< draft-ietf-ospf-segment-routing-extensions-03.txt		draft-ietf-ospf-segment-routing-extensions-04.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: June 5, 2015 Cisco Systems, Inc.		Expires: August 5, 2015 Cisco Systems, Inc.
	H. Gredler		H. Gredler
	Juniper Networks, Inc.		Juniper Networks, Inc.
	R. Shakir		R. Shakir
	British Telecom		British Telecom
	W. Henderickx		W. Henderickx
	Alcatel-Lucent		Alcatel-Lucent
	J. Tantsura		J. Tantsura
	Ericsson		Ericsson
	December 2, 2014		February 1, 2015
	OSPF Extensions for Segment Routing		OSPF Extensions for Segment Routing
	draft-ietf-ospf-segment-routing-extensions-03		draft-ietf-ospf-segment-routing-extensions-04
	Abstract		Abstract
	Segment Routing (SR) allows for a flexible definition of end-to-end		Segment Routing (SR) allows for a flexible definition of end-to-end
	paths within IGP topologies by encoding paths as sequences of		paths within IGP topologies by encoding paths as sequences of
	topological sub-paths, called "segments". These segments are		topological sub-paths, called "segments". These segments are
	advertised by the link-state routing protocols (IS-IS and OSPF).		advertised by the 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 June 5, 2015.		This Internet-Draft will expire on August 5, 2015.
	Copyright Notice		Copyright Notice
	Copyright (c) 2014 IETF Trust and the persons identified as the		Copyright (c) 2015 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 2, line 43 ¶		skipping to change at page 2, line 43 ¶
	6.2. ERO Sub-TLVs . . . . . . . . . . . . . . . . . . . . . . 14		6.2. ERO Sub-TLVs . . . . . . . . . . . . . . . . . . . . . . 14
	6.2.1. IPv4 ERO Sub-TLV . . . . . . . . . . . . . . . . . . 15		6.2.1. IPv4 ERO Sub-TLV . . . . . . . . . . . . . . . . . . 15
	6.2.2. Unnumbered Interface ID ERO Sub-TLV . . . . . . . . . 16		6.2.2. Unnumbered Interface ID ERO Sub-TLV . . . . . . . . . 16
	6.2.3. IPv4 Backup ERO Sub-TLV . . . . . . . . . . . . . . . 17		6.2.3. IPv4 Backup ERO Sub-TLV . . . . . . . . . . . . . . . 17
	6.2.4. Unnumbered Interface ID Backup ERO Sub-TLV . . . . . 18		6.2.4. Unnumbered Interface ID Backup ERO Sub-TLV . . . . . 18
	7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 19		7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 19
	7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 19		7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 19
	7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 20		7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 20
	8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 22		8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 22
	8.1. Intra-area Segment routing in OSPFv2 . . . . . . . . . . 22		8.1. Intra-area Segment routing in OSPFv2 . . . . . . . . . . 22
	8.2. Inter-area Segment routing in OSPFv2 . . . . . . . . . . 22		8.2. Inter-area Segment routing in OSPFv2 . . . . . . . . . . 23
	8.3. SID for External Prefixes . . . . . . . . . . . . . . . . 23		8.3. SID for External Prefixes . . . . . . . . . . . . . . . . 24
	8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 24		8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 24
	8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 24		8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 24
	8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 24		8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 25
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24		9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
	9.1. OSPF OSPF Router Information (RI) TLVs Registry . . . . . 25		9.1. OSPF OSPF Router Information (RI) TLVs Registry . . . . . 25
	9.2. OSPF Extended Prefix LSA TLV Registry . . . . . . . . . . 25		9.2. OSPF Extended Prefix LSA TLV Registry . . . . . . . . . . 25
	9.3. OSPF Extended Prefix LSA Sub-TLV Registry . . . . . . . . 25		9.3. OSPF Extended Prefix LSA Sub-TLV Registry . . . . . . . . 25
	9.4. OSPF Extended Link LSA Sub-TLV Registry . . . . . . . . . 25		9.4. OSPF Extended Link LSA Sub-TLV Registry . . . . . . . . . 26
	10. Security Considerations . . . . . . . . . . . . . . . . . . . 25		10. Security Considerations . . . . . . . . . . . . . . . . . . . 26
	11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 26		11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 26
	12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26		12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
	13. References . . . . . . . . . . . . . . . . . . . . . . . . . 26		13. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
	13.1. Normative References . . . . . . . . . . . . . . . . . . 26		13.1. Normative References . . . . . . . . . . . . . . . . . . 26
	13.2. Informative References . . . . . . . . . . . . . . . . . 27		13.2. Informative References . . . . . . . . . . . . . . . . . 27
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28
	1. Introduction		1. Introduction
	Segment Routing (SR) allows for a flexible definition of end-to-end		Segment Routing (SR) allows for a flexible definition of end-to-end
	paths within IGP topologies by encoding paths as sequences of		paths within IGP topologies by encoding paths as sequences of
	topological sub-paths, called "segments". These segments are		topological sub-paths, called "segments". These segments are
	advertised by the link-state routing protocols (IS-IS and OSPF).		advertised by the link-state routing protocols (IS-IS and OSPF).
	Prefix segments represent an ecmp-aware shortest-path to a prefix (or		Prefix segments represent an ecmp-aware shortest-path to a prefix (or
	a node), as per the state of the IGP topology. Adjacency segments		a node), as per the state of the IGP topology. Adjacency segments
	represent a hop over a specific adjacency between two nodes in the		represent a hop over a specific adjacency between two nodes in the
	skipping to change at page 3, line 34 ¶		skipping to change at page 3, line 34 ¶
	plane can be applied to both IPv6 and MPLS data-planes, and does not		plane can be applied to both IPv6 and MPLS data-planes, and does not
	require any additional signalling (other than IGP extensions). For		require any additional signalling (other than IGP extensions). For
	example, when used in MPLS networks, SR paths do not require any LDP		example, when used in MPLS networks, SR paths do not require any LDP
	or RSVP-TE signalling. However, SR can interoperate in the presence		or RSVP-TE signalling. However, SR can interoperate in the presence
	of LSPs established with RSVP or LDP.		of LSPs established with RSVP or LDP.
	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.filsfils-rtgwg-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-rtgwg-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		For the purpose of the advertisements of various SID values, new
	Opaque LSAs [RFC5250] are defined in		Opaque LSAs [RFC5250] are defined in
	[I-D.ietf-ospf-prefix-link-attr]. These new LSAs are defined as		[I-D.ietf-ospf-prefix-link-attr]. These new LSAs are defined as
	generic containers that can be used to advertise any additional		generic containers that can be used to advertise any additional
	skipping to change at page 7, line 36 ¶		skipping to change at page 7, line 36 ¶
	...		...
	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 purposes of the SR-		(link, area, or autonomous system (AS)). For the purposes of the SR-
	Capability TLV propagation, area scope flooding is required.		Capability TLV propagation, area scope flooding is required.
	4. OSPF Extended Prefix Range TLV		4. OSPF Extended Prefix Range TLV
	In some cases it is useful to advertise attributes for the range of		In some cases it is useful to advertise attributes for the range of
	prefixes. Segment Routing Mapping Server, which is described in		prefixes. Segment Routing Mapping Server, which is described in
	[I-D.filsfils-rtgwg-segment-routing] is an example, where we need a		[I-D.filsfils-spring-segment-routing-ldp-interop], is an example,
	single advertisement to advertise SIDs for multiple prefixes from a		where we need a single advertisement to advertise SIDs for multiple
	contiguous address range.		prefixes from a contiguous address range.
	OSPF Extended Prefix Range TLV, which is a new top level TLV of the		OSPF Extended Prefix Range TLV, which is a new top level TLV of the
	Extended Prefix LSA described in [I-D.ietf-ospf-prefix-link-attr] is		Extended Prefix LSA described in [I-D.ietf-ospf-prefix-link-attr] is
	defined for this purpose.		defined for this 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:
	skipping to change at page 9, line 47 ¶		skipping to change at page 9, line 47 ¶
	where:		where:
	Type: TBD, suggested value 2.		Type: TBD, suggested value 2.
	Length: variable		Length: variable
	Flags: 1 octet field. The following flags are defined:		Flags: 1 octet field. The following flags are defined:
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+
	|N |NP|M |E |V |L | | |		| |NP|M |E |V |L | | |
	+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+
	where:		where:
	N-Flag: Node-SID flag. If set, then the Prefix-SID refers to
	the router identified by the prefix. Typically, the N-Flag is
	set to Prefix-SIDs corresponding to a router loopback address.
	The N-Flag is set when the Prefix-SID is a Node-SID, as
	described in [I-D.filsfils-rtgwg-segment-routing].
	NP-Flag: No-PHP flag. If set, then the penultimate hop MUST		NP-Flag: No-PHP flag. If set, then the penultimate hop MUST
	NOT pop the Prefix-SID before delivering the packet to the node		NOT pop the Prefix-SID before delivering the packet to the node
	that advertised the Prefix-SID.		that advertised the Prefix-SID.
	M-Flag: Mapping Server Flag. If set, the SID is advertised		M-Flag: Mapping Server Flag. If set, the SID is advertised
	from the Segment Routing Mapping Server functionality as		from the Segment Routing Mapping Server functionality as
	described in [I-D.filsfils-rtgwg-segment-routing].		described in [I-D.filsfils-spring-segment-routing-ldp-interop].
	E-Flag: Explicit-Null Flag. If set, any upstream neighbor of		E-Flag: Explicit-Null Flag. If set, any upstream neighbor of
	the Prefix-SID originator MUST replace the Prefix-SID with a		the Prefix-SID originator MUST replace the Prefix-SID with a
	Prefix-SID having an Explicit-NULL value (0 for IPv4) before		Prefix-SID having an Explicit-NULL value (0 for IPv4) before
	forwarding the packet.		forwarding the packet.
	V-Flag: Value/Index Flag. If set, then the Prefix-SID carries		V-Flag: Value/Index Flag. If set, then the Prefix-SID carries
	an absolute value. If not set, then the Prefix-SID carries an		an absolute value. If not set, then the Prefix-SID carries an
	index.		index.
	skipping to change at page 13, line 51 ¶		skipping to change at page 13, line 46 ¶
	where:		where:
	M-bit - When the bit is set the binding represents the		M-bit - When the bit is set the binding represents the
	mirroring context as defined in		mirroring context as defined in
	[I-D.minto-rsvp-lsp-egress-fast-protection].		[I-D.minto-rsvp-lsp-egress-fast-protection].
	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: weight used for load-balancing purposes. The use of the
	weight is defined in [I-D.filsfils-rtgwg-segment-routing].		weight is defined in [I-D.ietf-spring-segment-routing].
	The SID/Label Binding TLV supports the following Sub-TLVs:		The SID/Label Binding 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 MUST only appear		appear in the SID/Label Binding Sub-TLV and it MUST only appear
	once.		once.
	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.
	skipping to change at page 19, line 20 ¶		skipping to change at page 19, line 20 ¶
	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
	[I-D.ietf-ospf-prefix-link-attr]. It MAY appear multiple times in		[I-D.ietf-ospf-prefix-link-attr]. It MAY appear multiple times in
	the Extended Link TLV. Examples where more than one Adj-SID may be		the Extended Link TLV. Examples where more than one Adj-SID may be
	used per neighbor are described in		used per neighbor are described in section 4 of
	[I-D.filsfils-rtgwg-segment-routing-use-cases]. The Adj-SID Sub-TLV		[I-D.filsfils-spring-segment-routing-use-cases]. The Adj-SID Sub-TLV
	has the following format:		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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Length |		| Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Flags | Reserved | MT-ID | Weight |		| Flags | Reserved | MT-ID | Weight |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| SID/Label/Index (variable) |		| SID/Label/Index (variable) |
	skipping to change at page 19, line 51 ¶		skipping to change at page 19, line 51 ¶
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	|B|V|L|S| |		|B|V|L|S| |
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	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 being protected (e.g.: using IPFRR or MPLS-FRR) as		adjacency being protected (e.g.: using IPFRR or MPLS-FRR) as
	described in [I-D.filsfils-rtgwg-segment-routing-use-cases].		described in section 3.1 of
			[I-D.filsfils-spring-segment-routing-use-cases].
	The V-Flag: Value/Index Flag. If set, then the Prefix-SID		The V-Flag: Value/Index Flag. If set, then the Adj-SID carries
	carries an absolute value. If not set, then the Prefix-SID		an absolute value. If not set, then the Adj-SID carries an
	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 Prefix-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
	significance.		significance.
	The S-Flag. Set Flag. When set, the S-Flag indicates that the		The S-Flag. Set Flag. When set, the S-Flag indicates that the
	Adj-SID refers to a set of adjacencies (and therefore MAY be		Adj-SID refers to a set of adjacencies (and therefore MAY be
	assigned to other adjacencies as well).		assigned to other adjacencies as well).
	Other bits: Reserved. These MUST be zero when sent and are		Other bits: Reserved. These MUST be zero when sent and are
	ignored when received.		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: weight used for load-balancing purposes. The use of the
	weight is defined in [I-D.filsfils-rtgwg-segment-routing].		weight is defined in [I-D.ietf-spring-segment-routing].
	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.
	An SR capable router MAY allocate an Adj-SID for each of its		An SR capable router MAY allocate an Adj-SID for each of its
	adjacencies and set the B-Flag when the adjacency is protected by an		adjacencies and set the B-Flag when the adjacency is protected by an
	FRR mechanism (IP or MPLS) as described in		FRR mechanism (IP or MPLS) as described in section 3.1 of
	[I-D.filsfils-rtgwg-segment-routing-use-cases].		[I-D.filsfils-spring-segment-routing-use-cases].
	7.2. LAN Adj-SID Sub-TLV		7.2. LAN Adj-SID Sub-TLV
	LAN Adj-SID is an optional Sub-TLV of the Extended Link TLV defined		LAN Adj-SID is an optional Sub-TLV of the Extended Link TLV defined
	in [I-D.ietf-ospf-prefix-link-attr]. It MAY appear multiple times in		in [I-D.ietf-ospf-prefix-link-attr]. It MAY appear multiple times in
	the Extended-Link TLV. It is used to advertise a SID/Label for an		the Extended-Link TLV. It is used to advertise a SID/Label for an
	adjacency to a non-DR node on a broadcast or NBMA network.		adjacency to a non-DR node on a broadcast or NBMA network.
	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 21, line 34 ¶		skipping to change at page 21, line 34 ¶
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	|B|V|L|S| |		|B|V|L|S| |
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	where:		where:
	B-Flag: Backup-flag: set if the LAN-Adj-SID refer to an		B-Flag: Backup-flag: set if the LAN-Adj-SID refer to an
	adjacency being protected (e.g.: using IPFRR or MPLS-FRR) as		adjacency being protected (e.g.: using IPFRR or MPLS-FRR) as
	described in [I-D.filsfils-rtgwg-segment-routing-use-cases].		described in section 3.1 of
			[I-D.filsfils-spring-segment-routing-use-cases].
	The V-Flag: Value/Index Flag. If set, then the Prefix-SID		The V-Flag: Value/Index Flag. If set, then the Prefix-SID
	carries an absolute value. If not set, then the Prefix-SID		carries an absolute value. If not set, then the Prefix-SID
	carries an index.		carries an 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 Prefix-SID has local significance. If not set,		carried by the Prefix-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
	significance.		significance.
	The S-Flag. Set Flag. When set, the S-Flag indicates that the		The S-Flag. Set Flag. When set, the S-Flag indicates that the
	Adj-SID refers to a set of adjacencies (and therefore MAY be		Adj-SID refers to a set of adjacencies (and therefore MAY be
	assigned to other adjacencies as well).		assigned to other adjacencies as well).
	Other bits: Reserved. These MUST be zero when sent and are		Other bits: Reserved. These MUST be zero when sent and are
	ignored when received.		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: weight used for load-balancing purposes. The use of the
	weight is defined in [I-D.filsfils-rtgwg-segment-routing].		weight is defined in [I-D.ietf-spring-segment-routing].
	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.
	skipping to change at page 22, line 31 ¶		skipping to change at page 22, line 33 ¶
	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 network.		destination exist in the network.
	Prefix-SID can also be advertised by the SR Mapping Servers (as		Prefix-SID can also be advertised by the SR Mapping Servers (as
	described in [I-D.filsfils-rtgwg-segment-routing-use-cases]). The		described in [I-D.filsfils-spring-segment-routing-ldp-interop]). The
	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.
			SR Mapping Server MUST use OSPF Extended Prefix Range TLV when
			advertising SIDs for prefixes. Prefixes of different route-types can
			be combined in a single OSPF Extended Prefix Range TLV advertised by
			the SR Mapping Server.
			Area scoped OSPF Extended Prefix Range TLV are propagated between
			areas. Similar to propagation of prefixes between areas, ABR only
			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
			OSPF Extended Prefix Range TLV is described in Section 4.
			When propagating OSPF Extended Prefix Range TLV between areas, ABR
			MUST set the IA-Flag, that is used to prevent redundant flooding of
			the OSPF Extended Prefix Range TLV between areas as described in
			Section 4.
			If the Prefix-SID that is advertised in Prefix SID Sub-TLV is also
			covered by the OSPF Extended Prefix Range TLV, the Prefix-SID
			advertised in Prefix SID Sub-TLV MUST be preferred.
	8.2. Inter-area Segment routing in OSPFv2		8.2. Inter-area Segment routing in OSPFv2
	In order to support SR in a multi-area environment, OSPFv2 must		In order to support SR in a multi-area environment, OSPFv2 must
	propagate Prefix-SID information between areas. The following		propagate Prefix-SID information between areas. The following
	procedure is used in order to propagate Prefix SIDs between areas.		procedure is used in order to propagate Prefix SIDs between areas.
	When an OSPF ABR advertises a Type-3 Summary LSA from an intra-area		When an OSPF ABR advertises a Type-3 Summary LSA from an intra-area
	prefix to all its connected areas, it will also originate an Extended		prefix to all its connected areas, it will also originate an Extended
	Prefix Opaque LSA, as described in [I-D.ietf-ospf-prefix-link-attr].		Prefix Opaque LSA, as described in [I-D.ietf-ospf-prefix-link-attr].
	The flooding scope of the Extended Prefix Opaque LSA type will be set		The flooding scope of the Extended Prefix Opaque LSA type will be set
	skipping to change at page 23, line 17 ¶		skipping to change at page 23, line 40 ¶
	to that prefix.		to that prefix.
	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 source area		If no Prefix-SID was advertised for the prefix in the source area
	by the router that contributes to the best path to the prefix, the		by the router that contributes to the best path to the prefix, the
	originating ABR will use the Prefix-SID advertised by any other		originating ABR will use the Prefix-SID advertised by any other
	router (e.g.: a Prefix-SID coming from an SR Mapping Server as		router (e.g.: a Prefix-SID coming from an SR Mapping Server as
	defined in [I-D.filsfils-rtgwg-segment-routing-use-cases]) when		defined in [I-D.filsfils-spring-segment-routing-ldp-interop]) when
	propagating the Prefix-SID for the prefix to other areas.		propagating the Prefix-SID for the prefix to other areas.
	When an OSPF ABR advertises Type-3 Summary LSAs from an inter-area		When an OSPF ABR advertises Type-3 Summary LSAs from an inter-area
	route to all its connected areas it will also originate an Extended		route to all its connected areas it will also originate an Extended
	Prefix Opaque LSA, as described in [I-D.ietf-ospf-prefix-link-attr].		Prefix Opaque LSA, as described in [I-D.ietf-ospf-prefix-link-attr].
	The flooding scope of the Extended Prefix Opaque LSA type will be set		The flooding scope of the Extended Prefix Opaque LSA type will be set
	to area-scope. The route-type in OSPF Extended Prefix TLV is set to		to area-scope. The route-type in OSPF Extended Prefix TLV is set to
	inter-area. The Prefix-SID Sub-TLV will be included in this LSA and		inter-area. The Prefix-SID Sub-TLV will be included in this LSA and
	the Prefix-SID will be set as follows:		the Prefix-SID will be set as follows:
	skipping to change at page 23, line 40 ¶		skipping to change at page 24, line 17 ¶
	to that prefix.		to that prefix.
	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 source area		If no Prefix-SID was advertised for the prefix in the source area
	by the ABR that contributes to the best path to the prefix, the		by the ABR that contributes to the best path to the prefix, the
	originating ABR will use the Prefix-SID advertised by any other		originating ABR will use the Prefix-SID advertised by any other
	router (e.g.: a Prefix-SID coming from an SR Mapping Server as		router (e.g.: a Prefix-SID coming from an SR Mapping Server as
	defined in [I-D.filsfils-rtgwg-segment-routing-use-cases]) when		defined in [I-D.filsfils-spring-segment-routing-ldp-interop]) when
	propagating the Prefix-SID for the prefix to other areas.		propagating the Prefix-SID for the prefix to other areas.
	8.3. SID for External Prefixes		8.3. SID 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 an Extended		SR, generates Type-5 LSAs, it should also originate an Extended
	Prefix Opaque LSAs, as described in [I-D.ietf-ospf-prefix-link-attr].		Prefix Opaque LSAs, as described in [I-D.ietf-ospf-prefix-link-attr].
	The flooding scope of the Extended Prefix Opaque LSA type is set to		The flooding scope of the Extended Prefix Opaque LSA type is set to
	AS-scope. The route-type in the OSPF Extended Prefix TLV is set to		AS-scope. The route-type in the OSPF Extended Prefix TLV is set to
	external. The Prefix-SID Sub-TLV is included in this LSA and the		external. The Prefix-SID Sub-TLV is included in this LSA and the
	skipping to change at page 24, line 13 ¶		skipping to change at page 24, line 39 ¶
	that prefix.		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
	also advertise the Prefix-SID for the prefix. The NSSA ABR		also advertise the Prefix-SID for the prefix. The NSSA ABR
	determines its best path to the prefix advertised in the translated		determines its best path to the prefix advertised in the translated
	Type-7 LSA and finds the advertising router associated with that		Type-7 LSA and finds the advertising router associated with that
	path. If the advertising router has advertised a Prefix-SID for the		path. If the advertising router has advertised a Prefix-SID for the
	prefix, then the NSSA ABR uses it when advertising the Prefix-SID for		prefix, then the NSSA ABR uses it when advertising the Prefix-SID for
	the Type-5 prefix. Otherwise, the Prefix-SID advertised by any other		the Type-5 prefix. Otherwise, the Prefix-SID advertised by any other
	router will be used (e.g.: a Prefix-SID coming from an SR Mapping		router will be used (e.g.: a Prefix-SID coming from an SR Mapping
	Server as defined in [I-D.filsfils-rtgwg-segment-routing-use-cases]).		Server as defined in
			[I-D.filsfils-spring-segment-routing-ldp-interop]).
	8.4. Advertisement of Adj-SID		8.4. Advertisement of Adj-SID
	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
	skipping to change at page 27, line 10 ¶		skipping to change at page 27, line 32 ¶
	[RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S.		[RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S.
	Shaffer, "Extensions to OSPF for Advertising Optional		Shaffer, "Extensions to OSPF for Advertising Optional
	Router Capabilities", RFC 4970, July 2007.		Router Capabilities", RFC 4970, July 2007.
	[RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The		[RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The
	OSPF Opaque LSA Option", RFC 5250, July 2008.		OSPF Opaque LSA Option", RFC 5250, July 2008.
	13.2. Informative References		13.2. Informative References
	[I-D.filsfils-rtgwg-segment-routing]		[I-D.filsfils-spring-segment-routing-ldp-interop]
	Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,		Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
	Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,		Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
	Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe,		Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe,
	"Segment Routing Architecture", draft-filsfils-rtgwg-		"Segment Routing interoperability with LDP", draft-
	segment-routing-01 (work in progress), October 2013.		filsfils-spring-segment-routing-ldp-interop-02 (work in
			progress), September 2014.
	[I-D.filsfils-rtgwg-segment-routing-use-cases]		[I-D.filsfils-spring-segment-routing-use-cases]
	Filsfils, C., Francois, P., Previdi, S., Decraene, B.,		Filsfils, C., Francois, P., Previdi, S., Decraene, B.,
	Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,		Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
	Ytti, S., Henderickx, W., Tantsura, J., Kini, S., and E.		Ytti, S., Henderickx, W., Tantsura, J., Kini, S., and E.
	Crabbe, "Segment Routing Use Cases", draft-filsfils-rtgwg-		Crabbe, "Segment Routing Use Cases", draft-filsfils-
	segment-routing-use-cases-02 (work in progress), October		spring-segment-routing-use-cases-01 (work in progress),
	2013.		October 2014.
	[I-D.gredler-ospf-label-advertisement]		[I-D.gredler-ospf-label-advertisement]
	Gredler, H., Amante, S., Scholl, T., and L. Jalil,		Gredler, H., Amante, S., Scholl, T., and L. Jalil,
	"Advertising MPLS labels in OSPF", draft-gredler-ospf-		"Advertising MPLS labels in OSPF", draft-gredler-ospf-
	label-advertisement-03 (work in progress), May 2013.		label-advertisement-03 (work in progress), May 2013.
	[I-D.ietf-ospf-prefix-link-attr]		[I-D.ietf-ospf-prefix-link-attr]
	Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,		Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
	Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute		Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
	Advertisement", draft-ietf-ospf-prefix-link-attr-01 (work		Advertisement", draft-ietf-ospf-prefix-link-attr-02 (work
	in progress), September 2014.		in progress), December 2014.
			[I-D.ietf-spring-segment-routing]
			Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
			Litkowski, S., Horneffer, M., Shakir, R., Tantsura, J.,
			and E. Crabbe, "Segment Routing Architecture", draft-ietf-
			spring-segment-routing-00 (work in progress), December
			2014.
	[I-D.minto-rsvp-lsp-egress-fast-protection]		[I-D.minto-rsvp-lsp-egress-fast-protection]
	Jeganathan, J., Gredler, H., and Y. Shen, "RSVP-TE LSP		Jeganathan, J., Gredler, H., and Y. Shen, "RSVP-TE LSP
	egress fast-protection", draft-minto-rsvp-lsp-egress-fast-		egress fast-protection", draft-minto-rsvp-lsp-egress-fast-
	protection-03 (work in progress), November 2013.		protection-03 (work in progress), November 2013.
	Authors' Addresses		Authors' Addresses
	Peter Psenak (editor)		Peter Psenak (editor)
	Cisco Systems, Inc.		Cisco Systems, Inc.
End of changes. 34 change blocks.
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