draft-ietf-mpls-tp-1ton-protection-01.txt		draft-ietf-mpls-tp-1ton-protection-02.txt
	Network Working Group E. Osborne		Network Working Group E. Osborne
	Internet-Draft Cisco		Internet-Draft Cisco
	Intended status: Standards Track F. Zhang		Intended status: Standards Track F. Zhang
	Expires: August 8, 2013 ZTE		Expires: February 7, 2014 ZTE
	Y. Weingarten		Y. Weingarten
	February 4, 2013		August 6, 2013
	MPLS-TP 1toN Protection		MPLS-TP 1toN Protection
	draft-ietf-mpls-tp-1ton-protection-01.txt		draft-ietf-mpls-tp-1ton-protection-02.txt
	Abstract		Abstract
	As part of the Transport Profile for Multiprotocol Label Switching		There is a requirement for Multiprotocol Label Switching Transport
	(MPLS-TP) there is a requirement to support 1:n linear protection for		Profile(MPLS-TP) to support 1:n linear protection for transport
	transport paths. This requirement is further elaborated in RFC6372		paths. This requirement is further elaborated in RFC6372
	[SurvivFwk]. The basic protocol for linear protection, specified in		[SurvivFwk]. The basic protocol for linear protection, specified in
	RFC6378 [LinProt], is limited to 1+1 and 1:1 protection. This		RFC6378 [LinProt], is limited to 1+1 and 1:1 protection. This
	document extends that protocol to address the additional		document extends that protocol to address the additional
	functionality necessary to support scenarios where a single		functionality necessary to support scenarios where a single
	protection path is preconfigured to provide protection of multiple		protection path is preconfigured to provide protection of multiple
	transport paths between two joint endpoints.		transport paths between two joint endpoints.
	This document is a product of a joint Internet Engineering Task Force		This document is a product of a joint Internet Engineering Task Force
	(IETF) / International Telecommunications Union Telecommunications		(IETF) / International Telecommunications Union Telecommunications
	Standardization Sector (ITU-T) effort to include an MPLS Transport		Standardization Sector (ITU-T) effort to include an MPLS Transport
	skipping to change at page 1, line 47		skipping to change at page 1, line 47
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on August 8, 2013.		This Internet-Draft will expire on February 7, 2014.
	Copyright Notice		Copyright Notice
	Copyright (c) 2013 IETF Trust and the persons identified as the		Copyright (c) 2013 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	skipping to change at page 7, line 17		skipping to change at page 7, line 17
	In non-locking protection operation mode, LER-A switches data traffic		In non-locking protection operation mode, LER-A switches data traffic
	onto P immediately upon failure detection. This minimizes traffic		onto P immediately upon failure detection. This minimizes traffic
	loss, but at the cost of temporary asymmetry of packet flow. At a		loss, but at the cost of temporary asymmetry of packet flow. At a
	high level, it works like this:		high level, it works like this:
	o LER-A detects the failure of W1 and stops sending traffic on W1.		o LER-A detects the failure of W1 and stops sending traffic on W1.
	o LER-A immediately begins to transport W1's data traffic over the		o LER-A immediately begins to transport W1's data traffic over the
	protection path P.		protection path P.
	o Simultaneously LER-A transmitts a PSC message to LER-Z indicating		o Simultaneously LER-A transmits a PSC message to LER-Z indicating
	that W1 has failed and is currently being protected in P.		that W1 has failed and is currently being protected in P.
	o LER-Z receives the PSC message from LER-A, switches all W1 data		o LER-Z receives the PSC message from LER-A, switches all W1 data
	traffic to P, and transmits a PSC message to LER-A indicating that		traffic to P, and transmits a PSC message to LER-A indicating that
	W1 is now protected in P.		W1 is now protected in P.
	o LER-A receives the PSC message from LER-Z and needs to take no		o LER-A receives the PSC message from LER-Z and needs to take no
	action, as the protection switch had already been completed.		action, as the protection switch had already been completed.
	In the non-locking case, the packet loss between the endpoints is		In the non-locking case, the packet loss between the endpoints is
	skipping to change at page 9, line 35		skipping to change at page 9, line 35
	2.2. Definitions and Terminology		2.2. Definitions and Terminology
	The terminology used in this document is based on the terminology		The terminology used in this document is based on the terminology
	defined in [RFC4427] and further adapted for MPLS-TP in [SurvivFwk].		defined in [RFC4427] and further adapted for MPLS-TP in [SurvivFwk].
	In addition, we use the term LER to refer to a MPLS Network Element,		In addition, we use the term LER to refer to a MPLS Network Element,
	whether it is a LSR, LER, T-PE, or S-PE.		whether it is a LSR, LER, T-PE, or S-PE.
	3. Use cases and scenarios		3. Use cases and scenarios
	This section presents some use-cases and scenarios that should		This section presents some use-cases and scenarios that should
	illucidate the use of PSC for 1:n protection.		elucidate the use of PSC for 1:n protection.
	3.1. Non-locking use case: Per-node label space		3.1. Non-locking use case: Per-node label space
	Non-locking protection can be used when the payload that is received		Non-locking protection can be used when the payload that is received
	from the protection path is unambiguous and can be properly forwarded		from the protection path is unambiguous and can be properly forwarded
	without the need to explicitly establish selector and bridge		without the need to explicitly establish selector and bridge
	configuration at the time of failure. One example where this applies		configuration at the time of failure. One example where this applies
	is when the endpoints of the protection domain are using per-platform		is when the endpoints of the protection domain are using per-platform
	label space [RFC3031].		label space [RFC3031].
	skipping to change at page 27, line 25		skipping to change at page 27, line 25
	protection path is available to switch the traffic from working		protection path is available to switch the traffic from working
	path W2.		path W2.
	4.3.4. Wait for Acknowledge (WFA) timer		4.3.4. Wait for Acknowledge (WFA) timer
	The protection system MUST include a timer called the Wait for		The protection system MUST include a timer called the Wait for
	Acknowledge (WFA) timer that SHALL be started when the LER enters WFA		Acknowledge (WFA) timer that SHALL be started when the LER enters WFA
	state and reset when the Acknowledge message is received. The length		state and reset when the Acknowledge message is received. The length
	of the WFA timer SHOULD be configured to allow protection switching		of the WFA timer SHOULD be configured to allow protection switching
	within the normal time constraints. The WFA timer will expire only		within the normal time constraints. The WFA timer will expire only
	if no Acknowledge message was recieved by the LER in WFA state. The		if no Acknowledge message was received by the LER in WFA state. The
	WFA Expires local input should have a priority just below that of the		WFA Expires local input should have a priority just below that of the
	WTRExpires signal.		WTRExpires signal.
	4.3.5. Additional PSC State		4.3.5. Additional PSC State
	As described above and demonstrated in the scenarios in Section 3.3,		As described above and demonstrated in the scenarios in Section 3.3,
	there is a need, in some scenarios, for the endpoint that is		there is a need, in some scenarios, for the endpoint that is
	reporting a trigger for protection-switching to delay the actual		reporting a trigger for protection-switching to delay the actual
	switchover until an acknowledge is received from the far end LER. In		switch-over until an acknowledge is received from the far end LER.
	order to facilitate this wait period it is necessary to define a new		In order to facilitate this wait period it is necessary to define a
	PSC State - Wait for Acknowledge (WFA) state. WFA is used in both		new PSC State - Wait for Acknowledge (WFA) state. WFA is used in
	the Locking and Non-Locking cases. It is more essential to the		both the Locking and Non-Locking cases. It is more essential to the
	Locking mode of operation, as agreement is the mechanism to establish		Locking mode of operation, as agreement is the mechanism to establish
	and release the lock on the protection LSP. However, it is necessary		and release the lock on the protection LSP. However, it is necessary
	for the Non-Locking mode as a persistent disagreement on the contents		for the Non-Locking mode as a persistent disagreement on the contents
	of the protection LSP indicates an error in the network devices and		of the protection LSP indicates an error in the network devices and
	WFA is the method used to detect this error.		WFA is the method used to detect this error.
	In the locking mode, WFA comes into play when a failed LSP preempts		In the locking mode, WFA comes into play when a failed LSP preempts
	another LSP. This is highlighted in the scenarios presented in		another LSP. This is highlighted in the scenarios presented in
	Figure 7 & Figure 9.		Figure 7 & Figure 9.
	skipping to change at page 29, line 9		skipping to change at page 29, line 9
	protected working path, i.e. the highest priority working path		protected working path, i.e. the highest priority working path
	indicating an SF condition]. If the LER is in WFA state due to		indicating an SF condition]. If the LER is in WFA state due to
	any other trigger, then begin transmitting a SF(x, 0) PSC message		any other trigger, then begin transmitting a SF(x, 0) PSC message
	[where x indicates the index of the working path that is		[where x indicates the index of the working path that is
	generating the SF condition].		generating the SF condition].
	o A local ClearSF indication where the working path is the same as		o A local ClearSF indication where the working path is the same as
	the path that triggered the LER into WFA state SHALL cause the LER		the path that triggered the LER into WFA state SHALL cause the LER
	to go into WTR state (note: 1:N protection is always revertive)		to go into WTR state (note: 1:N protection is always revertive)
	and to transmit the WTR(0, 0) message. If the ClearSF indicates a		and to transmit the WTR(0, 0) message. If the ClearSF indicates a
	different index from the protected working path or incates the		different index from the protected working path or indicates the
	protection path then the indication SHALL be ignored.		protection path then the indication SHALL be ignored.
	o A local MS operator command SHALL cause the LER to remain in WFA		o A local MS operator command SHALL cause the LER to remain in WFA
	state. If the LER is in WFA state due an existing MS trigger,		state. If the LER is in WFA state due an existing MS trigger,
	then the node continues to transmit MS(x, 0) messages [where x		then the node continues to transmit MS(x, 0) messages [where x
	indicates the index of the protected working path, i.e. the		indicates the index of the protected working path, i.e. the
	highest prirority working path indicating the MS condition]. If		highest priority working path indicating the MS condition]. If
	the LER is in WFA state due to any other trigger, ignore the MS		the LER is in WFA state due to any other trigger, ignore the MS
	command and continue transmitting the current message.		command and continue transmitting the current message.
	o If the WFA timer expires, i.e. the LER did not receive the		o If the WFA timer expires, i.e. the LER did not receive the
	Acknowledge message from the far end in a timely manner, then the		Acknowledge message from the far end in a timely manner, then the
	LER SHALL go to Unavailable state, i.e. it assumes that there is a		LER SHALL go to Unavailable state, i.e. it assumes that there is a
	problem on the protection path (where all PSC traffic is		problem on the protection path (where all PSC traffic is
	transmitted) and send an error notification to the management		transmitted) and send an error notification to the management
	system. The LER SHALL continue transmitting the current PSC		system. The LER SHALL continue transmitting the current PSC
	message with Path field set to 0.		message with Path field set to 0.
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	FS message and remain in WFA state. If the remote FS message		FS message and remain in WFA state. If the remote FS message
	indicates an index of higher priority or the LER is in WFA state		indicates an index of higher priority or the LER is in WFA state
	as a result of a SF or MS trigger, then the LER SHALL perform the		as a result of a SF or MS trigger, then the LER SHALL perform the
	protection switch for the protected working path indicated by the		protection switch for the protected working path indicated by the
	remote FS message, and SHALL go to Protecting administrative state		remote FS message, and SHALL go to Protecting administrative state
	and transmit the appropriate message for the local trigger with		and transmit the appropriate message for the local trigger with
	the Path field set to the index of the remote message and the		the Path field set to the index of the remote message and the
	Acknowledge flag set to 1.		Acknowledge flag set to 1.
	o A remote SF message indicating an error on the protection path		o A remote SF message indicating an error on the protection path
	SHALL cause the LER to go into Unavailable stateand transmit the		SHALL cause the LER to go into Unavailable state and transmit the
	appropriate message for the trigger that caused to WFA state.		appropriate message for the trigger that caused to WFA state.
	o A remote SF message indicating an error on the same working path		o A remote SF message indicating an error on the same working path
	as the local SF condition that triggered the WFA state SHALL be		as the local SF condition that triggered the WFA state SHALL be
	considered an Acknowledge message (even if the Acknowledge flag is		considered an Acknowledge message (even if the Acknowledge flag is
	not set). The LER SHALL perform the protection switch, go to		not set). The LER SHALL perform the protection switch, go to
	Protecting failure state and transmit the SF(x, x) message [where		Protecting failure state and transmit the SF(x, x) message [where
	x is the index of the protected working path]. If the remote SF		x is the index of the protected working path]. If the remote SF
	message indicates a different index than the one indicated in the		message indicates a different index than the one indicated in the
	local SF, then if the local command indicates a higher priority		local SF, then if the local command indicates a higher priority
	skipping to change at page 36, line 37		skipping to change at page 36, line 37
	Email: eosborne@cisco.com		Email: eosborne@cisco.com
	Fei Zhang		Fei Zhang
	ZTE		ZTE
	China		China
	Email: zhang.fei3@zte.com.cn		Email: zhang.fei3@zte.com.cn
	Yaacov Weingarten		Yaacov Weingarten
	34 Hagefen St		34 Hagefen St
	Karnei Shomron, 44853		Karnei Shomron, 4485500
	Israel		Israel
	Email: wyaacov@gmail.com		Email: wyaacov@gmail.com
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