draft-ietf-mpls-tp-identifiers-07.txt		rfc6370.txt
	MPLS Working Group M. Bocci		Internet Engineering Task Force (IETF) M. Bocci
	Internet-Draft Alcatel-Lucent		Request for Comments: 6370 Alcatel-Lucent
	Intended status: Standards Track G. Swallow		Category: Standards Track G. Swallow
	Expires: January 22, 2012 Cisco		ISSN: 2070-1721 Cisco
	E. Gray		E. Gray
	Ericsson		Ericsson
	July 21, 2011		September 2011
	MPLS-TP Identifiers		MPLS Transport Profile (MPLS-TP) Identifiers
	draft-ietf-mpls-tp-identifiers-07
	Abstract		Abstract
	This document specifies an initial set of identifiers to be used in		This document specifies an initial set of identifiers to be used in
	the Transport Profile of Multiprotocol Label Switching (MPLS-TP).		the Transport Profile of Multiprotocol Label Switching (MPLS-TP).
	The MPLS-TP requirements (RFC 5654) require that the elements and		The MPLS-TP requirements (RFC 5654) require that the elements and
	objects in an MPLS-TP environment are able to be configured and		objects in an MPLS-TP environment are able to be configured and
	managed without a control plane. In such an environment many		managed without a control plane. In such an environment, many
	conventions for defining identifiers are possible. This document		conventions for defining identifiers are possible. This document
	defines identifiers for MPLS-TP management and OAM functions		defines identifiers for MPLS-TP management and Operations,
	compatible with IP/MPLS conventions.		Administration, and Maintenance (OAM) functions compatible with IP/
			MPLS conventions.
	This document is a product of a joint Internet Engineering Task Force		This document is a product of a joint Internet Engineering Task Force
	(IETF) / International Telecommunication Union Telecommunication		(IETF) / International Telecommunication Union Telecommunication
	Standardization Sector (ITU-T) effort to include an MPLS Transport		Standardization Sector (ITU-T) effort to include an MPLS Transport
	Profile within the IETF MPLS and Pseudowire Emulation Edge-to-Edge		Profile within the IETF MPLS and Pseudowire Emulation Edge-to-Edge
	(PWE3) architectures to support the capabilities and functionalities		(PWE3) architectures to support the capabilities and functionalities
	of a packet transport network as defined by the ITU-T.		of a packet transport network as defined by the ITU-T.
	Status of this Memo		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		This is an Internet Standards Track document.
	Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		This document is a product of the Internet Engineering Task Force
	and may be updated, replaced, or obsoleted by other documents at any		(IETF). It represents the consensus of the IETF community. It has
	time. It is inappropriate to use Internet-Drafts as reference		received public review and has been approved for publication by the
	material or to cite them other than as "work in progress."		Internet Engineering Steering Group (IESG). Further information on
			Internet Standards is available in Section 2 of RFC 5741.
	This Internet-Draft will expire on January 22, 2012.		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/rfc6370.
	Copyright Notice		Copyright Notice
	Copyright (c) 2011 IETF Trust and the persons identified as the		Copyright (c) 2011 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	skipping to change at page 2, line 19		skipping to change at page 2, line 22
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction ....................................................3
	1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3		1.1. Terminology ................................................3
	1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4		1.2. Requirements Language ......................................4
	1.3. Notational Conventions . . . . . . . . . . . . . . . . . . 4		1.3. Notational Conventions .....................................4
	2. Named Entities . . . . . . . . . . . . . . . . . . . . . . . . 5		2. Named Entities ..................................................5
	3. Uniquely Identifying an Operator - the Global_ID . . . . . . . 5		3. Uniquely Identifying an Operator - the Global_ID ................5
	4. Node and Interface Identifiers . . . . . . . . . . . . . . . . 6		4. Node and Interface Identifiers ..................................6
	5. MPLS-TP Tunnel and LSP Identifiers . . . . . . . . . . . . . . 7		5. MPLS-TP Tunnel and LSP Identifiers ..............................7
	5.1. MPLS-TP Point to Point Tunnel Identifiers . . . . . . . . 8		5.1. MPLS-TP Point-to-Point Tunnel Identifiers ..................8
	5.2. MPLS-TP LSP Identifiers . . . . . . . . . . . . . . . . . 8		5.2. MPLS-TP LSP Identifiers ....................................9
	5.2.1. MPLS-TP Co-Routed Bidirectional LSP Identifiers . . . 9		5.2.1. MPLS-TP Co-Routed Bidirectional LSP Identifiers .....9
	5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers . . . 9		5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers ....9
	5.3. Mapping to RSVP Signaling . . . . . . . . . . . . . . . . 10		5.3. Mapping to RSVP Signaling .................................10
	6. Pseudowire Path Identifiers . . . . . . . . . . . . . . . . . 11		6. Pseudowire Path Identifiers ....................................11
	7. Maintenance Identifiers . . . . . . . . . . . . . . . . . . . 12		7. Maintenance Identifiers ........................................13
	7.1. Maintenance Entity Group Identifiers . . . . . . . . . . . 13		7.1. Maintenance Entity Group Identifiers ......................13
	7.1.1. MPLS-TP Section MEG_IDs . . . . . . . . . . . . . . . 13		7.1.1. MPLS-TP Section MEG_IDs ............................13
	7.1.2. MPLS-TP LSP MEG_IDs . . . . . . . . . . . . . . . . . 13		7.1.2. MPLS-TP LSP MEG_IDs ................................13
	7.1.3. Pseudowire MEG_IDs . . . . . . . . . . . . . . . . . . 13		7.1.3. Pseudowire MEG_IDs .................................14
	7.2. Maintenance Entity Group End Point Identifiers . . . . . . 14		7.2. Maintenance Entity Group End Point Identifiers ............14
	7.2.1. MPLS-TP Section MEP_IDs . . . . . . . . . . . . . . . 14		7.2.1. MPLS-TP Section MEP_IDs ............................14
	7.2.2. MPLS-TP LSP_MEP_ID . . . . . . . . . . . . . . . . . . 14		7.2.2. MPLS-TP LSP_MEP_ID .................................15
	7.2.3. MEP_IDs for Pseudowires . . . . . . . . . . . . . . . 15		7.2.3. MEP_IDs for Pseudowires ............................15
	7.3. Maintenance Entity Group Intermediate Point Identifiers . 15		7.3. Maintenance Entity Group Intermediate Point Identifiers ...15
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15		8. Security Considerations ........................................15
	9. Security Considerations . . . . . . . . . . . . . . . . . . . 15		9. References .....................................................16
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16		9.1. Normative References ......................................16
	10.1. Normative References . . . . . . . . . . . . . . . . . . . 16		9.2. Informative References ....................................17
	10.2. Informative References . . . . . . . . . . . . . . . . . . 16
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
	1. Introduction		1. Introduction
	This document specifies an initial set of identifiers to be used in		This document specifies an initial set of identifiers to be used in
	the Transport Profile of Multiprotocol Label Switching (MPLS-TP).		the Transport Profile of Multiprotocol Label Switching (MPLS-TP).
	The MPLS-TP requirements (RFC 5654) [7] require that the elements and		The MPLS-TP requirements (RFC 5654 [7]) require that the elements and
	objects in an MPLS-TP environment are able to be configured and		objects in an MPLS-TP environment are able to be configured and
	managed without a control plane. In such an environment many		managed without a control plane. In such an environment, many
	conventions for defining identifiers are possible. This document		conventions for defining identifiers are possible. This document
	defines identifiers for MPLS-TP management and OAM functions		defines identifiers for MPLS-TP management and OAM functions
	compatible with IP/MPLS conventions. That is, the identifiers have		compatible with IP/MPLS conventions. That is, the identifiers have
	been chosen to be compatible with existing IP, MPLS, GMPLS, and		been chosen to be compatible with existing IP, MPLS, GMPLS, and
	Pseudowire definitions.		Pseudowire definitions.
	This document is a product of a joint Internet Engineering Task Force		This document is a product of a joint Internet Engineering Task Force
	(IETF) / International Telecommunication Union Telecommunication		(IETF) / International Telecommunication Union Telecommunication
	Standardization Sector (ITU-T) effort to include an MPLS Transport		Standardization Sector (ITU-T) effort to include an MPLS Transport
	Profile within the IETF MPLS and Pseudowire Emulation Edge-to-Edge		Profile within the IETF MPLS and Pseudowire Emulation Edge-to-Edge
	(PWE3) architectures to support the capabilities and functionalities		(PWE3) architectures to support the capabilities and functionalities
	of a packet transport network as defined by the ITU-T.		of a packet transport network as defined by the ITU-T.
	1.1. Terminology		1.1. Terminology
			AGI: Attachment Group Identifier
	AII: Attachment Interface Identifier		AII: Attachment Interface Identifier
			AS: Autonomous System
	ASN: Autonomous System Number		ASN: Autonomous System Number
	EGP: Exterior Gateway Protocol		EGP: Exterior Gateway Protocol
	FEC: Forwarding Equivalence Class		FEC: Forwarding Equivalence Class
	GMPLS: Generalized Multi-Protocol Label Switching		GMPLS: Generalized Multiprotocol Label Switching
	IGP: Interior Gateway Protocol		IGP: Interior Gateway Protocol
	LSP: Label Switched Path		LSP: Label Switched Path
	LSR: Label Switching Router		LSR: Label Switching Router
	MEG: Maintenance Entity Group		MEG: Maintenance Entity Group
	MEP: Maintenance Entity Group End Point		MEP: Maintenance Entity Group End Point
	MIP: Maintenance Entity Group Intermediate Point		MIP: Maintenance Entity Group Intermediate Point
			MPLS: Multiprotocol Label Switching
	MPLS: Multi-Protocol Label Switching
	NNI: Network-to-Network Interface		NNI: Network-to-Network Interface
	OAM: Operations, Administration and Maintenance
	P2P: Point to Point		OAM: Operations, Administration, and Maintenance
	PW: Pseudowire		PW: Pseudowire
	RSVP: Resource Reservation Protocol		RSVP: Resource Reservation Protocol
	RSVP-TE: RSVP Traffic Engineering		RSVP-TE: RSVP Traffic Engineering
	SPME: Sub Path Maintenance Entities		SAII: Source AII
	S-PE: Switching Provider Edge		SPME: Sub-Path Maintenance Entity
	T-PE: Terminating Provider Edge		T-PE: Terminating Provider Edge
			TAII: Target AII
	1.2. Requirements Language		1.2. Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [1].		document are to be interpreted as described in RFC 2119 [1].
	1.3. Notational Conventions		1.3. Notational Conventions
	All multiple-word atomic identifiers use underscores (_) between the		All multiple-word atomic identifiers use underscores (_) between the
	words to join the words. Many of the identifiers are composed of a		words to join the words. Many of the identifiers are composed of a
	set of other identifiers. These are expressed by listing the latter		set of other identifiers. These are expressed by listing the latter
	identifiers joined with double-colon, "::", notation.		identifiers joined with double-colon "::" notation.
	Where the same identifier type is used multiple times in a		Where the same identifier type is used multiple times in a
	concatenation, they are qualified by a prefix joined to the		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		identifier by a dash (-). For example, A1-Node_ID is the Node_ID of
	node referred to as A1.		a node referred to as A1.
	The notation defines a preferred ordering of the fields.		The notation defines a preferred ordering of the fields.
	Specifically the designation A1 is used to indicate the lower sort		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		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		higher sort order of the same. The sort is either alphanumeric or
	numeric depending on the field's definition. Where the sort applies		numeric depending on the field's definition. Where the sort applies
	to a group of fields, those fields are grouped with {...}.		to a group of fields, those fields are grouped with {...}.
	Note, however, that the uniqueness of an identifier does not depend		Note, however, that the uniqueness of an identifier does not depend
	on the ordering, but rather, upon the uniqueness and scoping of the		on the ordering, but rather, upon the uniqueness and scoping of the
	fields that compose the identifier. Further the preferred ordering		fields that compose the identifier. Further, the preferred ordering
	is not intended to constrain protocol designs by dictating a		is not intended to constrain protocol designs by dictating a
	particular field sequence (for example see Section 5.2.1) or even		particular field sequence (for example, see Section 5.2.1) or even
	what fields appear in which objects (for example see Section 5.3).		what fields appear in which objects (for example, see Section 5.3).
	2. Named Entities		2. Named Entities
	In order to configure, operate and manage a transport network based		In order to configure, operate, and manage a transport network based
	on the MPLS Transport Profile, a number of entities require		on the MPLS Transport Profile, a number of entities require
	identification. Identifiers for the following entities are defined		identification. Identifiers for the following entities are defined
	in this document:		in this document:
	* Global_ID		* Global_ID
	* Node		* Node
	* Interface		* Interface
	skipping to change at page 5, line 30		skipping to change at page 5, line 33
	* LSP		* LSP
	* PW		* PW
	* MEG		* MEG
	* MEP		* MEP
	* MIP		* MIP
	Note that we have borrowed the term tunnel from RSVP-TE (RFC 3209)		Note that we have borrowed the term "tunnel" from RSVP-TE (RFC 3209
	[2] where it is used to describe an entity that provides a logical		[2]) where it is used to describe an entity that provides a logical
	association between a source and destination LSR. The tunnel in turn		association between a source and destination LSR. The tunnel, in
	is instantiated by one or more LSPs, where the additional LSPs are		turn, is instantiated by one or more LSPs, where the additional LSPs
	used for protection or re-grooming of the tunnel.		are used for protection or re-grooming of the tunnel.
	3. Uniquely Identifying an Operator - the Global_ID		3. Uniquely Identifying an Operator - the Global_ID
	The Global_ID is defined to uniquely identify an operator. RFC 5003		The Global_ID is defined to uniquely identify an operator. RFC 5003
	[3] defines a globally unique Attachment Interface Identifier (AII).		[3] defines a globally unique Attachment Interface Identifier (AII).
	That AII is composed of three parts, a Global_ID which uniquely		That AII is composed of three parts: a Global_ID that uniquely
	identifies an operator, a prefix, and finally, an attachment circuit		identifies an operator, a prefix, and, finally, an attachment circuit
	identifier. We have chosen to use that Global ID for MPLS-TP.		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		Quoting from RFC 5003, Section 3.2:
	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		The global ID can contain the 2-octet or 4-octet value of the
	globally unique ASN of the autonomous system hosting the PEs		provider's Autonomous System Number (ASN). It is expected that
	containing the actual AIIs. The presence of a global ID based on the		the global ID will be derived from the globally unique ASN of the
	operator's ASN ensures that the AII will be globally unique."		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 unique.
	A Global_ID is an unsigned 32-bit value and MUST be derived from a		A Global_ID is an unsigned 32-bit value and MUST be derived from a
	4-octet AS number assigned to the operator. Note that 2-octet AS		4-octet AS number assigned to the operator. Note that 2-octet AS
	numbers have been incorporated in the 4-octet by placing the 2-octet		numbers have been incorporated in the 4-octet by placing the 2-octet
	AS number, in the low-order octets and setting the two high-order		AS number in the low-order octets and setting the two high-order
	octets to zero.		octets to zero.
	ASN 0 is reserved and cannot be assigned to an operator. An		ASN 0 is reserved and cannot be assigned to an operator. An
	identifier containing a Global_ID of zero means that no Global_ID is		identifier containing a Global_ID of zero means that no Global_ID is
	specified. Note that a Global_ID of zero is limited to entities		specified. Note that a Global_ID of zero is limited to entities
	contained within a single operator and MUST NOT be used across an		contained within a single operator and MUST NOT be used across an
	NNI.		NNI.
	The Global_ID is used solely to provide a globally unique context for		The Global_ID is used solely to provide a globally unique context for
	other MPLS-TP identifiers. While the AS Number used in the Global_ID		other MPLS-TP identifiers. While the AS number used in the Global_ID
	MUST be one which the operator is entitled to use, the use of the		MUST be one that the operator is entitled to use, the use of the
	Global_ID is not related to the use of the ASN in protocols such as		Global_ID is not related to the use of the ASN in protocols such as
	BGP.		BGP.
	4. Node and Interface Identifiers		4. Node and Interface Identifiers
	An LSR requires identification of the node itself and of its		An LSR requires identification of the node itself and of its
	interfaces. An interface is the attachment point to a server		interfaces. An interface is the attachment point to a server
	(sub-)layer, e.g., MPLS-TP section or MPLS-TP tunnel.		(sub-)layer, e.g., MPLS-TP section or MPLS-TP tunnel.
	We call the identifier associated with a node a Node Identifier		We call the identifier associated with a node a "Node Identifier"
	(Node_ID). The Node_ID is a unique 32-bit value assigned by the		(Node_ID). The Node_ID is a unique 32-bit value assigned by the
	operator within the scope of a Global_ID. The structure of the		operator within the scope of a Global_ID. The structure of the
	Node_ID is operator specific and is outside the scope of this		Node_ID is operator-specific and is outside the scope of this
	document. However, the value zero is reserved and MUST NOT be used.		document. However, the value zero is reserved and MUST NOT be used.
	Where IPv4 addresses are used, it may be convenient to use the Node's		Where IPv4 addresses are used, it may be convenient to use the Node's
	IPv4 loopback address as the Node_ID, however the Node_ID does not		IPv4 loopback address as the Node_ID; however, the Node_ID does not
	need to have any association with the IPv4 address space used in the		need to have any association with the IPv4 address space used in the
	operator's IGP or EGP. Where IPv6 addresses are used exclusively, a		operator's IGP or EGP. Where IPv6 addresses are used exclusively, a
	32-bit value unique within the scope of a Global_ID is assigned.		32-bit value unique within the scope of a Global_ID is assigned.
	An LSR can support multiple layers (e.g. hierarchical LSPs) and the		An LSR can support multiple layers (e.g., hierarchical LSPs) and the
	Node_ID belongs to the multiple layer context i.e. it is applicable		Node_ID belongs to the multiple-layer context, i.e., it is applicable
	to all LSPs or PWs that originate on, have a intermediate point on,		to all LSPs or PWs that originate on, have an intermediate point on,
	or terminate on the node.		or terminate on the node.
	In situations where a Node_ID needs to be globally unique, this is		In situations where a Node_ID needs to be globally unique, this is
	accomplished by prefixing the identifier with the operator's		accomplished by prefixing the identifier with the operator's
	Global_ID.		Global_ID.
	The term interface is used for the attachment point to an MPLS-TP		The term "interface" is used for the attachment point to an MPLS-TP
	section. Within the context of a particular node, we call the		section. Within the context of a particular node, we call the
	identifier associated with an interface an Interface Number (IF_Num).		identifier associated with an interface an "Interface Number"
	The IF_Num is a 32-bit unsigned integer assigned by the operator and		(IF_Num). The IF_Num is a 32-bit unsigned integer assigned by the
	MUST be unique within the scope of a Node_ID. The IF_Num value 0 has		operator and MUST be unique within the scope of a Node_ID. The
	special meaning (see Section 7.3, MIP Identifiers) and MUST NOT be		IF_Num value 0 has special meaning (see Section 7.3, MIP Identifiers)
	used to identify an MPLS-TP interface.		and MUST NOT be used to identify an MPLS-TP interface.
	Note that IF_Num has no relation with the ifNum object defined in RFC		Note that IF_Num has no relation with the ifNum object defined in RFC
	2863 [8]. Further, no mapping is mandated between IF_Num and ifIndex		2863 [8]. Further, no mapping is mandated between IF_Num and ifIndex
	in RFC 2863.		in RFC 2863.
	An Interface Identifier (IF_ID) identifies an interface uniquely		An "Interface Identifier" (IF_ID) identifies an interface uniquely
	within the context of a Global_ID. It is formed by concatenating the		within the context of a Global_ID. It is formed by concatenating the
	Node_ID with the IF_Num. That is, an IF_ID is a 64-bit identifier		Node_ID with the IF_Num. That is, an IF_ID is a 64-bit identifier
	formed as Node_ID::IF_Num.		formed as Node_ID::IF_Num.
	This convention was chosen to allow compatibility with GMPLS. The		This convention was chosen to allow compatibility with GMPLS. The
	GMPLS signaling functional description [4] requires interface		GMPLS signaling functional description [4] requires interface
	identification. GMPLS allows three formats for the Interface_ID.		identification. GMPLS allows three formats for the Interface_ID.
	The third format consists of an IPv4 Address plus a 32-bit unsigned		The third format consists of an IPv4 address plus a 32-bit unsigned
	integer for the specific interface. The format defined for MPLS-TP		integer for the specific interface. The format defined for MPLS-TP
	is consistent with this format, but uses the Node_ID instead of an		is consistent with this format, but uses the Node_ID instead of an
	IPv4 Address.		IPv4 address.
	If an IF_ID needs to be globally unique, this is accomplished by		If an IF_ID needs to be globally unique, this is accomplished by
	prefixing the identifier with the operator's Global_ID.		prefixing the identifier with the operator's Global_ID.
	Note that MPLS-TP supports hierarchical sections. The attachment		Note that MPLS-TP supports hierarchical sections. The attachment
	point to a MPLS-TP Section at any (sub-)layer requires a node-unique		point to an MPLS-TP section at any (sub-)layer requires a node-unique
	IF_Num.		IF_Num.
	5. MPLS-TP Tunnel and LSP Identifiers		5. MPLS-TP Tunnel and LSP Identifiers
	In MPLS the actual transport of packets is provided by label switched		In MPLS, the actual transport of packets is provided by Label
	paths (LSPs). A transport service may be composed of multiple LSPs.		Switched Paths (LSPs). A transport service may be composed of
	Further the LSPs providing a service may change over time due to		multiple LSPs. Further, the LSPs providing a service may change over
	protection and restoration events. In order to clearly identify the		time due to protection and restoration events. In order to clearly
	service we use the term "MPLS-TP Tunnel" or simply "tunnel" for a		identify the service, we use the term "MPLS-TP Tunnel" or simply
	service provided by (for example) a working LSP and protected by a		"tunnel" for a service provided by (for example) a working LSP and
	protection LSP. The Tunnel Identifier (Tunnel_ID) identifies the		protected by a protection LSP. The "Tunnel Identifier" (Tunnel_ID)
	transport service and provides a stable binding to the client in the		identifies the transport service and provides a stable binding to the
	face of changes in the data plane LSPs used to provide the service		client in the face of changes in the data-plane LSPs used to provide
	due to protection or restoration events. This section defines an		the service due to protection or restoration events. This section
	MPLS-TP Tunnel_ID to uniquely identify a tunnel, and an MPLS-TP LSP		defines an MPLS-TP Tunnel_ID to uniquely identify a tunnel, and an
	Identifier (LSP_ID) to uniquely identify an LSP associated with a		MPLS-TP LSP Identifier (LSP_ID) to uniquely identify an LSP
	tunnel.		associated with a tunnel.
	For the case where multiple LSPs (for example) are used to support a		For the case where multiple LSPs (for example) are used to support a
	single service with a common set of end-points, using the Tunnel_ID		single service with a common set of end points, using the Tunnel_ID
	allows for a trivial mapping between the server and client layers,		allows for a trivial mapping between the server and client layers,
	providing a common service identifier which may be either defined by,		providing a common service identifier that may be either defined by
	or used by, the client.		or used by the client.
	Note that this usage is not intended to constrain protection schemes,		Note that this usage is not intended to constrain protection schemes,
	and may be used to identify any service (protected or unprotected)		and may be used to identify any service (protected or unprotected)
	that may appear to the client as a single service attachment point.		that may appear to the client as a single service attachment point.
	Keeping the Tunnel_ID consistent across working and protection LSPs		Keeping the Tunnel_ID consistent across working and protection LSPs
	is a useful construct currently employed within GMPLS. However, the		is a useful construct currently employed within GMPLS. However, the
	Tunnel_ID for a protection LSP MAY differ from that used by its		Tunnel_ID for a protection LSP MAY differ from that used by its
	corresponding working LSP.		corresponding working LSP.
	5.1. MPLS-TP Point to Point Tunnel Identifiers		5.1. MPLS-TP Point-to-Point Tunnel Identifiers
	At each endpoint a tunnel is uniquely identified by the endpoint's		At each end point, a tunnel is uniquely identified by the end point's
	Node_ID and a locally assigned tunnel number. Specifically a Tunnel		Node_ID and a locally assigned tunnel number. Specifically, a
	Number (Tunnel_Num) is a 16-bit unsigned integer unique within the		"Tunnel Number" (Tunnel_Num) is a 16-bit unsigned integer unique
	context of the Node_ID. The motivation for each endpoint having its		within the context of the Node_ID. The motivation for each end point
	own tunnel number is to allow a compact form for the MEP_ID. See		having its own tunnel number is to allow a compact form for the
	Section 7.2.2.		MEP_ID. See Section 7.2.2.
	Having two tunnel numbers also serves to simplify other signaling		Having two tunnel numbers also serves to simplify other signaling
	(e.g., setup of associated bidirectional tunnels as described in		(e.g., setup of associated bidirectional tunnels as described in
	Section 5.3).		Section 5.3).
	The concatenation of the two endpoint identifiers serves as the full		The concatenation of the two end point identifiers serves as the full
	identifier. Using the A1/Z9 convention the format of a Tunnel_ID is:		identifier. Using the A1/Z9 convention, the format of a Tunnel_ID
			is:
	A1-{Node_ID::Tunnel_Num}::Z9-{Node_ID::Tunnel_Num}		A1-{Node_ID::Tunnel_Num}::Z9-{Node_ID::Tunnel_Num}
	Where the Tunnel_ID needs to be globally unique, this is accomplished		Where the Tunnel_ID needs to be globally unique, this is accomplished
	by using globally unique Node_IDs as defined above. Thus a globally		by using globally unique Node_IDs as defined above. Thus, a globally
	unique Tunnel_ID becomes:		unique Tunnel_ID becomes:
	A1-{Global_ID::Node_ID::Tunnel_Num}::Z9-{Global_ID::Node_ID::		A1-{Global_ID::Node_ID::Tunnel_Num}::Z9-{Global_ID::Node_ID::
	Tunnel_Num}		Tunnel_Num}
	When an MPLS-TP Tunnel is configured, it MUST be assigned a unique		When an MPLS-TP Tunnel is configured, it MUST be assigned a unique
	IF_ID at each endpoint. As usual, the IF_ID is composed of the local		IF_ID at each end point. As usual, the IF_ID is composed of the
	Node_ID concatenated with a 32-bit IF_Num.		local Node_ID concatenated with a 32-bit IF_Num.
	5.2. MPLS-TP LSP Identifiers		5.2. MPLS-TP LSP Identifiers
	This section defines identifiers for MPLS-TP co-routed bidirectional		This section defines identifiers for MPLS-TP co-routed bidirectional
	and associated bidirectional LSPs. Note that MPLS-TP Sub Path		and associated bidirectional LSPs. Note that MPLS-TP Sub-Path
	Maintenance Entities (SPMEs) as defined in RFC 5921 [9] are also LSPs		Maintenance Entities (SPMEs), as defined in RFC 5921 [9], are also
	and use these same forms of identifiers.		LSPs and use these same forms of identifiers.
	5.2.1. MPLS-TP Co-Routed Bidirectional LSP Identifiers		5.2.1. MPLS-TP Co-Routed Bidirectional LSP Identifiers
	A co-routed bidirectional LSP can be uniquely identified by a single		A co-routed bidirectional LSP can be uniquely identified by a single
	LSP number within the scope of an MPLS-TP Tunnel_ID. Specifically an		LSP number within the scope of an MPLS-TP Tunnel_ID. Specifically,
	LSP Number (LSP_Num) is a 16-bit unsigned integer unique within the		an LSP Number (LSP_Num) is a 16-bit unsigned integer unique within
	Tunnel_ID. Thus the format of an MPLS-TP co-routed bidirectional		the Tunnel_ID. Thus, the format of an MPLS-TP co-routed
	LSP_ID is:		bidirectional LSP_ID is:
	A1-{Node_ID::Tunnel_Num}::Z9-{Node_ID::Tunnel_Num}::LSP_Num		A1-{Node_ID::Tunnel_Num}::Z9-{Node_ID::Tunnel_Num}::LSP_Num
	Note that the uniqueness of identifiers does not depend on the A1/Z9		Note that the uniqueness of identifiers does not depend on the A1/Z9
	sort ordering. Thus the identifier		sort ordering. Thus, the identifier:
	Z9-{Node_ID::Tunnel_Num}::A1-{Node_ID::Tunnel_Num}::LSP_Num		Z9-{Node_ID::Tunnel_Num}::A1-{Node_ID::Tunnel_Num}::LSP_Num
	is synonymous with the one above.		is synonymous with the one above.
	At the dataplane level, a co-routed bidirectional LSP is composed of		At the data-plane level, a co-routed bidirectional LSP is composed of
	two unidirectional LSPs traversing the same links in opposite		two unidirectional LSPs traversing the same links in opposite
	directions. Since a co-routed bidirectional LSP is provisioned or		directions. Since a co-routed bidirectional LSP is provisioned or
	signaled as a single entity, a single LSP_Num is used for both		signaled as a single entity, a single LSP_Num is used for both
	unidirectional LSPs. The unidirectional LSPs can be referenced by		unidirectional LSPs. The unidirectional LSPs can be referenced by
	the identifiers:		the identifiers:
	A1-Node_ID::A1-Tunnel_Num::LSP_Num::Z9-Node_ID and		A1-Node_ID::A1-Tunnel_Num::LSP_Num::Z9-Node_ID and
	Z9-Node_ID::Z9-Tunnel_Num::LSP_Num::A1-Node_ID respectively.		Z9-Node_ID::Z9-Tunnel_Num::LSP_Num::A1-Node_ID, respectively.
	Where the LSP_ID needs to be globally unique, this is accomplished by		Where the LSP_ID needs to be globally unique, this is accomplished by
	using globally unique Node_IDs as defined above. Thus a globally		using globally unique Node_IDs as defined above. Thus, a globally
	unique LSP_ID becomes:		unique LSP_ID becomes:
	A1-{Global_ID::Node_ID::Tunnel_Num}::Z9-{Global_ID::		A1-{Global_ID::Node_ID::Tunnel_Num}::Z9-{Global_ID::
	Node_ID::Tunnel_Num}::LSP_Num		Node_ID::Tunnel_Num}::LSP_Num
	5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers		5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers
	For an associated bidirectional LSP each of the unidirectional LSPs		For an associated bidirectional LSP, each of the unidirectional LSPs
	from A1 to Z9 and Z9 to A1 require LSP_Nums. Each unidirectional LSP		from A1 to Z9 and Z9 to A1 require LSP_Nums. Each unidirectional LSP
	is uniquely identified by a single LSP number within the scope of the		is uniquely identified by a single LSP number within the scope of the
	ingress's Tunnel_Num. Specifically an LSP Number (LSP_Num) is a 16-		ingress's Tunnel_Num. Specifically, an "LSP Number" (LSP_Num) is a
	bit unsigned integer unique within the scope of the ingress's		16-bit unsigned integer unique within the scope of the ingress's
	Tunnel_Num. Thus the format of an MPLS-TP associated bidirectional		Tunnel_Num. Thus, the format of an MPLS-TP associated bidirectional
	LSP_ID is:		LSP_ID is:
	A1-{Node_ID::Tunnel_Num::LSP_Num}::		A1-{Node_ID::Tunnel_Num::LSP_Num}::
	Z9-{Node_ID::Tunnel_Num::LSP_Num}		Z9-{Node_ID::Tunnel_Num::LSP_Num}
	At the dataplane level, an associated bidirectional LSP is composed		At the data-plane level, an associated bidirectional LSP is composed
	of two unidirectional LSPs between two nodes in opposite directions.		of two unidirectional LSPs between two nodes in opposite directions.
	The unidirectional LSPs may be referenced by the identifiers:		The unidirectional LSPs may be referenced by the identifiers:
	A1-Node_ID::A1-Tunnel_Num::A1-LSP_Num::Z9-Node_ID and		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.		Z9-Node_ID::Z9-Tunnel_Num::Z9-LSP_Num::A1-Node_ID, respectively.
	Where the LSP_ID needs to be globally unique, this is accomplished by		Where the LSP_ID needs to be globally unique, this is accomplished by
	using globally unique Node_IDs as defined above. Thus a globally		using globally unique Node_IDs as defined above. Thus, a globally
	unique LSP_ID becomes:		unique LSP_ID becomes:
	A1-{Global_ID::Node_ID::Tunnel_Num::LSP_Num}::		A1-{Global_ID::Node_ID::Tunnel_Num::LSP_Num}::
	Z9-{Global_ID::Node_ID::Tunnel_Num::LSP_Num}		Z9-{Global_ID::Node_ID::Tunnel_Num::LSP_Num}
	5.3. Mapping to RSVP Signaling		5.3. Mapping to RSVP Signaling
	This section is informative and exists to help understand the		This section is informative and exists to help understand the
	structure of the LSP IDs.		structure of the LSP IDs.
	GMPLS [5] is based on RSVP-TE [2]. This section defines the mapping		GMPLS [5] is based on RSVP-TE [2]. This section defines the mapping
	from an MPLS-TP LSP_ID to RSVP-TE. At this time, RSVP-TE has yet to		from an MPLS-TP LSP_ID to RSVP-TE. At this time, RSVP-TE has yet to
	be extended to accommodate Global_IDs. Thus a mapping is only made		be extended to accommodate Global_IDs. Thus, a mapping is only made
	for the network unique form of the LSP_ID and assumes that the		for the network unique form of the LSP_ID and assumes that the
	operator has chosen to derive its Node_IDs from valid IPv4 addresses.		operator has chosen to derive its Node_IDs from valid IPv4 addresses.
	GMPLS and RSVP-TE signaling use a 5-tuple to uniquely identify an LSP		GMPLS and RSVP-TE signaling use a 5-tuple to uniquely identify an LSP
	within a operator's network. This tuple is composed of a Tunnel		within an operator's network. This tuple is composed of a Tunnel
	Endpoint Address, Tunnel_ID, Extended Tunnel ID, and Tunnel Sender		End-point Address, Tunnel_ID, Extended Tunnel ID, Tunnel Sender
	Address and (RSVP) LSP_ID. RFC 3209 allows some flexibility in how		Address, and (RSVP) LSP_ID. RFC 3209 allows some flexibility in how
	the Extended Tunnel ID is chosen and a direct mapping is not		the Extended Tunnel ID is chosen, and a direct mapping is not
	mandated. One convention that is often used, however, is to populate		mandated. One convention that is often used, however, is to populate
	this field with the same value as the Tunnel Sender Address. The		this field with the same value as the Tunnel Sender Address. The
	examples below follow that convention. Note that these are only		examples below follow that convention. Note that these are only
	examples.		examples.
	For a co-routed bidirectional LSP signaled from A1 to Z9, the mapping		For a co-routed bidirectional LSP signaled from A1 to Z9, the mapping
	to the GMPLS 5-tuple is as follows:		to the GMPLS 5-tuple is as follows:
	* Tunnel Endpoint Address = Z9-Node_ID		* Tunnel End-point Address = Z9-Node_ID
	* Tunnel_ID = A1-Tunnel_Num		* Tunnel_ID = A1-Tunnel_Num
	* Extended Tunnel_ID = A1-Node_ID		* Extended Tunnel_ID = A1-Node_ID
	* Tunnel Sender Address = A1-Node_ID		* Tunnel Sender Address = A1-Node_ID
	* (RSVP) LSP_ID = LSP_Num		* (RSVP) LSP_ID = LSP_Num
	An associated bidirectional LSP between two nodes A1 and Z9 consists		An associated bidirectional LSP between two nodes A1 and Z9 consists
	of two unidirectional LSPs, one from A1 to Z9 and one from Z9 to A1.		of two unidirectional LSPs, one from A1 to Z9 and one from Z9 to A1.
	In situations where a mapping to the RSVP-TE 5-tuples is required,		In situations where a mapping to the RSVP-TE 5-tuples is required,
	the following mappings are used. For the A1 to Z9 LSP the mapping		the following mappings are used. For the A1 to Z9 LSP, the mapping
	would be:		would be:
	* Tunnel Endpoint Address = Z9-Node_ID		* Tunnel End-point Address = Z9-Node_ID
	* Tunnel_ID = A1-Tunnel_Num		* Tunnel_ID = A1-Tunnel_Num
	* Extended Tunnel_ID = A1-Node_ID		* Extended Tunnel_ID = A1-Node_ID
	* Tunnel Sender Address = A1-Node_ID		* Tunnel Sender Address = A1-Node_ID
	* (RSVP) LSP_ID = A1-LSP_Num		* (RSVP) LSP_ID = A1-LSP_Num
	Likewise, the Z9 to A1 LSP, the mapping would be:		Likewise, the Z9 to A1 LSP, the mapping would be:
	* Tunnel Endpoint Address = A1-Node_ID		* Tunnel End-point Address = A1-Node_ID
	* Tunnel_ID = Z9-Tunnel_Num		* Tunnel_ID = Z9-Tunnel_Num
	* Extended Tunnel_ID = Z9-Node_ID		* Extended Tunnel_ID = Z9-Node_ID
	* Tunnel Sender Address = Z9-Node_ID		* Tunnel Sender Address = Z9-Node_ID
	* (RSVP) LSP_ID = Z9-LSP_Num		* (RSVP) LSP_ID = Z9-LSP_Num
	6. Pseudowire Path Identifiers		6. Pseudowire Path Identifiers
	Pseudowire signaling (RFC 4447 [6]) defines two FECs used to signal		Pseudowire signaling (RFC 4447 [6]) defines two FECs used to signal
	pseudowires. Of these, FEC Type 129 along with AII Type 2 as defined		pseudowires. Of these, the Generalized PWid FEC (type 129) along
	in RFC 5003 [3] fits the identification requirements of MPLS-TP.		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		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		that can be mapped directly to the elements required by the
	AII Type 2. To distinguish this identifier from other Pseudowire		Generalized PWid FEC (type 129) and AII Type 2. To distinguish this
	Identifiers, we call this a Pseudowire Path Identifier (PW_Path_ID).		identifier from other Pseudowire Identifiers, we call this a
			Pseudowire Path Identifier (PW_Path_ID).
	The AII Type 2 is composed of three fields. These are the Global_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		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		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.		as the Prefix. The AC_ID is as defined in RFC 5003.
	To complete the FEC 129, all that is required is an Attachment Group		To complete the Generalized PWid FEC (type 129), all that is required
	Identifier (AGI). That field is exactly as specified in RFC 4447. A		is an Attachment Group Identifier (AGI). That field is exactly as
	(bidirectional) pseudowire consists of a pair of unidirectional LSPs,		specified in RFC 4447. A (bidirectional) pseudowire consists of a
	one in each direction. Thus for signaling, FEC 129 has a notion of		pair of unidirectional LSPs, one in each direction. Thus, for
	Source AII (SAII) and Target AII (TAII). These terms are used		signaling, the Generalized PWid FEC (type 129) has a notion of Source
	relative to the direction of the LSP.		AII (SAII) and Target AII (TAII). These terms are used relative to
			the direction of the LSP, i.e., the SAII is assigned to the end that
			allocates the PW label for a given direction, and the TAII to the
			other end.
	In a purely configured environment when referring to the entire PW,		In a purely configured environment, when referring to the entire PW,
	this distinction is not critical. That is a FEC 129 of AGIa::AIIb::		this distinction is not critical. That is, a Generalized PWid FEC
	AIIc is equivalent to AGIa::AIIc::AIIb.		(type 129) of AGIa::AIIb::AIIc is equivalent to AGIa::AIIc::AIIb.
	We note that in a signaled environment, the required convention in		We note that in a signaled environment, the required convention in
	RFC 4447 is that at a particular endpoint, the AII associated with		RFC 4447 is that at a particular end point, the AII associated with
	that endpoint comes first. The complete PW_Path_ID is:		that end point comes first. The complete PW_Path_ID is:
	AGI::A1-{Global_ID::Node_ID::AC_ID}::		AGI::A1-{Global_ID::Node_ID::AC_ID}::
	Z9-{Global_ID::Node_ID::AC_ID}.		Z9-{Global_ID::Node_ID::AC_ID}.
	In a signaled environment the LSP from A1 to Z9 would be initiated		In a signaled environment the LSP from A1 to Z9 would be initiated
	with a label request from A1 to Z9 with the fields of the FEC 129		with a label request from A1 to Z9 with the fields of the Generalized
	completed as follows:		PWid FEC (type 129) completed as follows:
	AGI = AGI		AGI = AGI
	SAII = A1-{Global_ID::Node_ID::AC_ID}		SAII = A1-{Global_ID::Node_ID::AC_ID}
	TAII = Z9-{Global_ID::Node_ID::AC_ID}		TAII = Z9-{Global_ID::Node_ID::AC_ID}
	The LSP from Z9 to A1 would signaled with:		The LSP from Z9 to A1 would signaled with:
	AGI = AGI		AGI = AGI
	SAII = Z9-{Global_ID::Node_ID::AC_ID}		SAII = Z9-{Global_ID::Node_ID::AC_ID}
	TAII = A1-{Global_ID::Node_ID::AC_ID}		TAII = A1-{Global_ID::Node_ID::AC_ID}
	7. Maintenance Identifiers		7. Maintenance Identifiers
	In MPLS-TP a Maintenance Entity Group (MEG) represents an Entity that		In MPLS-TP, a Maintenance Entity Group (MEG) represents an entity
	requires management and defines a relationship between a set of		that requires management and defines a relationship between a set of
	maintenance points. A maintenance point is either a Maintenance		maintenance points. A maintenance point is either a Maintenance
	Entity Group End-point (MEP), a Maintenance Entity Group Intermediate		Entity Group End Point (MEP), a Maintenance Entity Group Intermediate
	Point (MIP), or a Pseudowire Segment Endpoint. Within the context of		Point (MIP), or a Pseudowire Segment End Point. Within the context
	a MEG, MEPs and MIPs must be uniquely identified. This section		of a MEG, MEPs and MIPs must be uniquely identified. This section
	defines a means of uniquely identifying Maintenance Entity Groups,		defines a means of uniquely identifying Maintenance Entity Groups and
	Maintenance Entities and uniquely defining MEPs and MIPs within the		Maintenance Entities. It also uniquely defines MEPs and MIPs within
	context of a Maintenance Entity Group.		the context of a Maintenance Entity Group.
	7.1. Maintenance Entity Group Identifiers		7.1. Maintenance Entity Group Identifiers
	Maintenance Entity Group Identifiers (MEG_IDs) are required for		Maintenance Entity Group Identifiers (MEG_IDs) are required for
	MPLS-TP sections, LSPs and Pseudowires. The formats were chosen to		MPLS-TP sections, LSPs, and Pseudowires. The formats were chosen to
	follow the IP compatible identifiers defined above.		follow the IP-compatible identifiers defined above.
	7.1.1. MPLS-TP Section MEG_IDs		7.1.1. MPLS-TP Section MEG_IDs
	MPLS-TP allows a hierarchy of sections. See "MPLS-TP Data Plane		MPLS-TP allows a hierarchy of sections. See "MPLS-TP Data Plane
	Architecture" (RFC 5960)[10]. Sections above layer 0 are MPLS-TP		Architecture" (RFC 5960 [10]). Sections above layer 0 are MPLS-TP
	LSPs. These use their MPLS-TP LSP MEG IDs defined in Section 7.1.2.		LSPs. These use their MPLS-TP LSP MEG IDs defined in Section 7.1.2.
	IP compatible MEG_IDs for MPLS-TP sections at layer 0 are formed by		IP-compatible MEG_IDs for MPLS-TP sections at layer 0 are formed by
	concatenating the two IF_IDs of the corresponding section using the		concatenating the two IF_IDs of the corresponding section using the
	A1/Z9 ordering. For example:		A1/Z9 ordering. For example:
	A1-IF_ID::Z9-IF_ID		A1-IF_ID::Z9-IF_ID
	Where the Section_MEG_ID needs to be globally unique, this is		Where the Section_MEG_ID needs to be globally unique, this is
	accomplished by using globally unique Node_IDs as defined above.		accomplished by using globally unique Node_IDs as defined above.
	Thus a globally unique Section_MEG_ID becomes:		Thus, a globally unique Section_MEG_ID becomes:
	A1-{Global_ID::IF_ID}::Z9-{Global_ID::IF_ID}		A1-{Global_ID::IF_ID}::Z9-{Global_ID::IF_ID}
	7.1.2. MPLS-TP LSP MEG_IDs		7.1.2. MPLS-TP LSP MEG_IDs
	A MEG pertains to a unique MPLS-TP LSP. IP compatible MEG_IDs for		A MEG pertains to a unique MPLS-TP LSP. IP compatible MEG_IDs for
	MPLS-TP LSPs are simply the corresponding LSP_IDs, however, the A1/Z9		MPLS-TP LSPs are simply the corresponding LSP_IDs; however, the A1/Z9
	ordering MUST be used. For bidirectional co-routed LSPs the format		ordering MUST be used. For bidirectional co-routed LSPs, the format
	of the LSP_ID is found in Section 5.2.1. For associated		of the LSP_ID is found in Section 5.2.1. For associated
	bidirectional LSPs the format is in Section 5.2.2.		bidirectional LSPs, the format is in Section 5.2.2.
	We note that while the two identifiers are syntactically identical,		We note that while the two identifiers are syntactically identical,
	they have different semantics. This semantic difference needs to be		they have different semantics. This semantic difference needs to be
	made clear. For instance if both a MPLS-TP LSP_ID and MPLS-TP LSP		made clear. For instance, if both an MPLS-TP LSP_ID and MPLS-TP LSP
	MEG_IDs are to be encoded in TLVs, different types need to be		MEG_IDs are to be encoded in TLVs, different types need to be
	assigned for these two identifiers.		assigned for these two identifiers.
	7.1.3. Pseudowire MEG_IDs		7.1.3. Pseudowire MEG_IDs
	For Pseudowires a MEG pertains to a single PW. The IP compatible		For Pseudowires, a MEG pertains to a single PW. The IP-compatible
	MEG_ID for a PW is simply the corresponding PW_Path_ID, however, the		MEG_ID for a PW is simply the corresponding PW_Path_ID; however, the
	A1/Z9 ordering MUST be used. The PW_Path_ID is described in		A1/Z9 ordering MUST be used. The PW_Path_ID is described in
	Section 6. We note that while the two identifiers are syntactically		Section 6. We note that while the two identifiers are syntactically
	identical, they have different semantics. This semantic difference		identical, they have different semantics. This semantic difference
	needs to be made clear. For instance if both a PW_Path_ID and a		needs to be made clear. For instance, if both a PW_Path_ID and a
	PW_MEG_ID are to be encoded in TLVs, different types need to be		PW_MEG_ID are to be encoded in TLVs, different types need to be
	assigned for these two identifiers.		assigned for these two identifiers.
	7.2. Maintenance Entity Group End Point Identifiers		7.2. Maintenance Entity Group End Point Identifiers
	7.2.1. MPLS-TP Section MEP_IDs		7.2.1. MPLS-TP Section MEP_IDs
	IP compatible MEP_IDs for MPLS-TP sections above layer 0 are their		IP-compatible MEP_IDs for MPLS-TP sections above layer 0 are their
	MPLS-TP LSP_MEP_IDs. See Section 7.2.2.		MPLS-TP LSP_MEP_IDs. See Section 7.2.2.
	IP compatible MEP_IDs for MPLS-TP sections at layer 0 are simply the		IP-compatible MEP_IDs for MPLS-TP sections at layer 0 are simply the
	IF_IDs of each end of the section. For example, for a section whose		IF_IDs of each end of the section. For example, for a section whose
	MEG_ID is		MEG_ID is:
	A1-IF_ID::Z9-IF_ID		A1-IF_ID::Z9-IF_ID
	the Section MEP_ID at A1 would be		the Section MEP_ID at A1 would be:
	A1-IF_ID		A1-IF_ID
	and the Section MEP_ID at Z9 would be		and the Section MEP_ID at Z9 would be:
	Z9-IF_ID.		Z9-IF_ID.
	Where the Section MEP_ID needs to be globally unique, this is		Where the Section MEP_ID needs to be globally unique, this is
	accomplished by using globally unique Node_IDs as defined above.		accomplished by using globally unique Node_IDs as defined above.
	Thus a globally unique Section MEP_ID becomes		Thus, a globally unique Section MEP_ID becomes:
	Global_ID::IF_ID.		Global_ID::IF_ID.
	7.2.2. MPLS-TP LSP_MEP_ID		7.2.2. MPLS-TP LSP_MEP_ID
	In order to automatically generate MEP_IDs for MPLS-TP LSPs, we use		In order to automatically generate MEP_IDs for MPLS-TP LSPs, we use
	the elements of identification that are unique to an endpoint. This		the elements of identification that are unique to an end point. This
	ensures that MEP_IDs are unique for all LSPs within a operator. When		ensures that MEP_IDs are unique for all LSPs within an operator.
	Tunnels or LSPs cross operator boundaries, these are made unique by		When Tunnels or LSPs cross operator boundaries, these are made unique
	pre-pending them with the operator's Global_ID.		by pre-pending them with the operator's Global_ID.
	The MPLS-TP LSP_MEP_ID is		The MPLS-TP LSP_MEP_ID is:
	Node_ID::Tunnel_Num::LSP_Num		Node_ID::Tunnel_Num::LSP_Num
	where the Node_ID is the node in which the MEP is located and		where the Node_ID is the node in which the MEP is located and
	Tunnel_Num is the tunnel number unique to that node. In the case of		Tunnel_Num is the tunnel number unique to that node. In the case of
	co-routed bidirectional LSPs, the single LSP_Num is used at both		co-routed bidirectional LSPs, the single LSP_Num is used at both
	ends. In the case of associated bidirectional LSPs, the LSP_Num is		ends. In the case of associated bidirectional LSPs, the LSP_Num is
	the one unique to where the MEP resides.		the one unique to where the MEP resides.
	In situations where global uniqueness is required this becomes:		In situations where global uniqueness is required, this becomes:
	Global_ID::Node_ID::Tunnel_Num::LSP_Num		Global_ID::Node_ID::Tunnel_Num::LSP_Num
	7.2.3. MEP_IDs for Pseudowires		7.2.3. MEP_IDs for Pseudowires
	Like MPLS-TP LSPs, Pseudowire endpoints (T-PEs) require MEP_IDs. In		Like MPLS-TP LSPs, Pseudowire end points (T-PEs) require MEP_IDs. In
	order to automatically generate MEP_IDs for PWs, we simply use the		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		AGI plus the AII associated with that end of the PW. Thus, a MEP_ID
	for a Pseudowire T-PE takes the form		for a Pseudowire T-PE takes the form:
	AGI::Global_ID::Node_ID::AC_ID		AGI::Global_ID::Node_ID::AC_ID
	where the Node_ID is the node in which the MEP is located and the		where the Node_ID is the node in which the MEP is located and the
	AC_ID is the AC_ID of the Pseudowire at that node.		AC_ID is the AC_ID of the Pseudowire at that node.
	7.3. Maintenance Entity Group Intermediate Point Identifiers		7.3. Maintenance Entity Group Intermediate Point Identifiers
	For a MIP which is associated with particular interface, we simply		For a MIP that is associated with a particular interface, we simply
	use the IF_ID (see Section 4) of the interfaces which are cross-		use the IF_ID (see Section 4) of the interfaces that are cross-
	connected. This allows, MIPs to be independently identified in one		connected. This allows MIPs to be independently identified in one
	node where a per-interface MIP model is used. If only a per node MIP		node where a per-interface MIP model is used. If only a per-node MIP
	model is used then one MIP is configured. In this case the MIP_ID is		model is used, then one MIP is configured. In this case, the MIP_ID
	formed using the Node_ID and an IF_Num of 0.		is formed using the Node_ID and an IF_Num of 0.
	8. IANA Considerations
	There are no IANA actions resulting from this document.
	9. Security Considerations		8. Security Considerations
	This document describes an information model and, as such, does not		This document describes an information model and, as such, does not
	introduce security concerns. Protocol specifications that describe		introduce security concerns. Protocol specifications that describe
	use of this information model, however, may introduce security risks		use of this information model, however, may introduce security risks
	and concerns about authentication of participants. For this reason,		and concerns about authentication of participants. For this reason,
	the writers of protocol specifications for the purpose of describing		the writers of protocol specifications for the purpose of describing
	implementation of this information model need to describe security		implementation of this information model need to describe security
	and authentication concerns that may be raised by the particular		and authentication concerns that may be raised by the particular
	mechanisms defined and how those concerns may be addressed.		mechanisms defined and how those concerns may be addressed.
	Uniqueness of the identifiers from this document is guaranteed by the		Uniqueness of the identifiers from this document is guaranteed by the
	assigner (e.g., a Global_ID is unique based on the assignment of ASNs		assigner (e.g., a Global_ID is unique based on the assignment of ASNs
	from IANA and both a Node_ID and a IF_Num are unique based on the		from IANA and both a Node_ID and an IF_Num are unique based on the
	assignment by an operator). Failure by an assigner to use unique		assignment by an operator). Failure by an assigner to use unique
	values within the specified scoping for any of the identifiers		values within the specified scoping for any of the identifiers
	defined herein could result in operational problems. For example and		defined herein could result in operational problems. For example, a
	non-unique MEP value could result in failure to detect a mis-merged		non-unique MEP value could result in failure to detect a mis-merged
	LSP.		LSP.
	Protocol specifications that utilize the identifiers defined herein		Protocol specifications that utilize the identifiers defined herein
	need to consider the implications of guessable identifiers and, where		need to consider the implications of guessable identifiers and, where
	there is a security implication, SHOULD give advice on how to make		there is a security implication, SHOULD give advice on how to make
	identifiers less guessable.		identifiers less guessable.
	10. References		9. References
	10.1. Normative References		9.1. Normative References
	[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement		[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
	Levels", BCP 14, RFC 2119, March 1997.		Levels", BCP 14, RFC 2119, March 1997.
	[2] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and		[2] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and
	G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels",		G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels",
	RFC 3209, December 2001.		RFC 3209, December 2001.
	[3] Metz, C., Martini, L., Balus, F., and J. Sugimoto, "Attachment		[3] Metz, C., Martini, L., Balus, F., and J. Sugimoto, "Attachment
	Individual Identifier (AII) Types for Aggregation", RFC 5003,		Individual Identifier (AII) Types for Aggregation", RFC 5003,
	skipping to change at page 16, line 36		skipping to change at page 17, line 5
	Signaling Functional Description", RFC 3471, January 2003.		Signaling Functional Description", RFC 3471, January 2003.
	[5] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS)		[5] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS)
	Signaling Resource ReserVation Protocol-Traffic Engineering		Signaling Resource ReserVation Protocol-Traffic Engineering
	(RSVP-TE) Extensions", RFC 3473, January 2003.		(RSVP-TE) Extensions", RFC 3473, January 2003.
	[6] Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G. Heron,		[6] Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G. Heron,
	"Pseudowire Setup and Maintenance Using the Label Distribution		"Pseudowire Setup and Maintenance Using the Label Distribution
	Protocol (LDP)", RFC 4447, April 2006.		Protocol (LDP)", RFC 4447, April 2006.
	10.2. Informative References		9.2. Informative References
	[7] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., and		[7] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., and
	S. Ueno, "Requirements of an MPLS Transport Profile", RFC 5654,		S. Ueno, "Requirements of an MPLS Transport Profile", RFC 5654,
	September 2009.		September 2009.
	[8] McCloghrie, K. and F. Kastenholz, "The Interfaces Group MIB",		[8] McCloghrie, K. and F. Kastenholz, "The Interfaces Group MIB",
	RFC 2863, June 2000.		RFC 2863, June 2000.
	[9] Bocci, M., Bryant, S., Frost, D., Levrau, L., and L. Berger, "A		[9] Bocci, M., Bryant, S., Frost, D., Levrau, L., and L. Berger, "A
	Framework for MPLS in Transport Networks", RFC 5921, July 2010.		Framework for MPLS in Transport Networks", RFC 5921, July 2010.
	skipping to change at page 17, line 13		skipping to change at page 17, line 28
	Data Plane Architecture", RFC 5960, August 2010.		Data Plane Architecture", RFC 5960, August 2010.
	Authors' Addresses		Authors' Addresses
	Matthew Bocci		Matthew Bocci
	Alcatel-Lucent		Alcatel-Lucent
	Voyager Place, Shoppenhangers Road		Voyager Place, Shoppenhangers Road
	Maidenhead, Berks SL6 2PJ		Maidenhead, Berks SL6 2PJ
	UK		UK
	Email: matthew.bocci@alcatel-lucent.com		EMail: matthew.bocci@alcatel-lucent.com
	George Swallow		George Swallow
	Cisco		Cisco
	Email: swallow@cisco.com		EMail: swallow@cisco.com
	Eric Gray		Eric Gray
	Ericsson		Ericsson
	900 Chelmsford Street		900 Chelmsford Street
	Lowell, Massachussetts 01851-8100		Lowell, Massachussetts 01851-8100
	Email: eric.gray@ericsson.com		EMail: eric.gray@ericsson.com
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