draft-ietf-mpls-cr-ldp-03.txt		draft-ietf-mpls-cr-ldp-04.txt
	MPLS Working Group Bilel Jamoussi, Editor		MPLS Working Group Bilel Jamoussi, Editor
	Internet Draft Nortel Networks Corp.		Internet Draft Nortel Networks Corp.
	Expiration Date: March 2000		Expiration Date: January 2001
	September 1999
			O. Aboul-Magd, L. Andersson, P. Ashwood-Smith,
			F. Hellstrand, K. Sundell, Nortel Networks Corp.
			R. Callon, Juniper Networks.
			R. Dantu, IPmobile
			P. Doolan, T. Worster, Ennovate Networks Corp.
			N. Feldman, IBM Corp.
			A. Fredette, PhotonEx Corp.
			M. Girish, Atoga Systems
			E. Gray, Zaffire, Inc.
			J. Halpern, Longitude Systems, Inc.
			J. Heinanen, Telia Finland
			T. Kilty, Newbridge Networks, Inc.
			A. Malis, Vivace Networks
			P. Vaananen, Nokia Telecommunications
			L. Wu, Cisco Systems
			July 2000
	Constraint-Based LSP Setup using LDP		Constraint-Based LSP Setup using LDP
	draft-ietf-mpls-cr-ldp-03.txt		draft-ietf-mpls-cr-ldp-04.txt
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is in full conformance with		This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC2026.		all provisions of Section 10 of RFC2026.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	other groups may also distribute working documents as Internet-		other groups may also distribute working documents as Internet-
	Drafts.		Drafts.
	skipping to change at line 36		skipping to change at line 54
	http://www.ietf.org/ietf/1id-abstracts.txt		http://www.ietf.org/ietf/1id-abstracts.txt
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	Abstract		Abstract
	Label Distribution Protocol (LDP) is defined in [1] for distribution		Label Distribution Protocol (LDP) is defined in [1] for distribution
	of labels inside one MPLS domain. One of the most important		of labels inside one MPLS domain. One of the most important
	services that may be offered using MPLS in general and LDP in		services that may be offered using MPLS in general and LDP in
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 1Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	particular is support for constraint-based routing of traffic across		particular is support for constraint-based routing of traffic across
	the routed network. Constraint-based routing offers the opportunity		the routed network. Constraint-based routing offers the opportunity
	to extend the information used to setup paths beyond what is		to extend the information used to setup paths beyond what is
	available for the routing protocol. For instance, an LSP can be		available for the routing protocol. For instance, an LSP can be
	setup based on explicit route constraints, QoS constraints, and		setup based on explicit route constraints, QoS constraints, and
	other constraints. Constraint-based routing (CR) is a mechanism used		other constraints. Constraint-based routing (CR) is a mechanism used
	to meet Traffic Engineering requirements that have been proposed by		to meet Traffic Engineering requirements that have been proposed by
	[2], [3] and [4]. These requirements may be met by extending LDP for		[2], [3] and [4]. These requirements may be met by extending LDP for
	support of constraint-based routed label switched paths (CR-LSPs).		support of constraint-based routed label switched paths (CR-LSPs).
	Other uses for CR-LSPs include MPLS-based VPNs.		Other uses for CR-LSPs include MPLS-based VPNs [5]. More information
			about the applicability of CR-LDP can be found in [6].
	This draft specifies mechanisms and TLVs for support of CR-LSPs		This draft specifies mechanisms and TLVs for support of CR-LSPs
	using LDP.		using LDP.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 1 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		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 RFC 2119 [7].
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 2Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	Table of Contents		Table of Contents
	1. Introduction....................................................3		1. Introduction....................................................4
	2. Constraint-based Routing Overview...............................3		2. Constraint-based Routing Overview...............................4
	2.1 Strict and Loose Explicit Routes...............................4		2.1 Strict and Loose Explicit Routes...............................5
	2.2 Traffic Characteristics........................................4		2.2 Traffic Characteristics........................................5
	2.3 Pre-emption....................................................5		2.3 Pre-emption....................................................6
	2.4 Route Pinning..................................................5		2.4 Route Pinning..................................................6
	2.5 Resource Class.................................................5		2.5 Resource Class.................................................6
	3. Solution Overview...............................................6		3. Solution Overview...............................................7
	3.1 Required Messages and TLVs.....................................7		3.1 Required Messages and TLVs.....................................8
	3.2 Label Request Message..........................................7		3.2 Label Request Message..........................................8
	3.3 Label Mapping Message..........................................8		3.3 Label Mapping Message..........................................9
	3.4 Notification Message...........................................8		3.4 Notification Message..........................................10
	3.5 Release , Withdraw, and Abort Messages.........................9		3.5 Release , Withdraw, and Abort Messages........................10
	4. Protocol Specification..........................................9		4. Protocol Specification.........................................10
	4.1 Explicit Route TLV (ER-TLV)...................................10		4.1 Explicit Route TLV (ER-TLV)...................................11
	4.2 Explicit Route Hop TLV (ER-Hop TLV)...........................10		4.2 Explicit Route Hop TLV (ER-Hop TLV)...........................11
	4.3 Traffic Parameters TLV........................................11		4.3 Traffic Parameters TLV........................................12
	4.3.1 Semantics...................................................13		4.3.1 Semantics...................................................14
	4.3.1.1 Frequency.................................................13		4.3.1.1 Frequency.................................................14
	4.3.1.2 Peak Rate.................................................13		4.3.1.2 Peak Rate.................................................14
	4.3.1.3 Committed Rate............................................14		4.3.1.3 Committed Rate............................................15
	4.3.1.4 Excess Burst Size.........................................14		4.3.1.4 Excess Burst Size.........................................15
	4.3.1.5 Peak Rate Token Bucket....................................14		4.3.1.5 Peak Rate Token Bucket....................................15
	4.3.1.6 Committed Data Rate Token Bucket..........................14		4.3.1.6 Committed Data Rate Token Bucket..........................15
	4.3.1.7 Weight....................................................15		4.3.1.7 Weight....................................................16
	4.3.2 Procedures..................................................15		4.3.2 Procedures..................................................16
	4.3.2.1 Label Request Message.....................................15		4.3.2.1 Label Request Message.....................................16
	4.3.2.2 Label Mapping Message.....................................16		4.3.2.2 Label Mapping Message.....................................17
	4.3.2.3 Notification Message......................................16		4.3.2.3 Notification Message......................................17
	4.4 Preemption TLV................................................16		4.4 Preemption TLV................................................17
	4.5 LSPID TLV.....................................................17		4.5 LSPID TLV.....................................................18
	4.6 Resource Class (Color) TLV....................................18		4.6 Resource Class (Color) TLV....................................20
	4.7 ER-Hop semantics..............................................19		4.7 ER-Hop semantics..............................................20
	4.7.1. ER-Hop 1: The IPv4 prefix..................................19		4.7.1. ER-Hop 1: The IPv4 prefix..................................20
	4.7.2. ER-Hop 2: The IPv6 address.................................20		4.7.2. ER-Hop 2: The IPv6 address.................................21
	4.7.3. ER-Hop 3: The autonomous system number....................20		4.7.3. ER-Hop 3: The autonomous system number....................22
	4.7.4. ER-Hop 4: LSPID............................................21		4.7.4. ER-Hop 4: LSPID............................................22
	4.8. Processing of the Explicit Route TLV.........................22		4.8. Processing of the Explicit Route TLV.........................23
	4.8.1. Selection of the next hop..................................22		4.8.1. Selection of the next hop..................................23
	4.8.2. Adding ER-Hops to the explicit route TLV...................23		4.8.2. Adding ER-Hops to the explicit route TLV...................25
	4.9 Route Pinning TLV.............................................24		4.9 Route Pinning TLV.............................................25
	4.10 CR-LSP FEC Element...........................................24		4.10 CR-LSP FEC Element...........................................26
	4.11 Error subcodes...............................................25		4.11 TLV Type Summary.............................................26
	5. Security.......................................................25		4.12 FEC Type Summary.............................................27
	6. Acknowledgments................................................25		4.13 Status Code Summary..........................................27
	7. Intellectual Property Consideration............................26		5. IANA Considerations............................................27
	8. References.....................................................26		5.1 TLV Type Name Space...........................................27
	9. Author's Addresses.............................................26		5.2 FEC Type Name Space...........................................27
	Appendix A: CR-LSP Establishment Examples.........................29		5.3 Status Code Space.............................................27
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 2 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 3Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	A.1 Strict Explicit Route Example.................................29		6. Security.......................................................28
	A.2 Node Groups and Specific Nodes Example........................30		7. Acknowledgments................................................28
	Appendix B. QoS Service Examples..................................33		8. Intellectual Property Consideration............................28
	B.1 Service Examples..............................................33		9. References.....................................................28
	B.2 Establishing CR-LSP Supporting Real-Time Applications.........34		10. Author's Addresses............................................29
	B.3 Establishing CR-LSP Supporting Delay Insensitive Applications.35		Appendix A: CR-LSP Establishment Examples.........................31
	Appendix C. LSP Modification Using CR-LDP.........................36		A.1 Strict Explicit Route Example.................................31
	C.1 Introduction..................................................36		A.2 Node Groups and Specific Nodes Example........................32
	C.2 Basic Procedure...............................................37		Appendix B. QoS Service Examples..................................35
	C.3 Priority Handling.............................................38		B.1 Service Examples..............................................35
	C.4 Modification Failure Case Handling............................39		B.2 Establishing CR-LSP Supporting Real-Time Applications.........36
			B.3 Establishing CR-LSP Supporting Delay Insensitive Applications.37
	1. Introduction		1. Introduction
	The need for constraint-based routing (CR) in MPLS has been explored		The need for constraint-based routing (CR) in MPLS has been explored
	elsewhere [3], [2], and [4]. Explicit routing is a subset of the		elsewhere [3], [2], and [4]. Explicit routing is a subset of the
	more general constraint-based routing function. At the MPLS WG		more general constraint-based routing function. At the MPLS WG
	meeting held during the Washington IETF (December 1997) there was		meeting held during the Washington IETF (December 1997) there was
	consensus that LDP should support explicit routing of LSPs with		consensus that LDP should support explicit routing of LSPs with
	provision for indication of associated (forwarding) priority. In		provision for indication of associated (forwarding) priority. In
	the Chicago meeting (August 1998), a decision was made that support		the Chicago meeting (August 1998), a decision was made that support
	skipping to change at line 156		skipping to change at line 183
	Section 2 introduces the various constraints defined in this		Section 2 introduces the various constraints defined in this
	specification. Section 3 outlines the CR-LDP solution. Section 4		specification. Section 3 outlines the CR-LDP solution. Section 4
	defines the TLVs and procedures used to setup constraint-based		defines the TLVs and procedures used to setup constraint-based
	routed label switched paths. Appendix A provides several examples		routed label switched paths. Appendix A provides several examples
	of CR-LSP path setup. Appendix B provides Service Definition		of CR-LSP path setup. Appendix B provides Service Definition
	Examples.		Examples.
	2. Constraint-based Routing Overview		2. Constraint-based Routing Overview
	Constraint-based routing is a mechanism that supports the Traffic		Constraint-based routing is a mechanism that supports the Traffic
	Engineering requirements defined in [4]. Explicit Routing is a
	subset of the more general constraint-based routing where the
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 3 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 4Internet Draft Constraint-Based LSP Setup using LDP July, 2000
			Engineering requirements defined in [4]. Explicit Routing is a
			subset of the more general constraint-based routing where the
	constraint is the explicit route (ER). Other constraints are defined		constraint is the explicit route (ER). Other constraints are defined
	to provide a network operator with control over the path taken by an		to provide a network operator with control over the path taken by an
	LSP. This section is an overview of the various constraints		LSP. This section is an overview of the various constraints
	supported by this specification.		supported by this specification.
	2.1 Strict and Loose Explicit Routes
	Like any other LSP a CR-LSP is a path through an MPLS network. The		Like any other LSP a CR-LSP is a path through an MPLS network. The
	difference is that while other paths are setup solely based on		difference is that while other paths are setup solely based on
	information in routing tables or from a management system, the		information in routing tables or from a management system, the
	constraint-based route is calculated at one point at the edge of		constraint-based route is calculated at one point at the edge of
	network based on criteria, including but not limited to routing		network based on criteria, including but not limited to routing
	information. The intention is that this functionality shall give		information. The intention is that this functionality shall give
	desired special characteristics to the LSP in order to better		desired special characteristics to the LSP in order to better
	support the traffic sent over the LSP. The reason for setting up CR-		support the traffic sent over the LSP. The reason for setting up CR-
	LSPs might be that one wants to assign certain bandwidth or other		LSPs might be that one wants to assign certain bandwidth or other
	Service Class characteristics to the LSP, or that one wants to make		Service Class characteristics to the LSP, or that one wants to make
	sure that alternative routes use physically separate paths through		sure that alternative routes use physically separate paths through
	the network.		the network.
			2.1 Strict and Loose Explicit Routes
	An explicit route is represented in a Label Request Message as a		An explicit route is represented in a Label Request Message as a
	list of nodes or groups of nodes along the constraint-based route.		list of nodes or groups of nodes along the constraint-based route.
	When the CR-LSP is established, all or a subset of the nodes in a		When the CR-LSP is established, all or a subset of the nodes in a
	group may be traversed by the LSP. Certain operations to be		group may be traversed by the LSP. Certain operations to be
	performed along the path can also be encoded in the constraint-based		performed along the path can also be encoded in the constraint-based
	route.		route.
	The capability to specify, in addition to specified nodes, groups of		The capability to specify, in addition to specified nodes, groups of
	nodes, of which a subset will be traversed by the CR-LSP, allows the		nodes, of which a subset will be traversed by the CR-LSP, allows the
	system a significant amount of local flexibility in fulfilling a		system a significant amount of local flexibility in fulfilling a
	skipping to change at line 211		skipping to change at line 238
	To simplify the discussion, we call each group of nodes an abstract		To simplify the discussion, we call each group of nodes an abstract
	node. Thus, we can also say that a constraint-based route is a path		node. Thus, we can also say that a constraint-based route is a path
	including all of the abstract nodes, with the specified operations		including all of the abstract nodes, with the specified operations
	occurring along that path.		occurring along that path.
	2.2 Traffic Characteristics		2.2 Traffic Characteristics
	The traffic characteristics of a path are described in the Traffic		The traffic characteristics of a path are described in the Traffic
	Parameters TLV in terms of a peak rate, committed rate, and service		Parameters TLV in terms of a peak rate, committed rate, and service
	granularity. The peak and committed rates describe the bandwidth		granularity. The peak and committed rates describe the bandwidth
	constraints of a path while the service granularity can be used to
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 4 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 5Internet Draft Constraint-Based LSP Setup using LDP July, 2000
			constraints of a path while the service granularity can be used to
	specify a constraint on the delay variation that the CR-LDP MPLS		specify a constraint on the delay variation that the CR-LDP MPLS
	domain may introduce to a path's traffic.		domain may introduce to a path's traffic.
	2.3 Pre-emption		2.3 Pre-emption
	CR-LDP signals the resources required by a path on each hop of the		CR-LDP signals the resources required by a path on each hop of the
	route. If a route with sufficient resources can not be found,		route. If a route with sufficient resources can not be found,
	existing paths may be rerouted to reallocate resources to the new		existing paths may be rerouted to reallocate resources to the new
	path. This is the process of path pre-emption. Setup and holding		path. This is the process of path pre-emption. Setup and holding
	priorities are used to rank existing paths (holding priority) and		priorities are used to rank existing paths (holding priority) and
	skipping to change at line 244		skipping to change at line 271
	pre-empt other paths. The exact rules determining bumping are an		pre-empt other paths. The exact rules determining bumping are an
	aspect of network policy.		aspect of network policy.
	The allocation of setup and holding priority values to paths is an		The allocation of setup and holding priority values to paths is an
	aspect of network policy.		aspect of network policy.
	The setup and holding priority values range from zero (0) to seven		The setup and holding priority values range from zero (0) to seven
	(7). The value zero (0) is the priority assigned to the most		(7). The value zero (0) is the priority assigned to the most
	important path. It is referred to as the highest priority. Seven (7)		important path. It is referred to as the highest priority. Seven (7)
	is the priority for the least important path. The use of default		is the priority for the least important path. The use of default
	priority values is an aspect of network policy.		priority values is an aspect of network policy. The recommended
			default value is (4).
	The setupPriority of a CR-LSP should not be higher (numerically		The setupPriority of a CR-LSP should not be higher (numerically
	less) than its holdingPriority since it might bump an LSP and be		less) than its holdingPriority since it might bump an LSP and be
	bumped by the next _equivalent_ request.		bumped by the next _equivalent_ request.
	2.4 Route Pinning		2.4 Route Pinning
	Route pinning is applicable to segments of an LSP that are loosely		Route pinning is applicable to segments of an LSP that are loosely
	routed - i.e. those segments which are specified with a next hop		routed - i.e. those segments which are specified with a next hop
	with the `L' bit set or where the next hop is an _abstract node_. A		with the _L_ bit set or where the next hop is an _abstract node_. A
	CR-LSP may be setup using route pinning if it is undesirable to		CR-LSP may be setup using route pinning if it is undesirable to
	change the path used by an LSP even when a better next hop becomes		change the path used by an LSP even when a better next hop becomes
	available at some LSR along the loosely routed portion of the LSP.		available at some LSR along the loosely routed portion of the LSP.
	2.5 Resource Class		2.5 Resource Class
	The network operator may classify network resources in various ways.		The network operator may classify network resources in various ways.
	These classes are also known as _colors_ or _administrative groups_.		These classes are also known as _colors_ or _administrative groups_.
	When a CR-LSP is being established, it's necessary to indicate which		When a CR-LSP is being established, it's necessary to indicate which
	resource classes the CR-LSP can draw from.		resource classes the CR-LSP can draw from.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 5 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 6Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	3. Solution Overview		3. Solution Overview
	CR-LSP over LDP Specification is designed with the following goals:		CR-LSP over LDP Specification is designed with the following goals:
	1. Meet the requirements outlined in [4] for performing traffic		1. Meet the requirements outlined in [4] for performing traffic
	engineering and provide a solid foundation for performing		engineering and provide a solid foundation for performing
	more general constraint-based routing.		more general constraint-based routing.
	2. Build on already specified functionality that meets the		2. Build on already specified functionality that meets the
	skipping to change at line 316		skipping to change at line 344
	one or more CR-TLVs in the Label Request Message. This means		one or more CR-TLVs in the Label Request Message. This means
	that the LSR can still be configured for independent control		that the LSR can still be configured for independent control
	for LSPs established as a result of dynamic routing. However,		for LSPs established as a result of dynamic routing. However,
	when a Label Request Message includes one or more of the CR-		when a Label Request Message includes one or more of the CR-
	TLVs, then ordered control is used to setup the CR-LSP. Note		TLVs, then ordered control is used to setup the CR-LSP. Note
	that this is also true for the loosely routed parts of a CR-		that this is also true for the loosely routed parts of a CR-
	LSP.		LSP.
	- New status codes are defined to handle error notification for		- New status codes are defined to handle error notification for
	failure of established paths specified in the CR-TLVs.		failure of established paths specified in the CR-TLVs.
	Optional TLVs are not required in the CR-LDP messages for the		Optional TLVs MUST be implemented to be compliant with the protocol.
	messages to be compliant with the protocol. Optional parameters MAY		However, they are optionally carried in the CR-LDP messages to
	be required for a particular operation to work (or work correctly),
	however.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 6 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 7Internet Draft Constraint-Based LSP Setup using LDP July, 2000
			signal certain characteristics of the CR-LSP being established or
			modified.
	Examples of CR-LSP establishment are given in Appendix A to		Examples of CR-LSP establishment are given in Appendix A to
	illustrate how the mechanisms described in this draft work.		illustrate how the mechanisms described in this draft work.
	3.1 Required Messages and TLVs		3.1 Required Messages and TLVs
	Any Messages, TLVs, and procedures not defined explicitly in this		Any Messages, TLVs, and procedures not defined explicitly in this
	document are defined in the LDP Specification [1]. The state		document are defined in the LDP Specification [1]. The reader can
	transitions, which relate to CR-LDP messages, can be found in [5].		use [8] as an informational document about the state transitions,
			which relate to CR-LDP messages.
	The following subsections are meant as a cross-reference to the [1]		The following subsections are meant as a cross-reference to the [1]
	document and indication of additional functionality beyond what's		document and indication of additional functionality beyond what's
	defined in [1] where necessary.		defined in [1] where necessary.
			Note that use of the Status TLV is not limited to Notification
			messages as specified in Section 3.4.6 of [1]. A message other than
			a Notification message may carry a Status TLV as an Optional
			Parameter. When a message other than a Notification carries a
			Status TLV the U-bit of the Status TLV should be set to 1 to
			indicate that the receiver should silently discard the TLV if
			unprepared to handle it.
	3.2 Label Request Message		3.2 Label Request Message
	The Label Request Message is as defined in 3.5.8 of [1] with the		The Label Request Message is as defined in 3.5.8 of [1] with the
	following modifications (required only if any of the CR-TLVs is		following modifications (required only if any of the CR-TLVs is
	included in the Label Request Message):		included in the Label Request Message):
	- Only a single FEC-TLV may be included in the Label Request		- The Label Request Message MUST include a single FEC-TLV
	Message. The CR-LSP FEC TLV should be used.		element. The CR-LSP FEC TLV element SHOULD be used. However,
			the other FEC-TLVs defined in [1] MAY be used instead for
			certain applications.
	- The Optional Parameters TLV includes the definition of any of		- The Optional Parameters TLV includes the definition of any of
	the Constraint-based TLVs specified in Section 4.		the Constraint-based TLVs specified in Section 4.
	- The Procedures to handle the Label Request Message are		- The Procedures to handle the Label Request Message are
	augmented by the procedures for processing of the CR-TLVs as		augmented by the procedures for processing of the CR-TLVs as
	defined in Section 4.		defined in Section 4.
	The encoding for the CR-LDP Label Request Message is as follows:		The encoding for the CR-LDP Label Request Message is as follows:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0| Label Request (0x0401) | Message Length |		|0| Label Request (0x0401) | Message Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Message ID |		| Message ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 8Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	| FEC TLV |		| FEC TLV |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| LSPID TLV (CR-LDP, mandatory) |		| LSPID TLV (CR-LDP, mandatory) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| ER-TLV (CR-LDP, optional) |		| ER-TLV (CR-LDP, optional) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Traffic TLV (CR-LDP, optional) |		| Traffic TLV (CR-LDP, optional) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Pinning TLV (CR-LDP, optional) |		| Pinning TLV (CR-LDP, optional) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Resource Class TLV (CR-LDP, optional) |		| Resource Class TLV (CR-LDP, optional) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Pre-emption TLV (CR-LDP, optional) |		| Pre-emption TLV (CR-LDP, optional) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 7 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	3.3 Label Mapping Message		3.3 Label Mapping Message
	The Label Mapping Message is as defined in 3.5.7 of [1] with the		The Label Mapping Message is as defined in 3.5.7 of [1] with the
	following modifications:		following modifications:
	- Only a single Label-TLV may be included in the Label Mapping		- The Label Mapping Message MUST include a single Label-TLV.
	Message.
	- The Label Mapping Message Procedures are limited to downstream		- The Label Mapping Message Procedures are limited to downstream
	on demand ordered control mode.		on demand ordered control mode.
	A Mapping message is transmitted by a downstream LSR to an upstream		A Mapping message is transmitted by a downstream LSR to an upstream
	LSR under one of the following conditions:		LSR under one of the following conditions:
	1. The LSR is the egress end of the CR-LSP and an upstream		1. The LSR is the egress end of the CR-LSP and an upstream
	mapping has been requested.		mapping has been requested.
	skipping to change at line 415		skipping to change at line 456
	| Message ID |		| Message ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| FEC TLV |		| FEC TLV |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Label TLV |		| Label TLV |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Label Request Message ID TLV |		| Label Request Message ID TLV |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| LSPID TLV (CR-LDP, optional) |		| LSPID TLV (CR-LDP, optional) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 9Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	| Traffic TLV (CR-LDP, optional) |		| Traffic TLV (CR-LDP, optional) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	3.4 Notification Message		3.4 Notification Message
	The Notification Message is as defined in Section 3.5.1 of [1] and		The Notification Message is as defined in Section 3.5.1 of [1] and
	the Status TLV encoding is as defined in Section 3.4.6 of [1].		the Status TLV encoding is as defined in Section 3.4.6 of [1].
	Establishment of an CR-LSP may fail for a variety of reasons. All		Establishment of an CR-LSP may fail for a variety of reasons. All
	such failures are considered advisory conditions and they are		such failures are considered advisory conditions and they are
	signaled by the Notification Message.		signaled by the Notification Message.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 8 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	Notification Messages carry Status TLVs to specify events being		Notification Messages carry Status TLVs to specify events being
	signaled. New status codes are defined in Section 4.11 to signal		signaled. New status codes are defined in Section 4.11 to signal
	error notifications associated with the establishment of a CR-LSP		error notifications associated with the establishment of a CR-LSP
	and the processing of the CR-TLV.		and the processing of the CR-TLV.
	The Notification Message may carry the LSPID TLV of the		The Notification Message MAY carry the LSPID TLV of the
	corresponding CR-LSP.		corresponding CR-LSP.
	Notification Messages MUST be forwarded toward the LSR originating		Notification Messages MUST be forwarded toward the LSR originating
	the Label Request at each hop and at any time that procedures in		the Label Request at each hop and at any time that procedures in
	this specification - or in [1] - specify sending of a Notification		this specification - or in [1] - specify sending of a Notification
	Message in response to a Label Request Message.		Message in response to a Label Request Message.
	The encoding of the notification message is as follows:		The encoding of the notification message is as follows:
	0 1 2 3		0 1 2 3
	skipping to change at line 463		skipping to change at line 505
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	3.5 Release , Withdraw, and Abort Messages		3.5 Release , Withdraw, and Abort Messages
	The Label Release , Label Withdraw, and Label Abort Request Messages		The Label Release , Label Withdraw, and Label Abort Request Messages
	are used as specified in [1]. These messages may also carry the		are used as specified in [1]. These messages may also carry the
	LSPID TLV.		LSPID TLV.
	4. Protocol Specification		4. Protocol Specification
	The Label Request Message defined in [1] optionally carries one or		The Label Request Message defined in [1] MUST carry the LSPID TLV
	more of the optional Constraint-based Routing TLVs (CR-TLVs) defined		and MAY carry one or more of the optional Constraint-based Routing
	in this section. If needed, other constraints can be supported later		TLVs (CR-TLVs) defined in this section. If needed, other constraints
	through the definition of new TLVs. In this specification, the		can be supported later through the definition of new TLVs. In this
	following TLVs are defined:		specification, the following TLVs are defined:
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 10Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	- Explicit Route TLV		- Explicit Route TLV
	- Explicit Route Hop TLV		- Explicit Route Hop TLV
	- Traffic Parameters TLV		- Traffic Parameters TLV
	- Preemption TLV		- Preemption TLV
	- LSPID TLV		- LSPID TLV
	- Route Pinning TLV		- Route Pinning TLV
	- Resource Class TLV		- Resource Class TLV
	- CR-LSP FEC TLV		- CR-LSP FEC TLV
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 9 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	4.1 Explicit Route TLV (ER-TLV)		4.1 Explicit Route TLV (ER-TLV)
	The ER-TLV is an object that specifies the path to be taken by the		The ER-TLV is an object that specifies the path to be taken by the
	LSP being established. It is composed of one or more Explicit Route		LSP being established. It is composed of one or more Explicit Route
	Hop TLVs (ER-Hop TLVs) defined in Section 4.2.		Hop TLVs (ER-Hop TLVs) defined in Section 4.2.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| ER-TLV (0x0800) | Length |		|0|0| Type = 0x0800 | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| ER-Hop TLV 1 |		| ER-Hop TLV 1 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| ER-Hop TLV 2 |		| ER-Hop TLV 2 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ............ ~		~ ............ ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| ER-Hop TLV n |		| ER-Hop TLV n |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Type		Type
	A two-byte field carrying the value of the ER-TLV type whichis		A fourteen-bit field carrying the value of the ER-TLV Type =
	0x800.		0x0800.
	Length		Length
	Specifies the length of the value field in bytes.		Specifies the length of the value field in bytes.
	ER-Hop TLVs		ER-Hop TLVs
	One or more ER-Hop TLVs defined in Section 4.2.		One or more ER-Hop TLVs defined in Section 4.2.
	4.2 Explicit Route Hop TLV (ER-Hop TLV)		4.2 Explicit Route Hop TLV (ER-Hop TLV)
	The contents of an ER-TLV are a series of variable length ER-Hop		The contents of an ER-TLV are a series of variable length ER-Hop
	TLVs.		TLVs.
	A node receiving a label request message including an ER-Hop type		A node receiving a label request message including an ER-Hop type
	that is not supported should not progress the label request message		that is not supported MUST not progress the label request message to
	to the downstream LSR and should send back a _No Route_ Notification		the downstream LSR and MUST send back a _No Route_ Notification
	Message.		Message.
	Each ER-Hop TLV has the form:		Each ER-Hop TLV has the form:
	0 1 2 3		0 1 2 3
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 11Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| ER-Hop-Type | Length |		|0|0| Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|L| Content // |		|L| Content // |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	ER-Hop Type		ER-Hop Type
			A fourteen-bit field carrying the type of the ER-Hop contents.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 10 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		Currently defined values are:
	A fourteen-bit field indicating the type of contents of the ER-
	Hop. Currently defined values are:
	Value Type		Value Type
	----- ------------------------		------ ------------------------
	0x801 IPv4 prefix		0x0801 IPv4 prefix
	0x802 IPv6 prefix		0x0802 IPv6 prefix
	0x803 Autonomous system number		0x0803 Autonomous system number
	0x804 LSPID		0x0804 LSPID
	Length		Length
	Specifies the length of the value field in bytes.		Specifies the length of the value field in bytes.
	L bit		L bit
	The L bit in the ER-Hop is a one-bit attribute. If the L bit		The L bit in the ER-Hop is a one-bit attribute. If the L bit
	is set, then the value of the attribute is _loose._ Otherwise,		is set, then the value of the attribute is _loose._ Otherwise,
	the value of the attribute is _strict._ For brevity, we say		the value of the attribute is _strict._ For brevity, we say
	that if the value of the ER-Hop attribute is loose then it is a		that if the value of the ER-Hop attribute is loose then it is a
	_loose ER-Hop._ Otherwise, it's a _strict ER-Hop._ Further,		_loose ER-Hop._ Otherwise, it's a _strict ER-Hop._ Further,
	skipping to change at line 579		skipping to change at line 621
	4.3 Traffic Parameters TLV		4.3 Traffic Parameters TLV
	The following sections describe the CR-LSP Traffic Parameters. The		The following sections describe the CR-LSP Traffic Parameters. The
	required characteristics of a CR-LSP are expressed by the Traffic		required characteristics of a CR-LSP are expressed by the Traffic
	Parameter values.		Parameter values.
	A Traffic Parameters TLV, is used to signal the Traffic Parameter		A Traffic Parameters TLV, is used to signal the Traffic Parameter
	values. The Traffic Parameters are defined in the subsequent		values. The Traffic Parameters are defined in the subsequent
	sections.		sections.
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 12Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	The Traffic Parameters TLV contains a Flags field, a Frequency, a		The Traffic Parameters TLV contains a Flags field, a Frequency, a
	Weight, and the five Traffic Parameters PDR, PBS, CDR, CBS, EBS.		Weight, and the five Traffic Parameters PDR, PBS, CDR, CBS, EBS.
	The Traffic Parameters TLV is shown below:		The Traffic Parameters TLV is shown below:
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 11 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| Traf. Param. TLV (0x0810)| Length |		|0|0| Type = 0x0810 | Length = 24 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Flags | Frequency | Reserved | Weight |		| Flags | Frequency | Reserved | Weight |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Peak Data Rate (PDR) |		| Peak Data Rate (PDR) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Peak Burst Size (PBS) |		| Peak Burst Size (PBS) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Committed Data Rate (CDR) |		| Committed Data Rate (CDR) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Committed Burst Size (CBS) |		| Committed Burst Size (CBS) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Excess Burst Size (EBS) |		| Excess Burst Size (EBS) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Type		Type
	A fourteen-bit field carrying the value of the ER-TLV type		A fourteen-bit field carrying the value of the Traffic
	which is 0x810.		Parameters TLV Type = 0x0810.
	Length		Length
	Specifies the length of the value field in bytes.		Specifies the length of the value field in bytes = 24.
	Flags		Flags
	The Flags field is shown below:		The Flags field is shown below:
	+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+
	| Res |F6|F5|F4|F3|F2|F1|		| Res |F6|F5|F4|F3|F2|F1|
	+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+
	Res - These bits are reserved.		Res - These bits are reserved.
	Zero on transmission.		Zero on transmission.
	skipping to change at line 631		skipping to change at line 673
	F2 - Corresponds to the PBS.		F2 - Corresponds to the PBS.
	F3 - Corresponds to the CDR.		F3 - Corresponds to the CDR.
	F4 - Corresponds to the CBS.		F4 - Corresponds to the CBS.
	F5 - Corresponds to the EBS.		F5 - Corresponds to the EBS.
	F6 - Corresponds to the Weight.		F6 - Corresponds to the Weight.
	Each flag Fi is a Negotiable Flag corresponding to a Traffic		Each flag Fi is a Negotiable Flag corresponding to a Traffic
	Parameter. The Negotiable Flag value zero denotes NotNegotiable		Parameter. The Negotiable Flag value zero denotes NotNegotiable
	and value one denotes Negotiable.		and value one denotes Negotiable.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 12 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	Frequency		Frequency
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 13Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	The Frequency field is coded as an 8 bit unsigned integer with		The Frequency field is coded as an 8 bit unsigned integer with
	the following code points defined:		the following code points defined:
	0- Unspecified		0- Unspecified
	1- Frequent		1- Frequent
	2- VeryFrequent		2- VeryFrequent
	3-255 - Reserved		3-255 - Reserved
	Reserved - Zero on transmission. Ignored on receipt.		Reserved - Zero on transmission. Ignored on receipt.
	Weight		Weight
	skipping to change at line 684		skipping to change at line 727
	granularity.		granularity.
	4.3.1.2 Peak Rate		4.3.1.2 Peak Rate
	The Peak Rate defines the maximum rate at which traffic SHOULD be		The Peak Rate defines the maximum rate at which traffic SHOULD be
	sent to the CR-LSP. The Peak Rate is useful for the purpose of		sent to the CR-LSP. The Peak Rate is useful for the purpose of
	resource allocation. If resource allocation within the MPLS domain		resource allocation. If resource allocation within the MPLS domain
	depends on the Peak Rate value then it should be enforced at the		depends on the Peak Rate value then it should be enforced at the
	ingress to the MPLS domain.		ingress to the MPLS domain.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 13 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	The Peak Rate is defined in terms of the two Traffic Parameters PDR		The Peak Rate is defined in terms of the two Traffic Parameters PDR
	and PBS, see section 4.3.1.5 below.		and PBS, see section 4.3.1.5 below.
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 14Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	4.3.1.3 Committed Rate		4.3.1.3 Committed Rate
	The Committed Rate defines the rate that the MPLS domain commits to		The Committed Rate defines the rate that the MPLS domain commits to
	be available to the CR-LSP.		be available to the CR-LSP.
	The Committed Rate is defined in terms of the two Traffic Parameters		The Committed Rate is defined in terms of the two Traffic Parameters
	CDR and CBS, see section 4.3.1.6 below.		CDR and CBS, see section 4.3.1.6 below.
	4.3.1.4 Excess Burst Size		4.3.1.4 Excess Burst Size
	skipping to change at line 738		skipping to change at line 781
	in excess of the peak rate.		in excess of the peak rate.
	The actual implementation of an LSR doesn't need to be modeled		The actual implementation of an LSR doesn't need to be modeled
	according to the above formal token bucket specification.		according to the above formal token bucket specification.
	4.3.1.6 Committed Data Rate Token Bucket		4.3.1.6 Committed Data Rate Token Bucket
	The committed rate of a CR-LSP is specified in terms of a token		The committed rate of a CR-LSP is specified in terms of a token
	bucket C with rate CDR. The extent by which the offered rate		bucket C with rate CDR. The extent by which the offered rate
	exceeds the committed rate MAY be measured in terms of another token		exceeds the committed rate MAY be measured in terms of another token
			bucket E, which also operates at rate CDR. The maximum size of the
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 14 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 15Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	bucket E, which also operates at rate CDR. The maximum size of the
	token bucket C is CBS and the maximum size of the token bucket E is		token bucket C is CBS and the maximum size of the token bucket E is
	EBS.		EBS.
	The token buckets C and E are initially (at time 0) full, i.e., the		The token buckets C and E are initially (at time 0) full, i.e., the
	token count Tc(0) = CBS and the token count Te(0) = EBS.		token count Tc(0) = CBS and the token count Te(0) = EBS.
	Thereafter, the token counts Tc and Te are updated CDR times per		Thereafter, the token counts Tc and Te are updated CDR times per
	second as follows:		second as follows:
	- If Tc is less than CBS, Tc is incremented by one, else		- If Tc is less than CBS, Tc is incremented by one, else
	- if Te is less then EBS, Te is incremented by one, else		- if Te is less then EBS, Te is incremented by one, else
	skipping to change at line 791		skipping to change at line 834
	4.3.2 Procedures		4.3.2 Procedures
	4.3.2.1 Label Request Message		4.3.2.1 Label Request Message
	If an LSR receives an incorrectly encoded Traffic Parameters TLV in		If an LSR receives an incorrectly encoded Traffic Parameters TLV in
	which the value of PDR is less than the value of CDR then it MUST		which the value of PDR is less than the value of CDR then it MUST
	send a Notification Message including the Status code _Traffic		send a Notification Message including the Status code _Traffic
	Parameters Unavailable_ to the upstream LSR from which it received		Parameters Unavailable_ to the upstream LSR from which it received
	the erroneous message.		the erroneous message.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 15 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	If a Traffic Parameter is indicated as Negotiable in the Label		If a Traffic Parameter is indicated as Negotiable in the Label
	Request Message by the corresponding Negotiable Flag then an LSR MAY		Request Message by the corresponding Negotiable Flag then an LSR MAY
	replace the Traffic Parameter value with a smaller value.		replace the Traffic Parameter value with a smaller value.
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 16Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	If the Weight is indicated as Negotiable in the Label Request		If the Weight is indicated as Negotiable in the Label Request
	Message by the corresponding Negotiable Flag then an LSR may replace		Message by the corresponding Negotiable Flag then an LSR may replace
	the Weight value with a lower value (down to 0).		the Weight value with a lower value (down to 0).
	If, after possible Traffic Parameter negotiation, an LSR can support		If, after possible Traffic Parameter negotiation, an LSR can support
	the CR-LSP Traffic Parameters then the LSR MUST reserve the		the CR-LSP Traffic Parameters then the LSR MUST reserve the
	corresponding resources for the CR-LSP.		corresponding resources for the CR-LSP.
	If, after possible Traffic Parameter negotiation, an LSR cannot		If, after possible Traffic Parameter negotiation, an LSR cannot
	support the CR-LSP Traffic Parameters then the LSR MUST send a		support the CR-LSP Traffic Parameters then the LSR MUST send a
	skipping to change at line 843		skipping to change at line 886
	release any resources that it possibly had reserved for the CR-LSP.		release any resources that it possibly had reserved for the CR-LSP.
	In addition, on receiving a Notification Message from a Downstream		In addition, on receiving a Notification Message from a Downstream
	LSR that is associated with a Label Request from an upstream LSR,		LSR that is associated with a Label Request from an upstream LSR,
	the local LSR MUST propagate the Notification message using the		the local LSR MUST propagate the Notification message using the
	procedures in [1].		procedures in [1].
	4.4 Preemption TLV		4.4 Preemption TLV
	The defualt value of the setup and holding priorities should be in		The defualt value of the setup and holding priorities should be in
	the middle of the range (e.g., 4) so that this feature can be turned		the middle of the range (e.g., 4) so that this feature can be turned
	on gradually in an operational network by increasing or decerasing		on gradually in an operational network by increasing or decreasing
	the priority starting at the middle of the range.		the priority starting at the middle of the range.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 16 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 17Internet Draft Constraint-Based LSP Setup using LDP July, 2000
			Since the Preemption TLV is an optional TLV, LSPs that are setup
			without an explicitly signaled preemption TLV SHOULD be treated as
			LSPs with the default setup and holding priorities (e.g., 4).
			When an established LSP is preempted, the LSR that initiates the
			preemption sends a Withdraw Message upstream and a Release Message
			downstream.
			When an LSP in the process of being established (outstanding Label
			Request without getting a Label Mapping back) is preempted, the LSR
			that initiates the preemption, sends a Notification Message upstream
			and an Abort Message downstream.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| Preemption-TLV (0x0820) | Length |		|0|0| Type = 0x0820 | Length = 4 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| SetPrio | HoldPrio | Reserved |		| SetPrio | HoldPrio | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Type		Type
	A fourteen-bit field carrying the value of the Preemption-TLV		A fourteen-bit field carrying the value of the Preemption-TLV
	type which is 0x820.		Type = 0x0820.
	Length		Length
	Specifies the length of the value field in bytes.		Specifies the length of the value field in bytes = 4.
	Reserved		Reserved
	Zero on transmission. Ignored on receipt.		Zero on transmission. Ignored on receipt.
	SetPrio		SetPrio
	A SetupPriority of value zero (0) is the priority assigned to		A SetupPriority of value zero (0) is the priority assigned to
	the most important path. It is referred to as the highest		the most important path. It is referred to as the highest
	priority. Seven (7) is the priority for the least important		priority. Seven (7) is the priority for the least important
	path. The higher the setup priority, the more paths CR-LDP can		path. The higher the setup priority, the more paths CR-LDP can
	bump to set up the path. The default value should be 4.		bump to set up the path. The default value should be 4.
	skipping to change at line 888		skipping to change at line 944
	The higher the holding priority, the less likely it is for CR-		The higher the holding priority, the less likely it is for CR-
	LDP to reallocate its bandwidth to a new path.		LDP to reallocate its bandwidth to a new path.
	4.5 LSPID TLV		4.5 LSPID TLV
	LSPID is a unique identifier of a CR-LSP within an MPLS network.		LSPID is a unique identifier of a CR-LSP within an MPLS network.
	The LSPID is composed of the ingress LSR Router ID (or any of its		The LSPID is composed of the ingress LSR Router ID (or any of its
	own Ipv4 addresses) and a Locally unique CR-LSP ID to that LSR.		own Ipv4 addresses) and a Locally unique CR-LSP ID to that LSR.
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 18Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	The LSPID is useful in network management, in CR-LSP repair, and in		The LSPID is useful in network management, in CR-LSP repair, and in
	using an already established CR-LSP as a hop in an ER-TLV.		using an already established CR-LSP as a hop in an ER-TLV.
	An _action indicator flag_ is carried in the LSPID TLV. This _action		An _action indicator flag_ is carried in the LSPID TLV. This _action
	indicator flag_ indicates explicitly the action that should be taken		indicator flag_ indicates explicitly the action that should be taken
	if the LSP already exists on the LSR receiving the message.		if the LSP already exists on the LSR receiving the message.
	After a CR-LSP is set up, its bandwidth reservation may need to be		After a CR-LSP is set up, its bandwidth reservation may need to be
	changed by the network operator, due to the new requirements for the		changed by the network operator, due to the new requirements for the
	traffic carried on that CR-LSP. The _action indicator flag_ is used		traffic carried on that CR-LSP. The _action indicator flag_ is used
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 17 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	indicate the need to modify the bandwidth and possibly other		indicate the need to modify the bandwidth and possibly other
	parameters of an established CR-LSP without service interruption.		parameters of an established CR-LSP without service interruption.
	This feature has application in dynamic network resources management		This feature has application in dynamic network resources management
	where traffic of different priorities and service classes is		where traffic of different priorities and service classes is
	involved.		involved.
	The procedure for the code point _modify_ is defined in Appendix C.		The procedure for the code point _modify_ is defined in [9]. The
	The procedures for other flags are FFS.		procedures for other flags are FFS.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| LSPID-TLV (0x0821) | Length |		|0|0| Type = 0x0821 | Length = 4 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Reserved |ActFlg | Local CR-LSP ID |		| Reserved |ActFlg | Local CR-LSP ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Ingress LSR Router ID |		| Ingress LSR Router ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Type		Type
	A fourteen-bit field carrying the value of the LSPID-TLV type		A fourteen-bit field carrying the value of the LSPID-TLV
	which is 0x821.		Type = 0x0821.
	Length		Length
	Specifies the length of the value field in bytes.		Specifies the length of the value field in bytes = 4.
	ActFlg		ActFlg
	Action Indicator Flag: A 4-bit field that indicates explicitly		Action Indicator Flag: A 4-bit field that indicates explicitly
	the action that should be taken if the LSP already exists on		the action that should be taken if the LSP already exists on
	the LSR receiving the message. A set of indicator code points		the LSR receiving the message. A set of indicator code points
	is proposed as follows:		is proposed as follows:
	0000: indicates initial LSP setup		0000: indicates initial LSP setup
	0001: indicates modify LSP		0001: indicates modify LSP
	Reserved		Reserved
	Zero on transmission. Ignored on receipt.		Zero on transmission. Ignored on receipt.
	Local CR-LSP ID		Local CR-LSP ID
	The Local LSP ID is an identifier of the CR-LSP locally unique		The Local LSP ID is an identifier of the CR-LSP locally unique
	within the Ingress LSR originating the CR-LSP.		within the Ingress LSR originating the CR-LSP.
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 19Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	Ingress LSR Router ID		Ingress LSR Router ID
	An LSR may use any of its own IPv4 addresses in this field.		An LSR may use any of its own IPv4 addresses in this field.
	4.6 Resource Class (Color) TLV		4.6 Resource Class (Color) TLV
	The Resource Class as defined in [4] is used to specify which links		The Resource Class as defined in [4] is used to specify which links
	are acceptable by this CR-LSP. This information allows for the		are acceptable by this CR-LSP. This information allows for the
	network's topology to be pruned.		network's topology to be pruned.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 18 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| ResCls-TLV (0x0822) | Length |		|0|0| Type = 0x0822 | Length = 4 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| RsCls |		| RsCls |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Type		Type
	A fourteen-bit field carrying the value of the ResCls-TLV type		A fourteen-bit field carrying the value of the ResCls-TLV Type
	which is 0x822.		= 0x0822.
	Length		Length
	Specifies the length of the value field in bytes.		Specifies the length of the value field in bytes = 4.
	RsCls		RsCls
	The Resource Class bit mask indicating which of the 32		The Resource Class bit mask indicating which of the 32
	_administrative groups_ or _colors_ of links the CR-LSP can		_administrative groups_ or _colors_ of links the CR-LSP can
	traverse.		traverse.
	4.7 ER-Hop semantics		4.7 ER-Hop semantics
	4.7.1. ER-Hop 1: The IPv4 prefix		4.7.1. ER-Hop 1: The IPv4 prefix
	The abstract node represented by this ER-Hop is the set of nodes,		The abstract node represented by this ER-Hop is the set of nodes,
	which have an IP address, which lies within this prefix. Note that		which have an IP address, which lies within this prefix. Note that
	a prefix length of 32 indicates a single IPv4 node.		a prefix length of 32 indicates a single IPv4 node.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| 0x801 | Length |		|0|0| Type = 0x0801 | Length = 8 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|L| Reserved | PreLen |		|L| Reserved | PreLen |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| IPv4 Address (4 bytes) |		| IPv4 Address (4 bytes) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Type		Type
	IPv4 Address 0x801		A fourteen-bit field carrying the value of the ER-Hop 1, IPv4
			Address, Type = 0x0801
	Length		Length
	Specifies the length of the value field in bytes.
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 20Internet Draft Constraint-Based LSP Setup using LDP July, 2000
			Specifies the length of the value field in bytes = 8.
	L Bit		L Bit
	Set to indicate Loose hop.		Set to indicate Loose hop.
	Cleared to indicate a strict hop.		Cleared to indicate a strict hop.
	Reserved		Reserved
	Zero on transmission. Ignored on receipt.		Zero on transmission. Ignored on receipt.
	PreLen		PreLen
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 19 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	Prefix Length 1-32		Prefix Length 1-32
	IP Address		IP Address
	A four-byte field indicating the IP Address.		A four-byte field indicating the IP Address.
	4.7.2. ER-Hop 2: The IPv6 address		4.7.2. ER-Hop 2: The IPv6 address
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| 0x802 | Length |		|0|0| 0x0802 | Length = 20 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|L| Reserved | PreLen |		|L| Reserved | PreLen |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| IPV6 address |		| IPV6 address |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| IPV6 address (continued) |		| IPV6 address (continued) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| IPV6 address (continued) |		| IPV6 address (continued) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| IPV6 address (continued) |		| IPV6 address (continued) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Type		Type
	0x802 IPv6 address		A fourteen-bit field carrying the value of the ER-Hop 2, IPv6
			Address, Type = 0x0802
	Length		Length
	Specifies the length of the value field in bytes.		Specifies the length of the value field in bytes = 20.
	L Bit		L Bit
	Set to indicate Loose hop.		Set to indicate Loose hop.
	Cleared to indicate a strict hop.		Cleared to indicate a strict hop.
	Reserved		Reserved
	Zero on transmission. Ignored on receipt.		Zero on transmission. Ignored on receipt.
	PreLen		PreLen
	Prefix Length 1-128		Prefix Length 1-128
	IPv6 address		IPv6 address
	A 128-bit unicast host address.		A 128-bit unicast host address.
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 21Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	4.7.3. ER-Hop 3: The autonomous system number		4.7.3. ER-Hop 3: The autonomous system number
	The abstract node represented by this ER-Hop is the set of nodes		The abstract node represented by this ER-Hop is the set of nodes
	belonging to the autonomous system.		belonging to the autonomous system.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 20 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| 0x803 | Length |		|0|0| 0x0803 | Length = 4 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|L| Reserved | AS Number |		|L| Reserved | AS Number |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Type		Type
	AS Number 0x803		A fourteen-bit field carrying the value of the ER-Hop 3, AS
			Number, Type = 0x0803
	Length		Length
	Specifies the length of the value field in bytes.		Specifies the length of the value field in bytes = 4.
	L Bit		L Bit
	Set to indicate Loose hop.		Set to indicate Loose hop.
	Cleared to indicate a strict hop.		Cleared to indicate a strict hop.
	Reserved		Reserved
	Zero on transmission. Ignored on receipt.		Zero on transmission. Ignored on receipt.
	AS Number		AS Number
	Autonomous System number		Autonomous System number
	skipping to change at line 1102		skipping to change at line 1160
	the next ER-Hop after the loosely specified CR-LSP segment. Use of		the next ER-Hop after the loosely specified CR-LSP segment. Use of
	the LSPID Hop in this scenario eliminates the need for ER-Hops to		the LSPID Hop in this scenario eliminates the need for ER-Hops to
	keep the entire remaining ER-TLV at each LSR that is at either		keep the entire remaining ER-TLV at each LSR that is at either
	(upstream or downstream) end of a loosely specified CR-LSP segment		(upstream or downstream) end of a loosely specified CR-LSP segment
	as part of its state information. This is due to the fact that the		as part of its state information. This is due to the fact that the
	upstream LSR needs only to keep the next ER-Hop and the LSPID and		upstream LSR needs only to keep the next ER-Hop and the LSPID and
	the downstream LSR needs only to keep the LSPID in order for each		the downstream LSR needs only to keep the LSPID in order for each
	end to be able to recognize that the same LSP is being identified.		end to be able to recognize that the same LSP is being identified.
	If the LSPID Hop is not the last hop in an ER-TLV, the LSR must		If the LSPID Hop is not the last hop in an ER-TLV, the LSR must
	forward the remaining ER-TLV in a Label Request message, using the
	CR-LSP specified by the LSPID, to the LSR that is the CR-LSP's
	egress. That LSR will continue processing of the CR-LSP Label
	Request Message. The result is a tunneled, or stacked, CR-LSP.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 21 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 22Internet Draft Constraint-Based LSP Setup using LDP July, 2000
			remove the LSP-ID Hop and forward the remaining ER-TLV in a Label
			Request message using an LDP session established with the LSR that
			is the specified CR-LSP's egress. That LSR will continue processing
			of the CR-LSP Label Request Message. The result is a tunneled, or
			stacked, CR-LSP.
			To support labels negotiated for tunneled CR-LSP segments, an LDP
			session is required [1] between tunnel end points - possibly using
			the existing CR-LSP. Use of the existence of the CR-LSP in lieu of
			a session, or other possible session-less approaches, is FFS.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| 0x804 | Length |		|0|0| 0x0804 | Length = 8 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|L| Reserved | Local LSPID |		|L| Reserved | Local LSPID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Ingress LSR Router ID |		| Ingress LSR Router ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Type		Type
	LSPID 0x804		A fourteen-bit field carrying the value of the ER-Hop 4, LSPID,
			Type = 0x0804
	Length		Length
	Specifies the length of the value field in bytes.		Specifies the length of the value field in bytes = 8.
	L Bit		L Bit
	Set to indicate Loose hop.		Set to indicate Loose hop.
	Cleared to indicate a strict hop.		Cleared to indicate a strict hop.
	Reserved		Reserved
	Zero on transmission. Ignored on receipt.		Zero on transmission. Ignored on receipt.
	Local LSPID		Local LSPID
	A 2 byte field indicating the LSPID which is unique with		A 2 byte field indicating the LSPID which is unique with
	skipping to change at line 1148		skipping to change at line 1214
	4.8. Processing of the Explicit Route TLV		4.8. Processing of the Explicit Route TLV
	4.8.1. Selection of the next hop		4.8.1. Selection of the next hop
	A Label Request Message containing an explicit route TLV must		A Label Request Message containing an explicit route TLV must
	determine the next hop for this path. Selection of this next hop		determine the next hop for this path. Selection of this next hop
	may involve a selection from a set of possible alternatives. The		may involve a selection from a set of possible alternatives. The
	mechanism for making a selection from this set is implementation		mechanism for making a selection from this set is implementation
	dependent and is outside of the scope of this specification.		dependent and is outside of the scope of this specification.
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 23Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	Selection of particular paths is also outside of the scope of this		Selection of particular paths is also outside of the scope of this
	specification, but it is assumed that each node will make a best		specification, but it is assumed that each node will make a best
	effort attempt to determine a loop-free path. Note that such best		effort attempt to determine a loop-free path. Note that such best
	efforts may be overridden by local policy.		efforts may be overridden by local policy.
	To determine the next hop for the path, a node performs the		To determine the next hop for the path, a node performs the
	following steps:		following steps:
	1. The node receiving the Label Request Message must first		1. The node receiving the Label Request Message must first
	evaluate the first ER-Hop. If the L bit is not set in the		evaluate the first ER-Hop. If the L bit is not set in the
	first ER-Hop and if the node is not part of the abstract node		first ER-Hop and if the node is not part of the abstract node
	described by the first ER-Hop, it has received the message in		described by the first ER-Hop, it has received the message in
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 22 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	error, and should return a _Bad Initial ER-Hop_ error. If the		error, and should return a _Bad Initial ER-Hop_ error. If the
	L bit is set and the local node is not part of the abstract		L bit is set and the local node is not part of the abstract
	node described by the first ER-Hop, the node selects a next		node described by the first ER-Hop, the node selects a next
	hop that is along the path to the abstract node described by		hop that is along the path to the abstract node described by
	the first ER-Hop. If there is no first ER-Hop, the message is		the first ER-Hop. If there is no first ER-Hop, the message is
	also in error and the system should return a _Bad Explicit		also in error and the system should return a _Bad Explicit
	Routing TLV_ error using a Notification Message sent upstream.		Routing TLV_ error using a Notification Message sent upstream.
	2. If there is no second ER-Hop, this indicates the end of the		2. If there is no second ER-Hop, this indicates the end of the
	explicit route. The explicit route TLV should be removed from		explicit route. The explicit route TLV should be removed from
	skipping to change at line 1204		skipping to change at line 1270
	5.a If the second ER-Hop is a strict ER-Hop, then there is		5.a If the second ER-Hop is a strict ER-Hop, then there is
	an error and the node should return a _Bad Strict Node_		an error and the node should return a _Bad Strict Node_
	error.		error.
	5.b Otherwise, if the second ER-Hop is a loose ER-Hop, then		5.b Otherwise, if the second ER-Hop is a loose ER-Hop, then
	the node selects any next hop that is along the path to the		the node selects any next hop that is along the path to the
	next abstract node. If no path exists within the MPLS		next abstract node. If no path exists within the MPLS
	domain, then there is an error, and the node should return a		domain, then there is an error, and the node should return a
	_Bad loose node_ error.		_Bad loose node_ error.
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 24Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	6. Finally, the node replaces the first ER-Hop with any ER-Hop		6. Finally, the node replaces the first ER-Hop with any ER-Hop
	that denotes an abstract node containing the next hop. This		that denotes an abstract node containing the next hop. This
	is necessary so that when the explicit route is received by		is necessary so that when the explicit route is received by
	the next hop, it will be accepted.		the next hop, it will be accepted.
	7. Progress the Label Request Message to the next hop.		7. Progress the Label Request Message to the next hop.
	4.8.2. Adding ER-Hops to the explicit route TLV		4.8.2. Adding ER-Hops to the explicit route TLV
	After selecting a next hop, the node may alter the explicit route in		After selecting a next hop, the node may alter the explicit route in
	the following ways.		the following ways.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 23 Internet Draft Constraint-Based LSP Setup using LDP September, 1999
	If, as part of executing the algorithm in section 4.8.1, the		If, as part of executing the algorithm in section 4.8.1, the
	explicit route TLV is removed, the node may add a new explicit route		explicit route TLV is removed, the node may add a new explicit route
	TLV.		TLV.
	Otherwise, if the node is a member of the abstract node for the		Otherwise, if the node is a member of the abstract node for the
	first ER-Hop, then a series of ER-Hops may be inserted before the		first ER-Hop, then a series of ER-Hops may be inserted before the
	first ER-Hop or may replace the first ER-Hop. Each ER-Hop in this		first ER-Hop or may replace the first ER-Hop. Each ER-Hop in this
	series must denote an abstract node that is a subset of the current		series must denote an abstract node that is a subset of the current
	abstract node.		abstract node.
	skipping to change at line 1239		skipping to change at line 1305
	series of ER-Hops may be inserted prior to the first ER-Hop.		series of ER-Hops may be inserted prior to the first ER-Hop.
	4.9 Route Pinning TLV		4.9 Route Pinning TLV
	Section 2.4 describes the use of route pinning. The encoding of the		Section 2.4 describes the use of route pinning. The encoding of the
	Route Pinning TLV is as follows:		Route Pinning TLV is as follows:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| 0x823 | Length |		|0|0| Type = 0x0823 | Length = 4 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|P| Reserved |		|P| Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Type		Type
	Pinning-TLV type 0x823		A fourteen-bit field carrying the value of the Pinning-TLV
			Type = 0x0823
	Length		Length
	Specifies the length of the value field in bytes.		Specifies the length of the value field in bytes = 4.
	P Bit		P Bit
	The P bit is set to 1 to indicate that route pinning is		The P bit is set to 1 to indicate that route pinning is
	requested.		requested.
	The P bit is set to 0 to indicate that route pinning is not		The P bit is set to 0 to indicate that route pinning is not
	requested		requested
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 25Internet Draft Constraint-Based LSP Setup using LDP July, 2000
	Reserved		Reserved
	Zero on transmission. Ignored on receipt.		Zero on transmission. Ignored on receipt.
	4.10 CR-LSP FEC Element		4.10 CR-LSP FEC Element
	A new FEC element is introduced in this specification to support CR-		A new FEC element is introduced in this specification to support CR-
	LSPs. This new FEC element does not preclude the use of other FECs		LSPs. A FEC TLV containing a FEC of Element type CR-LSP (0x04) is a
	elements (Type=0x01, 0x02, 0x03) defined in the LDP spec in CR-LDP		CR-LSP FEC TLV. The CR-LSP FEC Element is an opaque FEC to be used
	messages. The CR-LDP FEC Element is an opaque FEC to be used only in		only in Messages of CR-LSPs.
	Messages of CR-LSPs.
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 24 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		A single FEC element MUST be included in the Label Request Message.
			The FEC Element SHOULD be the CR-LSP FEC Element. However, one of
			the other FEC elements (Type=0x01, 0x02, 0x03) defined in [1] MAY be
			in CR-LDP messages instead of the CR-LSP FEC Element for certain
			applications. A FEC TLV containing a FEC of Element type CR-LSP
			(0x04) is a CR-LSP FEC TLV.
	FEC Element Type Value		FEC Element Type Value
	Type name		Type name
	CR-LSP 0x04 No value; i.e., 0 value octets;		CR-LSP 0x04 No value; i.e., 0 value octets;
	The CR-LSP FEC TLV encoding is as follows:		The CR-LSP FEC TLV encoding is as follows:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| FEC(0x0100) | Length |		|0|0| Type = 0x0100 | Length = 1 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| CR-LSP (4) |		| CR-LSP (4) |
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	Type		Type
	FEC TLV type 0x0100		A fourteen-bit field carrying the value of the FEC TLV
			Type = 0x0100
	Length		Length
	Specifies the length of the value field in bytes.		Specifies the length of the value field in bytes = 1.
	CR-LSP FEC Element Type		CR-LSP FEC Element Type
	0x04		0x04
	4.11 Error subcodes		4.11 TLV Type Summary
	In the processing described above, certain errors need to be		TLV Type
	reported as part of the Notification Message. This section defines		-------------------------------------- ----------
	the status codes for the errors described in this specification.		Explicit Route TLV 0x0800
			Ipv4 Prefix ER-Hop TLV 0x0801
			Ipv6 Prefix ER-Hop TLV 0x0802
			Autonomous System Number ER-Hop TLV 0x0803
			LSP-ID ER-Hop TLV 0x0804
			Traffic Parameters TLV 0x0810
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 26Internet Draft Constraint-Based LSP Setup using LDP July, 2000
			Preemption TLV 0x0820
			LSPID TLV 0x0821
			Resource Class TLV 0x0822
			Route Pinning TLV 0x0823
			4.12 FEC Type Summary
			FEC Element TLV Type
			-------------------------------------- ----------
			CR-LSP FEC Element TLV 0x0100
			4.13 Status Code Summary
	Status Code Type		Status Code Type
	-------------------------------------- ----------		-------------------------------------- ----------
	Bad Explicit Routing TLV Error 0x44000001		Bad Explicit Routing TLV Error 0x44000001
	Bad Strict Node Error 0x44000002		Bad Strict Node Error 0x44000002
	Bad Loose Node Error 0x44000003		Bad Loose Node Error 0x44000003
	Bad Initial ER-Hop Error 0x44000004		Bad Initial ER-Hop Error 0x44000004
	Resource Unavailable 0x44000005		Resource Unavailable 0x44000005
	Traffic Parameters Unavailable 0x44000006		Traffic Parameters Unavailable 0x44000006
	Setup Abort (Label Request Aborted in [1]) 0x04000015		LSP Preempted 0x44000007
	Modify Request Not Supported 0x44000008		Modify Request Not Supported 0x44000008
			Setup Abort (Label Request Aborted in [1]) 0x04000015
	5. Security		5. IANA Considerations
	Pre-emption has to be controlled by the MPLS domain.		CR-LDP defines the following name spaces, which require management:
	Resource reservation requires the LSRs to have an LSP admission		- TLV types.
	control function.		- FEC types.
			- Status codes.
	Traffic Engineered LSPs can bypass normal routing.		The following sections provide guidelines for managing these name
			spaces.
	6. Acknowledgments		5.1 TLV Type Name Space
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 25 Internet Draft Constraint-Based LSP Setup using LDP September, 1999		TLV types in the range 0x0800 - 0x08FF are allocated to CR-LDP base
			protocol. Following the policies outlined in [IANA], TLV types in
			this range are allocated through an IETF Consensus action.
			5.2 FEC Type Name Space
			FEC Type 100 is allocated to CR-LDP.
			5.3 Status Code Space
			The range for Status Codes is 0x44000000 - 0x440000FF.
			Following the policies outlined in [IANA], Status Codes in the range
			0x44000000 - 0x440000FF are allocated through an IETF Consensus
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 27Internet Draft Constraint-Based LSP Setup using LDP July, 2000
			action.
			6. Security
			CR-LDP inherits the same security mechanism described in Section 4.0
			of [1] to protect against the introduction of spoofed TCP segments
			into LDP session connection streams.
			7. Acknowledgments
	The messages used to signal the CR-LSP setup are based on the work		The messages used to signal the CR-LSP setup are based on the work
	done by the [1] team.		done by the [1] team.
	The authors would also like to acknowledge the careful review and		The authors would also like to acknowledge the careful review and
	comments of Ken Hayward, Greg Wright, Geetha Brown, Brian Williams,		comments of Ken Hayward, Greg Wright, Geetha Brown, Brian Williams,
	Paul Beaubien, Matthew Yuen, Liam Casey, Ankur Anand, Adrian Farrel.		Paul Beaubien, Matthew Yuen, Liam Casey, Ankur Anand, Adrian Farrel.
	7. Intellectual Property Consideration		8. Intellectual Property Consideration
	The IETF has been notified of intellectual property rights claimed		The IETF has been notified of intellectual property rights claimed
	in regard to some or all of the specification contained in this		in regard to some or all of the specification contained in this
	document. For more information consult the online list of claimed		document. For more information consult the online list of claimed
	rights.		rights.
	8. References		9. References
	1 Andersson et al, "Label Distribution Protocol Specification"		1 Andersson et al, "Label Distribution Protocol Specification"
	work in progress (draft-ietf-mpls-ldp-05), June 1999.		work in progress (draft-ietf-mpls-ldp-08), June 2000.
	2 Callon et al, "Framework for Multiprotocol Label Switching",		2 Callon et al, "Framework for Multiprotocol Label Switching",
	work in progress (draft-ietf-mpls-framework-05), September 1999.		work in progress (draft-ietf-mpls-framework-05), September 1999.
	3 Rosen et al, "Multiprotocol Label Switching Architecture",		3 Rosen et al, "Multiprotocol Label Switching Architecture",
	work in progress (draft-ietf-mpls-arch-06), September 1999.		work in progress (draft-ietf-mpls-arch-06), August 1999.
	4 Awduche et al, "Requirements for Traffic Engineering Over		4 Awduche et al, "Requirements for Traffic Engineering Over
	MPLS", RFC 2702, September 1999.		MPLS", RFC 2702, September 1999.
	5 L. Wu, et. al., "LDP State Machine" work in progress		5 B. Gleeson, et. al., "A Framework for IP Based Virtual Private
	(draft-ietf-mpls-ldp-state-00), Feb 1999.		Networks", RFC 2764, February 2000.
	9. Author's Addresses		6 B. Jamoussi, et. al., _Applicability Statement for CR-LDP_, work
			in progress, (draft-ietf-mpls-crldp-applic-01), June 2000.
			7 S. Bradner, "Key words for use in RFCs to Indicate Requirement
			Levels_, RFC 2119, March 1997.
			8 L. Wu, et. al., "LDP State Machine", work in progress,
			(draft-ietf-mpls-ldp-state-03), January 2000.
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 28Internet Draft Constraint-Based LSP Setup using LDP July, 2000
			9 J. Ash, et. al., "LSP Modification Using CR-LDP", work in
			progress, (draft-ietf-mpls-crlsp-modify-01), February 2000.
			10. Author's Addresses
	Osama S. Aboul-Magd Loa Andersson		Osama S. Aboul-Magd Loa Andersson
	Nortel Networks Nortel Networks		Nortel Networks Nortel Networks
	P O Box 3511 Station C S:t Eriksgatan 115		P O Box 3511 Station C S:t Eriksgatan 115
	Ottawa, ON K1Y 4H7 PO Box 6701		Ottawa, ON K1Y 4H7 PO Box 6701
	Canada 113 85 Stockholm		Canada 113 85 Stockholm
	Phone: +1 613 763-5827 Tel: +46 8 508 835 00		Phone: +1 613 763-5827 Tel: +46 8 508 835 00
	Osama@nortelnetworks.com Fax: +46 8 508 835 01		Osama@nortelnetworks.com Fax: +46 8 508 835 01
	Loa_andersson@nortelnetworks.com		Loa_andersson@nortelnetworks.com
	Peter Ashwood-Smith Ross Callon		Peter Ashwood-Smith Ross Callon
	Nortel Networks IronBridge Networks		Nortel Networks Juniper Networks
	P O Box 3511 Station C 55 Hayden Avenue,		P O Box 3511 Station C 1194 North Mathilda Avenue,
	Ottawa, ON K1Y 4H7 Lexington, MA 02173		Ottawa, ON K1Y 4H7 Sunnyvale, CA 94089
	Canada Phone: +1-781-402-8017		Canada 978-692-6724
	Phone: +1 613 763-4534 Rcallon@ironbridgenetworks.com		Phone: +1 613 763-4534 rcallon@juniper.net
	Petera@nortelnetworks.com		Petera@nortelnetworks.com
	Ram Dantu Paul Doolan		Ram Dantu Paul Doolan
	Alcatel USA Inc. Ennovate Networks		IPmobile Ennovate Networks
			1651 North Glenville, Suite 216 330 Codman Hill Rd
	Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 26 Internet Draft Constraint-Based LSP Setup using LDP August, 1999		Richardson, TX 75081 Marlborough MA 01719
			+1-972-234-6070 extension 211 Phone: 978-263-2002
	IP Competence Center 330 Codman Hill Rd		rdantu@ipmobile.com Pdoolan@ennovatenetworks.com
	1201 E. Campbell Road.,446-315 Marlborough MA 01719
	Richadson, TX USA., 75081-2206 Phone: 978-263-2002
	Phone: 972 996 2938 Pdoolan@ennovatenetworks.com
	Fax: 972 996 5902
	Ram.dantu@alcatel.com
	Nancy Feldman Andre Fredette		Nancy Feldman Andre Fredette
	IBM Corp. Nortel Networks		IBM Corp. PhotonEx Corporation
	17 Skyline Drive 600 Technology Park Drive		17 Skyline Drive 135 South Road
	Hawthorne NY 10532 Billerica, MA 01821		Hawthorne NY 10532 Bedford, MA 01730
	Phone: 914-784-3254 978-288-8524		Phone: 914-784-3254 email: fredette@photonex.com
	Nkf@us.ibm.com Fredette@nortelnetworks.com		Nkf@us.ibm.com phone: 781-275-8500
	Eric Gray Joel M. Halpern		Eric Gray Joel M. Halpern
	Lucent Technologies, Inc Institutional Venture Partners		Zaffire, Inc Longitude Systems, Inc.
	1600 Osgood St. 650-926-5633		2630 Orchard Parkway, 1319 Shepard Road
	North Andover, MA 01847 Joel@mcquillan.com		San Jose, CA 95134-2020 Sterling, VA 20164
	Phone: 603-659-3386		Phone: 408-894-7362 703-433-0808 x207
	Ewgray@lucent.com		egray@zaffire.com joel@longsys.com
	Juha Heinanen Fiffi Hellstrand		Juha Heinanen Fiffi Hellstrand
	Telia Finland, Inc. Ericsson Telecom AB		Telia Finland, Inc. Nortel Networks
	Myyrmaentie 2 S-126 25 STOCKHOLM		Myyrmaentie 2 S:t Eriksgatan 115
	01600 VANTAA Sweden		01600 VANTAA PO Box 6701, 113 85 Stockholm
	Finland Tel: +46 8 719 4933		Finland Sweden
	Tel: +358 41 500 4808 Etxfiff@etxb.ericsson.se		Tel: +358 41 500 4808 +46705593687
	Jh@telia.fi		Jh@telia.fi fiffi@nortelnetworks.com
			Jamoussi, et. al. draft-ietf-mpls-crldp-04.txt 29Internet Draft Constraint-Based LSP Setup using LDP July 2000
	Bilel Jamoussi Timothy E. Kilty		Bilel Jamoussi Timothy E. Kilty
	Nortel Networks Corp. Northchurch Communications		Nortel Networks Corp. Newbridge Networks, Inc.
	600 Technology Park Drive 5 Corporate Drive,		600 Technology Park Drive 5 Corporate Drive
	Billerica, MA 01821 Andover, MA 018110		Billerica, MA 01821 Andover, MA 01810
	USA phone: 978 691-4656		USA USA
	Phone: +1 978 288-4506 Tkilty@northc.com		Phone: +1 978 288-4506 phone: 978 691-4656
	Jamoussi@nortelnetworks.com		Jamoussi@nortelnetworks.com tkilty@northchurch.net
	Andrew G. Malis Muckai K Girish		Andrew G. Malis Muckai K Girish
	Ascend Communications, Inc. SBC Technology Resources,		Vivace Networks Atoga Systems
	1 Robbins Road 4698 Willow Road		2730 Orchard Parkway 49026 Milmont Drive
	Westford, MA 01886 Pleasanton, CA 94588		San Jose, CA 95134 Fremont, CA 94538
	Phone: 978 952-7414 Phone: (925) 598-1263		Andy.Malis@vivacenetworks.com E-mail: muckai@atoga.com
	fax: 978 392-2074 Fax: (925) 598-1321		Tel: +1 408 383 7223
	Malis@ascend.com Mgirish@tri.sbc.com		Fax: +1 408 904 4748
	Kenneth Sundell Pasi Vaananen		Kenneth Sundell Pasi Vaananen
	Nortel Networks Nokia Telecommunications		Nortel Networks Nokia Telecommunications
	S:t Eriksgatan 115 3 Burlington Woods Drive,		S:t Eriksgatan 115 3 Burlington Woods Drive,
	PO Box 6701 Burlington, MA 01803		PO Box 6701 Burlington, MA 01803
	113 85 Stockholm Phone: +1-781-238-4981		113 85 Stockholm Phone: +1-781-238-4981
	Tel: +46 8 508 835 00 Pasi.vaanenen@ntc.nokia.com		Tel: +46 8 508 835 00 pasi.vaananen@nokia.com
	Fax: +46 8 508 835 01		Fax: +46 8 508 835 01
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 27 Internet Draft Constraint-Based LSP Setup using LDP August, 1999
	Ksundell@nortelnetworks.com		Ksundell@nortelnetworks.com
	Tom Worster Liwen Wu		Tom Worster Liwen Wu
	Nokia Alcatel U.S.A		Ennovate Networks Cisco Systems
	3 Burlington Woods Dr. 44983 Knoll Square		60 Codman Hill Rd 250 Apollo Drive
	Suite 250 Ashburn, Va. 20147		Boxborough Chelmsford, MA. 01824
	Burlington MA 01803 USA Phone: (703) 724-2619		MA 01719 Tel: 978-244-3087.
	+1 617 247 2624 FAX: (703) 724-2005		tworster@ennovatenetworks.com liwwu@cisco.com
	Tom.worster@nokia.com Liwen.wu@and.alcatel.com
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 28 Internet Draft Constraint-Based LSP Setup using LDP August, 1999		Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 30Internet Draft Constraint-Based LSP Setup using LDP July 2000
	Appendix A: CR-LSP Establishment Examples		Appendix A: CR-LSP Establishment Examples
	A.1 Strict Explicit Route Example		A.1 Strict Explicit Route Example
	This appendix provides an example for the setup of a strictly routed		This appendix provides an example for the setup of a strictly routed
	CR-LSP. In this example, a specific node represents each abstract		CR-LSP. In this example, a specific node represents each abstract
	node.		node.
	The sample network used here is a four node network with two edge		The sample network used here is a four node network with two edge
	skipping to change at line 1498		skipping to change at line 1627
	Also, LSR2 is not a member of the abstract node described by the		Also, LSR2 is not a member of the abstract node described by the
	first ER-Hop <b>.		first ER-Hop <b>.
	Finally, the first ER-Hop <b> is a strict hop.		Finally, the first ER-Hop <b> is a strict hop.
	Therefore, processing section 4.8.2 does not result in the insertion		Therefore, processing section 4.8.2 does not result in the insertion
	of new ER-Hops. The selection of the next hop has been already done		of new ER-Hops. The selection of the next hop has been already done
	is step 4 of Section 4.8.1 and the processing of the ER-TLV is		is step 4 of Section 4.8.1 and the processing of the ER-TLV is
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 29 Internet Draft Constraint-Based LSP Setup using LDP August, 1999		Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 31Internet Draft Constraint-Based LSP Setup using LDP July 2000
	completed at LSR2. In this case, the Label Request Message including		completed at LSR2. In this case, the Label Request Message including
	the ER-TLV <b, c> is progressed by LSR2 to LSR3.		the ER-TLV <b, c> is progressed by LSR2 to LSR3.
	At LSR3, a similar processing to the ER-TLV takes place except that		At LSR3, a similar processing to the ER-TLV takes place except that
	the incoming ER-TLV = <b, c> and the outgoing ER-TLV is <c>.		the incoming ER-TLV = <b, c> and the outgoing ER-TLV is <c>.
	At LSR4, the following processing of section 4.8.1 takes place:		At LSR4, the following processing of section 4.8.1 takes place:
	1) The node LSR4 is part of the abstract node described by the		1) The node LSR4 is part of the abstract node described by the
	skipping to change at line 1553		skipping to change at line 1682
	The ingress LSR uses information provided by the management system		The ingress LSR uses information provided by the management system
	or the application and possibly also information from the routing		or the application and possibly also information from the routing
	database to calculate the explicit route and to create the Label		database to calculate the explicit route and to create the Label
	Request Message.		Request Message.
	The Label request message carries together with other necessary		The Label request message carries together with other necessary
	information an ER-TLV defining the explicitly routed path. In our		information an ER-TLV defining the explicitly routed path. In our
	example the list of hops in the ER-Hop TLV is supposed to contain an		example the list of hops in the ER-Hop TLV is supposed to contain an
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 30 Internet Draft Constraint-Based LSP Setup using LDP August, 1999		Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 32Internet Draft Constraint-Based LSP Setup using LDP July 2000
	abstract node representing a group of nodes, an abstract node		abstract node representing a group of nodes, an abstract node
	representing a specific node, another abstract node representing a		representing a specific node, another abstract node representing a
	group of nodes, and an abstract node representing a specific egress		group of nodes, and an abstract node representing a specific egress
	point.		point.
	In--{Group 1}--{Specific A}--{Group 2}--{Specific Out: B}		In--{Group 1}--{Specific A}--{Group 2}--{Specific Out: B}
	The ER-TLV contains four ER-Hop TLVs:		The ER-TLV contains four ER-Hop TLVs:
	1. An ER-Hop TLV that specifies a group of LSR valid for the		1. An ER-Hop TLV that specifies a group of LSR valid for the
	skipping to change at line 1606		skipping to change at line 1735
	is not the specific node (A) in the second ER-Hop TLV.		is not the specific node (A) in the second ER-Hop TLV.
	Further it realizes that the specific node (A) is one of its		Further it realizes that the specific node (A) is one of its
	next hops.		next hops.
	5. It removes the first ER-Hop TLVs and sends a Label Request		5. It removes the first ER-Hop TLVs and sends a Label Request
	Message to the specific node (A).		Message to the specific node (A).
	6. The specific node (A) recognizes itself in the first ER-Hop		6. The specific node (A) recognizes itself in the first ER-Hop
	TLV. Removes the specific ER-Hop TLV.		TLV. Removes the specific ER-Hop TLV.
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 31 Internet Draft Constraint-Based LSP Setup using LDP August, 1999		Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 33Internet Draft Constraint-Based LSP Setup using LDP July 2000
	7. It sends a Label Request Message to a node that is a member		7. It sends a Label Request Message to a node that is a member
	of the group (Group 2) indicated in the ER-Hop TLV.		of the group (Group 2) indicated in the ER-Hop TLV.
	8. The node that receives the message identifies itself as part		8. The node that receives the message identifies itself as part
	of the group indicated in the first ER-Hop TLV, further it		of the group indicated in the first ER-Hop TLV, further it
	realizes that the specific egress node (B) is one of its		realizes that the specific egress node (B) is one of its
	next hops.		next hops.
	9. It sends a Label Request Message to the specific egress node		9. It sends a Label Request Message to the specific egress node
	skipping to change at line 1620		skipping to change at line 1749
	8. The node that receives the message identifies itself as part		8. The node that receives the message identifies itself as part
	of the group indicated in the first ER-Hop TLV, further it		of the group indicated in the first ER-Hop TLV, further it
	realizes that the specific egress node (B) is one of its		realizes that the specific egress node (B) is one of its
	next hops.		next hops.
	9. It sends a Label Request Message to the specific egress node		9. It sends a Label Request Message to the specific egress node
	(B).		(B).
	10.The specific egress node (B) recognizes itself as the egress		10.The specific egress node (B) recognizes itself as the egress
	for the CR-LSP, it returns a Label Mapping Message, that		for the CR-LSP, it returns a Label Mapping Message, that
	will traverse the same path as the Label Request Message in		will traverse the same path as the Label Request Message in
	the opposite direction.		the opposite direction.
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 32 Internet Draft Constraint-Based LSP Setup using LDP August, 1999		Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 34Internet Draft Constraint-Based LSP Setup using LDP July 2000
	Appendix B. QoS Service Examples		Appendix B. QoS Service Examples
	B.1 Service Examples		B.1 Service Examples
	Construction of an end-to-end service is the result of the rules		Construction of an end-to-end service is the result of the rules
	enforced at the edge and the treatment that packets receive at the		enforced at the edge and the treatment that packets receive at the
	network nodes. The rules define the traffic conditioning actions		network nodes. The rules define the traffic conditioning actions
	that are implemented at the edge and they include policing with		that are implemented at the edge and they include policing with
	pass, mark, and drop capabilities. The edge rules are expected tobe		pass, mark, and drop capabilities. The edge rules are expected tobe
	skipping to change at line 1680		skipping to change at line 1808
	ATM-VBR.3(nrt) PCR CDVT SCR MBS 0 Unspecified drop>PCR		ATM-VBR.3(nrt) PCR CDVT SCR MBS 0 Unspecified drop>PCR
	mark>SCR,MBS		mark>SCR,MBS
	ATM-UBR PCR CDVT - - 0 Unspecified drop>PCR		ATM-UBR PCR CDVT - - 0 Unspecified drop>PCR
	ATM-GFR.1 PCR CDVT MCR MBS 0 Unspecified drop>PCR		ATM-GFR.1 PCR CDVT MCR MBS 0 Unspecified drop>PCR
	ATM-GFR.2 PCR CDVT MCR MBS 0 Unspecified drop>PCR		ATM-GFR.2 PCR CDVT MCR MBS 0 Unspecified drop>PCR
	mark>MCR,MFS		mark>MCR,MFS
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 33 Internet Draft Constraint-Based LSP Setup using LDP August, 1999		Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 35Internet Draft Constraint-Based LSP Setup using LDP July 2000
	int-serv-CL p m r b 0 Frequent drop>p		int-serv-CL p m r b 0 Frequent drop>p
	drop>r,b		drop>r,b
	S= User specified		S= User specified
	In the above table, the DS refers to a delay sensitive service where		In the above table, the DS refers to a delay sensitive service where
	the network commits to deliver with high probability user datagrams		the network commits to deliver with high probability user datagrams
	at a rate of PDR with minimum delay and delay requirements.		at a rate of PDR with minimum delay and delay requirements.
	Datagrams in excess of PDR will be discarded.		Datagrams in excess of PDR will be discarded.
	skipping to change at line 1732		skipping to change at line 1860
	the edge. The specification of those actions is expected to be a		the edge. The specification of those actions is expected to be a
	part of the service level agreement (SLA) negotiation and is not		part of the service level agreement (SLA) negotiation and is not
	included in the signaling protocol. For DS service, the edge action		included in the signaling protocol. For DS service, the edge action
	is to drop packets that exceed the PDR and the PBS specifications.		is to drop packets that exceed the PDR and the PBS specifications.
	The signaling message will be sent in the direction of the ER path		The signaling message will be sent in the direction of the ER path
	and the LSP is established following the normal LDP procedures. Each		and the LSP is established following the normal LDP procedures. Each
	LSR applies its admission control rules. If sufficient resources are		LSR applies its admission control rules. If sufficient resources are
	not available and the parameter values are subject to negotiation,		not available and the parameter values are subject to negotiation,
	then the LSR could negotiate down the PDR, the PBS, or both.		then the LSR could negotiate down the PDR, the PBS, or both.
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 34 Internet Draft Constraint-Based LSP Setup using LDP August, 1999		Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 36Internet Draft Constraint-Based LSP Setup using LDP July 2000
	The new parameter values are echoed back in the Label Mapping		The new parameter values are echoed back in the Label Mapping
	Message. LSRs might need to re-adjust their resource reservations		Message. LSRs might need to re-adjust their resource reservations
	based on the new traffic parameter values.		based on the new traffic parameter values.
	B.3 Establishing CR-LSP Supporting Delay Insensitive Applications		B.3 Establishing CR-LSP Supporting Delay Insensitive Applications
	In this example we assume that a throughput sensitive (TS) service		In this example we assume that a throughput sensitive (TS) service
	is requested. For resource allocation the user assigns values for		is requested. For resource allocation the user assigns values for
	PDR, PBS, CDR, and CBS. The negotiation flag is set if the traffic		PDR, PBS, CDR, and CBS. The negotiation flag is set if the traffic
	skipping to change at line 1763		skipping to change at line 1891
	high discard precedence values for all packets that exceed CDR and		high discard precedence values for all packets that exceed CDR and
	the CBS. The edge rules will also include dropping of packets that		the CBS. The edge rules will also include dropping of packets that
	conform to neither PDR nor PBS.		conform to neither PDR nor PBS.
	Each LSR of the LSP is expected to run its admission control rules		Each LSR of the LSP is expected to run its admission control rules
	and negotiate traffic parameters down if sufficient resources do not		and negotiate traffic parameters down if sufficient resources do not
	exist. The new parameter values are echoed back in the Label Mapping		exist. The new parameter values are echoed back in the Label Mapping
	Message. LSRs might need to re-adjust their resources based on the		Message. LSRs might need to re-adjust their resources based on the
	new traffic parameter values.		new traffic parameter values.
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 35 Internet Draft Constraint-Based LSP Setup using LDP August, 1999		Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 37Internet Draft Constraint-Based LSP Setup using LDP July 2000
	Appendix C. LSP Modification Using CR-LDP
	After a CR-LSP is set up, its bandwidth reservation may need to be
	changed by the network operator, due to the new requirements for the
	traffic carried on that CR-LSP. This contribution presents an
	approach to modify the bandwidth and possibly other parameters of an
	established CR-LSP using CR-LDP without service interruption. The
	LSP modification feature can be supported by CR-LDP with a minor
	extension of an _action indicator flag_. This feature has
	application in dynamic network resources management where traffic of
	different priorities and service classes is involved.
	Conventions used in this Appendix:
	L: LSP (Label Switched Path)
	Lid: LSPID (LSP Identifier)
	T: Traffic Parameters
	R: LSR (Label Switching Router)
	FTN: FEC To NHLFE
	FEC: Forwarding Equivalence Class
	NHLFE: Next Hop Label Forwarding Entity
	TLV: Type Length Value
	C.1 Introduction
	Consider an LSP L1 that has been established with its set of traffic
	parameters T0. A certain amount of bandwidth is reserved along the
	path of L1. Consider then that some changes are required on L1. For
	example, the bandwidth of L1 needs to be increased to accommodate
	the increased traffic on L1. Or the SLA associated with L1 needs to
	be modified because a different service class is desired. The
	network operator, in these cases, would like to modify the
	characteristics of L1, for example, to change its traffic parameter
	set from T0 to T1, without releasing the LSP L1 to interrupt the
	service. In some other cases, network operators may want to reroute
	a CR-LSP to a different path for either improved performance or
	better network resource utilization. In all these cases, LSP
	modification is required. In section C.2 below, a method to modify
	an active LSP using CR-LDP is presented. The concept of LSPID in CR-
	LDP is used to achieve the LSP modification, without releasing the
	LSP and interrupting the service and, without double booking the
	bandwidth. Only a minimum extension on CR-LDP, an action indication
	flag of _modify_ is needed in order to explicitly specify the
	behavior, and allow the existing LSPID to support other networking
	capabilities in the future. Section 4.5 specifies the action
	indication flag of _modify_ for CR-LDP. An example is described to
	demonstrate an application of the presented method in dynamically
	managing network bandwidth requirements without interrupting
	service.
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 36 Internet Draft Constraint-Based LSP Setup using LDP August, 1999
	C.2 Basic Procedure
	LSP modification can only be allowed when the LSP is already set up
	and active. That is, modification is not defined nor allowed during
	the LSP establishment or label release/withdraw phases. Only
	modification requested by the ingress LSR of the LSP is considered
	in this draft for CR-LSP. Ingress LSR cannot modify an LSP before a
	previous modification procedure is completed.
	Assume that CR-LSP L1 is set up with LSPID L-id1, which is unique in
	the MPLS network. The ingress LSR R1 of L1 has in its FTN (FEC To
	NHLFE) table FEC1 -> Label A mapping where A is the outgoing label
	for LSP L1. To modify the characteristics of L1, R1 sends a Label
	Request Message. In the messages, the TLVs will have the new
	requested values, and the LSPID TLV is included which indicates the
	value of L-id1. The Traffic Parameters TLV, the ER-TLV, the Resource
	Class (color) TLV and the Preemption TLV can have values different
	from those in the original Label Request Message, which has been
	used to set up L1 earlier. Thus, L1 can be changed in its bandwidth
	request (traffic parameter TLV), its traffic service class (traffic
	parameter TLV), the route it traverses (ER TLV) and its setup and
	holding (Preemption TLV) priorities. The ingress LSR R1 now still
	has the entry in FTN as FEC1 -> Label A. R1 is waiting to establish
	another entry for FEC1.
	When an LSR Ri along the path of L1 receives the Label Request
	message, its behavior is the same as that of receiving any Label
	request message. The only extension is that Ri examines the LSPID
	carried in the Label Request Message, L-id1 and identifies if it
	already has L-id1. If Ri does not have L-id1, Ri behaves the same as
	receiving a new Label Request message. If Ri already has L-id1, Ri
	takes the newly received Traffic Parameter TLV and computes the new
	bandwidth required and derives the new service class. Compared with
	the already reserved bandwidth for L-id1, Ri now reserves only the
	difference of the bandwidth requirements. This prevents Ri from
	doing bandwidth double booking. If a new service class is requested,
	Ri also prepares to receive the traffic on L1 in, perhaps a
	different type of queue, just the same as handling it for a Label
	Request Message. Ri assigns a new label for the Label Request
	Message.
	When the Label Mapping message is received, two sets of labels exist
	for the same LSPID. Then the ingress LSR R1 will have two outgoing
	labels, A and B, associated with the same FEC, where B is the new
	outgoing label received for LSP L1. The ingress LSR R1 can now
	activate the new entry in FTN, FEC1 - > Label B. This means that R1
	swaps traffic on L1 to the new label _B_ (_new_ path) for L1. The
	packets can now be sent with the new label B, with the new set of
	traffic parameters if any, on a new path, that is, if a new path is
	requested in the Label Request Message for the modification. All the
	other LSRs along the path will start to receive the incoming packets
	with the new label. For the incoming new label, the LSR has already
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 37 Internet Draft Constraint-Based LSP Setup using LDP August, 1999
	established its mapping to the new outgoing label. Thus, the packets
	will be sent out with the new outgoing label. The LSRs do not have
	to implement new procedures to track the new and old
	characteristics of the LSP.
	The ingress LSR R1 then starts to release the original label A for
	LSP L1. The Label Release Message is sent by R1 towards the down
	stream LSRs. The Release message carries the LSPID of L-id1 and the
	Label TLV to indicate which label is to be released. The Release
	Message is propagated to the egress LSR to release the original
	labels previously used for L1. Upon receiving the Label Release
	Message, LSR R1 examines the LSPID, L-id1 and finds out that the L-
	id1 has still another set of label (incoming/outgoing) under it.
	Thus, the old label is released without releasing the resource in
	use. That is, if the bandwidth has been decreased for L1, the delta
	bandwidth is released. Otherwise, no bandwidth is released. This
	modification procedure can not only be applied to modify the traffic
	parameters and/or service class of an active LSP, but also to
	reroute an existing LSP, and/or change its setup/holding priority if
	desired. After the release procedure, the modification of the LSP is
	completed.
	The method described above follows the normal behavior of Label
	Request / Mapping / Notification / Release /Withdraw procedure of a
	CR-LDP operated LSR with a specific action taken on LSPID. If Label
	Withdraw Message is used to withdraw a label associated with an
	LSPID, the Label TLV should be included to specify which label to
	withdraw. Since the LSPID can also be used for other feature
	support, an action indication flag of _modify_ assigned to the LSPID
	would explicitly explain the action/semantics that should be
	associated with the messaging procedure. The details of this flag
	are addressed in Section 4.5.
	C.3 Priority Handling
	When sending a Label Request Message for an active LSP L1 to request
	changes, the setup priority used in the label Request Message can be
	different from the one used in the previous Label Request Message,
	effectively indicating the priority of this _modification_ request.
	Network operators can use this feature to decide what priority is to
	be assigned to a modification request, based on their
	policies/algorithms and other traffic situations in the network. For
	example, the priority for modification can be determined by the
	priority of the customer/LSP. If a customer has exceeded the
	reserved bandwidth of its VPN LSP tunnel by too much, the
	modification request's priority may be given higher.
	The Label Request message for the modification of an active LSP can
	also be sent with a holding priority different from its previous
	one. This effectively changes the holding priority of the LSP. Upon
	receiving a Label Request Message that requests a new holding
	priority, the LSR assigns the new holding priority to the bandwidth.
	That is, the new holding priority is assigned to both the existing
	Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 38 Internet Draft Constraint-Based LSP Setup using LDP August, 1999
	incoming / outgoing labels and the new labels to be established for
	the LSPID in question. In this way self-bumping is prevented.
	C.4 Modification Failure Case Handling
	A modification attempt may fail due to insufficient resource or
	other situations. A Notification message is sent back to the ingress
	LSR R1 to indicate the failure of Label Request Message that
	intended to modify the LSP. Retry may be attempted if desired by the
	network operator.
	If the LSP on the original path failed when a modification attempt
	is in progress, the attempt should be aborted by using the Label
	Abort Request message as specified in LDP draft.
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