< draft-ietf-ospf-segment-routing-extensions-12.txt		draft-ietf-ospf-segment-routing-extensions-13.txt >
	Open Shortest Path First IGP P. Psenak, Ed.		Open Shortest Path First IGP P. Psenak, Ed.
	Internet-Draft S. Previdi, Ed.		Internet-Draft S. Previdi, Ed.
	Intended status: Standards Track C. Filsfils		Intended status: Standards Track C. Filsfils
	Expires: September 9, 2017 Cisco Systems, Inc.		Expires: November 5, 2017 Cisco Systems, Inc.
	H. Gredler		H. Gredler
	RtBrick Inc.		RtBrick Inc.
	R. Shakir		R. Shakir
	Google, Inc.		Google, Inc.
	W. Henderickx		W. Henderickx
	Nokia		Nokia
	J. Tantsura		J. Tantsura
	Individual		Individual
	March 8, 2017		May 4, 2017
	OSPF Extensions for Segment Routing		OSPF Extensions for Segment Routing
	draft-ietf-ospf-segment-routing-extensions-12		draft-ietf-ospf-segment-routing-extensions-13
	Abstract		Abstract
	Segment Routing (SR) allows a flexible definition of end-to-end paths		Segment Routing (SR) allows a flexible definition of end-to-end paths
	within IGP topologies by encoding paths as sequences of topological		within IGP topologies by encoding paths as sequences of topological
	sub-paths, called "segments". These segments are advertised by the		sub-paths, called "segments". These segments are advertised by the
	link-state routing protocols (IS-IS and OSPF).		link-state routing protocols (IS-IS and OSPF).
	This draft describes the OSPF extensions required for Segment		This draft describes the OSPF extensions required for Segment
	Routing.		Routing.
	skipping to change at page 2, line 4 ¶		skipping to change at page 2, line 4 ¶
	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 September 9, 2017.		This Internet-Draft will expire on November 5, 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2017 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
	skipping to change at page 2, line 38 ¶		skipping to change at page 2, line 38 ¶
	3.2. SID/Label Range TLV . . . . . . . . . . . . . . . . . . . 6		3.2. SID/Label Range TLV . . . . . . . . . . . . . . . . . . . 6
	3.3. SR Local Block Sub-TLV . . . . . . . . . . . . . . . . . 8		3.3. SR Local Block Sub-TLV . . . . . . . . . . . . . . . . . 8
	3.4. SRMS Preference Sub-TLV . . . . . . . . . . . . . . . . . 9		3.4. SRMS Preference Sub-TLV . . . . . . . . . . . . . . . . . 9
	4. OSPF Extended Prefix Range TLV . . . . . . . . . . . . . . . 10		4. OSPF Extended Prefix Range TLV . . . . . . . . . . . . . . . 10
	5. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 12		5. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 12
	6. SID/Label Binding Sub-TLV . . . . . . . . . . . . . . . . . . 16		6. SID/Label Binding Sub-TLV . . . . . . . . . . . . . . . . . . 16
	6.1. ERO Metric Sub-TLV . . . . . . . . . . . . . . . . . . . 17		6.1. ERO Metric Sub-TLV . . . . . . . . . . . . . . . . . . . 17
	6.2. ERO Sub-TLVs . . . . . . . . . . . . . . . . . . . . . . 18		6.2. ERO Sub-TLVs . . . . . . . . . . . . . . . . . . . . . . 18
	6.2.1. IPv4 ERO Sub-TLV . . . . . . . . . . . . . . . . . . 18		6.2.1. IPv4 ERO Sub-TLV . . . . . . . . . . . . . . . . . . 18
	6.2.2. Unnumbered Interface ID ERO Sub-TLV . . . . . . . . . 19		6.2.2. Unnumbered Interface ID ERO Sub-TLV . . . . . . . . . 19
	6.2.3. IPv4 Backup ERO Sub-TLV . . . . . . . . . . . . . . . 20		6.2.3. IPv4 Backup ERO Sub-TLV . . . . . . . . . . . . . . . 21
	6.2.4. Unnumbered Interface ID Backup ERO Sub-TLV . . . . . 21		6.2.4. Unnumbered Interface ID Backup ERO Sub-TLV . . . . . 22
	7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 22		7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 23
	7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 23		7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 23
	7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 24		7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 25
	8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 26		8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 26
	8.1. Intra-area Segment routing in OSPFv2 . . . . . . . . . . 26		8.1. Intra-area Segment routing in OSPFv2 . . . . . . . . . . 26
	8.2. Inter-area Segment routing in OSPFv2 . . . . . . . . . . 27		8.2. Inter-area Segment routing in OSPFv2 . . . . . . . . . . 27
	8.3. SID for External Prefixes . . . . . . . . . . . . . . . . 28		8.3. Segment Routing for External Prefixes . . . . . . . . . . 28
	8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 28		8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 29
	8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 28		8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 29
	8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 29		8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 29
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29		9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
	9.1. OSPF OSPF Router Information (RI) TLVs Registry . . . . . 29		9.1. OSPF OSPF Router Information (RI) TLVs Registry . . . . . 29
	9.2. OSPF Extended Prefix LSA TLV Registry . . . . . . . . . . 29		9.2. OSPF Extended Prefix LSA TLV Registry . . . . . . . . . . 30
	9.3. OSPF Extended Prefix LSA Sub-TLV Registry . . . . . . . . 29		9.3. OSPF Extended Prefix LSA Sub-TLV Registry . . . . . . . . 30
	9.4. OSPF Extended Link LSA Sub-TLV Registry . . . . . . . . . 30		9.4. OSPF Extended Link LSA Sub-TLV Registry . . . . . . . . . 30
	10. Implementation Status . . . . . . . . . . . . . . . . . . . . 30		10. Implementation Status . . . . . . . . . . . . . . . . . . . . 30
	11. Security Considerations . . . . . . . . . . . . . . . . . . . 32		11. Security Considerations . . . . . . . . . . . . . . . . . . . 32
	12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 32		12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 32
	13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 32		13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 32
	14. References . . . . . . . . . . . . . . . . . . . . . . . . . 32		14. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
	14.1. Normative References . . . . . . . . . . . . . . . . . . 32		14.1. Normative References . . . . . . . . . . . . . . . . . . 32
	14.2. Informative References . . . . . . . . . . . . . . . . . 33		14.2. Informative References . . . . . . . . . . . . . . . . . 33
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
	skipping to change at page 3, line 35 ¶		skipping to change at page 3, line 35 ¶
	segment is typically a multi-hop path while an adjacency segment, in		segment is typically a multi-hop path while an adjacency segment, in
	most cases, is a one-hop path. SR's control-plane can be applied to		most cases, is a one-hop path. SR's control-plane can be applied to
	both IPv6 and MPLS data-planes, and does not require any additional		both IPv6 and MPLS data-planes, and does not require any additional
	signalling (other than IGP extensions). The IPv6 data plane is out		signalling (other than IGP extensions). The IPv6 data plane is out
	of the scope of this specification - it is not applicable to OSPFv2		of the scope of this specification - it is not applicable to OSPFv2
	which only supports the IPv4 address-family. For example, when used		which only supports the IPv4 address-family. For example, when used
	in MPLS networks, SR paths do not require any LDP or RSVP-TE		in MPLS networks, SR paths do not require any LDP or RSVP-TE
	signalling. However, SR can interoperate in the presence of LSPs		signalling. However, SR can interoperate in the presence of LSPs
	established with RSVP or LDP.		established with RSVP or LDP.
			There are additional segment types, e.g., Binding SID defined in
			[I-D.ietf-spring-segment-routing].
	This draft describes the OSPF extensions required for Segment		This draft describes the OSPF extensions required for Segment
	Routing.		Routing.
	Segment Routing architecture is described in		Segment Routing architecture is described in
	[I-D.ietf-spring-segment-routing].		[I-D.ietf-spring-segment-routing].
	Segment Routing use cases are described in		Segment Routing use cases are described in
	[I-D.filsfils-spring-segment-routing-use-cases].		[I-D.filsfils-spring-segment-routing-use-cases].
	2. Segment Routing Identifiers		2. Segment Routing Identifiers
	Segment Routing defines various types of Segment Identifiers (SIDs):		Segment Routing defines various types of Segment Identifiers (SIDs):
	Prefix-SID, Adjacency-SID, LAN Adjacency SID and Binding SID.		Prefix-SID, Adjacency-SID, LAN Adjacency SID, and Binding SID.
	For the purpose of the advertisements of various SID values, new		Extended Prefix/Link Opaque LSAs defined in [RFC7684] are used for
	Opaque LSAs [RFC5250] are defined in [RFC7684]. These LSAs are		advertisements of the various SID types.
	generic containers that can be used to advertise any additional
	attributes associated with a prefix or link. These Opaque LSAs are
	complementary to the existing LSAs and are not aimed to replace any
	of the existing LSAs.
	2.1. SID/Label Sub-TLV		2.1. SID/Label Sub-TLV
	The SID/Label Sub-TLV appears in multiple TLVs or Sub-TLVs defined		The SID/Label Sub-TLV appears in multiple TLVs or Sub-TLVs defined
	later in this document. It is used to advertise the SID or label		later in this document. It is used to advertise the SID or label
	associated with a prefix or adjacency. The SID/Label TLV has		associated with a prefix or adjacency. The SID/Label TLV has
	following format:		following format:
	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 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| SID/Label (variable) |		| SID/Label (variable) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	where:		where:
	Type: TBD, suggested value 1		Type: TBD, suggested value 1
	Length: variable, 3 or 4 octet		Length: Variable, 3 or 4 octet
	SID/Label: If length is set to 3, then the 20 rightmost bits		SID/Label: If length is set to 3, then the 20 rightmost bits
	represent a label. If length is set to 4, then the value		represent a label. If length is set to 4, then the value
	represents a 32-bit SID.		represents a 32-bit SID.
	The receiving router MUST ignore SID/Label Sub-TLV if the length		The receiving router MUST ignore the SID/Label Sub-TLV if the
	is other then 3 or 4.		length is other then 3 or 4.
	3. Segment Routing Capabilities		3. Segment Routing Capabilities
	Segment Routing requires some additional router capabilities to be		Segment Routing requires some additional router capabilities to be
	advertised to other routers in the area.		advertised to other routers in the area.
	These SR capabilities are advertised in the Router Information Opaque		These SR capabilities are advertised in the Router Information Opaque
	LSA (defined in [RFC7770]).		LSA (defined in [RFC7770]).
	3.1. SR-Algorithm TLV		3.1. SR-Algorithm TLV
	The SR-Algorithm TLV is a top-level TLV of the Router Information		The SR-Algorithm TLV is a top-level TLV of the Router Information
	Opaque LSA (defined in [RFC7770]).		Opaque LSA (defined in [RFC7770]).
	The SR-Algorithm Sub-TLV is optional. It MAY only be advertised once		The SR-Algorithm TLV is optional. It MUST only be advertised once in
	in the Router Information Opaque LSA. If the SID/Label Range TLV, as		the Router Information Opaque LSA. If the SID/Label Range TLV, as
	defined in Section 3.2, is advertised, then the SR-Algorithm TLV MUST		defined in Section 3.2, is advertised, then the SR-Algorithm TLV MUST
	also be advertised. If the SR-Algorithm TLV is not advertised by the		also be advertised. If the SR-Algorithm TLV is not advertised by the
	node, such node is considered as not being segment routing capable.		node, such node is considered as not being segment routing capable.
	An SR Router may use various algorithms when calculating reachability		An SR Router may use various algorithms when calculating reachability
	to OSPF routers or prefixes in an OSPF area. Examples of these		to OSPF routers or prefixes in an OSPF area. Examples of these
	algorithms are metric based Shortest Path First (SPF), various		algorithms are metric based Shortest Path First (SPF), various
	flavors of Constrained SPF, etc. The SR-Algorithm TLV allows a		flavors of Constrained SPF, etc. The SR-Algorithm TLV allows a
	router to advertise the algorithms currently used by the router to		router to advertise the algorithms currently used by the router to
	other routers in an OSPF area. The SR-Algorithm TLV has following		other routers in an OSPF area. The SR-Algorithm TLV has following
	skipping to change at page 5, line 29 ¶		skipping to change at page 5, line 29 ¶
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Algorithm 1 | Algorithm... | Algorithm n | |		| Algorithm 1 | Algorithm... | Algorithm n | |
	+- -+		+- -+
	| |		| |
	+ +		+ +
	where:		where:
	Type: TBD, suggested value 8		Type: TBD, suggested value 8
	Length: variable		Length: Variable
	Algorithm: Single octet identifying the algorithm. The following		Algorithm: Single octet identifying the algorithm. The following
	values are defined by this document:		values are defined by this document:
	0: Shortest Path First (SPF) algorithm based on link metric.		0: Shortest Path First (SPF) algorithm based on link metric.
	This is the standard shortest path algorithm as computed by the		This is the standard shortest path algorithm as computed by the
	OSPF protocol. Consistent with the deployed practice for link-		OSPF protocol. Consistent with the deployed practice for link-
	state protocols, Algorithm 0 permits any node to overwrite the		state protocols, Algorithm 0 permits any node to overwrite the
	SPF path with a different path based on its local policy. If		SPF path with a different path based on its local policy. If
	the SR-Algorithm Sub-TLV is advertised, Algorithm 0 MUST be		the SR-Algorithm TLV is advertised, Algorithm 0 MUST be
	included.		included.
	1: Strict Shortest Path First (SPF) algorithm based on link		1: Strict Shortest Path First (SPF) algorithm based on link
	metric. The algorithm is identical to Algorithm 0 but		metric. The algorithm is identical to Algorithm 0 but
	Algorithm 1 requires that all nodes along the path will honor		Algorithm 1 requires that all nodes along the path will honor
	the SPF routing decision. Local policy at the node claiming		the SPF routing decision. Local policy at the node claiming
	support for Algorithm 1 MUST NOT alter the SPF paths computed		support for Algorithm 1 MUST NOT alter the SPF paths computed
	by Algorithm 1.		by Algorithm 1.
	When multiple SR-Algorithm sub-TLVs are received from a given router		When multiple SR-Algorithm TLVs are received from a given router, the
	the receiver SHOULD use the first occurrence of the sub-TLV in the		receiver SHOULD use the first occurrence of the TLV in the Router
	Router Information LSA. If the SR-Algorithm sub-TLV appears in		Information LSA. If the SR-Algorithm TLV appears in multiple Router
	multiple Router Information LSAs that have different flooding scopes,		Information LSAs that have different flooding scopes, the SR-
	the SR-Algorithm sub-TLV in the Router Information LSA with the		Algorithm TLV in the Router Information LSA with the narrowest
	lowest flooding scope SHOULD be used. If the SR-Algorithm sub-TLV		flooding scope SHOULD be used. If the SR-Algorithm TLV appears in
	appears in multiple Router Information LSAs that have the same		multiple Router Information LSAs that have the same flooding scope,
	flooding scope, the SR-Algorithm sub-TLV in the Router Information		the SR-Algorithm TLV in the Router Information LSA with the
	LSA with the numerically smallest Instance ID SHOULD be used and		numerically smallest Instance ID SHOULD be used and subsequent
	subsequent instances of the SR-Algorithm sub-TLV SHOULD be ignored.		instances of the SR-Algorithm TLV SHOULD be ignored.
	The RI LSA can be advertised at any of the defined opaque flooding		The RI LSA can be advertised at any of the defined opaque flooding
	scopes (link, area, or Autonomous System (AS)). For the purpose of		scopes (link, area, or Autonomous System (AS)). For the purpose of
	SR-Algorithm TLV advertisement, area scope flooding is required.		SR-Algorithm TLV advertisement, area scope flooding is required.
	3.2. SID/Label Range TLV		3.2. SID/Label Range TLV
	The SID/Label Range TLV is a top-level TLV of the Router Information		The SID/Label Range TLV is a top-level TLV of the Router Information
	Opaque LSA (defined in [RFC7770]).		Opaque LSA (defined in [RFC7770]).
	skipping to change at page 6, line 40 ¶		skipping to change at page 6, line 40 ¶
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Sub-TLVs (variable) |		| Sub-TLVs (variable) |
	+- -+		+- -+
	| |		| |
	+ +		+ +
	where:		where:
	Type: TBD, suggested value 9		Type: TBD, suggested value 9
	Length: variable		Length: Variable
	Range Size: 3 octets of the SID/label range		Range Size: 3-octet SID/label range size (i.e., the number of SIDs
			or labels in the range including the first SID/label). It MUST be
			greater than 0.
	Initially, the only supported Sub-TLV is the SID/Label TLV as defined		Initially, the only supported Sub-TLV is the SID/Label TLV as defined
	in Section 2.1. The SID/Label advertised in the SID/Label TLV		in Section 2.1. The SID/Label advertised in the SID/Label TLV
	represents the first SID/Label in the advertised range.		represents the first SID/Label in the advertised range.
	Multiple occurrences of the SID/Label Range TLV MAY be advertised, in		Multiple occurrences of the SID/Label Range TLV MAY be advertised, in
	order to advertise multiple ranges. In such case:		order to advertise multiple ranges. In such case:
	o The originating router MUST encode each range into a different		o The originating router MUST encode each range into a different
	SID/Label Range TLV.		SID/Label Range TLV.
	o The originating router decides the order in which the set of SID/		o The originating router decides the order in which the set of SID/
	Label Range TLVs are advertised inside the Router Information		Label Range TLVs are advertised inside the Router Information
	Opaque LSA. The originating router MUST ensure the order is the		Opaque LSA. The originating router MUST ensure the order is the
	same after a graceful restart (using checkpointing, non-volatile		same after a graceful restart (using checkpointing, non-volatile
	storage or any other mechanism) in order to assure the SID/label		storage, or any other mechanism) in order to assure the SID/label
	range and SID index correspondence is preserved across graceful		range and SID index correspondence is preserved across graceful
	restarts.		restarts.
	o The receiving router must adhere to the order in which the ranges		o The receiving router MUST adhere to the order in which the ranges
	are advertised when calculating a SID/label from a SID index.		are advertised when calculating a SID/label from a SID index.
	The following example illustrates the advertisement of multiple		The following example illustrates the advertisement of multiple
	ranges:		ranges:
	The originating router advertises following ranges:		The originating router advertises the following ranges:
	Range 1: [100, 199]		Range 1: [100, 199]
	Range 2: [1000, 1099]		Range 2: [1000, 1099]
	Range 3: [500, 599]		Range 3: [500, 599]
	The receiving routers concatenate the ranges and build the Segment		The receiving routers concatenate the ranges and build the Segment
	Routing Global Block (SRGB) as follows:		Routing Global Block (SRGB) as follows:
	SRGB = [100, 199]		SRGB = [100, 199]
	[1000, 1099]		[1000, 1099]
	[500, 599]		[500, 599]
	skipping to change at page 8, line 9 ¶		skipping to change at page 8, line 9 ¶
	...		...
	The RI LSA can be advertised at any of the defined flooding scopes		The RI LSA can be advertised at any of the defined flooding scopes
	(link, area, or autonomous system (AS)). For the purpose of SID/		(link, area, or autonomous system (AS)). For the purpose of SID/
	Label Range TLV advertisement, area scope flooding is required.		Label Range TLV advertisement, area scope flooding is required.
	3.3. SR Local Block Sub-TLV		3.3. SR Local Block Sub-TLV
	The SR Local Block (SRLB) Sub-TLV contains the range of labels the		The SR Local Block (SRLB) Sub-TLV contains the range of labels the
	node has reserved for local SIDs. Local SIDs are used, e.g., for		node has reserved for local SIDs. Local SIDs are used, e.g., for
	Adjacency-SIDs, and may also be allocated by other components than		Adjacency-SIDs, and may also be allocated by components other than
	OSPF protocol. As an example, an application or a controller may		the OSPF protocol. As an example, an application or a controller may
	instruct the router to allocate a specific local SID. Therefore, in		instruct the router to allocate a specific local SID. Therefore, in
	order for such applications or controllers to know what are the local		order for such applications or controllers to know what local SIDs
	SIDs available in the router, it is required that the router		are available on the router, it is required that the router
	advertises its SRLB. The SRLB Sub-TLV is used for that purpose.		advertises its SRLB. The SRLB Sub-TLV is used for that purpose.
	The SR Local Block (SRLB) Sub-TLV is a top-level TLV of the Router		The SR Local Block (SRLB) Sub-TLV is a top-level TLV of the Router
	Information Opaque LSA (defined in [RFC7770]).		Information Opaque LSA (defined in [RFC7770]).
	The SR Local Block Sub-TLV MAY appear multiple times in the Router		The SR Local Block Sub-TLV MAY appear multiple times in the Router
	Information Opaque LSA and has the following format:		Information Opaque LSA and has the following format:
	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
	skipping to change at page 8, line 38 ¶		skipping to change at page 8, line 38 ¶
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Sub-TLVs (variable) |		| Sub-TLVs (variable) |
	+- -+		+- -+
	| |		| |
	+ +		+ +
	where:		where:
	Type: TBD, suggested value 12		Type: TBD, suggested value 12
	Length: variable		Length: Variable
	Range Size: 3 octets of the SID/label range. MUST be higher then		Range Size: 3-octet SID/label range size (i.e., the number of SIDs
	0.		or labels in the range including the first SID/label). It MUST be
			greater than 0.
	Initially, the only supported Sub-TLV is the SID/Label TLV as defined		Initially, the only supported Sub-TLV is the SID/Label TLV as defined
	in Section 2.1. The SID/Label advertised in the SID/Label TLV		in Section 2.1. The SID/Label advertised in the SID/Label TLV
	represents the first SID/Label in the advertised range.		represents the first SID/Label in the advertised range.
	The originating router MUST NOT advertise overlapping ranges.		The originating router MUST NOT advertise overlapping ranges.
	Each time a SID from the SRLB is allocated, it SHOULD also be		Each time a SID from the SRLB is allocated, it SHOULD also be
	reported to all components (e.g.: controller or applications) in		reported to all components (e.g., controller or applications) in
	order for these components to have an up-to-date view of the current		order for these components to have an up-to-date view of the current
	SRLB allocation. This is required to avoid collision between		SRLB allocation. This is required to avoid collisions between
	allocation instructions.		allocation instructions.
	Within the context of OSPF, the reporting of local SIDs is done		Within the context of OSPF, the reporting of local SIDs is done
	through OSPF Sub-TLVs such as the Adjacency-SID (Section 7).		through OSPF Sub-TLVs such as the Adjacency-SID (Section 7).
	However, the reporting of allocated local SIDs may also be done		However, the reporting of allocated local SIDs may also be done
	through other means and protocols which mechanisms are outside the		through other means and protocols which are outside the scope of this
	scope of this document.		document.
	A router advertising the SRLB TLV may also have other label ranges,		A router advertising the SRLB TLV may also have other label ranges,
	outside of the SRLB, used for its local allocation purposes which are		outside of the SRLB, used for its local allocation purposes which are
	NOT advertised in the SRLB. For example, it is possible that an		NOT advertised in the SRLB. For example, it is possible that an
	Adjacency-SID is allocated using a local label that is not part of		Adjacency-SID is allocated using a local label that is not part of
	the SRLB.		the SRLB.
	The RI LSA can be advertised at any of the defined flooding scopes		The RI LSA can be advertised at any of the defined flooding scopes
	(link, area, or autonomous system (AS)). For the purpose of SR Local		(link, area, or autonomous system (AS)). For the purpose of SR Local
	Block Sub-TLV TLV advertisement, area scope flooding is required.		Block Sub-TLV TLV advertisement, area scope flooding is required.
	3.4. SRMS Preference Sub-TLV		3.4. SRMS Preference Sub-TLV
	The Segment Routing Mapping Server (SRMS) Preference sub-TLV is used		The Segment Routing Mapping Server (SRMS) Preference sub-TLV is used
	to advertise a preference associated with the node that acts as a SR		to advertise a preference associated with the node that acts as an SR
	Mapping Server. SRMS preference is defined in		Mapping Server. SRMS preference is defined in
	[I-D.ietf-spring-conflict-resolution].		[I-D.ietf-spring-conflict-resolution].
	The SRMS Preference Sub-TLV is a top-level TLV of the Router		The SRMS Preference Sub-TLV is a top-level TLV of the Router
	Information Opaque LSA (defined in [RFC7770]).		Information Opaque LSA (defined in [RFC7770]).
	The SRMS Preference Sub-TLV MAY only be advertised once in the Router		The SRMS Preference Sub-TLV MAY only be advertised once in the Router
	Information Opaque LSA and has the following format:		Information Opaque LSA and has the following format:
	0 1 2 3		0 1 2 3
	skipping to change at page 10, line 6 ¶		skipping to change at page 10, line 6 ¶
	where:		where:
	Type: TBD, suggested value 13		Type: TBD, suggested value 13
	Length: 4 octets		Length: 4 octets
	Preference: 1 octet. SRMS preference value from 0 to 255.		Preference: 1 octet. SRMS preference value from 0 to 255.
	When multiple SRMS Preference sub-TLVs are received from a given		When multiple SRMS Preference sub-TLVs are received from a given
	router the receiver SHOULD use the first occurrence of the sub-TLV in		router, the receiver SHOULD use the first occurrence of the sub-TLV
	the Router Information LSA. If the SRMS Preference sub-TLV appears		in the Router Information LSA. If the SRMS Preference sub-TLV
	in multiple Router Information LSAs that have different flooding		appears in multiple Router Information LSAs that have different
	scopes, the SRLB sub-TLV in the Router Information LSA with the		flooding scopes, the SRLB sub-TLV in the Router Information LSA with
	lowest flooding scope SHOULD be used. If the SRMS Preference sub-TLV		the narrowest flooding scope SHOULD be used. If the SRMS Preference
	appears in multiple Router Information LSAs that have the same		sub-TLV appears in multiple Router Information LSAs that have the
	flooding scope, the SRMS Preference sub-TLV in the Router Information		same flooding scope, the SRMS Preference sub-TLV in the Router
	LSA with the numerically smallest Instance ID SHOULD be used and		Information LSA with the numerically smallest Instance ID SHOULD be
	subsequent instances of the SRMS Preference sub-TLV SHOULD be		used and subsequent instances of the SRMS Preference sub-TLV SHOULD
	ignored.		be ignored.
	The RI LSA can be advertised at any of the defined flooding scopes		The RI LSA can be advertised at any of the defined flooding scopes
	(link, area, or autonomous system (AS)). For the purpose of the SRMS		(link, area, or autonomous system (AS)). For the purpose of the SRMS
	Preference Sub-TLV advertisement, AS scope flooding is required. If		Preference Sub-TLV advertisement, AS scope flooding is required. If
	the SRMS advertisements from the SRMS server are only used inside the		the SRMS advertisements from the SRMS server are only used inside the
	area to which the SRMS server is attached, area scope flooding may be		area to which the SRMS server is attached, area scope flooding may be
	used.		used.
	4. OSPF Extended Prefix Range TLV		4. OSPF Extended Prefix Range TLV
	In some cases it is useful to advertise attributes for a range of		In some cases it is useful to advertise attributes for a range of
	prefixes. The Segment Routing Mapping Server, which is described in		prefixes. The Segment Routing Mapping Server, which is described in
	[I-D.filsfils-spring-segment-routing-ldp-interop], is an example		[I-D.filsfils-spring-segment-routing-ldp-interop], is an example
	where we need a single advertisement to advertise SIDs for multiple		where we need a single advertisement to advertise SIDs for multiple
	prefixes from a contiguous address range.		prefixes from a contiguous address range.
	The OSPF Extended Prefix Range TLV, which is a new top level TLV of		The OSPF Extended Prefix Range TLV, which is a top level TLV of the
	the Extended Prefix LSA described in [RFC7684] is defined for this		Extended Prefix LSA described in [RFC7684] is defined for this
	purpose.		purpose.
	Multiple OSPF Extended Prefix Range TLVs MAY be advertised in each		Multiple OSPF Extended Prefix Range TLVs MAY be advertised in each
	OSPF Extended Prefix Opaque LSA, but all prefix ranges included in a		OSPF Extended Prefix Opaque LSA, but all prefix ranges included in a
	single OSPF Extended Prefix Opaque LSA MUST have the same flooding		single OSPF Extended Prefix Opaque LSA MUST have the same flooding
	scope. The OSPF Extended Prefix Range TLV has the following format:		scope. The OSPF Extended Prefix Range TLV has the following format:
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 11, line 28 ¶		skipping to change at page 11, line 28 ¶
	| |		| |
	where:		where:
	Type: TBD, suggested value 2.		Type: TBD, suggested value 2.
	Length: Variable		Length: Variable
	Prefix length: Length of the prefix		Prefix length: Length of the prefix
	AF: 0 - IPv4 unicast		AF: Address family for the prefix. Currently, the only supported
			value is 0 for IPv4 unicast. The inclusion of address family in
			this TLV allows for future extension.
	Range size: Represents the number of prefixes that are covered by		Range size: Represents the number of prefixes that are covered by
	the advertisement. The Range Size MUST NOT exceed the number of		the advertisement. The Range Size MUST NOT exceed the number of
	prefixes that could be satisfied by the prefix length without		prefixes that could be satisfied by the prefix length without
	including the IPv4 multicast address range (224.0.0.0/3).		including the IPv4 multicast address range (224.0.0.0/3).
	Flags: Single octet field. The following flags are defined:		Flags: Single octet field. The following flags are defined:
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+
	|IA| | | | | | | |		|IA| | | | | | | |
	+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+
	where:		where:
	IA-Flag: Inter-Area flag. If set, advertisement is of inter-		IA-Flag: Inter-Area flag. If set, advertisement is of inter-
	area type. The ABR that is advertising the OSPF Extended		area type. An ABR that is advertising the OSPF Extended Prefix
	Prefix Range TLV between areas MUST set this bit.		Range TLV between areas MUST set this bit.
	This bit is used to prevent redundant flooding of Prefix Range		This bit is used to prevent redundant flooding of Prefix Range
	TLVs between areas as follows:		TLVs between areas as follows:
	An ABR always prefers intra-area Prefix Range advertisements		An ABR always prefers intra-area Prefix Range advertisements
	over inter-area advertisements.		over inter-area advertisements.
	An ABR does not consider inter-area Prefix Range		An ABR does not consider inter-area Prefix Range
	advertisements coming from non-backbone areas.		advertisements coming from non-backbone areas.
	An ABR only propagates an inter-area Prefix Range		An ABR only propagates an inter-area Prefix Range
	advertisement from the backbone area to connected non-		advertisement from the backbone area to connected non-
	backbone areas if the advertisement is considered to be the		backbone areas if the advertisement is considered to be the
	best one.		best one.
	Address Prefix: The prefix, encoded as an even multiple of 32-bit		Address Prefix: The prefix, encoded as 32-bit value, padded with
	words, padded with zero bits as necessary. This encoding consumes		zero bits as necessary. The prefix represents the first prefix in
	((PrefixLength + 31) / 32) 32-bit words. The Address Prefix		the prefix range.
	represents the first prefix in the prefix range.
	5. Prefix SID Sub-TLV		5. Prefix SID Sub-TLV
	The Prefix SID Sub-TLV is a Sub-TLV of the OSPF Extended Prefix TLV		The Prefix SID Sub-TLV is a Sub-TLV of the OSPF Extended Prefix TLV
	described in [RFC7684] and the OSPF Extended Prefix Range TLV		described in [RFC7684] and the OSPF Extended Prefix Range TLV
	described in Section 4. It MAY appear more than once in the parent		described in Section 4. It MAY appear more than once in the parent
	TLV and has the following format:		TLV and has the following format:
	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
	skipping to change at page 13, line 49 ¶		skipping to change at page 13, line 49 ¶
	SID/Index/Label: According to the V and L flags, it contains		SID/Index/Label: According to the V and L flags, it contains
	either:		either:
	A 32-bit index defining the offset in the SID/Label space		A 32-bit index defining the offset in the SID/Label space
	advertised by this router.		advertised by this router.
	A 24-bit label where the 20 rightmost bits are used for		A 24-bit label where the 20 rightmost bits are used for
	encoding the label value.		encoding the label value.
	If multiple Prefix-SIDs are advertised for the same prefix, the		If multiple Prefix-SIDs are advertised for the same prefix, the
	receiving router MUST use the first encoded SID and MAY use the		receiving router MUST use the first encoded SID and MAY use
	subsequent SIDs.		subsequent SIDs.
	When propagating Prefix-SIDs between areas, if multiple prefix-SIDs		When propagating Prefix-SIDs between areas, if multiple prefix-SIDs
	are advertised for a prefix, an implementation SHOULD preserve the		are advertised for a prefix, an implementation SHOULD preserve the
	original order when advertising prefix-SIDs to other areas. This		original order when advertising prefix-SIDs to other areas. This
	allows implementations that only support a single Prefix-SID to have		allows implementations that only support a single Prefix-SID to have
	a consistent view across areas.		a consistent view across areas.
	When calculating the outgoing label for the prefix, the router MUST		When calculating the outgoing label for the prefix, the router MUST
	take into account the E and P flags advertised by the next-hop router		take into account the E and P flags advertised by the next-hop router
	if that router advertised the SID for the prefix. This MUST be done		if that router advertised the SID for the prefix. This MUST be done
	regardless of whether the next-hop router contributes to the best		regardless of whether the next-hop router contributes to the best
	path to the prefix.		path to the prefix.
	The NP-Flag (No-PHP) MUST be set for Prefix-SIDs allocated to inter-		The NP-Flag (No-PHP) MUST be set for Prefix-SIDs allocated to inter-
	area prefixes that are originated by the ABR based on intra-area or		area prefixes that are originated by the ABR based on intra-area or
	inter-area reachability between areas. When the inter-area prefix is		inter-area reachability between areas. When the inter-area prefix is
	generated based on a prefix which is directly attached to the ABR,		generated based on a prefix which is directly attached to the ABR,
	the NP-Flag SHOULD NOT be set.		the NP-Flag SHOULD NOT be set.
	The NP-Flag (No-PHP) MUST be be set for the Prefix-SIDs allocated to		The NP-Flag (No-PHP) MUST be be set for Prefix-SIDs allocated to
	redistributed prefixes, unless the redistributed prefix is directly		redistributed prefixes, unless the redistributed prefix is directly
	attached to the ASBR, in which case the NP-flag SHOULD NOT be set.		attached to the ASBR, in which case the NP-flag SHOULD NOT be set.
	If the NP-Flag is not set, then any upstream neighbor of the Prefix-		If the NP-Flag is not set, then any upstream neighbor of the Prefix-
	SID originator MUST pop the Prefix-SID. This is equivalent to the		SID originator MUST pop the Prefix-SID. This is equivalent to the
	penultimate hop popping mechanism used in the MPLS dataplane. In		penultimate hop popping mechanism used in the MPLS dataplane. In
	such case, MPLS EXP bits of the Prefix-SID are not preserved for the		such case, MPLS EXP bits of the Prefix-SID are not preserved for the
	final destination (the Prefix-SID being removed). If the NP-flag is		final destination (the Prefix-SID being removed). If the NP-flag is
	not set then the received E-flag is ignored.		not set then the received E-flag is ignored.
	skipping to change at page 15, line 7 ¶		skipping to change at page 15, line 7 ¶
	label. This is useful, e.g., when the originator of the Prefix-		label. This is useful, e.g., when the originator of the Prefix-
	SID is the final destination for the related prefix and the		SID is the final destination for the related prefix and the
	originator wishes to receive the packet with the original EXP		originator wishes to receive the packet with the original EXP
	bits.		bits.
	When the M-Flag is set, the NP-flag and the E-flag MUST be ignored at		When the M-Flag is set, the NP-flag and the E-flag MUST be ignored at
	reception.		reception.
	As the Mapping Server does not specify the originator of a prefix		As the Mapping Server does not specify the originator of a prefix
	advertisement, it is not possible to determine PHP behavior solely		advertisement, it is not possible to determine PHP behavior solely
	based on the Mapping Server advertisement. However, PHP behavior may		based on the Mapping Server advertisement. However, PHP behavior
	safely be done in following cases:		SHOULD be done in following cases:
	The Prefix is intra-area type and the downstream neighbor is the		The Prefix is intra-area type and the downstream neighbor is the
	originator of the prefix.		originator of the prefix.
	The Prefix is inter-area type and downstream neighbor is an ABR,		The Prefix is inter-area type and downstream neighbor is an ABR,
	which is advertising the prefix reachability and is also		which is advertising prefix reachability and is also generating
	generating the Extended Prefix TLV with the A-flag set for this		the Extended Prefix TLV with the A-flag set for this prefix as
	prefix as described in section 2.1 of [RFC7684].		described in section 2.1 of [RFC7684].
	The Prefix is external type and downstream neighbor is an ASBR,		The Prefix is external type and downstream neighbor is an ASBR,
	which is advertising the prefix reachability and is also		which is advertising prefix reachability and is also generating
	generating the Extended Prefix TLV with the A-flag set for this		the Extended Prefix TLV with the A-flag set for this prefix as
	prefix as described in section 2.1 of [RFC7684].		described in section 2.1 of [RFC7684].
	When a Prefix-SID is advertised in an Extended Prefix Range TLV, then		When a Prefix-SID is advertised in an Extended Prefix Range TLV, then
	the value advertised in Prefix SID Sub-TLV is interpreted as a		the value advertised in the Prefix SID Sub-TLV is interpreted as a
	starting SID value.		starting SID value.
	Example 1: If the following router addresses (loopback addresses)		Example 1: If the following router addresses (loopback addresses)
	need to be mapped into the corresponding Prefix SID indexes:		need to be mapped into the corresponding Prefix SID indexes:
	Router-A: 192.0.2.1/32, Prefix-SID: Index 1		Router-A: 192.0.2.1/32, Prefix-SID: Index 1
	Router-B: 192.0.2.2/32, Prefix-SID: Index 2		Router-B: 192.0.2.2/32, Prefix-SID: Index 2
	Router-C: 192.0.2.3/32, Prefix-SID: Index 3		Router-C: 192.0.2.3/32, Prefix-SID: Index 3
	Router-D: 192.0.2.4/32, Prefix-SID: Index 4		Router-D: 192.0.2.4/32, Prefix-SID: Index 4
	skipping to change at page 16, line 12 ¶		skipping to change at page 16, line 12 ¶
	10.1.6/24, Prefix-SID: Index 56		10.1.6/24, Prefix-SID: Index 56
	10.1.7/24, Prefix-SID: Index 57		10.1.7/24, Prefix-SID: Index 57
	then the Prefix field in the Extended Prefix Range TLV would be set		then the Prefix field in the Extended Prefix Range TLV would be set
	to 10.1.1.0, Prefix Length would be set to 24, Range Size would be 7,		to 10.1.1.0, Prefix Length would be set to 24, Range Size would be 7,
	and the Index value in the Prefix-SID Sub-TLV would be set to 51.		and the Index value in the Prefix-SID Sub-TLV would be set to 51.
	6. SID/Label Binding Sub-TLV		6. SID/Label Binding Sub-TLV
	The SID/Label Binding Sub-TLV is used to advertise a SID/Label		The SID/Label Binding Sub-TLV is used to advertise a SID/Label
	mapping for a path to the prefix.		mapping for a path to the a prefix.
	The SID/Label Binding Sub-TLV MAY be originated by any router in an		The SID/Label Binding Sub-TLV MAY be originated by any router in an
	OSPF domain. The router may advertise a SID/Label binding to a FEC		OSPF domain. The router may advertise a SID/Label binding to a FEC
	along with at least a single 'nexthop style' anchor. The protocol		along with at least a single 'nexthop style' anchor. The protocol
	supports more than one 'nexthop style' anchor to be attached to a		supports more than one 'nexthop style' anchor to be attached to a
	SID/Label binding, which results in a simple path description		SID/Label binding, which results in a simple path description
	language. In analogy to RSVP, the terminology for this is called an		language. Analogous to RSVP, the terminology for this is called an
	'Explicit Route Object' (ERO). Since ERO style path notation allows		'Explicit Route Object' (ERO). Since ERO-style path notation allows
	anchoring SID/label bindings to both link and node IP addresses, any		anchoring SID/label bindings to both link and node IP addresses, any
	Label Switched Path (LSP) can be described. Additionally, SID/Label		Label Switched Path (LSP) can be described. Additionally, SID/Label
	Bindings from external protocols can be easily re-advertised.		Bindings from external protocols can be easily re-advertised.
	The SID/Label Binding Sub-TLV may be used for advertising SID/Label		The SID/Label Binding Sub-TLV may be used for advertising SID/Label
	Bindings and their associated Primary and Backup paths. In a single		Bindings and their associated Primary and Backup paths. In a single
	TLV, a primary ERO Path, backup ERO Path, or both can be advertised.		TLV, a primary ERO Path, backup ERO Path, or both can be advertised.
	If a router wants to advertise multiple parallel paths, then it can		If a router wants to advertise multiple parallel paths, then it can
	generate several TLVs for the same Prefix/FEC. Each occurrence of a		generate several TLVs for the same Prefix/FEC. Each occurrence of a
	Binding TLV for a given FEC Prefix will add a new path.		Binding TLV for a given FEC Prefix will add a new path.
	skipping to change at page 17, line 19 ¶		skipping to change at page 17, line 19 ¶
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	|M| |		|M| |
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	where:		where:
	M-bit - When the bit is set, the binding represents a mirroring		M-bit - When the bit is set, the binding represents a mirroring
	context as defined in		context as defined in
	[I-D.minto-rsvp-lsp-egress-fast-protection].		[I-D.minto-rsvp-lsp-egress-fast-protection].
			Other bits: Reserved. These MUST be zero when sent and are
			ignored when received.
	MT-ID: Multi-Topology ID (as defined in [RFC4915]).		MT-ID: Multi-Topology ID (as defined in [RFC4915]).
	Weight: Weight used for load-balancing purposes. The use of the		Weight: 8 bits of weight used for load-balancing purposes. The
	weight is defined in [I-D.ietf-spring-segment-routing].		use of the weight is defined in [I-D.ietf-spring-segment-routing].
	The SID/Label Binding Sub-TLV supports the following Sub-TLVs:		The SID/Label Binding Sub-TLV supports the following Sub-TLVs:
	SID/Label Sub-TLV as described in Section 2.1. This Sub-TLV MUST		SID/Label Sub-TLV as described in Section 2.1. This Sub-TLV MUST
	appear in the SID/Label Binding Sub-TLV and it SHOULD only appear		appear in the SID/Label Binding Sub-TLV and it SHOULD only appear
	once. If the SID/Label Sub-TLV is not included in the SID/Label		once. If the SID/Label Sub-TLV is not included in the SID/Label
	Binding Sub-TLV, the SID/Label Binding Sub-TLV MUST be ignored.		Binding Sub-TLV, the SID/Label Binding Sub-TLV MUST be ignored.
	If the SID/Label Sub-TLV appears in the SID/Label Binding Sub-TLV		If the SID/Label Sub-TLV appears in the SID/Label Binding Sub-TLV
	more than once, instances other than the first will be ignored and		more than once, instances other than the first SHOULD be ignored
	the condition SHOULD be logged for possible action by the network		and the condition SHOULD be logged for possible action by the
	operator.		network operator.
	ERO Metric Sub-TLV as defined in Section 6.1.		ERO Metric Sub-TLV as defined in Section 6.1.
	ERO Sub-TLVs as defined in Section 6.2.		ERO Sub-TLVs as defined in Section 6.2.
	6.1. ERO Metric Sub-TLV		6.1. ERO Metric Sub-TLV
	The ERO Metric Sub-TLV is a Sub-TLV of the SID/Label Binding TLV.		The ERO Metric Sub-TLV is a Sub-TLV of the SID/Label Binding TLV.
	The ERO Metric Sub-TLV advertises the cost of an ERO path. It is		The ERO Metric Sub-TLV advertises the cost of an ERO path. It is
	used to compare the cost of a given source/destination path. A		used to compare the cost of a given source/destination path. ERO
	router SHOULD advertise the ERO Metric Sub-TLV in an advertised ERO		Metric Sub-TLV is an option sub-TLV. The cost of the ERO Metric Sub-
	TLV. The cost of the ERO Metric Sub-TLV SHOULD be set to the		TLV SHOULD be set to the cumulative IGP or TE path cost of the
	cumulative IGP or TE path cost of the advertised ERO. Since		advertised ERO. Since manipulation of the Metric field may attract
	manipulation of the Metric field may attract or repel traffic to and		or repel traffic to and from the advertised segment, it MAY be
	from the advertised segment, it MAY be manually overridden.		manually overridden.
	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 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Metric (4 octets) |		| Metric (4 octets) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	ERO Metric Sub-TLV format		ERO Metric Sub-TLV format
	skipping to change at page 18, line 33 ¶		skipping to change at page 18, line 35 ¶
	6.2. ERO Sub-TLVs		6.2. ERO Sub-TLVs
	All ERO information represents an ordered set which describes the		All ERO information represents an ordered set which describes the
	segments of a path. The first ERO Sub-TLV describes the first		segments of a path. The first ERO Sub-TLV describes the first
	segment of a path. Similiarly, the last ERO Sub-TLV describes the		segment of a path. Similiarly, the last ERO Sub-TLV describes the
	segment closest to the egress point. If a router extends or stitches		segment closest to the egress point. If a router extends or stitches
	a path, it MUST prepend the new segment's path information to the ERO		a path, it MUST prepend the new segment's path information to the ERO
	list. This applies equally to advertised backup EROs.		list. This applies equally to advertised backup EROs.
	All ERO Sub-TLVs must immediately follow the SID/Label Sub-TLV.		All ERO sub-TLVs are sub-TLVs of the SID/Label Binding TLV.
	All Backup ERO Sub-TLVs must immediately follow the last ERO Sub-TLV.
	6.2.1. IPv4 ERO Sub-TLV		6.2.1. IPv4 ERO Sub-TLV
	The IPv4 ERO Sub-TLV is a Sub-TLV of the SID/Label Binding Sub-TLV.		The IPv4 ERO Sub-TLV is a Sub-TLV of the SID/Label Binding Sub-TLV.
	The IPv4 ERO Sub-TLV describes a path segment using IPv4 Address		The IPv4 ERO Sub-TLV describes a path segment using IPv4 Address
	style encoding. Its semantics have been borrowed from [RFC3209].		style encoding. Its semantics have been borrowed from [RFC3209].
	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
	skipping to change at page 19, line 37 ¶		skipping to change at page 19, line 37 ¶
	|L| |		|L| |
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	where:		where:
	L-bit - If the L-bit is set, then the segment path is		L-bit - If the L-bit is set, then the segment path is
	designated as 'loose'. Otherwise, the segment path is		designated as 'loose'. Otherwise, the segment path is
	designated as 'strict'. The terms 'loose' and 'strict' are		designated as 'strict'. The terms 'loose' and 'strict' are
	defined for RSVP subobjects in [RFC3209].		defined for RSVP subobjects in [RFC3209].
			Other bits: Reserved. These MUST be zero when sent and are
			ignored when received.
	IPv4 Address - The address of the explicit route hop.		IPv4 Address - The address of the explicit route hop.
	6.2.2. Unnumbered Interface ID ERO Sub-TLV		6.2.2. Unnumbered Interface ID ERO Sub-TLV
	The Unnumbered Interface ID ERO Sub-TLV is a Sub-TLV of the SID/Label		The Unnumbered Interface ID ERO Sub-TLV is a Sub-TLV of the SID/Label
	Binding Sub-TLV.		Binding Sub-TLV.
	The appearance and semantics of the 'Unnumbered Interface ID' have		The appearance and semantics of the 'Unnumbered Interface ID' have
	been borrowed from [RFC3477].		been borrowed from [RFC3477].
	The Unnumbered Interface-ID ERO Sub-TLV describes a path segment that		The Unnumbered Interface-ID ERO Sub-TLV describes a path segment that
	includes an unnumbered interface. Unnumbered interfaces are		includes an unnumbered interface. Unnumbered interfaces are
	referenced using the interface index. Interface indices are assigned		referenced using the interface index. Interface indices are assigned
	local to the router and therefore are not unique within a domain.		local to the router and therefore are not unique within a domain.
	All elements in an ERO path need to be unique within a domain and		All elements in an ERO path need to be unique within a domain and
	hence need to be disambiguated using a domain unique Router-ID.		hence need to be disambiguated using a domain-unique Router-ID.
	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 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Flags | Reserved |		| Flags | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Router ID |		| Router ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 20, line 39 ¶		skipping to change at page 20, line 42 ¶
	|L| |		|L| |
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	where:		where:
	L-bit - If the L-bit is set, then the segment path is		L-bit - If the L-bit is set, then the segment path is
	designated as 'loose'. Otherwise, the segment path is		designated as 'loose'. Otherwise, the segment path is
	designated as 'strict'. The terms 'loose' and 'strict' are		designated as 'strict'. The terms 'loose' and 'strict' are
	defined for RSVP subobjects in [RFC3209]		defined for RSVP subobjects in [RFC3209]
	Router-ID: Router-ID of the next-hop.		Other bits: Reserved. These MUST be zero when sent and are
			ignored when received.
			Router ID: Router ID of the next-hop.
	Interface ID: The identifier assigned to the link by the router		Interface ID: The identifier assigned to the link by the router
	specified by the Router-ID.		specified by the Router ID.
	6.2.3. IPv4 Backup ERO Sub-TLV		6.2.3. IPv4 Backup ERO Sub-TLV
	IPv4 Prefix Backup ERO Sub-TLV is a Sub-TLV of the SID/Label Binding		IPv4 Prefix Backup ERO Sub-TLV is a Sub-TLV of the SID/Label Binding
	Sub-TLV.		Sub-TLV.
	The IPv4 Backup ERO Sub-TLV describes a path segment using IPv4		The IPv4 Backup ERO Sub-TLV describes a path segment using IPv4
	Address style of encoding. Its semantics have been borrowed from		Address style of encoding. Its semantics have been borrowed from
	[RFC3209].		[RFC3209].
	skipping to change at page 21, line 37 ¶		skipping to change at page 21, line 46 ¶
	|L| |		|L| |
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	where:		where:
	L-bit - If the L-bit is set, then the segment path is		L-bit - If the L-bit is set, then the segment path is
	designated as 'loose'. Otherwise, the segment path is		designated as 'loose'. Otherwise, the segment path is
	designated as 'strict'. The terms 'loose' and 'strict' are		designated as 'strict'. The terms 'loose' and 'strict' are
	defined for RSVP subobjects in [RFC3209]		defined for RSVP subobjects in [RFC3209]
			Other bits: Reserved. These MUST be zero when sent and are
			ignored when received.
	IPv4 Address - The address of the explicit route hop.		IPv4 Address - The address of the explicit route hop.
	6.2.4. Unnumbered Interface ID Backup ERO Sub-TLV		6.2.4. Unnumbered Interface ID Backup ERO Sub-TLV
	The Unnumbered Interface ID Backup ERO Sub-TLV is a Sub-TLV of the		The Unnumbered Interface ID Backup ERO Sub-TLV is a Sub-TLV of the
	SID/Label Binding Sub-TLV.		SID/Label Binding Sub-TLV.
	The appearance and semantics of the 'Unnumbered Interface ID' have		The appearance and semantics of the 'Unnumbered Interface ID' have
	been borrowed from [RFC3477].		been borrowed from [RFC3477].
	The Unnumbered Interface-ID Backup ERO Sub-TLV describes a path		The Unnumbered Interface-ID Backup ERO Sub-TLV describes a path
	segment that includes an unnumbered interface. Unnumbered interfaces		segment that includes an unnumbered interface. Unnumbered interfaces
	are referenced using the interface index. Interface indices are		are referenced using the interface index. Interface indices are
	assigned local to the router and are therefore not unique within a		assigned local to the router and are therefore not unique within a
	domain. All elements in an ERO path need to be unique within a		domain. All elements in an ERO path need to be unique within a
	domain and hence need to be disambiguated with specification of the		domain and hence need to be disambiguated with specification of the
	domain unique Router-ID.		domain-unique Router-ID.
	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 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Flags | Reserved |		| Flags | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Router ID |		| Router ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 22, line 40 ¶		skipping to change at page 23, line 5 ¶
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	|L| |		|L| |
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	where:		where:
	L-bit - If the L-bit is set, then the segment path is		L-bit - If the L-bit is set, then the segment path is
	designated as 'loose'. Otherwise, the segment path is		designated as 'loose'. Otherwise, the segment path is
	designated as 'strict'.		designated as 'strict'.
	Router-ID: Router-ID of the next-hop.		Other bits: Reserved. These MUST be zero when sent and are
			ignored when received.
			Router ID: Router ID of the next-hop.
	Interface ID: The identifier assigned to the link by the router		Interface ID: The identifier assigned to the link by the router
	specified by the Router-ID.		specified by the Router ID.
	7. Adjacency Segment Identifier (Adj-SID)		7. Adjacency Segment Identifier (Adj-SID)
	An Adjacency Segment Identifier (Adj-SID) represents a router		An Adjacency Segment Identifier (Adj-SID) represents a router
	adjacency in Segment Routing.		adjacency in Segment Routing.
	7.1. Adj-SID Sub-TLV		7.1. Adj-SID Sub-TLV
	Adj-SID is an optional Sub-TLV of the Extended Link TLV defined in		Adj-SID is an optional Sub-TLV of the Extended Link TLV defined in
	[RFC7684]. It MAY appear multiple times in the Extended Link TLV.		[RFC7684]. It MAY appear multiple times in the Extended Link TLV.
	skipping to change at page 23, line 40 ¶		skipping to change at page 24, line 6 ¶
	Flags: Single octet field containing the following flags:		Flags: Single octet field containing the following flags:
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	|B|V|L|G|P| |		|B|V|L|G|P| |
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	where:		where:
	B-Flag: Backup Flag. If set, the Adj-SID refers to an		B-Flag: Backup Flag. If set, the Adj-SID refers to an
	adjacency that is eligible for protection (e.g.: using IPFRR or		adjacency that is eligible for protection (e.g., using IPFRR or
	MPLS-FRR) as described in section 3.5 of		MPLS-FRR) as described in section 3.5 of
	[I-D.ietf-spring-segment-routing].		[I-D.ietf-spring-segment-routing].
	The V-Flag: Value/Index Flag. If set, then the Adj-SID carries		The V-Flag: Value/Index Flag. If set, then the Adj-SID carries
	an absolute value. If not set, then the Adj-SID carries an		an absolute value. If not set, then the Adj-SID carries an
	index.		index.
	The L-Flag: Local/Global Flag. If set, then the value/index		The L-Flag: Local/Global Flag. If set, then the value/index
	carried by the Adj-SID has local significance. If not set,		carried by the Adj-SID has local significance. If not set,
	then the value/index carried by this Sub-TLV has global		then the value/index carried by this Sub-TLV has global
	skipping to change at page 26, line 41 ¶		skipping to change at page 27, line 5 ¶
	An OSPFv2 router that supports segment routing MAY advertise Prefix-		An OSPFv2 router that supports segment routing MAY advertise Prefix-
	SIDs for any prefix to which it is advertising reachability (e.g., a		SIDs for any prefix to which it is advertising reachability (e.g., a
	loopback IP address as described in Section 5).		loopback IP address as described in Section 5).
	If multiple routers advertise a Prefix-SID for the same prefix, then		If multiple routers advertise a Prefix-SID for the same prefix, then
	the Prefix-SID MUST be the same. This is required in order to allow		the Prefix-SID MUST be the same. This is required in order to allow
	traffic load-balancing when multiple equal cost paths to the		traffic load-balancing when multiple equal cost paths to the
	destination exist in the OSPFv2 routing domain.		destination exist in the OSPFv2 routing domain.
	Prefix-SID can also be advertised by the SR Mapping Servers (as		A Prefix-SID can also be advertised by the SR Mapping Servers (as
	described in [I-D.filsfils-spring-segment-routing-ldp-interop]). The		described in [I-D.filsfils-spring-segment-routing-ldp-interop]). A
	Mapping Server advertises Prefix-SIDs for remote prefixes that exist		Mapping Server advertises Prefix-SIDs for remote prefixes that exist
	in the OSPFv2 routing domain. Multiple Mapping Servers can advertise		in the OSPFv2 routing domain. Multiple Mapping Servers can advertise
	Prefix-SIDs for the same prefix, in which case the same Prefix-SID		Prefix-SIDs for the same prefix, in which case the same Prefix-SID
	MUST be advertised by all of them. The flooding scope of the OSPF		MUST be advertised by all of them. The flooding scope of the OSPF
	Extended Prefix Opaque LSA that is generated by the SR Mapping Server		Extended Prefix Opaque LSA that is generated by the SR Mapping Server
	could be either area scoped or AS scoped and is determined based on		could be either area scoped or AS scoped and is determined based on
	the configuration of the SR Mapping Server.		the configuration of the SR Mapping Server.
	The SR Mapping Server MUST use OSPF Extended Prefix Range TLV when		An SR Mapping Server MUST use the OSPF Extended Prefix Range TLV when
	advertising SIDs for prefixes. Prefixes of different route-types can		advertising SIDs for prefixes. Prefixes of different route-types can
	be combined in a single OSPF Extended Prefix Range TLV advertised by		be combined in a single OSPF Extended Prefix Range TLV advertised by
	the SR Mapping Server.		an SR Mapping Server.
	Area-scoped OSPF Extended Prefix Range TLV are propagated between		Area-scoped OSPF Extended Prefix Range TLV are propagated between
	areas. Similar to propagation of prefixes between areas, an ABR only		areas. Similar to propagation of prefixes between areas, an ABR only
	propagates the OSPF Extended Prefix Range TLV that it considers to be		propagates the OSPF Extended Prefix Range TLV that it considers to be
	the best from the set it received. The rules used to pick the best		the best from the set it received. The rules used to pick the best
	OSPF Extended Prefix Range TLV are described in Section 4.		OSPF Extended Prefix Range TLV are described in Section 4.
	When propagating an OSPF Extended Prefix Range TLV between areas,		When propagating an OSPF Extended Prefix Range TLV between areas,
	ABRs MUST set the IA-Flag, that is used to prevent redundant flooding		ABRs MUST set the IA-Flag, that is used to prevent redundant flooding
	of the OSPF Extended Prefix Range TLV between areas as described in		of the OSPF Extended Prefix Range TLV between areas as described in
	skipping to change at page 28, line 21 ¶		skipping to change at page 28, line 33 ¶
	The ABR will then determine if such router advertised a Prefix-SID		The ABR will then determine if such router advertised a Prefix-SID
	for the prefix and use it when advertising the Prefix-SID to other		for the prefix and use it when advertising the Prefix-SID to other
	connected areas.		connected areas.
	If no Prefix-SID was advertised for the prefix in the backbone		If no Prefix-SID was advertised for the prefix in the backbone
	area by the ABR that contributes to the best path to the prefix,		area by the ABR that contributes to the best path to the prefix,
	the originating ABR will use the Prefix-SID advertised by any		the originating ABR will use the Prefix-SID advertised by any
	other router when propagating the Prefix-SID for the prefix to		other router when propagating the Prefix-SID for the prefix to
	other areas.		other areas.
	8.3. SID for External Prefixes		8.3. Segment Routing for External Prefixes
	Type-5 LSAs are flooded domain wide. When an ASBR, which supports		Type-5 LSAs are flooded domain wide. When an ASBR, which supports
	SR, generates Type-5 LSAs, it should also originate Extended Prefix		SR, generates Type-5 LSAs, it should also originate Extended Prefix
	Opaque LSAs, as described in [RFC7684]. The flooding scope of the		Opaque LSAs, as described in [RFC7684]. The flooding scope of the
	Extended Prefix Opaque LSA type is set to AS-scope. The route-type		Extended Prefix Opaque LSA type is set to AS-scope. The route-type
	in the OSPF Extended Prefix TLV is set to external. The Prefix-SID		in the OSPF Extended Prefix TLV is set to external. The Prefix-SID
	Sub-TLV is included in this LSA and the Prefix-SID value will be set		Sub-TLV is included in this LSA and the Prefix-SID value will be set
	to the SID that has been reserved for that prefix.		to the SID that has been reserved for that prefix.
	When an NSSA ABR translates Type-7 LSAs into Type-5 LSAs, it should		When an NSSA ABR translates Type-7 LSAs into Type-5 LSAs, it should
	skipping to change at page 29, line 5 ¶		skipping to change at page 29, line 17 ¶
	The Adjacency Segment Routing Identifier (Adj-SID) is advertised		The Adjacency Segment Routing Identifier (Adj-SID) is advertised
	using the Adj-SID Sub-TLV as described in Section 7.		using the Adj-SID Sub-TLV as described in Section 7.
	8.4.1. Advertisement of Adj-SID on Point-to-Point Links		8.4.1. Advertisement of Adj-SID on Point-to-Point Links
	An Adj-SID MAY be advertised for any adjacency on a P2P link that is		An Adj-SID MAY be advertised for any adjacency on a P2P link that is
	in neighbor state 2-Way or higher. If the adjacency on a P2P link		in neighbor state 2-Way or higher. If the adjacency on a P2P link
	transitions from the FULL state, then the Adj-SID for that adjacency		transitions from the FULL state, then the Adj-SID for that adjacency
	MAY be removed from the area. If the adjacency transitions to a		MAY be removed from the area. If the adjacency transitions to a
	state lower then 2-Way, then the Adj-SID advertisement MUST be		state lower then 2-Way, then the Adj-SID advertisement MUST be
	removed from the area.		withdrawn from the area.
	8.4.2. Adjacency SID on Broadcast or NBMA Interfaces		8.4.2. Adjacency SID on Broadcast or NBMA Interfaces
	Broadcast, NBMA or or hybrid [RFC6845] networks in OSPF are		Broadcast, NBMA, or hybrid [RFC6845] networks in OSPF are represented
	represented by a star topology where the Designated Router (DR) is		by a star topology where the Designated Router (DR) is the central
	the central point to which all other routers on the broadcast, NBMA,		point to which all other routers on the broadcast, NBMA, or hybrid
	or hybrid network connect. As a result, routers on the broadcast,		network connect. As a result, routers on the broadcast, NBMA, or
	NBMA, or hybrid network advertise only their adjacency to the DR.		hybrid network advertise only their adjacency to the DR. Routers
	Routers that do not act as DR do not form or advertise adjacencies		that do not act as DR do not form or advertise adjacencies with each
	with each other. They do, however, maintain 2-Way adjacency state		other. They do, however, maintain 2-Way adjacency state with each
	with each other and are directly reachable.		other and are directly reachable.
	When Segment Routing is used, each router on the broadcast or NBMA		When Segment Routing is used, each router on the broadcast, NBMSA, or
	network MAY advertise the Adj-SID for its adjacency to the DR using		hybrid network MAY advertise the Adj-SID for its adjacency to the DR
	the Adj-SID Sub-TLV as described in Section 7.1.		using the Adj-SID Sub-TLV as described in Section 7.1.
	SR capable routers MAY also advertise an LAN-Adj-SID for other		SR capable routers MAY also advertise a LAN-Adj-SID for other
	neighbors (e.g., BDR, DR-OTHER) on the broadcast, NBMA or hybrid		neighbors (e.g., BDR, DR-OTHER) on the broadcast, NBMA, or hybrid
	network using the LAN-ADJ-SID Sub-TLV as described in Section 7.2.		network using the LAN-ADJ-SID Sub-TLV as described in Section 7.2.
	9. IANA Considerations		9. IANA Considerations
	This specification updates several existing OSPF registries.		This specification updates several existing OSPF registries.
	9.1. OSPF OSPF Router Information (RI) TLVs Registry		9.1. OSPF OSPF Router Information (RI) TLVs Registry
	o 8 (IANA Preallocated) - SR-Algorithm TLV		o 8 (IANA Preallocated) - SR-Algorithm TLV
	skipping to change at page 30, line 33 ¶		skipping to change at page 30, line 46 ¶
	o 2 - Adj-SID Sub-TLV		o 2 - Adj-SID Sub-TLV
	o 3 - LAN Adj-SID/Label Sub-TLV		o 3 - LAN Adj-SID/Label Sub-TLV
	10. Implementation Status		10. Implementation Status
	An implementation survey with seven questions related to the		An implementation survey with seven questions related to the
	implementer's support of OSPFv2 Segment Routing was sent to the OSPF		implementer's support of OSPFv2 Segment Routing was sent to the OSPF
	WG list and several known implementers. This section contains		WG list and several known implementers. This section contains
	responses from two implementers who completed the survey. No		responses from three implementers who completed the survey. No
	external means were used to verify the accuracy of the information		external means were used to verify the accuracy of the information
	submitted by the respondents. The respondents are considered experts		submitted by the respondents. The respondents are considered experts
	on the products they reported on. Additionally, responses were		on the products they reported on. Additionally, responses were
	omitted from implementers who indicated that they have not		omitted from implementers who indicated that they have not
	implemented the function yet.		implemented the function yet.
	Responses from Nokia (former Alcatel-Lucent):		Responses from Nokia (former Alcatel-Lucent):
	Link to a web page describing the implementation:		Link to a web page describing the implementation:
	https://infoproducts.alcatel-lucent.com/cgi-bin/dbaccessfilename.cgi/		https://infoproducts.alcatel-lucent.com/cgi-bin/dbaccessfilename.cgi/
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