draft-ietf-rtgwg-multihomed-prefix-lfa-03.txt		draft-ietf-rtgwg-multihomed-prefix-lfa-04.txt
	Routing Area Working Group P. Sarkar, Ed.		Routing Area Working Group P. Sarkar, Ed.
	Internet-Draft Arrcus, Inc.		Internet-Draft Arrcus, Inc.
	Updates: 5286 (if approved) S. Hegde		Updates: 5286 (if approved) S. Hegde
	Intended status: Standards Track C. Bowers		Intended status: Standards Track Juniper Networks, Inc.
	Expires: May 3, 2018 Juniper Networks, Inc.		Expires: June 4, 2018 U. Chunduri, Ed.
	U. Chunduri, Ed.
	Huawei Technologies		Huawei Technologies
	J. Tantsura		J. Tantsura
	Individual		Individual
	B. Decraene
	Orange
	H. Gredler		H. Gredler
	RtBrick, Inc.		RtBrick, Inc.
	October 30, 2017		December 1, 2017
	LFA selection for Multi-Homed Prefixes		LFA selection for Multi-Homed Prefixes
	draft-ietf-rtgwg-multihomed-prefix-lfa-03		draft-ietf-rtgwg-multihomed-prefix-lfa-04
	Abstract		Abstract
	This document shares experience gained from implementing algorithms		This document shares experience gained from implementing algorithms
	to determine Loop-Free Alternates for multi-homed prefixes. In		to determine Loop-Free Alternates for multi-homed prefixes. In
	particular, this document provides explicit inequalities that can be		particular, this document provides explicit inequalities that can be
	used to evaluate neighbors as a potential alternates for multi-homed		used to evaluate neighbors as a potential alternates for multi-homed
	prefixes. It also provides detailed criteria for evaluating		prefixes. It also provides detailed criteria for evaluating
	potential alternates for external prefixes advertised by OSPF ASBRs.		potential alternates for external prefixes advertised by OSPF ASBRs.
	This documents updates and expands some of the "Routing Aspects" as		This documents updates and expands some of the "Routing Aspects" as
	skipping to change at page 2, line 6 ¶		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 https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
			This Internet-Draft will expire on June 4, 2018.
	This Internet-Draft will expire on May 3, 2018.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2017 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(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 48 ¶		skipping to change at page 2, line 45 ¶
	4.2.4. RFC1583compatibility is set to enabled . . . . . . . 11		4.2.4. RFC1583compatibility is set to enabled . . . . . . . 11
	4.2.5. Type 7 routes . . . . . . . . . . . . . . . . . . . . 11		4.2.5. Type 7 routes . . . . . . . . . . . . . . . . . . . . 11
	4.2.6. Inequalities to be applied for alternate ASBR		4.2.6. Inequalities to be applied for alternate ASBR
	selection . . . . . . . . . . . . . . . . . . . . . . 11		selection . . . . . . . . . . . . . . . . . . . . . . 11
	4.2.6.1. Forwarding address set to non-zero value . . . . 11		4.2.6.1. Forwarding address set to non-zero value . . . . 11
	4.2.6.2. ASBRs advertising type1 and type2 cost . . . . . 12		4.2.6.2. ASBRs advertising type1 and type2 cost . . . . . 12
	5. LFA Extended Procedures . . . . . . . . . . . . . . . . . . . 13		5. LFA Extended Procedures . . . . . . . . . . . . . . . . . . . 13
	5.1. Links with IGP MAX_METRIC . . . . . . . . . . . . . . . . 13		5.1. Links with IGP MAX_METRIC . . . . . . . . . . . . . . . . 13
	5.2. Multi Topology Considerations . . . . . . . . . . . . . . 14		5.2. Multi Topology Considerations . . . . . . . . . . . . . . 14
	6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15		6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 15		7. Contributing Authors . . . . . . . . . . . . . . . . . . . . 15
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 15		8. Security Considerations . . . . . . . . . . . . . . . . . . . 15
	8.1. Normative References . . . . . . . . . . . . . . . . . . 15		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
	8.2. Informative References . . . . . . . . . . . . . . . . . 16		9.1. Normative References . . . . . . . . . . . . . . . . . . 16
			9.2. Informative References . . . . . . . . . . . . . . . . . 16
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
	1. Introduction		1. Introduction
	The use of Loop-Free Alternates (LFA) for IP Fast Reroute is		The use of Loop-Free Alternates (LFA) for IP Fast Reroute is
	specified in [RFC5286]. Section 6.1 of [RFC5286] describes a method		specified in [RFC5286]. Section 6.1 of [RFC5286] describes a method
	to determine loop-free alternates for a multi-homed prefixes (MHPs).		to determine loop-free alternates for a multi-homed prefixes (MHPs).
	This document describes a procedure using explicit inequalities that		This document describes a procedure using explicit inequalities that
	can be used by a computing router to evaluate a neighbor as a		can be used by a computing router to evaluate a neighbor as a
	potential alternate for a multi-homed prefix. The results obtained		potential alternate for a multi-homed prefix. The results obtained
	are equivalent to those obtained using the method described in		are equivalent to those obtained using the method described in
	skipping to change at page 15, line 12 ¶		skipping to change at page 15, line 12 ¶
	the LFA principles laid out in [RFC5286] are actually applicable for		the LFA principles laid out in [RFC5286] are actually applicable for
	MT IS-IS [RFC5120] LFA SPF. The primary difference in this case is,		MT IS-IS [RFC5120] LFA SPF. The primary difference in this case is,
	identifying the eligible-set of neighbors for each LFA computation		identifying the eligible-set of neighbors for each LFA computation
	which is done per MT ID. The eligible-set for each MT ID is		which is done per MT ID. The eligible-set for each MT ID is
	determined by the presence of IGP adjacency from Source to the		determined by the presence of IGP adjacency from Source to the
	neighboring node on that MT-ID apart from the administrative		neighboring node on that MT-ID apart from the administrative
	restrictions and other checks laid out in [RFC5286]. The same is		restrictions and other checks laid out in [RFC5286]. The same is
	also applicable for MT-OSPF [RFC4915] or different AFs in multi		also applicable for MT-OSPF [RFC4915] or different AFs in multi
	instance OSPFv3 [RFC5838].		instance OSPFv3 [RFC5838].
	However for MT IS-IS, if a "standart topology" is used with MT-ID #0		However for MT IS-IS, if a "standard topology" is used with MT-ID #0
	[RFC5286] and both IPv4 [RFC5305] and IPv6 routes/AFs [RFC5308] are		[RFC5286] and both IPv4 [RFC5305] and IPv6 routes/AFs [RFC5308] are
	present, then the condition of network congruency is applicable for		present, then the condition of network congruency is applicable for
	LFA computation as well. Network congruency here refers to, having		LFA computation as well. Network congruency here refers to, having
	same address families provisioned on all the links and all the nodes		same address families provisioned on all the links and all the nodes
	of the network with MT-ID #0. Here with single decision process both		of the network with MT-ID #0. Here with single decision process both
	IPv4 and IPv6 next-hops are computed for all the prefixes in the		IPv4 and IPv6 next-hops are computed for all the prefixes in the
	network and similarly with one LFA computation from all eligible		network and similarly with one LFA computation from all eligible
	neighbors per [RFC5286], all potential alternatives can be computed.		neighbors per [RFC5286], all potential alternatives can be computed.
	6. Acknowledgements		6. Acknowledgements
	Thanks to Alia Atlas and Salih K A for their useful feedback and		Thanks to Alia Atlas and Salih K A for their useful feedback and
	inputs. Thanks to Stewart Bryant for being document shepherd and		inputs. Thanks to Stewart Bryant for being document shepherd and
	providing detailed review comments.		providing detailed review comments.
	7. Security Considerations		7. Contributing Authors
			The following people contributed substantially to the content of this
			document and should be considered co-authors.
			Chris Bowers
			Juniper Networks, Inc.
			1194 N. Mathilda Ave,
			Sunnyvale, CA 94089, USA
			Email: cbowers@juniper.ne
			Bruno Decraene
			Orange,
			France
			Email: bruno.decraene@orange.com
			8. Security Considerations
	This document does not introduce any change in any of the protocol		This document does not introduce any change in any of the protocol
	[RFC1195] [RFC5120] [RFC2328] [RFC5838] specifications discussed here		[RFC1195] [RFC5120] [RFC2328] [RFC5838] specifications discussed here
	and also this does not introduce any new security issues other than		and also this does not introduce any new security issues other than
	as noted in the LFA base specification [RFC5286].		as noted in the LFA base specification [RFC5286].
	8. References		9. References
	8.1. Normative References		9.1. 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>.
	[RFC5286] Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for		[RFC5286] Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for
	IP Fast Reroute: Loop-Free Alternates", RFC 5286,		IP Fast Reroute: Loop-Free Alternates", RFC 5286,
	DOI 10.17487/RFC5286, September 2008,		DOI 10.17487/RFC5286, September 2008,
	<https://www.rfc-editor.org/info/rfc5286>.		<https://www.rfc-editor.org/info/rfc5286>.
	8.2. Informative References		9.2. Informative References
	[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and		[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
	dual environments", RFC 1195, DOI 10.17487/RFC1195,		dual environments", RFC 1195, DOI 10.17487/RFC1195,
	December 1990, <https://www.rfc-editor.org/info/rfc1195>.		December 1990, <https://www.rfc-editor.org/info/rfc1195>.
	[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>.
	[RFC3137] Retana, A., Nguyen, L., White, R., Zinin, A., and D.		[RFC3137] Retana, A., Nguyen, L., White, R., Zinin, A., and D.
	skipping to change at page 17, line 4 ¶		skipping to change at page 17, line 16 ¶
	R. Aggarwal, "Support of Address Families in OSPFv3",		R. Aggarwal, "Support of Address Families in OSPFv3",
	RFC 5838, DOI 10.17487/RFC5838, April 2010,		RFC 5838, DOI 10.17487/RFC5838, April 2010,
	<https://www.rfc-editor.org/info/rfc5838>.		<https://www.rfc-editor.org/info/rfc5838>.
	Authors' Addresses		Authors' Addresses
	Pushpasis Sarkar (editor)		Pushpasis Sarkar (editor)
	Arrcus, Inc.		Arrcus, Inc.
	Email: pushpasis.ietf@gmail.com		Email: pushpasis.ietf@gmail.com
	Shraddha Hegde		Shraddha Hegde
	Juniper Networks, Inc.		Juniper Networks, Inc.
	Electra, Exora Business Park		Electra, Exora Business Park
	Bangalore, KA 560103		Bangalore, KA 560103
	India		India
	Email: shraddha@juniper.net		Email: shraddha@juniper.net
	Chris Bowers
	Juniper Networks, Inc.
	1194 N. Mathilda Ave.
	Sunnyvale, CA 94089
	US
	Email: cbowers@juniper.net
	Uma Chunduri (editor)		Uma Chunduri (editor)
	Huawei Technologies		Huawei Technologies
	2330 Central Expressway		2330 Central Expressway
	Santa Clara, CA 95050		Santa Clara, CA 95050
	USA		USA
	Email: uma.chunduri@huawei.com		Email: uma.chunduri@huawei.com
	Jeff Tantsura		Jeff Tantsura
	Individual		Individual
	Email: jefftant.ietf@gmail.com		Email: jefftant.ietf@gmail.com
	Bruno Decraene
	Orange
	Email: bruno.decraene@orange.com
	Hannes Gredler		Hannes Gredler
	RtBrick, Inc.		RtBrick, Inc.
	Email: hannes@rtbrick.com		Email: hannes@rtbrick.com
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