be used as the MEP_ID. MIP_ID.

8.  Open issues

   1.  MEPs and MIPs need to be aligned with MPLS-TP OAM Framework.

   2.  Identifiers for P2MP entities.  IANA Considerations

9.  Security Considerations

10.  References


10.1.  Normative References

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

   [2]   Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and
         G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels",
         RFC 3209, December 2001.

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

   [4]   Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS)
         Signaling Functional Description", RFC 3471, January 2003.

   [5]   Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS)
         Signaling Resource ReserVation Protocol-Traffic Engineering
         (RSVP-TE) Extensions", RFC 3473, January 2003.

   [6]   Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G. Heron,
         "Pseudowire Setup and Maintenance Using the Label Distribution
         Protocol (LDP)", RFC 4447, April 2006.

   [7]   Kompella, K., Rekhter, Y., and A. Kullberg, "Signalling
         Unnumbered Links in CR-LDP (Constraint-Routing Label
         Distribution Protocol)", RFC 3480, February 2003.

   [8]   Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling in
         MPLS Traffic Engineering (TE)", RFC 4201, October 2005.

   [9]   Lang, J., Rekhter, Y., and D. Papadimitriou, "RSVP-TE
         Extensions in Support of End-to-End Generalized Multi-Protocol
         Label Switching (GMPLS) Recovery", RFC 4872, May 2007.

   [10]  Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow, "BFD
         For MPLS LSPs", draft-ietf-bfd-mpls-07 (work in progress),
         June 2008.

   [11]  Nadeau, T. and C. Pignataro, "Bidirectional Forwarding
         Detection (BFD) for the Pseudowire Virtual Circuit Connectivity
         Verification (VCCV)", draft-ietf-pwe3-vccv-bfd-07 (work in
         progress), July 2009.


10.2.  Informative References

   [12]  Vigoureux, M. and D. Ward, "Requirements for OAM in MPLS
         Transport Networks", draft-ietf-mpls-tp-oam-requirements-06
         (work in progress), March 2010.

   [13]  Kompella, K. and G. Swallow, "Detecting Multi-Protocol Label
         Switched (MPLS) Data Plane Failures", RFC 4379, February 2006.

   [14]  Ohta, H., "Assignment of the 'OAM Alert Label' for
         Multiprotocol Label Switching Architecture (MPLS) Operation and
         Maintenance (OAM) Functions", RFC 3429, November 2002.

   [15]  Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., and
         S. Ueno, "MPLS-TP Requirements",
         draft-ietf-mpls-tp-requirements-10 (work in progress),
         August 2009.

   [16]  Bocci, M., Bryant, S., Frost, D., Levrau, L., and L. Berger, "A
         Framework for MPLS in Transport Networks",
         draft-ietf-mpls-tp-framework-12 (work in progress),
         February May 2010.

Authors' Addresses

   Matthew Bocci
   Voyager Place, Shoppenhangers Road
   Maidenhead, Berks  SL6 2PJ


   George Swallow