draft-ietf-idr-bgp-flowspec-oid-11.txt		draft-ietf-idr-bgp-flowspec-oid-12.txt
	Network Working Group J. Uttaro		Network Working Group J. Uttaro
	Internet-Draft AT&T		Internet-Draft AT&T
	Updates: 5575bis (if approved) J. Alcaide		Updates: 5575bis (if approved) J. Alcaide
	Intended status: Standards Track C. Filsfils		Intended status: Standards Track C. Filsfils
	Expires: September 9, 2020 D. Smith		Expires: January 9, 2021 D. Smith
	Cisco		Cisco
	P. Mohapatra		P. Mohapatra
	Sproute Networks		Sproute Networks
	March 8, 2020		July 8, 2020
	Revised Validation Procedure for BGP Flow Specifications		Revised Validation Procedure for BGP Flow Specifications
	draft-ietf-idr-bgp-flowspec-oid-11		draft-ietf-idr-bgp-flowspec-oid-12
	Abstract		Abstract
	This document describes a modification to the validation procedure		This document describes a modification to the validation procedure
	defined in [RFC5575bis] for the dissemination of BGP Flow		defined for the dissemination of BGP Flow Specifications. The
	Specifications. [RFC5575bis] requires that the originator of the		dissemination of BGP Flow Specifications requires that the originator
	Flow Specification matches the originator of the best-match unicast		of the Flow Specification matches the originator of the best-match
	route for the destination prefix embedded in the Flow Specification.		unicast route for the destination prefix embedded in the Flow
	This allows only BGP speakers within the data forwarding path (such		Specification. This allows only BGP speakers within the data
	as autonomous system border routers) to originate BGP Flow		forwarding path (such as autonomous system border routers) to
	Specifications. Though it is possible to disseminate such Flow		originate BGP Flow Specifications. Though it is possible to
	Specifications directly from border routers, it may be operationally		disseminate such Flow Specifications directly from border routers, it
	cumbersome in an autonomous system with a large number of border		may be operationally cumbersome in an autonomous system with a large
	routers having complex BGP policies. The modification proposed		number of border routers having complex BGP policies. The
	herein enables Flow Specifications to be originated from a		modification proposed herein enables Flow Specifications to be
	centralized BGP route controller.		originated from a centralized BGP route controller.
			This document updates RFC5575bis.
	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 September 9, 2020.		This Internet-Draft will expire on January 9, 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 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
	skipping to change at page 2, line 44 ¶		skipping to change at page 2, line 44 ¶
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
	1. Requirements Language		1. 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", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	2. Introduction		2. Introduction
	[RFC5575bis] defined a new BGP [RFC4271] capability that can be used		[I-D.ietf-idr-rfc5575bis] defined a new BGP [RFC4271] capability that
	to distribute traffic Flow Specifications amongst BGP speakers in		can be used to distribute traffic Flow Specifications amongst BGP
	support of traffic filtering. The primary intention of [RFC5575bis]		speakers in support of traffic filtering. The primary intention of
	is to enable downstream autonomous systems to signal traffic		[I-D.ietf-idr-rfc5575bis] is to enable downstream autonomous systems
	filtering policies to upstream autonomous systems. In this way,		to signal traffic filtering policies to upstream autonomous systems.
	traffic is filtered closer to the source and the upstream autonomous		In this way, traffic is filtered closer to the source and the
	system(s) avoid carrying the traffic to the downstream autonomous		upstream autonomous system(s) avoid carrying the traffic to the
	system only to be discarded. [RFC5575bis] also enables more granular		downstream autonomous system only to be discarded. [I-D.ietf-idr-
	traffic filtering based upon upper layer protocol information (e.g.,		rfc5575bis] also enables more granular traffic filtering based upon
	protocol port numbers) as opposed to coarse IP destination prefix-		upper layer protocol information (e.g., protocol port numbers) as
	based filtering. Flow specification NLRIs received from a BGP peer		opposed to coarse IP destination prefix-based filtering. Flow
	are subject to validity checks before being considered feasible and		specification NLRIs received from a BGP peer are subject to validity
	subsequently installed within the respective Adj-RIB-In.		checks before being considered feasible and subsequently installed
			within the respective Adj-RIB-In.
	The validation procedure defined within [RFC5575bis] requires that		The validation procedure defined within [I-D.ietf-idr-rfc5575bis]
	the originator of the Flow Specification NLRI matches the originator		requires that the originator of the Flow Specification NLRI matches
	of the best-match unicast route for the destination prefix embedded		the originator of the best-match unicast route for the destination
	in the Flow Specification. This allows only BGP speakers within the		prefix embedded in the Flow Specification. This allows only BGP
	data forwarding path (such as autonomous system border routers) to		speakers within the data forwarding path (such as autonomous system
	originate BGP Flow Specification NLRIs. Though it is possible to		border routers) to originate BGP Flow Specification NLRIs. Though it
	disseminate such Flow Specification NLRIs directly from border		is possible to disseminate such Flow Specification NLRIs directly
	routers, it may be operationally cumbersome in an autonomous system		from border routers, it may be operationally cumbersome in an
	with a large number of border routers having complex BGP policies.		autonomous system with a large number of border routers having
			complex BGP policies.
	This document describes a modification to the [RFC5575bis] validation		This document describes a modification to the [I-D.ietf-idr-
	procedure allowing Flow Specification NLRIs to be originated from a		rfc5575bis] validation procedure allowing Flow Specification NLRIs to
	centralized BGP route controller within the local autonomous system		be originated from a centralized BGP route controller within the
	that is not in the data forwarding path. While the proposed		local autonomous system that is not in the data forwarding path.
	modification cannot be used for inter-domain coordination of traffic		While the proposed modification cannot be used for inter-domain
	filtering, it greatly simplifies distribution of intra-domain traffic		coordination of traffic filtering, it greatly simplifies distribution
	filtering policies within an autonomous system which has a large		of intra-domain traffic filtering policies within an autonomous
	number of border routers having complex BGP policies. By relaxing		system which has a large number of border routers having complex BGP
	the validation procedure for iBGP, the proposed modification allows		policies. By relaxing the validation procedure for iBGP, the
	Flow Specifications to be distributed in a standard and scalable		proposed modification allows Flow Specifications to be distributed in
	manner throughout an autonomous system.		a standard and scalable manner throughout an autonomous system.
	3. Motivation		3. Motivation
	Step (b) of the validation procedure in [RFC5575bis], section 6 is		Step (b) of the validation procedure in [I-D.ietf-idr-rfc5575bis],
	defined with the underlying assumption that the Flow Specification		section 6 is defined with the underlying assumption that the Flow
	NLRI traverses the same path, in the inter-domain and intra-domain		Specification NLRI traverses the same path, in the inter-domain and
	route distribution graph, as that of the longest-match unicast route		intra-domain route distribution graph, as that of the longest-match
	for the destination prefix embedded in the Flow Specification.		unicast route for the destination prefix embedded in the Flow
			Specification.
	In the case of inter-domain traffic filtering, the Flow Specification		In the case of inter-domain traffic filtering, the Flow Specification
	originator at the egress border routers of an AS (e.g. RTR-D and		originator at the egress border routers of an AS (e.g. RTR-D and
	RTR-E of ASN1 in figure 1) matches the eBGP neighbor that advertised		RTR-E of ASN1 in figure 1) matches the eBGP neighbor that advertised
	the longest match destination prefix (see RTR-F and RTR-G		the longest match destination prefix (see RTR-F and RTR-G
	respectively in figure 1). Similarly, at the ingress border routers		respectively in figure 1). Similarly, at the ingress border routers
	of ASN (see RTR-A and RTR-B of ASN1 in figure 1), the Flow		of ASN (see RTR-A and RTR-B of ASN1 in figure 1), the Flow
	Specification originator matches the egress iBGP border routers that		Specification originator matches the egress iBGP border routers that
	had advertised the unicast route for the best-match destination		had advertised the unicast route for the best-match destination
	prefix (see RTR-D and RTR-E respectively in figure 1). This is true		prefix (see RTR-D and RTR-E respectively in figure 1). This is true
	skipping to change at page 5, line 16 ¶		skipping to change at page 5, line 19 ¶
	plane. In this way, operators can direct border routers within their		plane. In this way, operators can direct border routers within their
	ASN with specific attack mitigation actions (drop the traffic,		ASN with specific attack mitigation actions (drop the traffic,
	forward to a clean-pipe center, etc.).		forward to a clean-pipe center, etc.).
	To originate a Flow Specification NLRI, a central BGP route		To originate a Flow Specification NLRI, a central BGP route
	controller must set itself as the originator in the Flow		controller must set itself as the originator in the Flow
	Specification NLRI. This is necessary given the route controller is		Specification NLRI. This is necessary given the route controller is
	originating the Flow Specification rather than reflecting it, and to		originating the Flow Specification rather than reflecting it, and to
	avoid the complexity of having to determine the egress border router		avoid the complexity of having to determine the egress border router
	whose path was chosen as the best in each of the ingress border		whose path was chosen as the best in each of the ingress border
	routers. Thus, it is necessary to modify step (b) of the		routers. Thus, it is necessary to modify step (b) of the [I-D.ietf-
	[RFC5575bis] validation procedure such that an iBGP peer that is not		idr-rfc5575bis] validation procedure such that an iBGP peer that is
	within the data forwarding plane may originate Flow Specification		not within the data forwarding plane may originate Flow Specification
	NLRIs.		NLRIs.
	4. Revised Validation Procedure		4. Revised Validation Procedure
	4.1. Revision of Route Feasibility		4.1. Revision of Route Feasibility
	Step (b) of the validation procedure specified in [RFC5575bis],		Step (b) of the validation procedure specified in [I-D.ietf-idr-
	section 6 is redefined as follows:		rfc5575bis], section 6 is redefined as follows:
	a. One of the following conditions MUST hold true:		b) One of the following conditions MUST hold true:
	1. The originator of the Flow Specification matches the		1. The originator of the Flow Specification matches the
	originator of the best-match unicast route for the		originator of the best-match unicast route for the destination
	destination prefix embedded in the Flow Specification (this		prefix embedded in the Flow Specification (This is the unicast
	is the unicast route with the longest possible prefix length		route with the longest possible prefix length covering the
	covering the destination prefix embedded in the Flow		destination prefix embedded in the Flow Specification).
	Specification).
	2. The AS_PATH attribute of the Flow Specification does not		2. The AS_PATH attribute of the Flow Specification does not
	contain AS_SET and/or AS_SEQUENCE segments.		contain AS_SET and/or AS_SEQUENCE segments.
	1. This condition SHOULD be enabled by default. This		1. This condition SHOULD be enabled by default. This default
	default behavior should validate an empty AS_PATH.		behavior should validate an empty AS_PATH.
	2. This condition MAY be disabled by configuration on a BGP		2. This condition MAY be disabled by configuration on a BGP
	speaker.		speaker.
	3. As an exception to this rule, a given AS_PATH with AS_SET		3. As an exception to this rule, a given AS_PATH with AS_SET
	and/or AS_SEQUENCE segments MAY be validated by policy.		and/or AS_SEQUENCE segments MAY be validated by policy.
	Explanation:		Explanation:
	In this context, an empty AS_PATH means that it does not have		In this context, an empty AS_PATH means that it does not have
	AS_SET and/or AS_SEQUENCE segments, and local domain means the		AS_SET and/or AS_SEQUENCE segments, and local domain means the
	local AS [RFC4271] or the local confederation of ASes (in the case		local AS [RFC4271] or the local confederation of ASes (in the case
	that the local AS belongs to a confederation of ASes [RFC5065]).		that the local AS belongs to a confederation of ASes [RFC5065]).
	Thus, receiving a Flow Specification with an empty AS_PATH		Thus, receiving a Flow Specification with an empty AS_PATH
	indicates that the Flow Specification was originated inside the		indicates that the Flow Specification was originated inside the
	local domain.		local domain.
	With the above modification to the [RFC5575bis] validation		With the above modification to the [I-D.ietf-idr-rfc5575bis]
	procedure, a BGP peer within the local domain that is not within		validation procedure, a BGP peer within the local domain that is
	the data forwarding path can originate a Flow Specification.		not within the data forwarding path can originate a Flow
			Specification.
	Disabling the new condition above (b.2.2) may be a good practice		Disabling the new condition above (b.2.2) may be a good practice
	when the operator knows with certainty that there is not a Flow		when the operator knows with certainty that there is not a Flow
	Specification originated inside the local domain.		Specification originated inside the local domain.
	Also, policy may be useful to validate a specific set of non-empty		Also, policy may be useful to validate a specific set of non-empty
	AS_PATHs (b.2.3). For example, it could validate a Flow		AS_PATHs (b.2.3). For example, it could validate a Flow
	Specification whose AS_PATH contains only an AS_SEQUENCE with ASes		Specification whose AS_PATH contains only an AS_SEQUENCE with ASes
	that are all known to belong to the same administrative domain.		that are all known to belong to the same administrative domain.
	4.2. Revision of AS_PATH Validation		4.2. Revision of AS_PATH Validation
	[RFC5575bis] states:		[I-D.ietf-idr-rfc5575bis] states:
	o BGP implementations MUST also enforce that the AS_PATH attribute		o BGP implementations MUST also enforce that the AS_PATH attribute
	of a route received via the External Border Gateway Protocol		of a route received via the External Border Gateway Protocol
	(eBGP) contains the neighboring AS in the left-most position of		(eBGP) contains the neighboring AS in the left-most position of
	the AS_PATH attribute.		the AS_PATH attribute.
	This rule prevents the exchange of BGP Flow Specification NLRIs at		This rule prevents the exchange of BGP Flow Specification NLRIs at
	Internet exchanges with BGP route servers. Therefore, this document		Internet exchanges with BGP route servers. Therefore, this document
	also redefines the [RFC5575bis] AS_PATH validation procedure		also redefines the [I-D.ietf-idr-rfc5575bis] AS_PATH validation
	referenced above as follows:		procedure referenced above as follows:
	o BGP Flow Specification implementations MUST enforce that the AS in		o BGP Flow Specification implementations MUST enforce that the AS in
	the left-most position of the AS_PATH attribute of a Flow		the left-most position of the AS_PATH attribute of a Flow
	Specification route received via the External Border Gateway		Specification route received via the External Border Gateway
	Protocol (eBGP) matches the AS in the left-most position of the		Protocol (eBGP) matches the AS in the left-most position of the
	AS_PATH attribute of the best-match unicast route for the		AS_PATH attribute of the best-match unicast route for the
	destination prefix embedded in the Flow Specification NLRI.		destination prefix embedded in the Flow Specification NLRI.
	Explanation:		Explanation:
	skipping to change at page 7, line 21 ¶		skipping to change at page 7, line 21 ¶
	Comparing only the last ASes added is sufficient for eBGP learned		Comparing only the last ASes added is sufficient for eBGP learned
	Flow Specification NLRIs. Requiring a full AS_PATH match would		Flow Specification NLRIs. Requiring a full AS_PATH match would
	limit origination of inter-domain Flow Specifications to the		limit origination of inter-domain Flow Specifications to the
	origin AS of the best-match unicast route for the destination		origin AS of the best-match unicast route for the destination
	prefix embedded in the Flow Specification only. As such, a full		prefix embedded in the Flow Specification only. As such, a full
	AS_PATH validity check may prevent transit ASes from originating		AS_PATH validity check may prevent transit ASes from originating
	inter-domain Flow Specifications, which is not desirable.		inter-domain Flow Specifications, which is not desirable.
	Redefinition of this AS_PATH validation rule for a Flow		Redefinition of this AS_PATH validation rule for a Flow
	Specification does not mean that the original rule in [RFC5575bis]		Specification does not mean that the original rule in [I-D.ietf-
	cannot be enforced as well. Its enforcement remains optional per		idr-rfc5575bis] cannot be enforced as well. Its enforcement
	[RFC4271] section 6.3. That is, we can enforce the first AS in		remains optional per [RFC4271] section 6.3. That is, we can
	the AS_PATH to be the same as the neighbor AS for any address-		enforce the first AS in the AS_PATH to be the same as the neighbor
	family route (including a Flow Specification).		AS for any address-family route (including a Flow Specification).
	Using the new rule to validate a Flow Specification received from		Using the new rule to validate a Flow Specification received from
	an Internal Border Gateway Protocol (iBGP) peer is out of the		an Internal Border Gateway Protocol (iBGP) peer is out of the
	scope of this document. Note that in most scenarios such		scope of this document. Note that in most scenarios such
	validation would be redundant.		validation would be redundant.
	Using the new rule to validate a Flow Specification route received		Using the new rule to validate a Flow Specification route received
	from an External Border Gateway Protocol (eBGP) peer belonging to		from an External Border Gateway Protocol (eBGP) peer belonging to
	the same local domain (in the case that the local AS belongs to a		the same local domain (in the case that the local AS belongs to a
	confederation of ASes) is out of the scope of this document. Note		confederation of ASes) is out of the scope of this document. Note
	that although it's possible, its utility is dubious.		that although it's possible, its utility is dubious.
	5. Other RFC5575bis Considerations		5. Other RFC5575bis Considerations
	This section clarifies some of the terminology and rules referenced		This section clarifies some of the terminology and rules referenced
	in [RFC5575bis]. Namely:		in [I-D.ietf-idr-rfc5575bis]. Namely:
	o In the context of this document and [RFC5575bis], AS_PATH		o In the context of this document and [I-D.ietf-idr-rfc5575bis],
	attribute is defined as the reconstructed AS path information (by		AS_PATH attribute is defined as the reconstructed AS path
	combining AS_PATH and AS4_PATH attributes, if the BGP speaker is a		information (by combining AS_PATH and AS4_PATH attributes, if the
	NEW speaker and receives the route from an OLD speaker), according		BGP speaker is a NEW speaker and receives the route from an OLD
	to section 4.2.3 of [RFC6793].		speaker), according to section 4.2.3 of [RFC6793].
	o Support for two-octet AS only implementations is out of the scope		o Support for two-octet AS only implementations is out of the scope
	of this document (i.e. it's assumed that the BGP speaker supports		of this document (i.e. it's assumed that the BGP speaker supports
	[RFC6793]).		[RFC6793]).
	6. Topology Considerations		6. Topology Considerations
	[RFC5575bis] indicates that the originator may refer to the		[I-D.ietf-idr-rfc5575bis] indicates that the originator may refer to
	originator path attribute (ORIGINATOR_ID) or (if the attribute is not		the originator path attribute (ORIGINATOR_ID) or (if the attribute is
	present) the transport address of the peer from which we received the		not present) the transport address of the peer from which we received
	update. If the latter applies, a network should be designed so it		the update. If the latter applies, a network should be designed so
	has a congruent topology.		it has a congruent topology.
	With the additional second condition (b.2) in the validation		With the additional second condition (b.2) in the validation
	procedure, non-congruent topologies are supported within the local		procedure, non-congruent topologies are supported within the local
	domain if the Flow Specification is originated within the local		domain if the Flow Specification is originated within the local
	domain.		domain.
	Explanation:		Explanation:
	Consider the following scenarios without the second condition		Consider the following scenarios without the second condition
	(b.2) being added to the validation procedure:		(b.2) being added to the validation procedure:
	skipping to change at page 9, line 35 ¶		skipping to change at page 9, line 35 ¶
	the security characteristics of BGP Flow Specifications remain		the security characteristics of BGP Flow Specifications remain
	equivalent to the existing security properties of BGP unicast		equivalent to the existing security properties of BGP unicast
	routing.		routing.
	BGP updates learned from iBGP peers are trusted so the Traffic Flow		BGP updates learned from iBGP peers are trusted so the Traffic Flow
	Specifications contained in BGP updates are trusted. Therefore it is		Specifications contained in BGP updates are trusted. Therefore it is
	not required to validate that the originator of an intra-domain		not required to validate that the originator of an intra-domain
	Traffic Flow Specification matches the originator of the best-match		Traffic Flow Specification matches the originator of the best-match
	unicast route for the flow destination prefix. This proposal		unicast route for the flow destination prefix. This proposal
	continues to enforce the validation Procedure for eBGP learned		continues to enforce the validation Procedure for eBGP learned
	Traffic Flow Specifications, as per [RFC5575bis] rules. In this way,		Traffic Flow Specifications, as per [I-D.ietf-idr-rfc5575bis] rules.
	the security properties of [RFC5575bis] are maintained such that an		In this way, the security properties of [I-D.ietf-idr-rfc5575bis] are
	EBGP peer cannot cause a denial-of-service attack by advertising an		maintained such that an EBGP peer cannot cause a denial-of-service
	inter-domain Flow Specification for a destination prefix that it does		attack by advertising an inter-domain Flow Specification for a
	not provide reachability information for.		destination prefix that it does not provide reachability information
			for.
	9. Acknowledgements		9. Acknowledgements
	The authors would like to thank Han Nguyen for his direction on this		The authors would like to thank Han Nguyen for his direction on this
	work as well as Waqas Alam, Keyur Patel, Robert Raszuk, Eric Rosen		work as well as Waqas Alam, Keyur Patel, Robert Raszuk, Eric Rosen
	and Shyam Sethuram for their review comments.		and Shyam Sethuram for their review comments.
	10. Normative References		10. Normative References
	[I-D.ietf-idr-rfc5575bis]		[I-D.ietf-idr-rfc5575bis]
	Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.		Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
	Bacher, "Dissemination of Flow Specification Rules",		Bacher, "Dissemination of Flow Specification Rules",
	draft-ietf-idr-rfc5575bis-19 (work in progress), January		draft-ietf-idr-rfc5575bis-25 (work in progress), May 2020.
	2020.
	[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>.
	[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A		[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
	Border Gateway Protocol 4 (BGP-4)", RFC 4271,		Border Gateway Protocol 4 (BGP-4)", RFC 4271,
	DOI 10.17487/RFC4271, January 2006,		DOI 10.17487/RFC4271, January 2006,
	<https://www.rfc-editor.org/info/rfc4271>.		<https://www.rfc-editor.org/info/rfc4271>.
	[RFC4456] Bates, T., Chen, E., and R. Chandra, "BGP Route
	Reflection: An Alternative to Full Mesh Internal BGP
	(IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006,
	<https://www.rfc-editor.org/info/rfc4456>.
	[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous		[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous
	System Confederations for BGP", RFC 5065,		System Confederations for BGP", RFC 5065,
	DOI 10.17487/RFC5065, August 2007,		DOI 10.17487/RFC5065, August 2007,
	<https://www.rfc-editor.org/info/rfc5065>.		<https://www.rfc-editor.org/info/rfc5065>.
	[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet		[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
	Autonomous System (AS) Number Space", RFC 6793,		Autonomous System (AS) Number Space", RFC 6793,
	DOI 10.17487/RFC6793, December 2012,		DOI 10.17487/RFC6793, December 2012,
	<https://www.rfc-editor.org/info/rfc6793>.		<https://www.rfc-editor.org/info/rfc6793>.
End of changes. 27 change blocks.
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