< draft-ietf-ospf-ospfv2-hbit-08.txt		draft-ietf-ospf-ospfv2-hbit-09.txt >
	OSPF K. Patel		OSPF K. Patel
	Internet-Draft Arrcus		Internet-Draft Arrcus
	Updates: 2328,6987 (if approved) P. Pillay-Esnault		Updates: 6987 (if approved) P. Pillay-Esnault
	Intended status: Standards Track Futurewei		Intended status: Standards Track PPE Consulting
	Expires: January 9, 2020 M. Bhardwaj		Expires: March 16, 2020 M. Bhardwaj
	S. Bayraktar		S. Bayraktar
	Cisco Systems		Cisco Systems
	July 8, 2019		September 13, 2019
	Host Router Support for OSPFv2		Host Router Support for OSPFv2
	draft-ietf-ospf-ospfv2-hbit-08		draft-ietf-ospf-ospfv2-hbit-09
	Abstract		Abstract
	The OSPFv2 specifies an SPF algorithm that identifies transit		The Open Shortest Path First Version 2 (OSPFv2) does not have a
	vertices based on their adjacencies. Therefore, OSPFv2 does not have		mechanism for a node to repel transit traffic if it is on the
	a mechanism to prevent traffic transiting a participating node if it		shortest path. This document assigns a new bit (Host-bit) in the
	is a transit vertex in the only existing or shortest path to the		OSPF Router-LSA bit registry and in the OSPF Router Informational
	destination. The use of metrics to make the node undesirable can		Capability Bits Registry that enables a host router to advertise that
	only help to repel traffic if an alternative better route exists.		it is a non-transit router. It also describes the changes needed to
	This document defines the Host-bit functionality to prevent other		support the Host-bit in the domain. In addition, this document
	OSPFv2 routers from using the router for transit traffic in OSPFv2		updates OSPF Stub Router Advertisement (RFC6987) to advertise for
	routing domains. This document updates the Open Shortest Path First		type-2 External and NSSA LSAs with a high cost in order to repel
	v2 specification (OSPFv2 rfc2328) by assigning a new bit (Host-bit)		traffic effectively.
	in the OSPF Router-LSA bit registry. In addition, if the Host-bit is
	set, the calculation of the shortest-path tree for an area, as
	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-
	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 January 9, 2020.
			This Internet-Draft will expire on March 16, 2020.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 IETF Trust and the persons identified as the		Copyright (c) 2019 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
	skipping to change at page 2, line 39 ¶		skipping to change at page 2, line 33 ¶
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 8		8. Security Considerations . . . . . . . . . . . . . . . . . . . 8
	9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8		9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8		10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
	10.1. Normative References . . . . . . . . . . . . . . . . . . 9		10.1. Normative References . . . . . . . . . . . . . . . . . . 9
	10.2. Informative References . . . . . . . . . . . . . . . . . 9		10.2. Informative References . . . . . . . . . . . . . . . . . 9
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
	1. Introduction		1. Introduction
	The OSPFv2 specifies an SPF algorithm that identifies transit		The OSPFv2 specifies a Shortest Path First (SPF) algorithm that
	vertices based on their adjacencies. Therefore, OSPFv2 does not have		identifies transit vertices based on their adjacencies. Therefore,
	a mechanism to prevent traffic transiting a participating node if it		OSPFv2 does not have a mechanism to prevent traffic transiting a
	is a transit vertex in the only existing or shortest path to the		participating node if it is a transit vertex in the only existing or
	destination. The use of metrics to make the node undesirable can		shortest path to the destination. The use of metrics to make the
	only help to repel traffic if an alternative better route exists.		node undesirable can help to repel traffic only 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 temporarily		3. Overloaded routers could use such a capability to temporarily
	repel traffic 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 reachability
	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 describes the Host-bit (H-Bit)functionality that
	other OSPFv2 routers from using the router for transit traffic in		prevents other OSPFv2 routers from using the router for transit
	OSPFv2 routing domains. This document updates the [RFC2328] by -		traffic in OSPFv2 routing domains. This document defines the Host-
	assigning the Host-bit in the OSPFv2 Router Properties Registry - if		bit in the OSPFv2 Router Properties Registry and if the host-bit is
	the host-bit is set then the calculation of the shortest-path tree		set then the calculation of the shortest-path tree for an area, as
	for an area, as described in section 16.1 of [RFC2328], is modified		described in section 16.1 of [RFC2328], is modified by including a
	by including a new check to verify that transit vertices DO NOT have		new check to verify that transit vertices DO NOT have the host-bit
	the host-bit set.		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 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) by other OSPFv2 routers in the area supporting the
	section 4).		functionality.
	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 |
	skipping to change at page 4, line 36 ¶		skipping to change at page 4, line 36 ¶
	| ... |		| ... |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| TOS | 0 | TOS metric |		| TOS | 0 | TOS metric |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Link ID |		| Link ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Link Data |		| Link Data |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| ... |		| ... |
	Host Bit in router-LSA		Figure 1
			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 Host (non-transit) router and is incapable of		OSPFv2 router is a Host (non-transit) router and is incapable of
	forwarding transit traffic.		forwarding transit traffic. In this mode, the other OSPFv2 routers
			in the area MUST NOT use the host router for transit traffic, but use
			the host router only for its local destinations.
	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 the		When the H-bit is set, an Area Border Router (ABR) MUST advertise the
	same 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. The consistency of the setting will prevent inter-		attached areas. The consistency of the setting will prevent inter-
	area traffic transiting through the router by suppressing the		area traffic transiting through the router by suppressing
	suppressing advertisement of prefixes from other routers in the area		advertisement of prefixes from other routers in the area in its
	in its summary LSAs. ONLY IPv4 prefixes associated with its local		summary LSAs. Only IPv4 prefixes associated with its local
	interfaces MAY be advertised in summary LSAs to provide reachability		interfaces MUST be advertised in summary LSAs to provide reachability
	to end hosts attached behind a router with the H-bit set.		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 the host router cannot act as an AS Boundary
	ASBR are transit routers to prefixes that are typically imported		Router (ASBR). Indeed, ASBR are transit routers to prefixes that are
	through redistribution of prefixes of other routing protocols.		typically imported through redistribution of prefixes of other
	Therefore, non-local IPv4 prefixes, e.g., those exported from other		routing protocols. Therefore, non-local IPv4 prefixes, e.g., those
	routing protocols, MUST NOT be advertised in AS-external-LSAs for		exported from other routing protocols, MUST NOT be advertised in AS-
	routers acting permanly as a host. However, in use cases such as an		external-LSAs for routers acting permanently as a host. However, in
	overloaded router or a router being gracefully isolated, these		use cases such as an overloaded router or a router being gracefully
	routers are only temporarily acting as host routers and therefore		isolated, these routers are only temporarily acting as host routers
	should continue to advertise their External LSAs but ensure they do		and therefore SHOULD continue to advertise their External LSAs but
	not attract traffic. In addition to the procedure described above,		ensure that they do not attract traffic. In addition to the
	temporary host routers advertising type 2-metric External LSAs MUST		procedure described above, temporary host routers advertising type
	set the metrics to LSInfinity to repel traffic.(see Section 6 of this		2-metric External LSAs MUST set the metrics to LSInfinity to repel
	document).		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 28 ¶		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
	[RFC7770] with and area flooding scope and a new bit assigned in the		[RFC7770] with and an area flooding scope and a new bit assigned in
	OSPF Router Informational Capability Bits Registry. Bit:		the 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 MUST only take effect if all the routers in a given OSPF		SPF changes MUST only take effect if all the routers in a given OSPF
	area support this functionality.		area support this functionality.
	In normal operations, there is no guarantee that the RI LSA will		In normal operations, there is no guarantee that the RI LSA will
	reach all routers in an area in a timely manner which may result in		reach all routers in an area in a timely manner that may result in
	rooting loops in partial deployments. For example, in a new router		rooting loops in partial deployments. For example, in a new router
	joins an area which previous had only H-bit capable routers with		joins an area which previous had only H-bit capable routers with
	H-bit set then it may take some time for the RI to propagate to all		H-bit set then it may take some time for the RI to propagate to all
	routers.		routers.
	The following recommendations will mitigate transient routing loops:		The following recommendations will mitigate transient routing loops:
	o Implementations are RECOMMENDED to provide a configuration		o Implementations are RECOMMENDED to provide a configuration
	parameter to manually override enforcement of the H-bit		parameter to manually override enforcement of the H-bit
	functionality in partial deployments where the topology guarantees		functionality in partial deployments where the topology guarantees
	skipping to change at page 8, line 19 ¶		skipping to change at page 8, line 19 ¶
	Bit Number Capability Name Reference		Bit Number Capability Name Reference
	7 OSPF Host Router This Document		7 OSPF Host Router This Document
	8. Security Considerations		8. Security Considerations
	This document introduces the H-bit which is a capability that		This document introduces the H-bit which is a capability that
	restricts the use of a router for transit except for its local		restricts the use of a router for transit except for its local
	destinations. This is a subset of the operations of a normal router		destinations. This is a subset of the operations of a normal router
	and therefore should not introduce new security considerations beyond		and therefore should not introduce new security considerations beyond
	those already known in OSPF. The feature however does introduce the		those already known in OSPF. The feature, however does introduce the
	flooding of a capability information that allows discovery and		flooding of a capability information that allows discovery and
	verification that all routers in an area are capable before turning		verification that all routers in an area are capable before turning
	on the feature. In case. a rogue or buggy router advertise		on the feature. In the event that a rogue or buggy router advertises
	incorrectly its capability there are two possible cases:		incorrectly its capability there are two possible cases:
	o The router does not have the capability but send H-Bit set in its		o The router does not have the capability but sends H-Bit set in its
	LSAs: In this case, there is a possibility of a routing loop.		LSAs: In this case, there is a possibility of a routing loop.
	However this is mitigated by the fact that this router should be		However this is mitigated by the fact that this router should be
	avoided anyway. Moreover, the link metrics cost of this router		avoided anyway. Moreover, the link metrics cost (MaxLinkMetric)
	should be MaxLinkMetric and will mitigate this situation. In any		of this router will mitigate this situation. In any case, a
	case a router advertising the H-bit capability without its links		router advertising the H-bit capability without its links cost
	cost equal to MaxLinkMetric may be an indicator that this is a		equal to MaxLinkMetric may be an indicator that this is a rogue
	rogue router.		router and to be avoided.
	o The router has the capability but sends the H-Bit clear in its		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		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		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		SPF. The impact is also mitigated as other H-Bit routers in the
	area also advertise MaxLinkMetric cost so they will still be		area also advertise MaxLinkMetric cost so they will still be
	avoided unless they are the last resort path.		avoided unless they are the last resort path.
	9. Acknowledgements		9. Acknowledgements
	skipping to change at page 9, line 15 ¶		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>.
			[RFC6987] Retana, A., Nguyen, L., Zinin, A., White, R., and D.
			McPherson, "OSPF Stub Router Advertisement", RFC 6987,
			DOI 10.17487/RFC6987, September 2013,
			<https://www.rfc-editor.org/info/rfc6987>.
	[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-19 (work in
	progress), April 2019.		progress), July 2019.
	[RFC6987] Retana, A., Nguyen, L., Zinin, A., White, R., and D.
	McPherson, "OSPF Stub Router Advertisement", RFC 6987,
	DOI 10.17487/RFC6987, September 2013,
	<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
	Futurewei		PPE Consulting
	2330 Central Expressway
	Santa Clara, CA 95050
	USA
	Email: padma.ietf@gmail.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
End of changes. 22 change blocks.
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