draft-cui-mpls-tp-mfp-use-case-and-requirements-05.txt		draft-cui-mpls-tp-mfp-use-case-and-requirements-06.txt
	Network Working Group Z. Cui		Network Working Group Z. Cui
	Internet-Draft R. Winter		Internet-Draft R. Winter
	Intended status: Informational NEC		Intended status: Informational NEC
	Expires: January 7, 2016 H. Shah		Expires: July 9, 2016 H. Shah
	Ciena		Ciena
	S. Aldrin		S. Aldrin
	Huawei Technologies		Huawei Technologies
	M. Daikoku		M. Daikoku
	KDDI		KDDI
	July 6, 2015		January 6, 2016
	Use Cases and Requirements for MPLS-TP multi-failure protection		Use Cases and Requirements for MPLS-TP multi-failure protection
	draft-cui-mpls-tp-mfp-use-case-and-requirements-05		draft-cui-mpls-tp-mfp-use-case-and-requirements-06
	Abstract		Abstract
	For the Multiprotocol Label Switching Transport Profile (MPLS-TP)		For the Multiprotocol Label Switching Transport Profile (MPLS-TP)
	linear protection capable of 1+1 and 1:1 protection has already been		linear protection capable of 1+1 and 1:1 protection has already been
	defined. That linear protection mechanism has not been designed for		defined. That linear protection mechanism has not been designed for
	handling multiple, simultaneously occuring failures, i.e. multiple		handling multiple, simultaneously occuring failures, i.e. multiple
	failures that affect the working and the protection entity during the		failures that affect the working and the protection entity during the
	same time period. In these situations currently defined protection		same time period. In these situations currently defined protection
	mechanisms would fail.		mechanisms would fail.
	skipping to change at page 1, line 46		skipping to change at page 1, line 46
	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 January 7, 2016.		This Internet-Draft will expire on July 9, 2016.
	Copyright Notice		Copyright Notice
	Copyright (c) 2015 IETF Trust and the persons identified as the		Copyright (c) 2016 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 3, line 20		skipping to change at page 3, line 20
	calls. Existing 1+1 or 1:n protection however is limited to cover		calls. Existing 1+1 or 1:n protection however is limited to cover
	single failures which has proven as not sufficient during past		single failures which has proven as not sufficient during past
	events.		events.
	Beyond the natural disaster use case above, multi-failure protection		Beyond the natural disaster use case above, multi-failure protection
	is also beneficial in situations where the network is particularly		is also beneficial in situations where the network is particularly
	vulnerable, e.g., when a working entity or protection entity was		vulnerable, e.g., when a working entity or protection entity was
	closed for maintenance or construction work. During this time, the		closed for maintenance or construction work. During this time, the
	network service becomes vulnerable to single failures since one		network service becomes vulnerable to single failures since one
	entity is already down. If a failure occurs during this time, an		entity is already down. If a failure occurs during this time, an
	operator might not be ablt to meet service level agreements (SLA).		operator might not be able to meet service level agreements (SLA).
	Thus, a technical means for multi-failure protection could take		Thus, a technical means for multi-failure protection could take
	pressure off network operations.		pressure off network operations.
	1.1. Document scope		1.1. Document scope
	This document describes use cases and requirements for m:1 and m:n		This document describes use cases and requirements for m:1 and m:n
	protection in MPLS-TP networks without the use of control plane		protection in MPLS-TP networks without the use of control plane
	protocols. Existing solutions based on a control plane such as GMPLS		protocols. Existing solutions based on a control plane such as GMPLS
	may be able to restore user traffic when multiple failures occur.		may be able to restore user traffic when multiple failures occur.
	Some networks however do not use full control plane operation for		Some networks however do not use full control plane operation for
	skipping to change at page 4, line 44		skipping to change at page 4, line 44
	This general scenario is illustrated in Figure 1 which shows a		This general scenario is illustrated in Figure 1 which shows a
	protection domain with n working entities and m protection entities		protection domain with n working entities and m protection entities
	between Node A and Node Z.		between Node A and Node Z.
	At Node A, traffic is transported over its respective working entity		At Node A, traffic is transported over its respective working entity
	and may be simultaneously transported over one of its protection		and may be simultaneously transported over one of its protection
	entities (in case of a broadcast bridge), or it is transported over		entities (in case of a broadcast bridge), or it is transported over
	its working entity and only in case of failure over one of the		its working entity and only in case of failure over one of the
	protection entities (in case of a selector bridge). At Node Z, the		protection entities (in case of a selector bridge). At Node Z, the
	traffic is selected from either its working entity or one of the		traffic is selected from either its working entity or one of the
	protection entities.		protection entities. Note that any of the n working entities and m
			protection entities should follow a disjoint path through the network
			from Node A to Node Z.
	+------+ +------+		+------+ +------+
	|Node A| working entity #1 |Node Z|		|Node A| working entity #1 |Node Z|
	| |=============================| |		| |=============================| |
	| | .... | |		| | .... | |
	| | working entity #n | |		| | working entity #n | |
	| |=============================| |		| |=============================| |
	| | | |		| | | |
	| | | |		| | | |
	| | protection entity #1 | |		| | protection entity #1 | |
	skipping to change at page 5, line 29		skipping to change at page 5, line 29
	|--------Protection Domain--------|		|--------Protection Domain--------|
	Figure 1: m:n protection domain		Figure 1: m:n protection domain
	3. Use cases		3. Use cases
	3.1. m:1 (m > 1) protection		3.1. m:1 (m > 1) protection
	With MPLS-TP linear protection such as 1+1/1:1 protection, when a		With MPLS-TP linear protection such as 1+1/1:1 protection, when a
	single failure is detected on the working entity, the service can be		single failure is detected on the working entity, the service can be
	restored using the protection entity. During this time however, the		restored using the protection entity. However, during the time the
	traffic is unprotected until the working entity is restored.		protection is active the traffic is unprotected until the working
			entity is restored.
	m:1 protection can increase service availability and reduce		m:1 protection can increase service availability and reduce
	operational pressure since multiple protection entities are		operational pressure since multiple protection entities are
	available. For any m > 1, m - 1 protection entities may fail and the		available. For any m > 1, m - 1 protection entities may fail and the
	service still would have a protection entity available.		service still would have a protection entity available.
	There are different ways to provision these alternative protection		There are different ways to provision these alternative protection
	entities which are outlined in the following sub-sections.		entities which are outlined in the following sub-sections.
	3.1.1. Pre-configuration		3.1.1. Pre-configuration
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	as long as these entities do not carry protected traffic.		as long as these entities do not carry protected traffic.
	3.1.2. On-demand configuration		3.1.2. On-demand configuration
	The protection relationship between a working entity and a protection		The protection relationship between a working entity and a protection
	entity is configured while the system is in operation.		entity is configured while the system is in operation.
	Additional protection entities are configured by either a control		Additional protection entities are configured by either a control
	plane protocol or static configuration using a management system		plane protocol or static configuration using a management system
	directly after failure detection and/or notification of either the		directly after failure detection and/or notification of either the
	working entity or the protection entities.		working entity or the protection entities. In case a management
			system is used, there is no need for a standardized solution.
	3.2. m:n (m, n > 1, n >= m > 1) protection		3.2. m:n (m, n > 1, n >= m > 1) protection
	In order to reduce the cost of protection entities, in the m:n		In order to reduce the cost of protection entities, in the m:n
	scenario, m dedicated protection transport entities are sharing		scenario, m dedicated protection transport entities are sharing
	protection resources for n working transport entities.		protection resources for n working transport entities.
	The bandwidth of each protection entity should be allocated in such a		The bandwidth of each protection entity should be allocated in such a
	way that it may be possible to protect any of the n working entities		way that it may be possible to protect any of the n working entities
	in case at least one of the m protection entities is available. When		in case at least one of the m protection entities is available. When
	skipping to change at page 7, line 14		skipping to change at page 7, line 14
	R2. MPLS-TP SHOULD support m:n (m, n > 1, n >= m > 1) protection.		R2. MPLS-TP SHOULD support m:n (m, n > 1, n >= m > 1) protection.
	1. An m:n protection mechanism MUST protect against multiple		1. An m:n protection mechanism MUST protect against multiple
	failures that are simultaneously detected on both a working		failures that are simultaneously detected on both a working
	entity and a protection entity or multiple working entities.		entity and a protection entity or multiple working entities.
	2. A priority scheme MUST be provided, since protection resources		2. A priority scheme MUST be provided, since protection resources
	are shared by multiple working entities dynamically.		are shared by multiple working entities dynamically.
			If a solution is designed based on an existing mechanism such as PSC,
			then this solution MUST be backward compatible and not break such
			mechanisms.
	5. Security Considerations		5. Security Considerations
	General security considerations for MPLS-TP are covered in [RFC5921].		General security considerations for MPLS-TP are covered in [RFC5921].
	The security considerations for the generic associated control		The security considerations for the generic associated control
	channel are described in [RFC5586]. The requirements described in		channel are described in [RFC5586]. The requirements described in
	this document are extensions to the requirements presented in		this document are extensions to the requirements presented in
	[RFC5654] and does not introduce any new security risks.		[RFC5654] and does not introduce any new security risks.
	6. Normative References		6. Normative References
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