draft-ietf-grow-route-leak-detection-mitigation-01.txt		draft-ietf-grow-route-leak-detection-mitigation-02.txt
	IDR and SIDR K. Sriram, Ed.		IDR and SIDR K. Sriram, Ed.
	Internet-Draft USA NIST		Internet-Draft USA NIST
	Intended status: Standards Track A. Azimov, Ed.		Intended status: Standards Track A. Azimov, Ed.
	Expires: January 26, 2020 Yandex		Expires: July 28, 2020 Yandex
	July 25, 2019		January 25, 2020
	Methods for Detection and Mitigation of BGP Route Leaks		Methods for Detection and Mitigation of BGP Route Leaks
	draft-ietf-grow-route-leak-detection-mitigation-01		draft-ietf-grow-route-leak-detection-mitigation-02
	Abstract		Abstract
	Problem definition for route leaks and enumeration of types of route		Problem definition for route leaks and enumeration of types of route
	leaks are provided in [RFC7908]. This document describes a new well-		leaks are provided in [RFC7908]. This document describes a new well-
	known Large Community that provides a way for route leak prevention,		known Large Community that provides a way for route leak prevention,
	detection, and mitigation. The configuration process for this		detection, and mitigation. The configuration process for this
	Community can be automated with the methodology for setting BGP roles		Community can be automated with the methodology for setting BGP roles
	that is described in ietf-idr-bgp-open-policy draft.		that is described in ietf-idr-bgp-open-policy draft.
	skipping to change at page 1, line 36 ¶		skipping to change at page 1, line 36 ¶
	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 26, 2020.		This Internet-Draft will expire on July 28, 2020.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 IETF Trust and the persons identified as the		Copyright (c) 2020 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 2, line 16 ¶		skipping to change at page 2, line 16 ¶
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Peering Relationships . . . . . . . . . . . . . . . . . . . . 2		2. Peering Relationships . . . . . . . . . . . . . . . . . . . . 2
	3. Community vs Attribute . . . . . . . . . . . . . . . . . . . 3		3. Community vs Attribute . . . . . . . . . . . . . . . . . . . 3
	4. Down Only Community . . . . . . . . . . . . . . . . . . . . . 4		4. Down Only Community . . . . . . . . . . . . . . . . . . . . . 4
	4.1. Route Leak Mitigation . . . . . . . . . . . . . . . . . . 5		4.1. Route Leak Mitigation . . . . . . . . . . . . . . . . . . 5
	4.2. Only Marking . . . . . . . . . . . . . . . . . . . . . . 6		4.2. Only Marking . . . . . . . . . . . . . . . . . . . . . . 6
	5. Implementation Considerations . . . . . . . . . . . . . . . . 6		5. Implementation Considerations . . . . . . . . . . . . . . . . 6
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 7		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7		7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
	8. Informative References . . . . . . . . . . . . . . . . . . . 7		8. Informative References . . . . . . . . . . . . . . . . . . . 7
	Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8		Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8
	Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 8		Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 8
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
	1. Introduction		1. Introduction
	[RFC7908] provides a definition of the route leak problem and		[RFC7908] provides a definition of the route leak problem and
	enumerates several types of route leaks. For this document, the		enumerates several types of route leaks. For this document, the
	definition that is applied is that a route leak occurs when a route		definition that is applied is that a route leak occurs when a route
	skipping to change at page 3, line 41 ¶		skipping to change at page 3, line 41 ¶
	3. Community vs Attribute		3. Community vs Attribute
	This section presents a brief discussion of the advantages and		This section presents a brief discussion of the advantages and
	disadvantages of communities and BGP path attributes for the purpose		disadvantages of communities and BGP path attributes for the purpose
	of route leak detection.		of route leak detection.
	A transitive path attribute is a native way to implement the route-		A transitive path attribute is a native way to implement the route-
	leak detection signal. Based on the way BGP protocol works, the use		leak detection signal. Based on the way BGP protocol works, the use
	of a transitive attribute makes it more certain that the route-leak		of a transitive attribute makes it more certain that the route-leak
	detection signal would pass unaltered through non-participating		detection signal would pass unaltered through non-participating
	(i.e., not updated) BGP routers. The main disadvantage of this		(i.e., not upgraded) BGP routers. The main disadvantage of this
	approach is that the deployment of a new BGP attribute requires a		approach is that the deployment of a new BGP attribute requires a
	software update in router OS which may delay wide adoption for years.		software upgrade in router OS which may delay wide adoption for
			years.
	On the other hand, BGP communities do not require a router OS update.		On the other hand, BGP communities do not require a router OS update.
	The potential disadvantage of using a Community for the route-leak		The potential disadvantage of using a Community for the route-leak
	detection signal is that it is more likely to be dropped somewhere		detection signal is that it is more likely to be dropped somewhere
	along the way in the AS path. Currently, the use of BGP Communities		along the way in the AS path. Currently, the use of BGP Communities
	is somewhat overloaded. BGP Communities are already used for		is somewhat overloaded. BGP Communities are already used for
	numerous applications: different types of route marking, route policy		numerous applications: different types of route marking, route policy
	control, black-holing, etc. It is observed that some ASes seem to		control, black-holing, etc. It is observed that some ASes seem to
	purposefully or accidentally remove transitive communities on		purposefully or accidentally remove transitive communities on
	receipt, sometimes well-known ones. Perhaps this issue may be		receipt, sometimes well-known ones. Perhaps this issue may be
	skipping to change at page 4, line 17 ¶		skipping to change at page 4, line 18 ¶
	Due to frequently occurring regional and global disruptions in		Due to frequently occurring regional and global disruptions in
	Internet connectivity, it is critical to move forward with a solution		Internet connectivity, it is critical to move forward with a solution
	that is viable in the near term. That solution would be route leak		that is viable in the near term. That solution would be route leak
	detection using BGP Community.		detection using BGP Community.
	Large Communities have much higher capacity, and therefore they are		Large Communities have much higher capacity, and therefore they are
	likely to be less overloaded. Hence, Large Community is proposed to		likely to be less overloaded. Hence, Large Community is proposed to
	be used for route-leak detection. This document suggests reserving		be used for route-leak detection. This document suggests reserving
	<TBD1> class for the purpose of transitive well-known Large		<TBD1> class for the purpose of transitive well-known Large
	Communities that MUST not be stripped on ingress or egress.		Communities that MUST NOT be stripped on ingress or egress.
	While it is not part of this document, the route-leak detection		While it is not part of this document, the route-leak detection
	signal described here can also be carried in a BGP path attribute,		signal described here can also be carried in a BGP path attribute,
	and the same prevention and mitigation techniques as described here		and the same prevention and mitigation techniques as described here
	would apply. The authors are pursuing a separate internet draft in		would apply. The authors are pursuing a separate internet draft in
	the IDR WG on that approach.		the IDR WG on that approach.
	4. Down Only Community		4. Down Only Community
	This section specifies the semantics of route-leak-detection		This section specifies the semantics of route-leak-detection
	Community and its usage. This Community is given the specific name		Community and its usage. This Community is given the specific name
	Down Only (DO) Community. The DO Community is carried in a BGP Large		Down Only (DO) Community. The DO Community is carried in a BGP Large
	Community with a format as shown in Figure 1.		Community with a format as shown in Figure 1.
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| TBD1 (class for well-known transit communities) |		| TBD1 (class for transitive well-known Large Communities) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| TBD2 (subclass for DO) |		| TBD2 (subclass for DO) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| ASN |		| ASN |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 1: Format of the DO Community using a Large Community		Figure 1: Format of the DO Community using a Large Community
	[RFC8092].		[RFC8092].
	The authors studied different options for route leak mitigation. The		The authors studied different options for route leak mitigation. The
	skipping to change at page 5, line 46 ¶		skipping to change at page 5, line 47 ¶
	transit) and DO value is not equal to the sending neighbor's ASN,		transit) and DO value is not equal to the sending neighbor's ASN,
	then it is a route leak and MUST be rejected. The procedure		then it is a route leak and MUST be rejected. The procedure
	halts.		halts.
	3. If a route is received from a Provider, Peer or RS, then the DO		3. If a route is received from a Provider, Peer or RS, then the DO
	Community MUST be added with a value equal to the sending		Community MUST be added with a value equal to the sending
	neighbor's ASN.		neighbor's ASN.
	The egress policy MUST use the following procedure:		The egress policy MUST use the following procedure:
	1. A route with DO Community set MUST not be sent to Providers,		1. A route with DO Community set MUST NOT be sent to Providers,
	Peers, and RS.		Peers, and RS.
	2. If a route is sent to a Customer or Peer, then the DO Community		2. If a route is sent to a Customer or Peer, then the DO Community
	MUST be added with a value equal to the ASN of the sender.		MUST be added with a value equal to the ASN of the sender.
	The above procedures comprehensively provide route-leak prevention,		The above procedures comprehensively provide route-leak prevention,
	detection and mitigation. Policy consisting of these procedures		detection and mitigation. Policy consisting of these procedures
	SHOULD be used as a default behavior.		SHOULD be used as a default behavior.
	4.2. Only Marking		4.2. Only Marking
	skipping to change at page 7, line 15 ¶		skipping to change at page 7, line 15 ¶
	If a route with DO Community set is received from a Peer and DO value		If a route with DO Community set is received from a Peer and DO value
	is equal to the sending neighbor's ASN, then it is a valid route,		is equal to the sending neighbor's ASN, then it is a valid route,
	otherwise it is a route leak. The procedure halts.		otherwise it is a route leak. The procedure halts.
	This rule is based on a weaker assumption that a peer that is doing		This rule is based on a weaker assumption that a peer that is doing
	marking is also doing filtering (dropping detected leaks). That is		marking is also doing filtering (dropping detected leaks). That is
	why networks that do not follow the route leak mitigation policy in		why networks that do not follow the route leak mitigation policy in
	Section 4.1 MUST carefully follow marking rules described in		Section 4.1 MUST carefully follow marking rules described in
	Section 4.2.		Section 4.2.
	6. Security Considerations		6. IANA Considerations
			The draft suggests to reserve a Global Administrator ID <TBD1> for
			transitive well-known Large Community registry. IANA is requested to
			register a subclass <TBD2> for DO Community in this registry.
			7. Security Considerations
	In specific circumstances in a state of partial adoption, route leak		In specific circumstances in a state of partial adoption, route leak
	mitigation mechanism can result in Denial of Service (DoS) for the		mitigation mechanism can result in Denial of Service (DoS) for the
	victim prefix. Such a scenario may happen only for a prefix that has		victim prefix. Such a scenario may happen only for a prefix that has
	a single path from the originator to a Tier-1 ISP and only when the		a single path from the originator to a Tier-1 ISP and only when the
	prefix is not covered with a less specific prefix with multiple paths		prefix is not covered with a less specific prefix with multiple paths
	to the Tier-1 ISP. If, in such unreliable topology, route leak is		to the Tier-1 ISP. If, in such unreliable topology, route leak is
	injected somewhere inside this single path, then it may be rejected		injected somewhere inside this single path, then it may be rejected
	by upper layer providers in the path, thus limiting prefix		by upper layer providers in the path, thus limiting prefix
	visibility. While such anomaly is unlikely to happen, such an issue		visibility. While such anomaly is unlikely to happen, such an issue
	should be easy to debug, since it directly affects the sequence of		should be easy to debug, since it directly affects the sequence of
	originator's providers.		originator's providers.
	With the use of BGP Community, there is often a concern that the		With the use of BGP Community, there is often a concern that the
	Community propagates beyond its intended perimeter and causes harm		Community propagates beyond its intended perimeter and causes harm
	[streibelt]. However, that concern does not apply to the DO		[streibelt]. However, that concern does not apply to the DO
	Community because it is a transitive Community that must propagate as		Community because it is a transitive Community that must propagate as
	far as the update goes.		far as the update goes.
	7. IANA Considerations
	The draft suggests to reserve a Global Administrator ID <TBD1> for
	transitive well-known Large Community registry. IANA is requested to
	register a subclass <TBD2> for DO Community in this registry.
	8. Informative References		8. Informative References
	[I-D.ietf-idr-bgp-open-policy]		[I-D.ietf-idr-bgp-open-policy]
	Azimov, A., Bogomazov, E., Bush, R., Patel, K., and K.		Azimov, A., Bogomazov, E., Bush, R., Patel, K., and K.
	Sriram, "Route Leak Prevention using Roles in Update and		Sriram, "Route Leak Prevention using Roles in Update and
	Open messages", draft-ietf-idr-bgp-open-policy-06 (work in		Open messages", draft-ietf-idr-bgp-open-policy-07 (work in
	progress), July 2019.		progress), January 2020.
	[RFC4264] Griffin, T. and G. Huston, "BGP Wedgies", RFC 4264,		[RFC4264] Griffin, T. and G. Huston, "BGP Wedgies", RFC 4264,
	DOI 10.17487/RFC4264, November 2005,		DOI 10.17487/RFC4264, November 2005,
	<https://www.rfc-editor.org/info/rfc4264>.		<https://www.rfc-editor.org/info/rfc4264>.
	[RFC7908] Sriram, K., Montgomery, D., McPherson, D., Osterweil, E.,		[RFC7908] Sriram, K., Montgomery, D., McPherson, D., Osterweil, E.,
	and B. Dickson, "Problem Definition and Classification of		and B. Dickson, "Problem Definition and Classification of
	BGP Route Leaks", RFC 7908, DOI 10.17487/RFC7908, June		BGP Route Leaks", RFC 7908, DOI 10.17487/RFC7908, June
	2016, <https://www.rfc-editor.org/info/rfc7908>.		2016, <https://www.rfc-editor.org/info/rfc7908>.
	skipping to change at page 8, line 23 ¶		skipping to change at page 8, line 23 ¶
	<https://www.rfc-editor.org/info/rfc8092>.		<https://www.rfc-editor.org/info/rfc8092>.
	[streibelt]		[streibelt]
	Streibelt et al., F., "BGP Communities: Even more Worms in		Streibelt et al., F., "BGP Communities: Even more Worms in
	the Routing Can", ACM IMC, October 2018,		the Routing Can", ACM IMC, October 2018,
	<https://archive.psg.com//181101.imc-communities.pdf>.		<https://archive.psg.com//181101.imc-communities.pdf>.
	Acknowledgements		Acknowledgements
	The authors wish to thank John Scudder, Susan Hares, Ruediger Volk,		The authors wish to thank John Scudder, Susan Hares, Ruediger Volk,
	Mat Ford, Greg Skinner for their review and comments.		Jeffrey Haas, Mat Ford, Greg Skinner for their review and comments.
	Contributors		Contributors
	The following people made significant contributions to this document		The following people made significant contributions to this document
	and should be considered co-authors:		and should be considered co-authors:
	Brian Dickson		Brian Dickson
	Independent		Independent
	Email: brian.peter.dickson@gmail.com		Email: brian.peter.dickson@gmail.com
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