draft-ietf-ospf-ospfv3-segment-routing-extensions-20.txt		draft-ietf-ospf-ospfv3-segment-routing-extensions-21.txt
	Open Shortest Path First IGP P. Psenak, Ed.		Open Shortest Path First IGP P. Psenak, Ed.
	Internet-Draft Cisco Systems, Inc.		Internet-Draft Cisco Systems, Inc.
	Intended status: Standards Track S. Previdi, Ed.		Intended status: Standards Track S. Previdi, Ed.
	Expires: June 6, 2019 Individual		Expires: June 17, 2019 Individual
	December 3, 2018		December 14, 2018
	OSPFv3 Extensions for Segment Routing		OSPFv3 Extensions for Segment Routing
	draft-ietf-ospf-ospfv3-segment-routing-extensions-20		draft-ietf-ospf-ospfv3-segment-routing-extensions-21
	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 OSPFv3 extensions required for Segment		This draft describes the OSPFv3 extensions required for Segment
	Routing with MPLS data plane.		Routing with MPLS data plane.
	Requirements Language		Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	document are to be interpreted as described in [RFC2119].		"OPTIONAL" in this document are to be interpreted as described in
			BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all
			capitals, as shown here.
	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 June 6, 2019.		This Internet-Draft will expire on June 17, 2019.
	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.
	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
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Segment Routing Identifiers . . . . . . . . . . . . . . . . . 4		3. Segment Routing Identifiers . . . . . . . . . . . . . . . . . 4
	3.1. SID/Label Sub-TLV . . . . . . . . . . . . . . . . . . . . 4		3.1. SID/Label Sub-TLV . . . . . . . . . . . . . . . . . . . . 4
	4. Segment Routing Capabilities . . . . . . . . . . . . . . . . 4		4. Segment Routing Capabilities . . . . . . . . . . . . . . . . 5
	5. OSPFv3 Extended Prefix Range TLV . . . . . . . . . . . . . . 5		5. OSPFv3 Extended Prefix Range TLV . . . . . . . . . . . . . . 5
	6. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 7		6. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 7
	7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 10		7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 11
	7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 11		7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 11
	7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 12		7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 13
	8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 13		8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 14
	8.1. Intra-area Segment routing in OSPFv3 . . . . . . . . . . 13		8.1. Intra-area Segment routing in OSPFv3 . . . . . . . . . . 14
	8.2. Inter-area Segment routing in OSPFv3 . . . . . . . . . . 14		8.2. Inter-area Segment routing in OSPFv3 . . . . . . . . . . 15
	8.3. Segment Routing for External Prefixes . . . . . . . . . . 15		8.3. Segment Routing for External Prefixes . . . . . . . . . . 16
	8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 16		8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 16
	8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 16		8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 16
	8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 16		8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 16
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16		9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
	9.1. OSPFv3 Extended-LSA TLV Registry . . . . . . . . . . . . 16		9.1. OSPFv3 Extended-LSA TLV Registry . . . . . . . . . . . . 17
	9.2. OSPFv3 Extended-LSA Sub-TLV registry . . . . . . . . . . 16		9.2. OSPFv3 Extended-LSA Sub-TLV registry . . . . . . . . . . 17
	10. Security Considerations . . . . . . . . . . . . . . . . . . . 17		10. Security Considerations . . . . . . . . . . . . . . . . . . . 17
	11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17		11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18
	12. References . . . . . . . . . . . . . . . . . . . . . . . . . 18		12. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
	12.1. Normative References . . . . . . . . . . . . . . . . . . 18		12.1. Normative References . . . . . . . . . . . . . . . . . . 19
	12.2. Informative References . . . . . . . . . . . . . . . . . 20		12.2. Informative References . . . . . . . . . . . . . . . . . 20
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
	1. Introduction		1. Introduction
	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). Prefix segments		link-state routing protocols (IS-IS and OSPF). Prefix segments
	represent an ECMP-aware shortest-path to a prefix (or a node), as per		represent an ECMP-aware shortest-path to a prefix (or a node), as per
	the state of the IGP topology. Adjacency segments represent a hop		the state of the IGP topology. Adjacency segments represent a hop
	over a specific adjacency between two nodes in the IGP. A prefix		over a specific adjacency between two nodes in the IGP. A prefix
	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 - OSPFv3 extension for SR with		of the scope of this specification - OSPFv3 extension for SR with
	IPv6 data plane will be specified in a separate document. When used		IPv6 data plane will be specified in a separate document. 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
	[RFC8402].
	This draft describes the OSPFv3 extensions required for Segment		This draft describes the OSPFv3 extensions required for Segment
	Routing with MPLS data plane.		Routing with MPLS data plane.
	Segment Routing architecture is described in [RFC8402].		Segment Routing architecture is described in [RFC8402].
	Segment Routing use cases are described in [RFC7855].		Segment Routing use cases are described in [RFC7855].
	2. Terminology		2. Terminology
	This section lists some of the terminology used in this document:		This section lists some of the terminology used in this document:
	ABR - Area Border Router		ABR - Area Border Router
	Adj-SID - Adjacency Segment Identifier		Adj-SID - Adjacency Segment Identifier
	AS - Autonomous System		AS - Autonomous System
	ASBR - Autonomous System Boundary Router		ASBR - Autonomous System Boundary Router
			DR - Designated Router
	IS-IS - Intermediate System to Intermediate System		IS-IS - Intermediate System to Intermediate System
	LDP - Label Distribution Protocol		LDP - Label Distribution Protocol
	LSP - Label Switched Path		LSP - Label Switched Path
	MPLS - Multi Protocol Label Switching		MPLS - Multi Protocol Label Switching
	OSPF - Open Shortest Path First		OSPF - Open Shortest Path First
	SPF - Shortest Path First		SPF - Shortest Path First
	RSVP - Resource Reservation Protocol		RSVP - Resource Reservation Protocol
	SID - Segment Identifier		SID - Segment Identifier
	SR - Segment Routing		SR - Segment Routing
	SRGB - Segment Routing Global Block		SRGB - Segment Routing Global Block
	SRLB - Segment Routing Local Block		SRLB - Segment Routing Local Block
	SRMS - Segment Routing Mapping Server		SRMS - Segment Routing Mapping Server
	TLV - Type Length Value		TLV - Type Length Value
	skipping to change at page 4, line 17 ¶		skipping to change at page 4, line 25 ¶
	SRLB - Segment Routing Local Block		SRLB - Segment Routing Local Block
	SRMS - Segment Routing Mapping Server		SRMS - Segment Routing Mapping Server
	TLV - Type Length Value		TLV - Type Length Value
	3. Segment Routing Identifiers		3. 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, and LAN Adjacency SID.
	3.1. SID/Label Sub-TLV		3.1. 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 Sub-TLV has		associated with a prefix or adjacency. The SID/Label Sub-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
	skipping to change at page 6, line 45 ¶		skipping to change at page 7, line 17 ¶
	a prefix of length 0.		a prefix of length 0.
	For the address family IPv6 unicast, the prefix, encoded as an		For the address family IPv6 unicast, the prefix, encoded as an
	even multiple of 32-bit words, padded with zeroed bits as		even multiple of 32-bit words, padded with zeroed bits as
	necessary. This encoding consumes ((PrefixLength + 31) / 32)		necessary. This encoding consumes ((PrefixLength + 31) / 32)
	32-bit words.		32-bit words.
	Prefix encoding for other address families is beyond the scope		Prefix encoding for other address families is beyond the scope
	of this specification.		of this specification.
			The range represents the contiguous set of prefixes with the same
			prefix length as specified by the Prefix Length field. The set
			starts with the prefix that is specified by the Address Prefix field.
			The number of prefixes in the range is equal to the Range size.
	If the OSPFv3 Extended Prefix Range TLVs advertising the exact same		If the OSPFv3 Extended Prefix Range TLVs advertising the exact same
	range appears in multiple LSAs of the same type, originated by the		range appears in multiple LSAs of the same type, originated by the
	same OSPFv3 router, the LSA with the numerically smallest Instance ID		same OSPFv3 router, the LSA with the numerically smallest Instance ID
	MUST be used and subsequent instances of the OSPFv3 Extended Prefix		MUST be used and subsequent instances of the OSPFv3 Extended Prefix
	Range TLVs MUST be ignored.		Range TLVs MUST be ignored.
	6. Prefix SID Sub-TLV		6. Prefix SID Sub-TLV
	The Prefix SID Sub-TLV is a Sub-TLV of the following OSPFv3 TLVs as		The Prefix SID Sub-TLV is a Sub-TLV of the following OSPFv3 TLVs as
	defined in [RFC8362] and in Section 5:		defined in [RFC8362] and in Section 5:
	skipping to change at page 9, line 15 ¶		skipping to change at page 9, line 47 ¶
	for the prefix. This MUST be done regardless of whether the next-hop		for the prefix. This MUST be done regardless of whether the next-hop
	router contributes to the best path to the prefix.		router contributes to the best path to the prefix.
	The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for		The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for
	Prefix-SIDs allocated to prefixes that are propagated between areas		Prefix-SIDs allocated to prefixes that are propagated between areas
	by an ABR based on intra-area or inter-area reachability, unless the		by an ABR based on intra-area or inter-area reachability, unless the
	advertised prefix is directly attached to such ABR.		advertised prefix is directly attached to such ABR.
	The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for		The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for
	Prefix-SIDs allocated to redistributed prefixes, unless the		Prefix-SIDs allocated to redistributed prefixes, unless the
	redistributed prefix is directly attached to the advertising		redistributed prefix is directly attached to the advertising ASBR.
	Autonomous System Boundary Router (ASBR).
	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. If the		penultimate hop popping mechanism used in the MPLS dataplane. If the
	NP-flag is not set, then the received E-flag is ignored.		NP-flag is not set, then the received E-flag is ignored.
	If the NP-flag is set then:		If the NP-flag is set then:
	If the E-flag is not set, then any upstream neighbor of the		If the E-flag is not set, then any upstream neighbor of the
	Prefix-SID originator MUST keep the Prefix-SID on top of the		Prefix-SID originator MUST keep the Prefix-SID on top of the
	stack. This is useful when the originator of the Prefix-SID needs		stack. This is useful when the originator of the Prefix-SID needs
	to stitch the incoming packet into a continuing MPLS LSP to the		to stitch the incoming packet into a continuing MPLS LSP to the
	final destination. This could occur at an Area Border Router		final destination. This could occur at an ABR (prefix propagation
	(prefix propagation from one area to another) or at an AS Boundary		from one area to another) or at an ASBR (prefix propagation from
	Router (prefix propagation from one domain to another).		one domain to another).
	If the E-flag is set, then any upstream neighbor of the Prefix-SID		If the E-flag is set, then any upstream neighbor of the Prefix-SID
	originator MUST replace the Prefix-SID with an Explicit-NULL		originator MUST replace the Prefix-SID with an Explicit-NULL
	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 Traffic
	bits.		Class field [RFC5462].
	When the M-Flag is set, the NP-flag and the E-flag MUST be ignored on		When the M-Flag is set, the NP-flag and the E-flag MUST be ignored on
	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		based on the Mapping Server advertisement. However, PHP behavior
	SHOULD 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
	skipping to change at page 13, line 36 ¶		skipping to change at page 13, line 49 ¶
	weight is defined in [RFC8402].		weight is defined in [RFC8402].
	Reserved: SHOULD be set to 0 on transmission and MUST be ignored		Reserved: SHOULD be set to 0 on transmission and MUST be ignored
	on reception.		on reception.
	Neighbor ID: The Router ID of the neighbor for which the LAN-Adj-		Neighbor ID: The Router ID of the neighbor for which the LAN-Adj-
	SID is advertised.		SID is advertised.
	SID/Index/Label: as described in Section 6.		SID/Index/Label: as described in Section 6.
	When the P-flag is not set, the Adj-SID MAY be persistent. When		When the P-flag is not set, the LAN Adj-SID MAY be persistent.
	the P-flag is set, the Adj-SID MUST be persistent.		When the P-flag is set, the LAN Adj-SID MUST be persistent.
	8. Elements of Procedure		8. Elements of Procedure
	8.1. Intra-area Segment routing in OSPFv3		8.1. Intra-area Segment routing in OSPFv3
	An OSPFv3 router that supports segment routing MAY advertise Prefix-		An OSPFv3 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 6).		loopback IP address as described in Section 6).
	A Prefix-SID can also be advertised by SR Mapping Servers (as		A Prefix-SID can also be advertised by SR Mapping Servers (as
	skipping to change at page 14, line 20 ¶		skipping to change at page 14, line 35 ¶
	External-LSA [RFC8362] is used.		External-LSA [RFC8362] is used.
	When a Prefix-SID is advertised by the Mapping Server, which is		When a Prefix-SID is advertised by the Mapping Server, which is
	indicated by the M-flag in the Prefix-SID Sub-TLV (Section 6), the		indicated by the M-flag in the Prefix-SID Sub-TLV (Section 6), the
	route type as implied by the LSA type is ignored and the Prefix-SID		route type as implied by the LSA type is ignored and the Prefix-SID
	is bound to the corresponding prefix independent of the route type.		is bound to the corresponding prefix independent of the route type.
	Advertisement of the Prefix-SID by the Mapping Server using an Inter-		Advertisement of the Prefix-SID by the Mapping Server using an Inter-
	Area Prefix TLV, External-Prefix TLV, or Intra-Area-Prefix TLV		Area Prefix TLV, External-Prefix TLV, or Intra-Area-Prefix TLV
	[RFC8362] does not itself contribute to the prefix reachability. The		[RFC8362] does not itself contribute to the prefix reachability. The
	NU-bit MUST be set in the PrefixOptions field of the LSA which is		NU-bit [RFC5340] MUST be set in the PrefixOptions field of the LSA
	used by the Mapping Server to advertise SID or SID Range, which		which is used by the Mapping Server to advertise SID or SID Range,
	prevents the advertisement from contributing to prefix reachability.		which prevents the advertisement from contributing to prefix
			reachability.
	An SR Mapping Server MUST use the OSPFv3 Extended Prefix Range TLVs		An SR Mapping Server MUST use the OSPFv3 Extended Prefix Range TLVs
	when advertising SIDs for prefixes. Prefixes of different route-		when advertising SIDs for prefixes. Prefixes of different route-
	types can be combined in a single OSPFv3 Extended Prefix Range TLV		types can be combined in a single OSPFv3 Extended Prefix Range TLV
	advertised by an SR Mapping Server.		advertised by an SR Mapping Server.
	Area-scoped OSPFv3 Extended Prefix Range TLVs are propagated between		Area-scoped OSPFv3 Extended Prefix Range TLVs are propagated between
	areas. Similar to propagation of prefixes between areas, an ABR only		areas, similar to propagation of prefixes between areas. Same rules
	propagates the OSPFv3 Extended Prefix Range TLV that it considers to		that are used for propagating prefixes between areas [RFC5340] are
	be the best from the set it received. The rules used to pick the		used for the propagation of the prefix ranges.
	best OSPFv3 Extended Prefix Range TLV are described in Section 5.
	8.2. Inter-area Segment routing in OSPFv3		8.2. Inter-area Segment routing in OSPFv3
	In order to support SR in a multi-area environment, OSPFv3 MUST		In order to support SR in a multi-area environment, OSPFv3 MUST
	propagate Prefix-SID information between areas. The following		propagate Prefix-SID information between areas. The following
	procedure is used to propagate Prefix SIDs between areas.		procedure is used to propagate Prefix SIDs between areas.
	When an OSPFv3 ABR advertises an Inter-Area-Prefix-LSA from an intra-		When an OSPFv3 ABR advertises an Inter-Area-Prefix-LSA from an intra-
	area prefix to all its connected areas, it will also include the		area prefix to all its connected areas, it will also include the
	Prefix-SID Sub-TLV, as described in Section 6. The Prefix-SID value		Prefix-SID Sub-TLV, as described in Section 6. The Prefix-SID value
	skipping to change at page 16, line 22 ¶		skipping to change at page 16, line 38 ¶
	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 than 2-Way, then the Adj-SID advertisement MUST be		state lower than 2-Way, then the Adj-SID advertisement MUST be
	withdrawn 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 hybrid [RFC6845] networks in OSPFv3 are		Broadcast, NBMA, or hybrid [RFC6845] networks in OSPFv3 are
	represented by a star topology where the Designated Router (DR) is		represented by a star topology where the DR is the central point to
	the central point to which all other routers on the broadcast, NBMA,		which all other routers on the broadcast, NBMA, or hybrid network
	or hybrid network connect. As a result, routers on the broadcast,		connect. As a result, routers on the broadcast, NBMA, or hybrid
	NBMA, or hybrid network advertise only their adjacency to the DR.		network advertise only their adjacency to the DR. Routers that do
	Routers that do not act as DR do not form or advertise adjacencies		not act as DR do not form or advertise adjacencies with each other.
	with each other. They do, however, maintain 2-Way adjacency state		They do, however, maintain 2-Way adjacency state with each other and
	with each other and are directly reachable.		are directly reachable.
	When Segment Routing is used, each router on the broadcast, NBMA, or		When Segment Routing is used, each router on the broadcast, NBMA, or
	hybrid network MAY advertise the Adj-SID for its adjacency to the DR		hybrid network MAY advertise the Adj-SID for its adjacency to the DR
	using 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 a 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
	skipping to change at page 19, line 9 ¶		skipping to change at page 19, line 16 ¶
	12.1. Normative References		12.1. Normative References
	[ALGOREG] "IGP Algorithm Types", <https://www.iana.org/assignments/		[ALGOREG] "IGP Algorithm Types", <https://www.iana.org/assignments/
	igp-parameters/igp-parameters.xhtml#igp-algorithm-types>.		igp-parameters/igp-parameters.xhtml#igp-algorithm-types>.
	[I-D.ietf-ospf-segment-routing-extensions]		[I-D.ietf-ospf-segment-routing-extensions]
	Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,		Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
	Shakir, R., Henderickx, W., and J. Tantsura, "OSPF		Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
	Extensions for Segment Routing", draft-ietf-ospf-segment-		Extensions for Segment Routing", draft-ietf-ospf-segment-
	routing-extensions-26 (work in progress), November 2018.		routing-extensions-27 (work in progress), December 2018.
	[I-D.ietf-spring-segment-routing-ldp-interop]		[I-D.ietf-spring-segment-routing-ldp-interop]
	Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and		Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and
	S. Litkowski, "Segment Routing interworking with LDP",		S. Litkowski, "Segment Routing interworking with LDP",
	draft-ietf-spring-segment-routing-ldp-interop-15 (work in		draft-ietf-spring-segment-routing-ldp-interop-15 (work in
	progress), September 2018.		progress), September 2018.
	[I-D.ietf-spring-segment-routing-mpls]		[I-D.ietf-spring-segment-routing-mpls]
	Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,		Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
	Litkowski, S., and R. Shakir, "Segment Routing with MPLS		Litkowski, S., and R. Shakir, "Segment Routing with MPLS
	data plane", draft-ietf-spring-segment-routing-mpls-16		data plane", draft-ietf-spring-segment-routing-mpls-18
	(work in progress), November 2018.		(work in progress), December 2018.
	[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>.
	[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol		[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
	Label Switching Architecture", RFC 3031,		Label Switching Architecture", RFC 3031,
	DOI 10.17487/RFC3031, January 2001,		DOI 10.17487/RFC3031, January 2001,
	<https://www.rfc-editor.org/info/rfc3031>.		<https://www.rfc-editor.org/info/rfc3031>.
	skipping to change at page 19, line 45 ¶		skipping to change at page 20, line 5 ¶
	<https://www.rfc-editor.org/info/rfc3101>.		<https://www.rfc-editor.org/info/rfc3101>.
	[RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,		[RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
	"LDP Specification", RFC 5036, DOI 10.17487/RFC5036,		"LDP Specification", RFC 5036, DOI 10.17487/RFC5036,
	October 2007, <https://www.rfc-editor.org/info/rfc5036>.		October 2007, <https://www.rfc-editor.org/info/rfc5036>.
	[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF		[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
	for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,		for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
	<https://www.rfc-editor.org/info/rfc5340>.		<https://www.rfc-editor.org/info/rfc5340>.
			[RFC5462] Andersson, L. and R. Asati, "Multiprotocol Label Switching
			(MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic
			Class" Field", RFC 5462, DOI 10.17487/RFC5462, February
			2009, <https://www.rfc-editor.org/info/rfc5462>.
	[RFC6845] Sheth, N., Wang, L., and J. Zhang, "OSPF Hybrid Broadcast		[RFC6845] Sheth, N., Wang, L., and J. Zhang, "OSPF Hybrid Broadcast
	and Point-to-Multipoint Interface Type", RFC 6845,		and Point-to-Multipoint Interface Type", RFC 6845,
	DOI 10.17487/RFC6845, January 2013,		DOI 10.17487/RFC6845, January 2013,
	<https://www.rfc-editor.org/info/rfc6845>.		<https://www.rfc-editor.org/info/rfc6845>.
	[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
			2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
			May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and		[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
	F. Baker, "OSPFv3 Link State Advertisement (LSA)		F. Baker, "OSPFv3 Link State Advertisement (LSA)
	Extensibility", RFC 8362, DOI 10.17487/RFC8362, April		Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
	2018, <https://www.rfc-editor.org/info/rfc8362>.		2018, <https://www.rfc-editor.org/info/rfc8362>.
	[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,		[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
	Decraene, B., Litkowski, S., and R. Shakir, "Segment		Decraene, B., Litkowski, S., and R. Shakir, "Segment
	Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,		Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
	July 2018, <https://www.rfc-editor.org/info/rfc8402>.		July 2018, <https://www.rfc-editor.org/info/rfc8402>.
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