draft-ietf-ospf-segment-routing-msd-10.txt		draft-ietf-ospf-segment-routing-msd-11.txt
	OSPF Working Group J. Tantsura		OSPF Working Group J. Tantsura
	Internet-Draft Nuage Networks		Internet-Draft Nuage Networks
	Intended status: Standards Track U. Chunduri		Intended status: Standards Track U. Chunduri
	Expires: October 7, 2018 Huawei Technologies		Expires: November 8, 2018 Huawei Technologies
	S. Aldrin		S. Aldrin
	Google, Inc		Google, Inc
	P. Psenak		P. Psenak
	Cisco Systems		Cisco Systems
	April 05, 2018		May 07, 2018
	Signaling MSD (Maximum SID Depth) using OSPF		Signaling MSD (Maximum SID Depth) using OSPF
	draft-ietf-ospf-segment-routing-msd-10		draft-ietf-ospf-segment-routing-msd-11
	Abstract		Abstract
	This document defines a way for an OSPF Router to advertise multiple		This document defines a way for an OSPF Router to advertise multiple
	types of supported Maximum SID Depths (MSDs) at node and/or link		types of supported Maximum SID Depths (MSDs) at node and/or link
	granularity. Such advertisements allow entities (e.g., centralized		granularity. Such advertisements allow entities (e.g., centralized
	controllers) to determine whether a particular SID stack can be		controllers) to determine whether a particular SID stack can be
	supported in a given network. This document only defines one type of		supported in a given network. This document defines only one type of
	MSD maximum label imposition, but defines an encoding which can		MSD, but defines an encoding that can support other MSD types. Here
	support other MSD types. Here the term OSPF means both OSPFv2 and		the term OSPF means both OSPFv2 and OSPFv3.
	OSPFv3.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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 https://datatracker.ietf.org/drafts/current/.		Drafts is at https://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 October 7, 2018.		This Internet-Draft will expire on November 8, 2018.
	Copyright Notice		Copyright Notice
	Copyright (c) 2018 IETF Trust and the persons identified as the		Copyright (c) 2018 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
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	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
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	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 20 ¶		skipping to change at page 2, line 17 ¶
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Conventions used in this document . . . . . . . . . . . . 3		1.1. Conventions used in this document . . . . . . . . . . . . 3
	1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3		1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
	1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3		1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4		2. Node MSD Advertisement . . . . . . . . . . . . . . . . . . . 4
	3. Node MSD TLV . . . . . . . . . . . . . . . . . . . . . . . . 4		3. Link MSD sub-TLV . . . . . . . . . . . . . . . . . . . . . . 5
	4. Link MSD sub-TLV . . . . . . . . . . . . . . . . . . . . . . 5		4. Using Node and Link MSD Advertisements . . . . . . . . . . . 6
	5. Using Node and Link MSD Advertisements . . . . . . . . . . . 5		5. Base MPLS Imposition MSD . . . . . . . . . . . . . . . . . . 6
	6. Base MPLS Imposition MSD . . . . . . . . . . . . . . . . . . 6		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6		7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 7		8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7
	9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7		9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
	10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7		10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7		10.1. Normative References . . . . . . . . . . . . . . . . . . 7
	11.1. Normative References . . . . . . . . . . . . . . . . . . 7		10.2. Informative References . . . . . . . . . . . . . . . . . 8
	11.2. Informative References . . . . . . . . . . . . . . . . . 7		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
	1. Introduction		1. Introduction
	When Segment Routing(SR) paths are computed by a centralized		When Segment Routing(SR) paths are computed by a centralized
	controller, it is critical that the controller learns the Maximum SID		controller, it is critical that the controller learns the Maximum SID
	Depth(MSD) that can be imposed at each node/link a given SR path to		Depth(MSD) that can be imposed at each node/link on a given SR path
	insure that the SID stack depth of a computed path doesn't exceed the		to insure that the SID stack depth of a computed path doesn't exceed
	number of SIDs the node is capable of imposing.		the number of SIDs the node is capable of imposing.
	The PCEP SR extensions draft [I-D.ietf-pce-segment-routing] signals		The PCEP SR extensions draft [I-D.ietf-pce-segment-routing] signals
	MSD in SR PCE Capability TLV and METRIC Object. However, if PCEP is		MSD in SR PCE Capability TLV and METRIC Object. However, if PCEP is
	not supported/configured on the head-end of an SR tunnel or a		not supported/configured on the head-end of an SR tunnel or a
	Binding-SID anchor node and controller does not participate in IGP		Binding-SID anchor node and controller does not participate in IGP
	routing, it has no way to learn the MSD of nodes and links which has		routing, it has no way to learn the MSD of nodes and links. BGP-LS
	been configured. BGP-LS [RFC7752] defines a way to expose topology		[RFC7752] defines a way to expose topology and associated attributes
	and associated attributes and capabilities of the nodes in that		and capabilities of the nodes in that topology to a centralized
	topology to a centralized controller. MSD signaling by BGP-LS has		controller. MSD signaling by BGP-LS has been defined in
	been defined in [I-D.ietf-idr-bgp-ls-segment-routing-msd].		[I-D.ietf-idr-bgp-ls-segment-routing-msd]. Typically, BGP-LS is
	Typically, BGP-LS is configured on a small number of nodes that do		configured on a small number of nodes that do not necessarily act as
	not necessarily act as head-ends. In order for BGP-LS to signal MSD		head-ends. In order for BGP-LS to signal MSD for all the nodes and
	for all the nodes and links in the network MSD is relevant, MSD		links in the network MSD is relevant, MSD capabilites should be
	capabilites should be advertised to every OSPF router in the network.		advertised by every OSPF router in the network.
	Other types of MSD are known to be useful. For example,		Other types of MSD are known to be useful. For example,
	[I-D.ietf-ospf-mpls-elc] defines Readable Label Depth Capability		[I-D.ietf-ospf-mpls-elc] defines Readable Label Depth Capability
	(RLDC) that is used by a head-end to insert an Entropy Label (EL) at		(RLDC) that is used by a head-end to insert an Entropy Label (EL) at
	a depth that can be read by transit nodes.		a depth that can be read by transit nodes.
	This document defines an extension to OSPF used to advertise one or		This document defines an extension to OSPF used to advertise one or
	more types of MSD at node and/or link granularity. It also creates		more types of MSD at node and/or link granularity. It also creates
	an IANA registry for assigning MSD type identifiers. It laso defines		an IANA registry for assigning MSD type identifiers. It also defines
	the Base MPLS Imposition MSD type. In the future it is expected,		the Base MPLS Imposition MSD type. In the future it is expected,
	that new MSD types will be defined to signal additional capabilities		that new MSD types will be defined to signal additional capabilities
	e.g., entropy labels, SIDs that can be imposed through recirculation,		e.g., entropy labels, SIDs that can be imposed through recirculation,
	or SIDs associated with another dataplane e.g., IPv6.		or SIDs associated with another dataplane e.g., IPv6. Although MSD
			advertisements are associated with Segment Routing, the
			advertisements MAY be present even if Segment Routing itself is not
			enabled.
	1.1. Conventions used in this document		1.1. Conventions used in this document
	1.1.1. Terminology		1.1.1. Terminology
			This memo makes use of the terms defined in [RFC7770]
	BGP-LS: Distribution of Link-State and TE Information using Border		BGP-LS: Distribution of Link-State and TE Information using Border
	Gateway Protocol		Gateway Protocol
	BMI: Base MPLS Imposition is the number of MPLS labels that can be		BMI: Base MPLS Imposition is the number of MPLS labels that can be
	imposed inclusive of any service/transport labels		imposed inclusive of all service/transport/special labels
	OSPF: Open Shortest Path First		OSPF: Open Shortest Path First
	MSD: Maximum SID Depth - the number of SIDs a node or one of its		MSD: Maximum SID Depth - the number of SIDs a node or one of its
	links can support		links can support
	PCC: Path Computation Client		PCC: Path Computation Client
	PCE: Path Computation Element		PCE: Path Computation Element
	PCEP: Path Computation Element Protocol		PCEP: Path Computation Element Protocol
			SR: Segment Routing
	SID: Segment Identifier		SID: Segment Identifier
	SR: Segment Routing		LSA: Link state advertisement
			RI: Router Information LSA
	1.2. Requirements Language		1.2. Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in		"OPTIONAL" in this document are to be interpreted as described in
	BCP14 [RFC2119], [RFC8174] when, and only when they appear in all		BCP14 [RFC2119], [RFC8174] when, and only when they appear in all
	capitals, as shown here .		capitals, as shown here .
	2. Terminology		2. Node MSD Advertisement
	This memo makes use of the terms defined in [RFC4970].
	3. Node MSD TLV
	The node MSD TLV within the body of the OSPF RI Opaque LSA is defined		The node MSD TLV within the body of the OSPF RI Opaque LSA is defined
	to carry the provisioned SID depth of the router originating the RI		to carry the provisioned SID depth of the router originating the RI
	LSA. Node MSD is the minimum MSD supported by the node.		LSA. Node MSD is the smallest MSD supported by the node on the set
			of interfaces configured for use by the advertising IGP instance.
			MSD values may be learned via a hardware API or may be provisioned..
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Length |		| Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Sub-Type and Value ...		| MSD Type and Value ...
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...
	Figure 1: Node MSD TLV		Figure 1: Node MSD TLV
	The Type: TBD1		The Type: TBD1
	Length: variable (minimum of 2, multiple of 2 octets) and represents		Length: variable (minimum of 2, multiple of 2 octets) and represents
	the total length of value field.		the total length of value field.
	Value: consists of a 1 octet sub-type (IANA Registry) and 1 octet		Value: consists of one or more pairs of a 1 octet sub-type (IANA
	value.		Registry) and 1 octet value.
	Sub-Type 1 (IANA Section), MSD and the Value field contains maximum		MSD Type 1 (IANA Section), MSD and the Value field contains the MSD
	MSD of the router originating the RI LSA. Node Maximum MSD is a		of the originating router. Node MSD is a number in the range of
	number in the range of 0-254. 0 represents lack of the ability to		0-255. 0 represents lack of the ability to impose MSD stack of any
	impose MSD stack of any depth; any other value represents that of the		depth; any other value represents that of the node. This value
	node. This value SHOULD represent the minimum value supported by a		SHOULD represent the minimum value supported by a node.
	node.
	Other Sub-types other than defined above are reserved for future		Other MSD Types are reserved for future extensions.
	extensions.
	This TLV is applicable to OSPFv2 and to OSPFv3 [RFC5838] and is		This TLV is applicable to OSPFv2 and to OSPFv3 [RFC5838] and is
	optional. The scope of the advertisement is specific to the		optional. The scope of the advertisement is specific to the
	deployment.		deployment.
	4. Link MSD sub-TLV		3. Link MSD sub-TLV
	A new sub-TLV called Link MSD sub-TLV is defined to carry the		The link sub-TLV is defined to carry the MSD of the interface
	provisioned SID depth of the interface associated with the link.		associated with the link. MSD values may be learned via a hardware
			API or may be provisioned.
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Length |		| Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Sub-Type and Value ...		| MSD Type and Value ...
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...
	Figure 2: Link MSD Sub-TLV		Figure 2: Link MSD Sub-TLV
	Type:		Type:
	For OSPFv2, the Link level MSD value is advertised as an optional		For OSPFv2, the Link level MSD value is advertised as an optional
	Sub-TLV of the OSPFv2 Extended Link TLV as defined in [RFC7684], and		Sub-TLV of the OSPFv2 Extended Link TLV as defined in [RFC7684], and
	has value of TBD2.		has value of TBD2.
	For OSPFv3, the Link level MSD value is advertised as an optional		For OSPFv3, the Link level MSD value is advertised as an optional
	Sub-TLV of the Router-Link TLV as defined in		Sub-TLV of the E-Router-LSA TLV as defined in [RFC8362], and has
	[I-D.ietf-ospf-ospfv3-lsa-extend], and has value of TBD3.		value of TBD3.
	Length: variable and similar to what is defined in Section 3.		Length: variable and similar to that, defined in Section 2.
	Value: consists of a 1 octet sub-type (IANA Registry) and 1 octet		Value: consists of one or more pairs of a 1 octet MSD Type (IANA
	value.		Registry) and 1 octet value.
	Sub-Type 1 (IANA Section), MSD and the Value field contains Link MSD		MSD Type 1 (IANA Section), MSD and the Value field contains Link MSD
	of the router originating the corresponding LSA as specified for		of the router originating the corresponding LSA as specified for
	OSPFv2 and OSPFv3. Link MSD is a number in the range of 0-254. 0		OSPFv2 and OSPFv3. Link MSD is a number in the range of 0-255. 0
	represents lack of the ability to impose MSD stack of any depth; any		represents lack of the ability to impose MSD stack of any depth; any
	other value represents that of the particular link MSD value.		other value represents that of the particular link MSD value.
	Other Sub-types other than defined above are reserved for future		Other MSD Types are reserved for future extensions.
	extensions.
	5. Using Node and Link MSD Advertisements		If these TLVs are advertised multiple times, only the first instance
			of the TLV is used by receiving OSPF routers. This situation SHOULD
			be logged as an error.
			If these TLV is advertised multiple times for the same link in
			different LSAs originated by the same OSPF router, the TLV with the
			smallest Opaque ID/Link State ID is used by receiving OSPF routers.
			This situation MAY be logged as a warning.
			4. Using Node and Link MSD Advertisements
	When Link MSD is present for a given MSD type, the value of the Link		When Link MSD is present for a given MSD type, the value of the Link
	MSD MUST take preference over the Node MSD.		MSD MUST take preference over the Node MSD. When a Link MSD type is
			not signalled but the Node MSD type is, then the value of that Link
			MSD type MUST be considered as the corresponding Node MSD type value.
			In order to increase flooding efficiency, it is RECOMMENDED, that
			routers with homogenous link MSD values advertise just the Node MSD
			value.
	The meaning of the absence of both Node and Link MSD advertisements		The meaning of the absence of both Node and Link MSD advertisements
	for a given MSD type is specific to the MSD type. Generally it can		for a given MSD type is specific to the MSD type. Generally it can
	only be inferred that the advertising node does not support		only be inferred that the advertising node does not support
	advertisement of that MSD type. However, in some cases the lack of		advertisement of that MSD type. However, in some cases the lack of
	advertisement might imply that the functionality associated with the		advertisement might imply that the functionality associated with the
	MSD type is not supported. The correct interpretation MUST be		MSD type is not supported. The correct interpretation MUST be
	specified when an MSD type is defined.		specified when an MSD type is defined.
	6. Base MPLS Imposition MSD		5. Base MPLS Imposition MSD
	The Base MPLS Imposition MSD (BMI-MSD) signals the total number of		The Base MPLS Imposition MSD (BMI-MSD) signals the total number of
	MPLS labels a node is capable of imposing, including any service/		MPLS labels a node is capable of imposing, including any service/
	transport labels.		transport labels.
	Absence of BMI-MSD advertisements indicates solely that the		Absence of BMI-MSD advertisements indicates solely that the
	advertising node does not support advertisement of this capability.		advertising node does not support advertisement of this capability.
	7. IANA Considerations		6. IANA Considerations
	This document requests IANA to allocate TLV type (TBD1) from the OSPF		This document requests IANA to allocate TLV type (TBD1) from the OSPF
	Router Information (RI) TLVs Registry as defined by [RFC4970]. IANA		Router Information (RI) TLVs Registry as defined by [RFC4970]. IANA
	has allocated the value 12 through the early assignment process.		has allocated the value 12 through the early assignment process.
	Also, this document requests IANA to allocate a sub-TLV type (TBD2)		Also, this document requests IANA to allocate a sub-TLV type (TBD2)
	from the OSPFv2 Extended Link TLV Sub-TLVs registry. IANA has		from the OSPFv2 Extended Link TLV Sub-TLVs registry. IANA has
	allocated the the value 6 through the early assignment process.		allocated the the value 6 through the early assignment process.
	Finally, this document requests IANA to allocate a sub-TLV type		Finally, this document requests IANA to allocate a sub-TLV type
	(TBD3) from the OSPFv3 Extended-LSA Sub-TLV registry.		(TBD3) from the OSPFv3 Extended-LSA Sub-TLV registry.
	This document requests creation of an IANA managed registry under a		This document requests creation of an IANA managed registry under a
	new category of "Interior Gateway Protocol (IGP) Parameters" IANA		new category of "Interior Gateway Protocol (IGP) Parameters" IANA
	registries to identify MSD types as proposed in Section 3, Section 4.		registries to identify MSD types as proposed in Section 2, Section 3.
	The registration procedure is "Expert Review" as defined in		The registration procedure is "Expert Review" as defined in
	[RFC8126]. The suggested registry name is "MSD types". Types are an		[RFC8126]. The suggested registry name is "MSD types". Types are an
	unsigned 8 bit number. The following values are defined by this		unsigned 8 bit number. The following values are defined by this
	document.		document.
	Value Name Reference		Value Name Reference
	----- --------------------- -------------		----- --------------------- -------------
	0 Reserved This document		0 Reserved This document
	1 Base MPLS Imposition MSD This document		1 Base MPLS Imposition MSD This document
	2-250 Unassigned This document		2-250 Unassigned This document
	251-254 Experimental This document		251-254 Experimental This document
	255 Reserved This document		255 Reserved This document
	Figure 3: MSD Types Codepoints Registry		Figure 3: MSD Types Codepoints Registry
	8. Security Considerations		7. Security Considerations
	Security considerations, as specified by [RFC7770] are applicable to		Security concerns for OSPF are addressed in [RFC7474] and [RFC5310].
	this document		Further security analysis for OSPF protocol is done in [RFC6853]
			including analysis of both the above documents. Security
			considerations, as specified by [RFC7770] are applicable to this
			document.
	9. Contributors		Advertisement of the additional information defined in this document
			that is false, e.g. MSD that is incorrect may result: in a path
			computation failing and the service unavailable or instantiation of a
			path that can't be supported by the head-end (the node performing the
			imposition).
			8. Contributors
	The following people contributed to this document:		The following people contributed to this document:
	Les Ginsberg		Les Ginsberg
	Email: ginsberg@cisco.com		Email: ginsberg@cisco.com
	10. Acknowledgements		9. Acknowledgements
	The authors would like to thank Acee Lindem, Stephane Litkowski and		The authors would like to thank Acee Lindem, Stephane Litkowski and
	Bruno Decraene for their reviews and valuable comments.		Bruno Decraene for their reviews and valuable comments.
	11. References		10. References
	11.1. Normative References		10.1. 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,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and		[RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
	S. Shaffer, "Extensions to OSPF for Advertising Optional		S. Shaffer, "Extensions to OSPF for Advertising Optional
	Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July		Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July
	2007, <https://www.rfc-editor.org/info/rfc4970>.		2007, <https://www.rfc-editor.org/info/rfc4970>.
	[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and		[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
	S. Shaffer, "Extensions to OSPF for Advertising Optional		S. Shaffer, "Extensions to OSPF for Advertising Optional
	Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,		Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
	February 2016, <https://www.rfc-editor.org/info/rfc7770>.		February 2016, <https://www.rfc-editor.org/info/rfc7770>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	11.2. Informative References		[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
			F. Baker, "OSPFv3 Link State Advertisement (LSA)
			Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
			2018, <https://www.rfc-editor.org/info/rfc8362>.
			10.2. Informative References
	[I-D.ietf-idr-bgp-ls-segment-routing-msd]		[I-D.ietf-idr-bgp-ls-segment-routing-msd]
	Tantsura, J., Chunduri, U., Mirsky, G., and S. Sivabalan,		Tantsura, J., Chunduri, U., Mirsky, G., and S. Sivabalan,
	"Signaling Maximum SID Depth using Border Gateway Protocol		"Signaling Maximum SID Depth using Border Gateway Protocol
	Link-State", draft-ietf-idr-bgp-ls-segment-routing-msd-01		Link-State", draft-ietf-idr-bgp-ls-segment-routing-msd-01
	(work in progress), October 2017.		(work in progress), October 2017.
	[I-D.ietf-ospf-mpls-elc]		[I-D.ietf-ospf-mpls-elc]
	Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.		Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.
	Litkowski, "Signaling Entropy Label Capability and		Litkowski, "Signaling Entropy Label Capability and
	Readable Label-stack Depth Using OSPF", draft-ietf-ospf-		Readable Label-stack Depth Using OSPF", draft-ietf-ospf-
	mpls-elc-05 (work in progress), January 2018.		mpls-elc-05 (work in progress), January 2018.
	[I-D.ietf-ospf-ospfv3-lsa-extend]
	Lindem, A., Roy, A., Goethals, D., Vallem, V., and F.
	Baker, "OSPFv3 LSA Extendibility", draft-ietf-ospf-ospfv3-
	lsa-extend-23 (work in progress), January 2018.
	[I-D.ietf-pce-segment-routing]		[I-D.ietf-pce-segment-routing]
	Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,		Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
	and J. Hardwick, "PCEP Extensions for Segment Routing",		and J. Hardwick, "PCEP Extensions for Segment Routing",
	draft-ietf-pce-segment-routing-11 (work in progress),		draft-ietf-pce-segment-routing-11 (work in progress),
	November 2017.		November 2017.
	[RFC5838] Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and		[RFC5838] Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and
	R. Aggarwal, "Support of Address Families in OSPFv3",		R. Aggarwal, "Support of Address Families in OSPFv3",
	RFC 5838, DOI 10.17487/RFC5838, April 2010,		RFC 5838, DOI 10.17487/RFC5838, April 2010,
	<https://www.rfc-editor.org/info/rfc5838>.		<https://www.rfc-editor.org/info/rfc5838>.
End of changes. 42 change blocks.
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