< draft-ietf-idr-deprecate-as-set-confed-set-01.txt		draft-ietf-idr-deprecate-as-set-confed-set-02.txt >
	Network Working Group W. Kumari		Network Working Group W. Kumari
	Internet-Draft Google, Inc.		Internet-Draft Google, Inc.
	Obsoletes: 6472 (if approved) K. Sriram		Obsoletes: 6472 (if approved) K. Sriram
	Updates: 4271 5065 (if approved) L. Hannachi		Updates: 4271 5065 (if approved) L. Hannachi
	Intended status: Standards Track USA NIST		Intended status: Standards Track USA NIST
	Expires: May 1, 2020 October 29, 2019		Expires: May 6, 2020 November 3, 2019
	Deprecation of AS_SET and AS_CONFED_SET in BGP		Deprecation of AS_SET and AS_CONFED_SET in BGP
	draft-ietf-idr-deprecate-as-set-confed-set-01		draft-ietf-idr-deprecate-as-set-confed-set-02
	Abstract		Abstract
	BCP 172 (i.e., RFC 6472) recommends not using AS_SET and		BCP 172 (i.e., RFC 6472) recommends not using AS_SET and
	AS_CONFED_SET in the Border Gateway Protocol. This document advances		AS_CONFED_SET in the Border Gateway Protocol. This document advances
	this recommendation to a standards requirement in BGP; it proscribes		this recommendation to a standards requirement in BGP; it proscribes
	the use of the AS_SET and AS_CONFED_SET types of path segments in the		the use of the AS_SET and AS_CONFED_SET types of path segments in the
	AS_PATH. This is done to simplify the design and implementation of		AS_PATH. This is done to simplify the design and implementation of
	BGP and to make the semantics of the originator of a route clearer.		BGP and to make the semantics of the originator of a route clearer.
	This will also simplify the design, implementation, and deployment of		This will also simplify the design, implementation, and deployment of
	skipping to change at page 1, line 41 ¶		skipping to change at page 1, line 41 ¶
	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 May 1, 2020.		This Internet-Draft will expire on May 6, 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.
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	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
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3		2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
	3. Recommendation to Network Operators . . . . . . . . . . . . . 3		3. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 3
	4. Updates to Existing RFCs . . . . . . . . . . . . . . . . . . 4		4. Updates to Existing RFCs . . . . . . . . . . . . . . . . . . 4
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 4		5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
	8.1. Normative References . . . . . . . . . . . . . . . . . . 5		8.1. Normative References . . . . . . . . . . . . . . . . . . 5
	8.2. Informative References . . . . . . . . . . . . . . . . . 5		8.2. Informative References . . . . . . . . . . . . . . . . . 5
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
	1. Introduction		1. Introduction
	BCP 172 [RFC6472] makes a recommendation for not using AS_SET (see		BCP 172 [RFC6472] makes a recommendation for not using AS_SET (see
	[RFC4271]) and AS_CONFED_SET (see [RFC5065]) in the Border Gateway		[RFC4271]) and AS_CONFED_SET (see [RFC5065]) in the Border Gateway
	skipping to change at page 3, line 24 ¶		skipping to change at page 3, line 24 ¶
	incorrectly -- only a single AS in the AS_SET are by far the most		incorrectly -- only a single AS in the AS_SET are by far the most
	common cases. Also, very often the same AS appears in the		common cases. Also, very often the same AS appears in the
	AS_SEQUENCE and the AS_SET in the BGP update. The occurrence of		AS_SEQUENCE and the AS_SET in the BGP update. The occurrence of
	reserved AS numbers ([IANA-SP-ASN]) is also somewhat frequent.		reserved AS numbers ([IANA-SP-ASN]) is also somewhat frequent.
	Because the aggregation involving AS_SETs is very rarely used, the		Because the aggregation involving AS_SETs is very rarely used, the
	reduction in table size provided by this is extremely small, and any		reduction in table size provided by this is extremely small, and any
	advantage thereof is outweighed by additional complexity in BGP. As		advantage thereof is outweighed by additional complexity in BGP. As
	noted above, AS_SETs also pose impediments to implementation of new		noted above, AS_SETs also pose impediments to implementation of new
	BGP security technologies.		BGP security technologies.
	In the past, AS_SET had been used in a few rare cases to allow route
	aggregation where two or more providers could form the same aggregate
	prefix, using the exact match of the other's aggregate prefix in some
	advertisement and configuring the aggregation differently elsewhere.
	The key to configuring this correctly was to form the aggregate at
	the border in the outbound BGP policy and omit prefixes from the AS
	that the aggregate was being advertised to. The AS_SET therefore
	allowed this practice without the loss of BGP's AS_PATH loop
	protection. This use of AS_SET served a purpose that fell in line
	with the original intended use. Without the use of AS_SET,
	aggregates must always contain only less-specific prefixes (not less
	than or equal to) and must never aggregate an exact match.
	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. Recommendation to Network Operators		3. Recommendations
	Network operators MUST NOT generate any new announcements containing		BGP speakers conforming to this document (i.e., conformant BGP
	AS_SETs or AS_CONFED_SETs. If they have already announced routes		speakers) MUST NOT locally generate BGP UPDATE messages containing
	with AS_SETs or AS_CONFED_SETs in them, then they MUST withdraw those		AS_SET or AS_CONFED_SET. Conformant BGP speakers SHOULD NOT send BGP
	routes and re-announce routes for the component prefixes (i.e., the		UPDATE messages containing AS_SET or AS_CONFED_SET. Upon receipt of
	more-specific routes subsumed by the previously aggregated route)		such messages, conformant BGP speakers SHOULD use the "Treat-as-
	without AS_SETs or AS_CONFED_SETs in the updates. A sending router		withdraw" error handling behavior as per [RFC7606].
	MUST not generate a BGP UPDATE with AS_SET or AS_CONFED_SET. A
	receiving router MUST treat the announced routes in a BGP UPDATE with
	AS_SET or AS_CONFED_SET as withdrawn routes.
	If a network operator wishes to consider a BGP UPDATE with AS_SET or		If a network operator wishes to consider BGP UPDATE messages with
	AS_CONFED_SET for path selection, they MAY have a feature (knob) in		AS_SET or AS_CONFED_SET (received from an external peer) for path
	the router to opt to do so. The operator should understand the full		selection, they MAY have a feature (knob) in their BGP speaker to opt
	implications of choosing this option.		to do so on a per peer basis. The operator should understand the
			full implications of choosing this option. There is no knob
			concerning locally generated BGP UPDATE messages, i.e., as stated
			before a conformant BGP speaker must not locally generate BGP UPDATE
			messages with AS_SET or AS_CONFED_SET.
	Route aggregation that was previously performed by proxy aggregation		Network operators MUST NOT locally generate any new announcements
	without the use of AS_SETs is still possible under some conditions.		containing AS_SET or AS_CONFED_SET. If they have announced routes
	When doing this, operators MUST form the aggregate at the border in		with AS_SET or AS_CONFED_SET in them, then they SHOULD withdraw those
	the outbound BGP policy and omit any prefixes from the AS that the		routes and re-announce routes for the aggregate or component prefixes
	aggregate is being advertised to. As with any change, the operator		(i.e., the more-specific routes subsumed by the previously aggregated
	should understand the full implications of the change.		route) without AS_SET or AS_CONFED_SET in the updates.
	It is worth noting that new BGP security technologies (such as those		It is worth noting that new BGP security technologies (such as those
	that take advantage of X.509 extensions for IP addresses and AS		that take advantage of X.509 extensions for IP addresses and AS
	identifiers [RFC3779] [RFC6480] [RFC6811] [RFC8205]) might not		identifiers [RFC3779] [RFC6480] [RFC6811] [RFC8205]) might not
	support routes with AS_SETs/AS_CONFED_SETs in them, and may treat		support routes with AS_SET or AS_CONFED_SET in them, and may treat
	routes containing them as infeasible even before the updated BGP in		routes containing them as infeasible even before the updated BGP in
	this document is implemented.		this document is implemented.
	4. Updates to Existing RFCs		4. Updates to Existing RFCs
	This document eliminates AS_PATH segment type 1, namely, AS_SET that		This document deprecates the AS_SET (type 1) AS_PATH segment type
	is specified in Section 4.3 of [RFC4271]. That is, in a future		from [RFC4271]. BGP speakers conforming to this document (i.e.,
	specification of BGP -- one that would obsolete RFC 4271 -- the use		conformant BGP speakers) MUST NOT locally generate BGP UPDATE
	of AS_SET will not be specified.		messages containing AS_SET. Conformant BGP speakers SHOULD NOT send
			BGP UPDATE messages containing AS_SET. Upon receipt of such
			messages, conformant BGP speakers SHOULD use the "Treat-as-withdraw"
			error handling behavior as per [RFC7606].
	This document also eliminates AS_PATH segment type 4, namely,		This document deprecates the AS_CONFED_SET (type 4) AS_PATH segment
	AS_CONFED_SET that is specified in Section 3 of [RFC5065]. That is,		type from [RFC5065]. Conformant BGP speakers MUST NOT locally
	in a future specification of Autonomous System Confederations for BGP		generate BGP UPDATE messages containing AS_CONFED_SET. Conformant
	-- one that would obsolete RFC 5065 -- the use of AS_CONFED_SET will		BGP speakers SHOULD NOT send BGP UPDATE messages containing
	not be specified.		AS_CONFED_SET. Upon receipt of such messages, conformant BGP
			speakers SHOULD use the "Treat-as-withdraw" error handling behavior
			as per [RFC7606].
			Wherever mentions of AS_SET or AS_CONFED_SET occur in [RFC4271] and
			[RFC5065], appropriate modification or elimination of the text must
			be made in future RFCs that would replace these RFCs, consistent with
			the deprecation of AS_SET and AS_CONFED_SET.
	5. Security Considerations		5. Security Considerations
	This document obsoletes the use of aggregation techniques that create		This document obsoletes the use of aggregation techniques that create
	AS_SETs or AS_CONFED_SETs. Obsoleting these path segment types from		AS_SETs or AS_CONFED_SETs. Obsoleting these path segment types from
	BGP and removal of the related code from implementations would		BGP and removal of the related code from implementations would
	potentially decrease the attack surface for BGP. Deployments of new		potentially decrease the attack surface for BGP. Deployments of new
	BGP security technologies [RFC6480] [RFC6811] [RFC8205] benefit		BGP security technologies [RFC6480] [RFC6811] [RFC8205] benefit
	greatly if AS_SET and AS_CONFED_SET are not used in BGP.		greatly if AS_SET and AS_CONFED_SET are not used in BGP.
	skipping to change at page 6, line 24 ¶		skipping to change at page 6, line 19 ¶
	[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support		[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
	Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,		Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
	February 2012, <https://www.rfc-editor.org/info/rfc6480>.		February 2012, <https://www.rfc-editor.org/info/rfc6480>.
	[RFC6811] Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.		[RFC6811] Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
	Austein, "BGP Prefix Origin Validation", RFC 6811,		Austein, "BGP Prefix Origin Validation", RFC 6811,
	DOI 10.17487/RFC6811, January 2013,		DOI 10.17487/RFC6811, January 2013,
	<https://www.rfc-editor.org/info/rfc6811>.		<https://www.rfc-editor.org/info/rfc6811>.
			[RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
			Patel, "Revised Error Handling for BGP UPDATE Messages",
			RFC 7606, DOI 10.17487/RFC7606, August 2015,
			<https://www.rfc-editor.org/info/rfc7606>.
	[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>.
	[RFC8205] Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol		[RFC8205] Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol
	Specification", RFC 8205, DOI 10.17487/RFC8205, September		Specification", RFC 8205, DOI 10.17487/RFC8205, September
	2017, <https://www.rfc-editor.org/info/rfc8205>.		2017, <https://www.rfc-editor.org/info/rfc8205>.
	Authors' Addresses		Authors' Addresses
End of changes. 14 change blocks.
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