draft-ietf-mpls-3209-patherr-01.txt		draft-ietf-mpls-3209-patherr-02.txt
	Networking Working Group JP. Vasseur, Ed.		Networking Working Group JP. Vasseur, Ed.
	Internet-Draft George. Swallow		Internet-Draft George. Swallow
	Intended status: Best Current Cisco Systems, Inc		Intended status: Best Current Cisco Systems, Inc
	Practice Adrian. Farrel		Practice Ina. Minei
	Expires: August 11, 2008 Old Dog Consulting		Expires: August 21, 2008 Juniper Networks
	Ina. Minei		February 18, 2008
	Juniper Networks
	February 8, 2008
	Node behavior upon originating and receiving Resource ReserVation		Node behavior upon originating and receiving Resource ReserVation
	Protocol (RSVP) Path Error message		Protocol (RSVP) Path Error message
	draft-ietf-mpls-3209-patherr-01.txt		draft-ietf-mpls-3209-patherr-02.txt
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		applicable patent or other IPR claims of which he or she is aware
	have been or will be disclosed, and any of which he or she becomes		have been or will be disclosed, and any of which he or she becomes
	aware will be disclosed, in accordance with Section 6 of BCP 79.		aware will be disclosed, in accordance with Section 6 of BCP 79.
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	skipping to change at page 1, line 39		skipping to change at page 1, line 37
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	This Internet-Draft will expire on August 11, 2008.		This Internet-Draft will expire on August 21, 2008.
	Copyright Notice		Copyright Notice
	Copyright (C) The IETF Trust (2008).		Copyright (C) The IETF Trust (2008).
	Abstract		Abstract
	The aim of this document is to describe a common practice with regard		The aim of this document is to describe a common practice with regard
	to the behavior of a node sending a Resource ReserVation Protocol		to the behavior of a node sending a Resource ReserVation Protocol
	(RSVP) Traffic Engineering (TE) Path Error message and to the		(RSVP) Traffic Engineering (TE) Path Error message and to the
	skipping to change at page 2, line 17		skipping to change at page 2, line 15
	protocol extensions.		protocol extensions.
	Requirements Language		Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	Table of Contents		Table of Contents
	1. Protocol behavior . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.1. Behavior at Detecting Nodes . . . . . . . . . . . . . . . . 4		2. Protocol behavior . . . . . . . . . . . . . . . . . . . . . . . 3
	1.2. Behavior at Receiving Nodes . . . . . . . . . . . . . . . . 4		2.1. Behavior at Detecting Nodes . . . . . . . . . . . . . . . . 4
	1.3. Data Plane Behavior . . . . . . . . . . . . . . . . . . . . 5		2.2. Behavior at Receiving Nodes . . . . . . . . . . . . . . . . 5
	2. RSVP PathErr Messages For a Preempted TE LSP . . . . . . . . . 5		2.3. Data Plane Behavior . . . . . . . . . . . . . . . . . . . . 5
	3. Security Considerations . . . . . . . . . . . . . . . . . . . . 5		3. RSVP PathErr Messages For a Preempted TE LSP . . . . . . . . . 5
	4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5		4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
	5. Normative References . . . . . . . . . . . . . . . . . . . . . 6		5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
			6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
			7. Normative References . . . . . . . . . . . . . . . . . . . . . 6
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
	Intellectual Property and Copyright Statements . . . . . . . . . . 8		Intellectual Property and Copyright Statements . . . . . . . . . . 8
	1. Protocol behavior		1. Introduction
			The aim of this document is to describe a common practice with regard
			to the behavior of a node sending a Resource ReserVation Protocol
			(RSVP) Traffic Engineering (TE) Path Error message and to the
			behavior of a node receiving an RSVP Path Error message for a
			preempted Multi-Protocol Label Switching (MPLS) Traffic Engineering
			Label Switched Path (TE LSP).
	[RFC2205] defines two RSVP error message types: PathErr and ResvErr		[RFC2205] defines two RSVP error message types: PathErr and ResvErr
	that are generated when an error occurs. Path Error Messages		that are generated when an error occurs. Path Error Messages
	(PathErr) are used to report errors and travel upstream toward the		(PathErr) are used to report errors and travel upstream toward the
	head-end of the flow. Resv Error messages (ResvErr) travel		head-end of the flow. Resv Error messages (ResvErr) travel
	downstream toward the tail-end of the flow.		downstream toward the tail-end of the flow.
	This document describes only PathErr message processing for the		This document describes only PathErr message processing for the
	specific case of a preempted Traffic Engineering Label Switched Path		specific case of a preempted Traffic Engineering Label Switched Path
	(TE LSP) where the term preemption is defined in [RFC3209]. PathErr		(TE LSP) where the term preemption is defined in [RFC3209].
	messages are routed hop-by-hop using the path state established when
	a Path message is routed through the network from the head-end to its		2. Protocol behavior
	tail-end.
			PathErr messages are routed hop-by-hop using the path state
			established when a Path message is routed through the network from
			the head-end to its tail-end.
	As stated in [RFC2205], PathErr messages do not modify the state of		As stated in [RFC2205], PathErr messages do not modify the state of
	any node through which they pass; they are only reported to the head-		any node through which they pass; they are only reported to the head-
	end of the TE LSP (Traffic Engineering Label Switched Path).		end of the TE LSP (Traffic Engineering Label Switched Path).
	The format of the PathErr message as defined in [RFC2205] is as		The format of the PathErr message as defined in [RFC2205] is as
	follows:		follows:
	<PathErr message> ::= <Common Header> [ <INTEGRITY> ]		<PathErr message> ::= <Common Header> [ <INTEGRITY> ]
	<SESSION> <ERROR_SPEC>		<SESSION> <ERROR_SPEC>
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	o After a TE LSP has been successfully established.		o After a TE LSP has been successfully established.
	Nodal behavior is dependent on which combination of the four cases		Nodal behavior is dependent on which combination of the four cases
	listed above applies. The following sections describe the expected		listed above applies. The following sections describe the expected
	behavior at nodes that perform a preemption action for a TE LSP (and		behavior at nodes that perform a preemption action for a TE LSP (and
	therefore report using error PathErr messages), and at nodes that		therefore report using error PathErr messages), and at nodes that
	receive PathErr messages. This text is a clarification and re-		receive PathErr messages. This text is a clarification and re-
	statement of the procedures set out in [RFC3209] and does not define		statement of the procedures set out in [RFC3209] and does not define
	any new behavior.		any new behavior.
	1.1. Behavior at Detecting Nodes		2.1. Behavior at Detecting Nodes
	In the case of fatal errors, the detecting node must send a PathErr		In the case of fatal errors, the detecting node must send a PathErr
	message reporting the error condition, and must clear the		message reporting the error condition, and must clear the
	corresponding Path and Resv (control plane) states. A direct		corresponding Path and Resv (control plane) states. A direct
	implication is that the data plane resources of such a TE LSP are		implication is that the data plane resources of such a TE LSP are
	also released, thus resulting in traffic disruption. It should be		also released, thus resulting in traffic disruption. It should be
	noted, however, that in fatal error cases, the LSP has usually		noted, however, that in fatal error cases, the LSP has usually
	already failed in the data plane, and traffic has already been		already failed in the data plane, and traffic has already been
	disrupted. When the error arises during LSP establishment, the		disrupted. When the error arises during LSP establishment, the
	implications are different to when it arises on an active LSP since		implications are different to when it arises on an active LSP since
	no traffic flows until the LSP has been fully established. In the		no traffic flows until the LSP has been fully established. In the
	case of non-fatal errors, the detecting node should send a PathErr		case of non-fatal errors, the detecting node should send a PathErr
	message, and must not clear control plane or data plane state.		message, and must not clear control plane or data plane state.
	1.2. Behavior at Receiving Nodes		2.2. Behavior at Receiving Nodes
	Nodes that receive PathErr messages are all of the nodes along the		Nodes that receive PathErr messages are all of the nodes along the
	path of the TE LSP upstream of the node that detected the error.		path of the TE LSP upstream of the node that detected the error.
	This includes the head-end node. In accordance with [RFC2205] a node		This includes the head-end node. In accordance with [RFC2205] a node
	receiving a PathErr message takes no action upon it and consequently		receiving a PathErr message takes no action upon it and consequently
	it must not clear Path or Resv control plane or data plane state.		it must not clear Path or Resv control plane or data plane state.
	This is true regardless of whether the error condition reported by		This is true regardless of whether the error condition reported by
	the PathErr is fatal or non-fatal. RSVP states should only be		the PathErr is fatal or non-fatal. RSVP states should only be
	affected upon receiving a PathTear or ResvTear message, or in the		affected upon receiving a PathTear or ResvTear message, or in the
	event of a Path or Resv state timeout. Further discussion of the		event of a Path or Resv state timeout. Further discussion of the
	processing of these events is outside the scope of this document.		processing of these events is outside the scope of this document.
	Note that [RFC3473] defines a Path_State_Removed flag in the		Note that [RFC3473] defines a Path_State_Removed flag in the
	ERROR_SPEC object carried on a PathErr message. This field may be		ERROR_SPEC object carried on a PathErr message. This field may be
	set to change the behavior of upstream nodes that receive the PathErr		set to change the behavior of upstream nodes that receive the PathErr
	message. When set, the flag indicates that the message sender has		message. When set, the flag indicates that the message sender has
	removed Path state (and any associated Resv and data plane state) for		removed Path state (and any associated Resv and data plane state) for
	the TE LSP. The message receiver should do likewise before		the TE LSP. The message receiver should do likewise before
	forwarding the message, but may retain state and clear the flag		forwarding the message, but may retain state and clear the flag
	before forwarding the message.		before forwarding the message.
	1.3. Data Plane Behavior		2.3. Data Plane Behavior
	Any node clearing either or both the Path or the Resv state of a TE		Any node clearing either or both the Path or the Resv state of a TE
	LSP MUST also free up the data plane resources allocated to the		LSP MUST also free up the data plane resources allocated to the
	corresponding TE LSP.		corresponding TE LSP.
	2. RSVP PathErr Messages For a Preempted TE LSP		3. RSVP PathErr Messages For a Preempted TE LSP
	Two Error-code can be used to report a preempted TE LSPs:		Two Error-code can be used to report a preempted TE LSPs:
	o As defined in [RFC2750]:Error Code=2: "Policy Control Failure",		o As defined in [RFC2750]:Error Code=2: "Policy Control Failure",
	Error Value=5 "Flow was preempted"		Error Value=5 "Flow was preempted"
	o As defined in [RFC2205], Error Code=12: "Service preempted"		o As defined in [RFC2205], Error Code=12: "Service preempted"
	In both cases, these are fatal errors.		In both cases, these are fatal errors.
	3. Security Considerations		4. IANA Considerations
			This document does not define any new protocol extensions and thus no
			action is requested to IANA.
			5. Security Considerations
	This document does not define any new procedures, but clarifies those		This document does not define any new procedures, but clarifies those
	defined in other documents where security considerations are already		defined in other documents where security considerations are already
	specified. This document does not raise specific security issues		specified. This document does not raise specific security issues
	beyond those of existing MPLS-TE. By clarifying the procedures, this		beyond those of existing MPLS-TE. By clarifying the procedures, this
	document reduces the security risk introduced by non-conformant		document reduces the security risk introduced by non-conformant
	implementations.		implementations.
	4. Acknowledgements		6. Acknowledgements
	The author would like to thank Carol Iturralde, Ashok Narayanan, Rom		The author would like to thank Carol Iturralde, Ashok Narayanan, Rom
	Reuther and Reshad Rahman.		Reuther and Reshad Rahman.
	5. Normative References		7. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.		[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
	Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1		Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
	Functional Specification", RFC 2205, September 1997.		Functional Specification", RFC 2205, September 1997.
	[RFC2750] Herzog, S., "RSVP Extensions for Policy Control",		[RFC2750] Herzog, S., "RSVP Extensions for Policy Control",
	RFC 2750, January 2000.		RFC 2750, January 2000.
	skipping to change at page 6, line 34		skipping to change at page 7, line 4
	Authors' Addresses		Authors' Addresses
	JP Vasseur (editor)		JP Vasseur (editor)
	Cisco Systems, Inc		Cisco Systems, Inc
	1414 Massachusetts Avenue		1414 Massachusetts Avenue
	Boxborough, MA 01719		Boxborough, MA 01719
	USA		USA
	Email: jpv@cisco.com		Email: jpv@cisco.com
	George Swallow		George Swallow
	Cisco Systems, Inc		Cisco Systems, Inc
	1414 Massachusetts Avenue		1414 Massachusetts Avenue
	Boxborough, MA 01719		Boxborough, MA 01719
	USA		USA
	Email: swallow@cisco.com		Email: swallow@cisco.com
	Adrian Farrel
	Old Dog Consulting
	Email: adrian@olddog.co.uk
	Ina Minei		Ina Minei
	Juniper Networks		Juniper Networks
	1194 North Mathilda Ave.		1194 North Mathilda Ave.
	Sunnyvale, 94089		Sunnyvale, 94089
	Email: ina@juniper.net		Email: ina@juniper.net
	Full Copyright Statement		Full Copyright Statement
	Copyright (C) The IETF Trust (2008).		Copyright (C) The IETF Trust (2008).
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