draft-ietf-ospf-ospfv2-hbit-07.txt		draft-ietf-ospf-ospfv2-hbit-08.txt
	OSPF K. Patel		OSPF K. Patel
	Internet-Draft Arrcus		Internet-Draft Arrcus
	Updates: 2328 (if approved) P. Pillay-Esnault		Updates: 2328,6987 (if approved) P. Pillay-Esnault
	Intended status: Standards Track Huawei Technologies		Intended status: Standards Track Futurewei
	Expires: November 20, 2019 M. Bhardwaj		Expires: January 9, 2020 M. Bhardwaj
	S. Bayraktar		S. Bayraktar
	Cisco Systems		Cisco Systems
	May 19, 2019		July 8, 2019
	Host Router Support for OSPFv2		Host Router Support for OSPFv2
	draft-ietf-ospf-ospfv2-hbit-07		draft-ietf-ospf-ospfv2-hbit-08
	Abstract		Abstract
	The OSPFv2 specifies an SPF algorithm that identifies transit		The OSPFv2 specifies an SPF algorithm that identifies transit
	vertices based on their adjacencies. Therefore, OSPFv2 does not have		vertices based on their adjacencies. Therefore, OSPFv2 does not have
	a mechanism to prevent traffic transiting a participating node if it		a mechanism to prevent traffic transiting a participating node if it
	is a transit vertex in the only existing or shortest path to the		is a transit vertex in the only existing or shortest path to the
	destination. The use of metrics to make the node undesirable can		destination. The use of metrics to make the node undesirable can
	only help to repel traffic if an alternative better route exists.		only help to repel traffic if an alternative better route exists.
	This document defines the Host-bit functionality to prevent other		This document defines the Host-bit functionality to prevent other
	OSPFv2 routers from using the router for transit traffic in OSPFv2		OSPFv2 routers from using the router for transit traffic in OSPFv2
	routing domains. This document updates the [RFC2328] by assigning a		routing domains. This document updates the Open Shortest Path First
	new bit (Host-bit) in the OSPF Router-LSA bit registry. If the Host-		v2 specification (OSPFv2 rfc2328) by assigning a new bit (Host-bit)
	bit is set, the calculation of the shortest-path tree for an area, as		in the OSPF Router-LSA bit registry. In addition, if the Host-bit is
	described in [RFC2328], is modified by including a new check to		set, the calculation of the shortest-path tree for an area, as
	verify that transit vertices have the Host-bit clear.		described in OSPFv2, is modified by including a new check to verify
			that transit vertices have the Host-bit clear. In addition, this
			document updates OSPF Stub Router Advertisement (rfc6987) to
			advertise for type-2 External and NSSA LSAs with a high cost in order
			to repel traffic effectively.
	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-
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			This Internet-Draft will expire on January 9, 2020.
	This Internet-Draft will expire on November 20, 2019.
	Copyright Notice		Copyright Notice
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	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3		2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
	3. Host-bit Support . . . . . . . . . . . . . . . . . . . . . . 3		3. Host-bit Support . . . . . . . . . . . . . . . . . . . . . . 3
	4. SPF Modifications . . . . . . . . . . . . . . . . . . . . . . 5		4. SPF Modifications . . . . . . . . . . . . . . . . . . . . . . 5
	5. Auto Discovery and Backward Compatibility . . . . . . . . . . 6		5. Auto Discovery and Backward Compatibility . . . . . . . . . . 6
	6. OSPF AS-External-LSAs/NSSA LSAs with Type 2 Metrics . . . . . 6		6. OSPF AS-External-LSAs/NSSA LSAs with Type 2 Metrics . . . . . 7
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 7		8. Security Considerations . . . . . . . . . . . . . . . . . . . 8
	9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7		9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7		10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
	10.1. Normative References . . . . . . . . . . . . . . . . . . 7		10.1. Normative References . . . . . . . . . . . . . . . . . . 9
	10.2. Informative References . . . . . . . . . . . . . . . . . 8		10.2. Informative References . . . . . . . . . . . . . . . . . 9
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
	1. Introduction		1. Introduction
	The OSPFv2 specifies an SPF algorithm that identifies transit		The OSPFv2 specifies an SPF algorithm that identifies transit
	vertices based on their adjacencies. Therefore, OSPFv2 does not have		vertices based on their adjacencies. Therefore, OSPFv2 does not have
	a mechanism to prevent traffic transiting a participating node if it		a mechanism to prevent traffic transiting a participating node if it
	is a transit vertex in the only existing or shortest path to the		is a transit vertex in the only existing or shortest path to the
	destination. The use of metrics to make the node undesirable can		destination. The use of metrics to make the node undesirable can
	only help to repel traffic if an alternative better route exists.		only help to repel traffic if an alternative better route exists.
	This functionality is particularly useful for a number of use cases:		This functionality is particularly useful for a number of use cases:
	1. To isolate a router to avoid blackhole scenarios when there is a		1. To isolate a router to avoid blackhole scenarios when there is a
	reload and possible long reconvergence times.		reload and possible long reconvergence times.
	2. Closet Switches are usually not used for transit traffic but need		2. Closet Switches are usually not used for transit traffic but need
	to participate in the topology.		to participate in the topology.
	3. Overloaded routers could use such a capability to repel traffic		3. Overloaded routers could use such a capability to temporarily
	until they stabilize.		repel traffic until they stabilize.
	4. BGP Route reflectors known as virtual Route Reflectors (vRRs),		4. BGP Route reflectors known as virtual Route Reflectors (vRRs),
	that are not in the forwarding path but are in central locations		that are not in the forwarding path but are in central locations
	such as data centers. Such Route Reflectors typically are used		such as data centers. Such Route Reflectors typically are used
	for route distribution and are not capable of forwarding transit		for route distribution and are not capable of forwarding transit
	traffic. However, they need to learn the OSPF topology to		traffic. However, they need to learn the OSPF topology to
	perform spf computation for optimal routes and reachbility		perform spf computation for optimal routes and reachbility
	resolution for its clients		resolution for its clients
	[I-D.ietf-idr-bgp-optimal-route-reflection].		[I-D.ietf-idr-bgp-optimal-route-reflection].
	This document defines the Host-bit (H-Bit)functionality to prevent		This document defines the Host-bit (H-Bit)functionality to prevent
	other OSPFv2 routers from using the router for transit traffic in		other OSPFv2 routers from using the router for transit traffic in
	OSPFv2 routing domains. This document updates the [RFC2328] by -		OSPFv2 routing domains. This document updates the [RFC2328] by -
	assigning the Host-bit in the OSPF Router-LSA bit registry - if the		assigning the Host-bit in the OSPFv2 Router Properties Registry - if
	host-bit is set then the calculation of the shortest-path tree for an		the host-bit is set then the calculation of the shortest-path tree
	area, as described in section 16.1 of [RFC2328], is modified by		for an area, as described in section 16.1 of [RFC2328], is modified
	including a new check to verify that transit vertices DO NOT have the		by including a new check to verify that transit vertices DO NOT have
	host-bit set.		the host-bit set.
	2. Requirements Language		2. Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	3. Host-bit Support		3. Host-bit Support
	This document defines a new router-LSA bit known as the Host Bit or		This document defines a new router-LSA bit known as the Host Bit or
	the H-bit. An OSPFv2 router advertising a router-LSA with the H-bit		the H-bit. An OSPFv2 router advertising a router-LSA with the H-bit
	set indicates to other OSPFv2 routers in the area supporting the		set indicates to other OSPFv2 routers in the area supporting the
	functionality that it MUST NOT be used as a transit router (see		functionality that it MUST NOT be used as a transit router (see
	section 4).		section 4).
	If the host-bit is NOT set routers MUST act transit routers as		If the host-bit is NOT set routers MUST act transit routers as
	described in [RFC2328] ensuring backward compatibility.		described in [RFC2328] ensuring backward compatibility.
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| LS age | Options | 1 |		| LS age | Options | 1 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Link State ID |		| Link State ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Advertising Router |		| Advertising Router |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| LS sequence number |		| LS sequence number |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| LS checksum | length |		| LS checksum | length |
	skipping to change at page 4, line 49 ¶		skipping to change at page 4, line 46 ¶
	Host Bit in router-LSA		Host Bit in router-LSA
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	|H|0|0|N|W|V|E|B|		|H|0|0|N|W|V|E|B|
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	Host Bit		Host Bit
	Bit H is the high-order bit of the OSPF as shown above. When set, an		Bit H is the high-order bit of the OSPF as shown above. When set, an
	OSPFv2 router is a non-transit router and is incapable of forwarding		OSPFv2 router is a Host (non-transit) router and is incapable of
	transit traffic.		forwarding transit traffic.
	An OSPFv2 router originating a router-LSA with the H-bit set MUST		An OSPFv2 router originating a router-LSA with the H-bit set MUST
	advertise all its router links with a link cost of MaxLinkMetric		advertise all its router links with a link cost of MaxLinkMetric
	[RFC6987]. This is to increase the applicability of the H-bit to		[RFC6987]. This is to increase the applicability of the H-bit to
	partial deployments where it is the responsibility of the operator to		partial deployments where it is the responsibility of the operator to
	ensure that OSPFv2 routers not supporting the H-bit do not install		ensure that OSPFv2 routers not supporting the H-bit do not install
	routes causing routing loops.		routes causing routing loops.
	When the H-bit is set, an Area Border Router (ABR) MUST advertise a		When the H-bit is set, an Area Border Router (ABR) MUST advertise the
	consistent H-bit setting in its self-originated router-LSAs for all		same H-bit setting in its self-originated router-LSAs for all
	attached areas. ONLY IPv4 prefixes associated with its local		attached areas. The consistency of the setting will prevent inter-
	interfaces MAY be advertised in summary LSAs.		area traffic transiting through the router by suppressing the
			suppressing advertisement of prefixes from other routers in the area
			in its summary LSAs. ONLY IPv4 prefixes associated with its local
			interfaces MAY be advertised in summary LSAs to provide reachability
			to end hosts attached behind a router with the H-bit set.
	When the H-bit is set cannot act as an AS Boundary Router (ASBR), as		When the H-bit is set cannot act as an AS Boundary Router (ASBR), as
	non-local IPv4 prefixes, e.g., those exported from other routing		ASBR are transit routers to prefixes that are typically imported
	protocols, MUST NOT be advertised in AS-external-LSAs.		through redistribution of prefixes of other routing protocols.
			Therefore, non-local IPv4 prefixes, e.g., those exported from other
			routing protocols, MUST NOT be advertised in AS-external-LSAs for
			routers acting permanly as a host. However, in use cases such as an
			overloaded router or a router being gracefully isolated, these
			routers are only temporarily acting as host routers and therefore
			should continue to advertise their External LSAs but ensure they do
			not attract traffic. In addition to the procedure described above,
			temporary host routers advertising type 2-metric External LSAs MUST
			set the metrics to LSInfinity to repel traffic.(see Section 6 of this
			document).
	4. SPF Modifications		4. SPF Modifications
	The SPF calculation described in section 16.1 [RFC2328] will be		The SPF calculation described in section 16.1 [RFC2328] will be
	modified to ensure that the routers originating router-LSAs with the		modified to ensure that the routers originating router-LSAs with the
	H-bit set will not be used for transit traffic. Step 2 is modified		H-bit set will not be used for transit traffic. Step 2 is modified
	as follows:		as follows:
	2) Call the vertex just added to the		2) Call the vertex just added to the
	tree vertex V. Examine the LSA		tree vertex V. Examine the LSA
	skipping to change at page 6, line 9 ¶		skipping to change at page 6, line 28 ¶
	TransitCapability to TRUE. In any case,		TransitCapability to TRUE. In any case,
	each link described by the LSA gives		each link described by the LSA gives
	the cost to an adjacent vertex. For		the cost to an adjacent vertex. For
	each described link, (say it joins		each described link, (say it joins
	vertex V to vertex W):		vertex V to vertex W):
	5. Auto Discovery and Backward Compatibility		5. Auto Discovery and Backward Compatibility
	To avoid the possibility of any routing loops due to partial		To avoid the possibility of any routing loops due to partial
	deployment, this document defines a OSPF Router Information (RI) LSA		deployment, this document defines a OSPF Router Information (RI) LSA
	with a Router Functional Capability TLV that includes the following		[RFC7770] with and area flooding scope and a new bit assigned in the
	Router Functional Capability Bit:		OSPF Router Informational Capability Bits Registry. Bit:
	Bit Capabilities		Bit Capabilities
	7 Host Router Support capability		7 Host Router Support capability
	Auto Discovery via announcement of the Host Support Functional		Auto Discovery via announcement of the Host Support Functional
	Capability ensures that the H-bit functionality and its associated		Capability ensures that the H-bit functionality and its associated
	SPF changes SHOULD only take effect if all the routers in a given		SPF changes MUST only take effect if all the routers in a given OSPF
	OSPF area support this functionality.		area support this functionality.
	Implementations are encouraged to provide a configuration parameter		In normal operations, there is no guarantee that the RI LSA will
	to manually override enforcement of the H-bit functionality in		reach all routers in an area in a timely manner which may result in
	partial deployments where the topology guarantees that OSPFv2 routers		rooting loops in partial deployments. For example, in a new router
	not supporting the H-bit do not compute routes resulting in routing		joins an area which previous had only H-bit capable routers with
	loops. More precisely, the advertisement of MaxLinkMetric for the		H-bit set then it may take some time for the RI to propagate to all
	router's non-local links will prevent OSPFv2 routers not supporting		routers.
	the H-bit from attempting to use it for transit traffic.
			The following recommendations will mitigate transient routing loops:
			o Implementations are RECOMMENDED to provide a configuration
			parameter to manually override enforcement of the H-bit
			functionality in partial deployments where the topology guarantees
			that OSPFv2 routers not supporting the H-bit do not compute routes
			resulting in routing loops.
			o All routers, with the H-bit set, MUST advertise all of the
			router's non-local links with a metric equal to MaxLinkMetric in
			its LSAs in order to avoid OSPFv2 (unless last resort) routers not
			supporting the H-bit from attempting to use it for transit
			traffic.
			o All routers supporting H-Bit MUST check all the RI LSAs of nodes
			in the area before actively running the modified SPF to account
			for the H-bit in order to verify that all routers are in routing
			capability. If any router does not have the H-Bit support then
			all routers in the areas MUST run the normal SPF.
			o Any router not supporting the H-bit capability is detected (by
			examination of RI- LSA or RTR LSA in the area database) then all
			routers in the area MUST revert back to normal operations.
	6. OSPF AS-External-LSAs/NSSA LSAs with Type 2 Metrics		6. OSPF AS-External-LSAs/NSSA LSAs with Type 2 Metrics
	When calculating the path to an OSPF AS-External-LSA or NSSA-LSA with		When calculating the path to an OSPF AS-External-LSA or NSSA-LSA with
	a Type-2 metric, the advertised Type-2 metric is taken as more		a Type-2 metric, the advertised Type-2 metric is taken as more
	significant than the OSPF intra-area or inter-area path. Hence,		significant than the OSPF intra-area or inter-area path. Hence,
	advertising the links with MaxLinkMetric as specified in [RFC6987]		advertising the links with MaxLinkMetric as specified in [RFC6987]
	does not discourage transit traffic when calculating AS external or		does not discourage transit traffic when calculating AS external or
	NSSA routes. Consequently, OSPF routers implementing [RFC6987] or		NSSA routes with Type-2 metrics.
	this specification should advertise a Type-2 metric of LSInfinity for
	any self-originated AS-External-LSAs or NSSA-LSAs in situations when		Consequently, OSPF routers implementing [RFC6987] and required to be
	the OSPF router is acting as a stub router [RFC6987] or implementing		the last resort transit then they MUST advertise a Type-2 metric of
	this specification.		LSInfinity-1 for any self-originated type 2 AS-External-LSAs or NSSA-
			LSAs. However, in situations, the router needs to repel traffic and
			acts as a host router then, in addition of the host bit procedure
			described in this document they MUST advertise a Type-2 metric of
			LSInfinity for any self-originated type 2 AS-External-LSAs or NSSA-
			LSAs.
	7. IANA Considerations		7. IANA Considerations
	IANA is requested to create the OSPF Router-LSA bit registry with the		This document requests the IANA to assign the 0x80 value to the Host-
	following assignments:		Bit (H-bit)in the OSPFv2 Router Properties Registry
	Value Description Reference		Value Description Reference
	0x01 Area Border Router (B-bit) [RFC2328]
	0x02 AS Boundary Router (E-bit) [RFC2328]
	0x04 Virtual Link Endpoint (V-bit) [RFC2328]
	0x08 Historic (W-bit) [RFC1584]
	0x10 Unconditional NSSA Translator (Nt-bit) [RFC3101]
	0x20 Unassigned
	0x40 Unassigned
	0x80 Host (H-bit) This Document
	This document also defines a new Router Functional Capability		0x80 Host (H-bit) This Document
	[RFC7770] known as the Host Router Support Functional Capability.
	This document requests IANA to allocate the value of this capability		This document requests the IANA to assign the Bit Number value of 7
	from the Router Functional Capability Bits TLV.		to the Host Router Support Capability in the OSPF Router
			Informational Capability Bits Registry. [RFC7770]
			Bit Number Capability Name Reference
			7 OSPF Host Router This Document
	8. Security Considerations		8. Security Considerations
	This document introduces no new security considerations beyond those		This document introduces the H-bit which is a capability that
	already specified in [RFC6987], [RFC2328], and [RFC5340].		restricts the use of a router for transit except for its local
			destinations. This is a subset of the operations of a normal router
			and therefore should not introduce new security considerations beyond
			those already known in OSPF. The feature however does introduce the
			flooding of a capability information that allows discovery and
			verification that all routers in an area are capable before turning
			on the feature. In case. a rogue or buggy router advertise
			incorrectly its capability there are two possible cases:
			o The router does not have the capability but send H-Bit set in its
			LSAs: In this case, there is a possibility of a routing loop.
			However this is mitigated by the fact that this router should be
			avoided anyway. Moreover, the link metrics cost of this router
			should be MaxLinkMetric and will mitigate this situation. In any
			case a router advertising the H-bit capability without its links
			cost equal to MaxLinkMetric may be an indicator that this is a
			rogue router.
			o The router has the capability but sends the H-Bit clear in its
			LSAs: In this case, the router merely prevents support of other
			H-bit routers in the area and all the routers to run the modified
			SPF. The impact is also mitigated as other H-Bit routers in the
			area also advertise MaxLinkMetric cost so they will still be
			avoided unless they are the last resort path.
	9. Acknowledgements		9. Acknowledgements
	The authors would like to acknowledge Hasmit Grover for discovery of		The authors would like to acknowledge Hasmit Grover for discovery of
	the limitation in [RFC6987], Acee Lindem, Abhay Roy, David Ward,		the limitation in [RFC6987], Acee Lindem, Abhay Roy, David Ward,
	Burjiz Pithawala and Michael Barnes for their comments.		Burjiz Pithawala and Michael Barnes for their comments.
	10. References		10. References
	10.1. Normative References		10.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,		[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
	DOI 10.17487/RFC2328, April 1998,		DOI 10.17487/RFC2328, April 1998,
	<https://www.rfc-editor.org/info/rfc2328>.		<https://www.rfc-editor.org/info/rfc2328>.
	skipping to change at page 7, line 44 ¶		skipping to change at page 9, line 15 ¶
	[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>.
	[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,		[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
	DOI 10.17487/RFC2328, April 1998,		DOI 10.17487/RFC2328, April 1998,
	<https://www.rfc-editor.org/info/rfc2328>.		<https://www.rfc-editor.org/info/rfc2328>.
	[RFC3101] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option",
	RFC 3101, DOI 10.17487/RFC3101, January 2003,
	<https://www.rfc-editor.org/info/rfc3101>.
	[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
	for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
	<https://www.rfc-editor.org/info/rfc5340>.
	[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and		[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
	S. Shaffer, "Extensions to OSPF for Advertising Optional		S. Shaffer, "Extensions to OSPF for Advertising Optional
	Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,		Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
	February 2016, <https://www.rfc-editor.org/info/rfc7770>.		February 2016, <https://www.rfc-editor.org/info/rfc7770>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	10.2. Informative References		10.2. Informative References
	[I-D.ietf-idr-bgp-optimal-route-reflection]		[I-D.ietf-idr-bgp-optimal-route-reflection]
	Raszuk, R., Cassar, C., Aman, E., Decraene, B., and K.		Raszuk, R., Cassar, C., Aman, E., Decraene, B., and K.
	Wang, "BGP Optimal Route Reflection (BGP-ORR)", draft-		Wang, "BGP Optimal Route Reflection (BGP-ORR)", draft-
	ietf-idr-bgp-optimal-route-reflection-18 (work in		ietf-idr-bgp-optimal-route-reflection-18 (work in
	progress), April 2019.		progress), April 2019.
	[RFC1584] Moy, J., "Multicast Extensions to OSPF", RFC 1584,
	DOI 10.17487/RFC1584, March 1994,
	<https://www.rfc-editor.org/info/rfc1584>.
	[RFC6987] Retana, A., Nguyen, L., Zinin, A., White, R., and D.		[RFC6987] Retana, A., Nguyen, L., Zinin, A., White, R., and D.
	McPherson, "OSPF Stub Router Advertisement", RFC 6987,		McPherson, "OSPF Stub Router Advertisement", RFC 6987,
	DOI 10.17487/RFC6987, September 2013,		DOI 10.17487/RFC6987, September 2013,
	<https://www.rfc-editor.org/info/rfc6987>.		<https://www.rfc-editor.org/info/rfc6987>.
	Authors' Addresses		Authors' Addresses
	Keyur Patel		Keyur Patel
	Arrcus		Arrcus
	Email: keyur@arrcus.com		Email: keyur@arrcus.com
	Padma Pillay-Esnault		Padma Pillay-Esnault
	Huawei Technologies		Futurewei
	2330 Central Expressway		2330 Central Expressway
	Santa Clara, CA 95050		Santa Clara, CA 95050
	USA		USA
	Email: padma@huawei.com		Email: padma.ietf@gmail.com
	Manish Bhardwaj		Manish Bhardwaj
	Cisco Systems		Cisco Systems
	170 W. Tasman Drive		170 W. Tasman Drive
	San Jose, CA 95134		San Jose, CA 95134
	USA		USA
	Email: manbhard@cisco.com		Email: manbhard@cisco.com
	Serpil Bayraktar		Serpil Bayraktar
	Cisco Systems		Cisco Systems
End of changes. 26 change blocks.
	97 lines changed or deleted		137 lines changed or added
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