draft-ietf-grow-large-communities-usage-07.txt		rfc8195.txt
	Global Routing Operations J. Snijders		Internet Engineering Task Force (IETF) J. Snijders
	Internet-Draft J. Heasley		Request for Comments: 8195 J. Heasley
	Intended status: Informational NTT		Category: Informational NTT
	Expires: October 21, 2017 M. Schmidt		ISSN: 2070-1721 M. Schmidt
	i3D.net		i3D.net
	April 19, 2017		June 2017
	Use of BGP Large Communities		Use of BGP Large Communities
	draft-ietf-grow-large-communities-usage-07
	Abstract		Abstract
	This document presents examples and inspiration for operator's		This document presents examples and inspiration for operator
	application of BGP Large Communities. Based on operational		application of BGP Large Communities. Based on operational
	experience with BGP Communties, this document suggests logical		experience with BGP Communities, this document suggests logical
	categories of BGP Large Communities and demonstrates an orderly		categories of BGP Large Communities and demonstrates an orderly
	manner of organizing community values within them to achieve typical		manner of organizing community values within them to achieve typical
	goals in routing policy. Any operator can consider using the		goals in routing policy. Any operator can consider using the
	concepts presented as the basis for their own BGP Large Communities		concepts presented as the basis for their own BGP Large Communities
	repertoire.		repertoire.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This document is not an Internet Standards Track specification; it is
	provisions of BCP 78 and BCP 79.		published for informational purposes.
	Internet-Drafts are working documents of the Internet Engineering
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			Standard; see Section 2 of RFC 7841.
	This Internet-Draft will expire on October 21, 2017.		Information about the current status of this document, any errata,
			and how to provide feedback on it may be obtained at
			http://www.rfc-editor.org/info/rfc8195.
	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.
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	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
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	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. The Design Overview . . . . . . . . . . . . . . . . . . . . . 3		2. The Design Overview . . . . . . . . . . . . . . . . . . . . . 3
	2.1. Informational Communities . . . . . . . . . . . . . . . . 4		2.1. Informational Communities . . . . . . . . . . . . . . . . 4
	2.2. Action Communities . . . . . . . . . . . . . . . . . . . 4		2.2. Action Communities . . . . . . . . . . . . . . . . . . . 5
	3. Examples of Informational Communities . . . . . . . . . . . . 5		3. Examples of Informational Communities . . . . . . . . . . . . 5
	3.1. Location . . . . . . . . . . . . . . . . . . . . . . . . 5		3.1. Location . . . . . . . . . . . . . . . . . . . . . . . . 5
	3.1.1. An ISO 3166-1 Numeric Function . . . . . . . . . . . 5		3.1.1. An ISO 3166-1 Numeric Function . . . . . . . . . . . 6
	3.1.2. An UN M.49 Region Function . . . . . . . . . . . . . 5		3.1.2. A UN M.49 Region Function . . . . . . . . . . . . . . 6
	3.2. Relation Function . . . . . . . . . . . . . . . . . . . . 6		3.2. Relation Function . . . . . . . . . . . . . . . . . . . . 7
	3.3. Combining Informational Communities . . . . . . . . . . . 6		3.3. Combining Informational Communities . . . . . . . . . . . 7
	4. Examples of Action Communities . . . . . . . . . . . . . . . 7		4. Examples of Action Communities . . . . . . . . . . . . . . . 7
	4.1. Selective NO_EXPORT . . . . . . . . . . . . . . . . . . . 7		4.1. Selective NO_EXPORT . . . . . . . . . . . . . . . . . . . 7
	4.1.1. ASN Based Selective NO_EXPORT . . . . . . . . . . . . 7		4.1.1. ASN-Based Selective NO_EXPORT . . . . . . . . . . . . 8
	4.1.2. Location Based Selective NO_EXPORT . . . . . . . . . 7		4.1.2. Location-Based Selective NO_EXPORT . . . . . . . . . 8
	4.2. Selective AS_PATH Prepending . . . . . . . . . . . . . . 8		4.2. Selective AS_PATH Prepending . . . . . . . . . . . . . . 9
	4.2.1. ASN Based Selective AS_PATH Prepending . . . . . . . 8		4.2.1. ASN-Based Selective AS_PATH Prepending . . . . . . . 9
	4.2.2. Location Based Selective AS_PATH Prepending . . . . . 9		4.2.2. Location-Based Selective AS_PATH Prepending . . . . . 10
	4.3. Manipulation of the LOCAL_PREF Attribute . . . . . . . . 9		4.3. Manipulation of the LOCAL_PREF Attribute . . . . . . . . 10
	4.3.1. Global Manipulation of LOCAL_PREF . . . . . . . . . . 10		4.3.1. Global Manipulation of LOCAL_PREF . . . . . . . . . . 11
	4.3.2. Region Based Manipulation of LOCAL_PREF . . . . . . . 10		4.3.2. Region-Based Manipulation of LOCAL_PREF . . . . . . . 11
	4.3.3. Note of Caution for LOCAL_PREF Functions . . . . . . 11		4.3.3. Note of Caution for LOCAL_PREF Functions . . . . . . 12
	4.4. Route Server Prefix Distribution Control . . . . . . . . 11		4.4. Route Server Prefix Distribution Control . . . . . . . . 12
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 12		5. Security Considerations . . . . . . . . . . . . . . . . . . . 13
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
	7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13		7. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 13		7.1. Normative References . . . . . . . . . . . . . . . . . . 14
	8.1. Normative References . . . . . . . . . . . . . . . . . . 13		7.2. Informative References . . . . . . . . . . . . . . . . . 14
	8.2. Informative References . . . . . . . . . . . . . . . . . 13		Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 15
	8.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 14		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
	1. Introduction		1. Introduction
	BGP Large Communities [RFC8092] provide a mechanism to signal opaque		BGP Large Communities [RFC8092] provide a mechanism to signal opaque
	information between Autonomous Systems (ASs). In very much the same		information between and within Autonomous Systems (ASes). In very
	way that [RFC1998] provides a concrete real-world application for		much the same way that [RFC1998] provides a concrete real-world
	[RFC1997] communities, this document presents examples of how		application for BGP Communities [RFC1997], this document presents
	operators might utilize BGP Large Communities to achieve various		examples of how operators might utilize BGP Large Communities to
	goals. This document draws on the experience of operator communities		achieve various goals. This document draws on the experience of
	such as NANOG [1] and NLNOG [2].		operator communities such as the North American Network Operators'
			Group (NANOG) <https://www.nanog.org/> and the Netherlands Network
			Operator Group (NLNOG) <https://nlnog.net/>.
	2. The Design Overview		2. The Design Overview
	BGP Large Communities are composed of three 4-octet fields. The		BGP Large Communities are composed of three 4-octet fields. The
	first is the Global Administrator (GA) field, whose value is the		first is the Global Administrator (GA) field, whose value is the
	Autonomous System Number (ASN) of the AS that has defined the meaning		Autonomous System Number (ASN) of the AS that has defined the meaning
	of the remaining two 4-octet fields, known as "Local Data Part 1" and		of the remaining two 4-octet fields, known as "Local Data Part 1" and
	"Local Data Part 2". This document describes an approach where the		"Local Data Part 2". This document describes an approach where the
	"Local Data Part 1" field contains a function identifier and the		"Local Data Part 1" field contains a function identifier and the
	"Local Data Part 2" contains a parameter value. Using the canonical		"Local Data Part 2" contains a parameter value. Using the canonical
	notation this format can be summarized as "ASN:Function:Parameter".		notation this format can be summarized as "ASN:Function:Parameter".
	+----------------------+---------------+		+----------------------+---------------+
	| RFC 8092 | this document |		| RFC 8092 | this document |
	+----------------------+---------------+		+----------------------+---------------+
	| Global Administrator | ASN |		| Global Administrator | ASN |
	| Local Data Part 1 | Function |		| Local Data Part 1 | Function |
	| Local Data Part 2 | Parameter |		| Local Data Part 2 | Parameter |
	+----------------------+---------------+		+----------------------+---------------+
	A mapping table on the use of fields in BGP Large Communities between
	[RFC8092] and this document.
	Table 1: Field Mapping		Table 1: Field Mapping
			The table above shows a mapping table between the fields in BGP Large
			Communities [RFC8092] and this document.
	In contemporary deployments of both BGP Communities [RFC1997] and BGP		In contemporary deployments of both BGP Communities [RFC1997] and BGP
	Large Communities, the function of a community can be divided into		Large Communities [RFC8092], the function of a community can be
	two categories:		divided into two categories:
	o Informational Communities		o Informational Communities
	o Action Communities		o Action Communities
			Throughout the document, a topology of four ASes is used to
	Throughout the document a topology of four ASs is used to illustrate		illustrate the use of communities in the following configuration:
	the use of communities in the following configuration:
	AS 65551		AS 65551
	|		|
	^		^
	|		|
	AS 64497		AS 64497
	/ \		/ \
	^ \		^ \
	/ ^		/ ^
	AS 64498 \		AS 64498 \
	skipping to change at page 4, line 14 ¶		skipping to change at page 4, line 28 ¶
	AS 64497 obtains transit services from (is a customer of) AS 65551, a		AS 64497 obtains transit services from (is a customer of) AS 65551, a
	4-octet ASN. AS 64497 provides transit services to both AS 64498 and		4-octet ASN. AS 64497 provides transit services to both AS 64498 and
	AS 64499. AS 64498 and AS 64499 maintain a peering relationship in		AS 64499. AS 64498 and AS 64499 maintain a peering relationship in
	which they only exchange their customer routes.		which they only exchange their customer routes.
	The opaque nature of BGP Large Communities allows for rapid		The opaque nature of BGP Large Communities allows for rapid
	deployment of new features or changes to their routing policy that		deployment of new features or changes to their routing policy that
	perform an action. Operators are encouraged to publicly publish and		perform an action. Operators are encouraged to publicly publish and
	maintain documentation on the purpose of each BGP Large Community,		maintain documentation on the purpose of each BGP Large Community,
	both informational and action, that they support or are visible in		both Informational and Action, that they support or that are visible
	BGP RIBs.		in BGP RIBs.
	2.1. Informational Communities		2.1. Informational Communities
	Informational Communities are labels for attributes such as the		Informational Communities are labels for attributes such as the
	origin of the route announcement, the nature of the relation with an		origin of the route announcement, the nature of the relation with an
	EBGP neighbor or the intended propagation audience. Informational		External BGP (EBGP) neighbor, or the intended propagation audience.
	Communities can also assist in providing valuable information for		Informational Communities can also assist in providing valuable
	day-to-day network operations such as debugging or capacity planning.		information for day-to-day network operations such as debugging or
			capacity planning.
	The Global Administrator field is set to the ASN which labels the		The Global Administrator field is set to the ASN of the network that
	routes with the Informational Communities. For example, AS 64497		tags the routes with the Informational Communities. For example, AS
	might add a community with the GA 64497 to a route accepted from an		64497 might add a community with the GA 64497 to a route accepted
	IBGP or EBGP neighbor as a means of signaling that it was imported in		from an Internal BGP (IBGP) or EBGP neighbor as a means of signaling
	a certain geographical region.		that it was imported in a certain geographical region.
	In general, the intended audiences of Informational Communities are		In general, the intended audiences of Informational Communities are
	downstream networks and the Global Administrator itself, but any AS		downstream networks and the GA itself, but any AS could benefit from
	could benefit from receiving these communities.		receiving these communities.
	2.2. Action Communities		2.2. Action Communities
	Action Communities are added as a label to request that a route be		Action Communities are added as labels to request that a route be
	treated in a particular way within an AS. The operator of the AS		treated in a particular way within an AS. The operator of the AS
	defines a routing policy that adjusts path attributes based on the		defines a routing policy that adjusts path attributes based on the
	community. For example, the route's propagation characteristics, the		community. For example, the route's propagation characteristics, the
	LOCAL_PREF (local preference), the next-hop, or the number of AS_PATH		LOCAL_PREF (local preference), the next hop, or the number of AS_PATH
	prepends to be added when it is received or propagated can be		prepends to be added when it is received or propagated can be
	changed.		changed.
	The Global Administrator field is set to the ASN which has defined		The Global Administrator field is set to the ASN that has defined the
	the functionality of that BGP Large Community and is the ASN that is		functionality of that BGP Large Community and is the ASN that is
	expected to perform the action. For example, AS 64499 might label a		expected to perform the action. For example, AS 64499 might label a
	route with a BGP Large Community containing GA 64497 to request that		route with a BGP Large Community containing GA 64497 to request that
	AS 64497 perform a pre-defined action on that route.		AS 64497 perform a predefined action on that route.
	In general, the intended audience of Action Communities are transit		In general, the intended audience of Action Communities are transit
	providers taking action on behalf of a customer or the Global		providers taking action on behalf of a customer or the GA itself, but
	Administrator itself, but any AS could take action if they choose and		any AS could take action if they choose and any AS could add an
	any AS could add an Action Community with the GA of a non-adjacent		Action Community with the GA of a non-adjacent ASN. However, note
	ASN. However, note that an Action Community could also be		that an Action Community could also be Informational. Its presence
	informational. Its presence is an indicator that the GA may have		is an indicator that the GA may have performed the action and that an
	performed the action and that an AS in the AS_PATH requested it.		AS in the AS_PATH requested it.
	Operators are recommended to publish the relative order in which		Operators are recommended to publish the relative order in which
	Action Communities (both BGP Communities and BGP Large Communities)		Action Communities (both BGP Communities and BGP Large Communities)
	are processed in their routing policy.		are processed in their routing policy.
	3. Examples of Informational Communities		3. Examples of Informational Communities
	3.1. Location		3.1. Location
	An AS, AS 64497 in these examples, may inform other networks about		An AS, AS 64497 in these examples, may inform other networks about
	the geographical region where AS 64497 imported a route by labeling		the geographical region where AS 64497 imported a route by labeling
	it with BGP Large Communities following one of the following schemes		it with BGP Large Communities following one of the following schemes
	or a combination of them.		or a combination of them.
	3.1.1. An ISO 3166-1 Numeric Function		3.1.1. An ISO 3166-1 Numeric Function
	AS 64497 could assign a value of 1 to the Function field to designate		AS 64497 could assign a value of 1 to the Function field to designate
	the content of the Parameter field as an ISO-3166-1 [3] numeric		the content of the Parameter field as an ISO 3166-1 numeric country
	country identifier.		identifier <https://www.iso.org/iso-3166-country-codes.html>.
	+---------------------+---------------------------------------------+		+---------------------+---------------------------------------------+
	| BGP Large Community | Description |		| BGP Large Community | Description |
	+---------------------+---------------------------------------------+		+---------------------+---------------------------------------------+
	| 64497:1:528 | Route learned in the Netherlands |		| 64497:1:528 | Route learned in the Netherlands |
	| 64497:1:392 | Route learned in Japan |		| 64497:1:392 | Route learned in Japan |
	| 64497:1:840 | Route learned in the United States of |		| 64497:1:840 | Route learned in the United States of |
	| | America |		| | America |
	+---------------------+---------------------------------------------+		+---------------------+---------------------------------------------+
	Example documentation for Informational Communities deployed by AS		Table 2: Informational: ISO 3166-1
	64497 to describe the location where a route was imported using ISO
	3166-1 numeric identifiers.
	Table 2: Information: ISO 3166-1		The table above shows example documentation for Informational
			Communities deployed by AS 64497 to describe the location where a
			route was imported using ISO 3166-1 numeric identifiers.
	3.1.2. An UN M.49 Region Function		3.1.2. A UN M.49 Region Function
	AS 64497 could assign a value of 2 to the Function field to designate		AS 64497 could assign a value of 2 to the Function field to designate
	the content of the Parameter field as the M.49 numeric code published		the content of the Parameter field as the M.49 numeric code published
	by the United Nations Statistics Division (UNSD) [4] for macro		by the United Nations Statistics Division (UNSD)
	geographical (continental) regions, geographical sub-regions, or		<https://unstats.un.org/unsd/methodology/m49/> for macro-geographical
	selected economic and other groupings.		(continental) regions, geographical sub-regions, or selected economic
			and other groupings.
	+---------------------+-------------------------------+		+---------------------+-------------------------------+
	| BGP Large Community | Description |		| BGP Large Community | Description |
	+---------------------+-------------------------------+		+---------------------+-------------------------------+
	| 64497:2:2 | Route learned in Africa |		| 64497:2:2 | Route learned in Africa |
	| 64497:2:9 | Route learned in Oceania |		| 64497:2:9 | Route learned in Oceania |
	| 64497:2:145 | Route learned in Western Asia |		| 64497:2:145 | Route learned in Western Asia |
	| 64497:2:150 | Route learned in Europe |		| 64497:2:150 | Route learned in Europe |
	+---------------------+-------------------------------+		+---------------------+-------------------------------+
	Example documentation for Informational Communities deployed by AS		Table 3: Informational: UNSD Regions
	64497 to describe the location where a route was imported using M.49
	numeric codes published by the United Nations Statistics Division.
	Table 3: Information: UNSD Regions		The table above shows example documentation for Informational
			Communities deployed by AS 64497 to describe the location where a
			route was imported using M.49 numeric codes published by the UNSD.
	3.2. Relation Function		3.2. Relation Function
	An AS, AS 64497 in this example, could assign a value of 3 to the		An AS, AS 64497 in this example, could assign a value of 3 to the
	Function field to designate the content of the Parameter field as a		Function field to designate the content of the Parameter field as a
	number indicating whether the route originated inside its own network		number indicating whether the route originated inside its own network
	or was learned externally, and if learned externally, it might		or was learned externally, and if learned externally, it might
	simultaneously characterize the nature of the relation with that		simultaneously characterize the nature of the relation with that
	specific EBGP neighbor.		specific EBGP neighbor.
	+---------------------+---------------------------------------+		+---------------------+---------------------------------------+
	| BGP Large Community | Description |		| BGP Large Community | Description |
	+---------------------+---------------------------------------+		+---------------------+---------------------------------------+
	| 64497:3:1 | Route originated internally |		| 64497:3:1 | Route originated internally |
	| 64497:3:2 | Route learned from a customer |		| 64497:3:2 | Route learned from a customer |
	| 64497:3:3 | Route learned from a peering partner |		| 64497:3:3 | Route learned from a peering partner |
	| 64497:3:4 | Route learned from a transit provider |		| 64497:3:4 | Route learned from a transit provider |
	+---------------------+---------------------------------------+		+---------------------+---------------------------------------+
	Example documentation for Informational Communities deployed by AS		Table 4: Informational: Relation
	64497 to describe the relation to the ASN from which the route was
	learned.
	Table 4: Information: Relation		The table above shows example documentation for Informational
			Communities deployed by AS 64497 to describe the relation to the ASN
			from which the route was learned.
	3.3. Combining Informational Communities		3.3. Combining Informational Communities
	A route may be labeled with multiple Informational Communities. For		A route may be labeled with multiple Informational Communities. For
	example, a route learned in the Netherlands from a customer might be		example, a route learned in the Netherlands from a customer might be
	labeled with communities 64497:1:528, 64497:2:150 and 64497:3:2 at		labeled with communities 64497:1:528, 64497:2:150, and 64497:3:2 at
	the same time.		the same time.
	4. Examples of Action Communities		4. Examples of Action Communities
	4.1. Selective NO_EXPORT		4.1. Selective NO_EXPORT
	As part of an agreement, often a commercial transit agreement,		As part of an agreement, often a commercial transit agreement,
	between AS 64497 and AS 64498, AS 64497 might expose BGP traffic		between AS 64497 and AS 64498, AS 64497 might expose BGP traffic-
	engineering functions to AS 64498. One such BGP traffic engineering		engineering functions to AS 64498. One such BGP traffic-engineering
	function could be selective NO_EXPORT, which is the selective		function could be selective NO_EXPORT, which is the selective
	filtering of a route learned from one AS, AS 64498, to certain EBGP		filtering of a route learned from one AS, AS 64498, to certain EBGP
	neighbors of the GA, AS 64497.		neighbors of the GA, AS 64497.
	4.1.1. ASN Based Selective NO_EXPORT		4.1.1. ASN-Based Selective NO_EXPORT
	AS 64497 could assign a value of 4 to the Function field to designate		AS 64497 could assign a value of 4 to the Function field to designate
	the content of the Parameter field as a neighboring ASN to which a		the content of the Parameter field as a neighboring ASN to which a
	route should not be propagated.		route should not be propagated.
	+---------------------+---------------------------------+		+---------------------+---------------------------------+
	| BGP Large Community | Description |		| BGP Large Community | Description |
	+---------------------+---------------------------------+		+---------------------+---------------------------------+
	| 64497:4:64498 | Do not export route to AS 64498 |		| 64497:4:64498 | Do not export route to AS 64498 |
	| 64497:4:64499 | Do not export route to AS 64499 |		| 64497:4:64499 | Do not export route to AS 64499 |
	| 64497:4:65551 | Do not export route to AS 65551 |		| 64497:4:65551 | Do not export route to AS 65551 |
	+---------------------+---------------------------------+		+---------------------+---------------------------------+
	Example documentation for Action Communities deployed by AS 64497 to
	expose a BGP traffic engineering function which selectively prevents
	the propagation of routes to the neighboring ASN specified in the
	Parameter field.
	Table 5: Action: ASN NO_EXPORT		Table 5: Action: ASN NO_EXPORT
	4.1.2. Location Based Selective NO_EXPORT		The table above shows example documentation for Action Communities
			deployed by AS 64497 to expose a BGP traffic-engineering function
			that selectively prevents the propagation of routes to the
			neighboring ASN specified in the Parameter field.
			4.1.2. Location-Based Selective NO_EXPORT
	AS 64497 could assign a value of 5 to the Function field to designate		AS 64497 could assign a value of 5 to the Function field to designate
	the content of the Parameter field as an ISO 3166-1 numeric country		the content of the Parameter field as an ISO 3166-1 numeric country
	identifier within which a labeled route is not propagated to EBGP		identifier within which a labeled route is not propagated to EBGP
	neighbors. However, this might not prevent one of those EBGP		neighbors. However, this might not prevent one of those EBGP
	neighbors from learning that route in another country and making it		neighbors from learning that route in another country and making it
	available in the country specified by the BGP Large Community.		available in the country specified by the BGP Large Community.
	+-----------------+-------------------------------------------------+		+-----------------+-------------------------------------------------+
	| BGP Large | Description |		| BGP Large | Description |
	| Community | |		| Community | |
	+-----------------+-------------------------------------------------+		+-----------------+-------------------------------------------------+
	| 64497:5:528 | Do not export to EBGP neighbors in the |		| 64497:5:528 | Do not export to EBGP neighbors in the |
	| | Netherlands |		| | Netherlands |
	| 64497:5:392 | Do not export to EBGP neighbors in Japan |		| 64497:5:392 | Do not export to EBGP neighbors in Japan |
	| 64497:5:840 | Do not export to EBGP neighbors in the United |		| 64497:5:840 | Do not export to EBGP neighbors in the United |
	| | States of America |		| | States of America |
	+-----------------+-------------------------------------------------+		+-----------------+-------------------------------------------------+
	Example documentation for Action Communities deployed by AS 64497 to
	expose a BGP traffic engineering function which selectively prevents
	the propagation of routes to all EBGP neighbors in the geographical
	region specified in the Parameter field.
	Table 6: Action: NO_EXPORT in Region		Table 6: Action: NO_EXPORT in Region
			The table above shows example documentation for Action Communities
			deployed by AS 64497 to expose a BGP traffic-engineering function
			that selectively prevents the propagation of routes to all EBGP
			neighbors in the geographical region specified in the Parameter
			field.
	4.2. Selective AS_PATH Prepending		4.2. Selective AS_PATH Prepending
	As part of an agreement between AS 64497 and AS 64498, AS 64497 might		As part of an agreement between AS 64497 and AS 64498, AS 64497 might
	expose BGP traffic engineering functions to AS 64498. One such BGP		expose BGP traffic-engineering functions to AS 64498. One such BGP
	traffic engineering function could be selective prepending of the		traffic-engineering function could be selective prepending of the
	AS_PATH with AS 64497 to certain certain EBGP neighbors of AS 64497.		AS_PATH with AS 64497 to certain EBGP neighbors of AS 64497.
	4.2.1. ASN Based Selective AS_PATH Prepending		4.2.1. ASN-Based Selective AS_PATH Prepending
	AS 64497 could assign a value of 6 to the Function field to designate		AS 64497 could assign a value of 6 to the Function field to designate
	the content of the Parameter field as a neighboring ASN to which		the content of the Parameter field as a neighboring ASN to which
	prepending of the AS_PATH with AS 64497 is requested on propagation		prepending of the AS_PATH with AS 64497 is requested on propagation
	of the route. Additional AS_PATH prepending functions might also be		of the route. Additional AS_PATH prepending functions might also be
	defined to support multiples of prepending, that is two, three or		defined to support multiples of prepending, that is, two, three, or
	more prepends of AS 64497.		more prepends of AS 64497.
	+---------------------+------------------------------------------+		+---------------------+------------------------------------------+
	| BGP Large Community | Description |		| BGP Large Community | Description |
	+---------------------+------------------------------------------+		+---------------------+------------------------------------------+
	| 64497:6:64498 | Prepend 64497 once on export to AS 64498 |		| 64497:6:64498 | Prepend 64497 once on export to AS 64498 |
	| 64497:6:64499 | Prepend 64497 once on export to AS 64499 |		| 64497:6:64499 | Prepend 64497 once on export to AS 64499 |
	| 64497:6:65551 | Prepend 64497 once on export to AS 65551 |		| 64497:6:65551 | Prepend 64497 once on export to AS 65551 |
	+---------------------+------------------------------------------+		+---------------------+------------------------------------------+
	Example documentation for Action Communities deployed by AS 64497 to
	expose a BGP traffic engineering function which selectively prepends
	the AS_PATH with AS 64497 when propagating the route to the specified
	EBGP neighbor.
	Table 7: Action: Prepend to ASN		Table 7: Action: Prepend to ASN
	4.2.2. Location Based Selective AS_PATH Prepending		The table above shows example documentation for Action Communities
			deployed by AS 64497 to expose a BGP traffic-engineering function
			that selectively prepends the AS_PATH with AS 64497 when propagating
			the route to the specified EBGP neighbor.
			4.2.2. Location-Based Selective AS_PATH Prepending
	AS 64497 could assign a value of 7 to the Function field to designate		AS 64497 could assign a value of 7 to the Function field to designate
	the content of the Parameter field as an ISO 3166-1 numeric country		the content of the Parameter field as an ISO 3166-1 numeric country
	identifier to which the prepending of the AS_PATH with AS 64497 is		identifier to which the prepending of the AS_PATH with AS 64497 is
	requested on propagation of the route to all EBGP neighbors in that		requested on propagation of the route to all EBGP neighbors in that
	region.		region.
	+------------------+------------------------------------------------+		+-----------------+-------------------------------------------------+
	| BGP Large | Description |		| BGP Large | Description |
	| Community | |		| Community | |
	+------------------+------------------------------------------------+		+-----------------+-------------------------------------------------+
	| 64497:7:528 | Prepend once to EBGP neighbors in the |		| 64497:7:528 | Prepend once to EBGP neighbors in the |
	| | Netherlands |		| | Netherlands |
	| 64497:7:392 | Prepend once to EBGP neighbors in Japan |		| 64497:7:392 | Prepend once to EBGP neighbors in Japan |
	| 64497:7:840 | Prepend once to EBGP neighbors in United |		| 64497:7:840 | Prepend once to EBGP neighbors in the United |
	| | States of America |		| | States of America |
	+------------------+------------------------------------------------+		+-----------------+-------------------------------------------------+
	Example documentation for Action Communities deployed by AS 64497 to
	expose a BGP traffic engineering function which selectively prepends
	the AS_PATH with AS 64497 when propagating the route to all EBGP
	neighbors in the geographical region specified in the Parameter
	field.
	Table 8: Action: Prepend in Region		Table 8: Action: Prepend in Region
			The table above shows example documentation for Action Communities
			deployed by AS 64497 to expose a BGP traffic-engineering function
			that selectively prepends the AS_PATH with AS 64497 when propagating
			the route to all EBGP neighbors in the geographical region specified
			in the Parameter field.
	4.3. Manipulation of the LOCAL_PREF Attribute		4.3. Manipulation of the LOCAL_PREF Attribute
	As part of an agreement between AS 64497 and AS 64498, AS 64497 might		As part of an agreement between AS 64497 and AS 64498, AS 64497 might
	expose BGP traffic engineering functions to AS 64498. One such BGP		expose BGP traffic-engineering functions to AS 64498. One such BGP
	traffic engineering function might allow AS 64498 to manipulate the		traffic-engineering function might allow AS 64498 to manipulate the
	value of the LOCAL_PREF attribute of routes learned from AS 64498		value of the LOCAL_PREF attribute of routes learned from AS 64498
	within AS 64497, even though the LOCAL_PREF attribute is non-		within AS 64497, even though the LOCAL_PREF attribute is
	transitive and is not propagated to EBGP neighbors.		non-transitive and is not propagated to EBGP neighbors.
	The LOCAL_PREF value of routes are locally significant within each AS		The LOCAL_PREF value of routes are locally significant within each AS
	and are impossible to list in this document. Instead, the typical		and are impossible to list in this document. Instead, the typical
	LOCAL_PREF values could be classified as a hierarchy and a BGP Large		LOCAL_PREF values could be classified as a hierarchy, and a BGP Large
	Community function exposed allowing an EBGP neighbor to affect the		Community function could be exposed, allowing an EBGP neighbor to
	LOCAL_PREF value within the specified GA. The following example list		affect the LOCAL_PREF value within the specified GA. The following
	defines the classes of routes in the order of descending LOCAL_PREF		example list defines the classes of routes in the order of descending
	value and assigns a function identifier which could be used in the		LOCAL_PREF value and assigns a function identifier that could be used
	Function field of a BGP Large Community.		in the Function field of a BGP Large Community.
	+----------+--------------------------------------------------------+		+----------+--------------------------------------------------------+
	| Function | Preference Class |		| Function | Preference Class |
	+----------+--------------------------------------------------------+		+----------+--------------------------------------------------------+
	| 8 | Normal customer route |		| 8 | Normal customer route |
	| 9 | Backup customer route |		| 9 | Backup customer route |
	| 10 | Peering route |		| 10 | Peering route |
	| 11 | Upstream transit route |		| 11 | Upstream transit route |
	| 12 | Fallback route, to be installed if no other path is |		| 12 | Fallback route, to be installed if no other path is |
	| | available |		| | available |
	skipping to change at page 10, line 35 ¶		skipping to change at page 11, line 35 ¶
	+---------------------+---------------------------------------------+		+---------------------+---------------------------------------------+
	| BGP Large Community | Description |		| BGP Large Community | Description |
	+---------------------+---------------------------------------------+		+---------------------+---------------------------------------------+
	| 64497:9:0 | Assign LOCAL_PREF for a customer backup |		| 64497:9:0 | Assign LOCAL_PREF for a customer backup |
	| | route |		| | route |
	| 64497:10:0 | Assign LOCAL_PREF for a peering route |		| 64497:10:0 | Assign LOCAL_PREF for a peering route |
	| 64497:12:0 | Assign LOCAL_PREF for a fallback route |		| 64497:12:0 | Assign LOCAL_PREF for a fallback route |
	+---------------------+---------------------------------------------+		+---------------------+---------------------------------------------+
	Example documentation for Action Communities deployed by AS 64497 to
	expose a BGP traffic engineering function which allows a BGP neighbor
	to globally manipulate the LOCAL_PREF attribute for the route within
	AS 64497.
	Table 10: Action: Global LOCAL_PREF Manipulation		Table 10: Action: Global LOCAL_PREF Manipulation
	4.3.2. Region Based Manipulation of LOCAL_PREF		The table above shows example documentation for Action Communities
			deployed by AS 64497 to expose a BGP traffic-engineering function
			that allows a BGP neighbor to globally manipulate the LOCAL_PREF
			attribute for the route within AS 64497.
			4.3.2. Region-Based Manipulation of LOCAL_PREF
	AS 64497 could place one of the previously defined Preference		AS 64497 could place one of the previously defined Preference
	Function Identifiers in the Function field and use an UN M.49 numeric		Function Identifiers in the Function field and use a UN M.49 numeric
	region identifier in the Parameter field to designate the		region identifier in the Parameter field to designate the
	geographical region within which the non-default LOCAL_PREF		geographical region within which the non-default LOCAL_PREF
	associated with that function identifier should be applied to the		associated with that function identifier should be applied to the
	route. The value of the LOCAL_PREF attribute should not deviate from		route. The value of the LOCAL_PREF attribute should not deviate from
	the default for that route class in any region not specified by one		the default for that route class in any region not specified by one
	or more of these Action Communities.		or more of these Action Communities.
	+--------------+----------------------------------------------------+		+--------------+----------------------------------------------------+
	| BGP Large | Description |		| BGP Large | Description |
	| Community | |		| Community | |
	skipping to change at page 11, line 20 ¶		skipping to change at page 12, line 20 ¶
	| | customer backup class route on BGP routers in the |		| | customer backup class route on BGP routers in the |
	| | North America region |		| | North America region |
	| 64497:10:5 | Assign the LOCAL_PREF value equivalent to a |		| 64497:10:5 | Assign the LOCAL_PREF value equivalent to a |
	| | peering class route on BGP routers in the South |		| | peering class route on BGP routers in the South |
	| | America region |		| | America region |
	| 64497:12:142 | Assign the LOCAL_PREF value equivalent to a |		| 64497:12:142 | Assign the LOCAL_PREF value equivalent to a |
	| | fallback class route on BGP routers in the Asia |		| | fallback class route on BGP routers in the Asia |
	| | region |		| | region |
	+--------------+----------------------------------------------------+		+--------------+----------------------------------------------------+
	Example documentation for Action Communities deployed by AS 64497 to
	expose a BGP traffic engineering function which allows a BGP neighbor
	to selectively manipulate the LOCAL_PREF attribute within AS 64497 in
	the geographical region specified in the Parameter field.
	Table 11: Action: Regional LOCAL_PREF Manipulation		Table 11: Action: Regional LOCAL_PREF Manipulation
			The table above shows example documentation for Action Communities
			deployed by AS 64497 to expose a BGP traffic-engineering function
			that allows a BGP neighbor to selectively manipulate the LOCAL_PREF
			attribute within AS 64497 in the geographical region specified in the
			Parameter field.
	4.3.3. Note of Caution for LOCAL_PREF Functions		4.3.3. Note of Caution for LOCAL_PREF Functions
	The LOCAL_PREF attribute strongly influences the BGP Decision		The LOCAL_PREF attribute strongly influences the BGP Decision
	Process, which in turn affects the scope of route propagation.		Process, which in turn affects the scope of route propagation.
	Operators should take special care when using Action Communities that		Operators should take special care when using Action Communities that
	decrease the LOCAL_PREF value, and the degree of preference, to a		decrease the LOCAL_PREF value, and the degree of preference, to a
	value below that of another route class. Some of the unintended BGP		value below that of another route class. Some of the unintended BGP
	states that might arise as a result of these traffic engineering		states that might arise as a result of these traffic-engineering
	decisions are described as "BGP Wedgies" in [RFC4264].		decisions are described as "BGP Wedgies" in [RFC4264].
	4.4. Route Server Prefix Distribution Control		4.4. Route Server Prefix Distribution Control
	Route Servers [RFC7947] use BGP to broker network reachability		Route servers [RFC7947] use BGP to broker network reachability
	information among their clients. As not all route server clients may		information among their clients. As not all route server clients may
	wish to interconnect with each other, the route server operator will		wish to interconnect with each other, the route server operator will
	usually implement a mechanism to allow each client to control the		usually implement a mechanism to allow each client to control the
	route server's export routing policy, as described in Section 4.6 of		route server's export routing policy, as described in Section 4.6 of
	[RFC7948]. One widely-used mechanism is a route server specific		[RFC7948]. One widely used mechanism is an adaption of "ASN-Based
	adaption of "ASN Based Selective NO_EXPORT" (Section 4.1.1).		Selective NO_EXPORT" (Section 4.1.1) that is specific to route
			servers.
	An example BGP Large Communities policy which enables client-		An example BGP Large Communities policy that enables client-
	controlled prefix distribution for a route server operating as AS		controlled prefix distribution for a route server operating as AS
	64497, is outlined as follows:		64511 is outlined as follows:
	+-------------------+-----------------------------------------------+		+-------------------+-----------------------------------------------+
	| BGP Large | Description |		| BGP Large | Description |
	| Community | |		| Community | |
	+-------------------+-----------------------------------------------+		+-------------------+-----------------------------------------------+
	| 64497:13:peer-as | Explicitly prevent announcement of route to |		| 64511:0:peer-as | Explicitly prevent announcement of route to |
	| | peer-as |		| | peer-as |
	| 64497:14:peer-as | Explicitly announce route to peer-as |		| 64511:1:peer-as | Explicitly announce route to peer-as |
	| 64497:13:0 | Do not announce route to any peers by default |		| 64511:0:0 | Do not announce route to any peers by default |
	| 64497:14:0 | Announce route to all peers by default |		| 64511:1:0 | Announce route to all peers by default |
	+-------------------+-----------------------------------------------+		+-------------------+-----------------------------------------------+
	Table 12: Action: Route Server Prefix Distribution Control		Table 12: Action: Route Server Prefix Distribution Control
	Multiple BGP Large Community values can be used together to implement		Multiple BGP Large Community values can be used together to implement
	fine-grained route distribution control. For example, route server		fine-grained route distribution control. For example, route server
	client AS 64500 might wish to use a route server for interconnecting		client AS 64500 might wish to use a route server for interconnecting
	to all other clients except AS 64510. In this case, they would label		to all other clients except AS 64509. In this case, they would label
	all their outbound routes to the route server with 64497:14:0 (to		all their outbound routes to the route server with 64511:1:0 (to
	announce to all clients by default) and 64497:13:64510 (to prevent		announce to all clients by default) and 64511:0:64509 (to prevent
	announcement to AS 64510).		announcement to AS 64509).
	Alternatively, route server client AS 64501 may have a selective		Alternatively, route server client AS 64501 may have a selective
	routing policy and may wish to interconnect with only AS 64505 and AS		routing policy and may wish to interconnect with only AS 64505 and AS
	64506. This could be implemented by announcing routes labeled with		64506. This could be implemented by announcing routes labeled with
	64497:13:0 (blocking all distribution by default) and 64497:14:64505,		64511:0:0 (blocking all distribution by default) and 64511:1:64505,
	64497:14:64506 to instruct the route server to force announcement to		64511:1:64506 to instruct the route server to force announcement to
	those two ASNs.		those two ASNs.
	5. Security Considerations		5. Security Considerations
	Operators should note the recommendations in Section 11 of BGP		Operators should note the recommendations in Section 11 of "BGP
	Operations and Security [RFC7454] and handle BGP Large Communities		Operations and Security" [RFC7454] and handle BGP Large Communities
	with their ASN in the Global Administrator field similarly.		with their ASN in the Global Administrator field similarly.
	In particular and in the same respect as BGP Communities [RFC1997],		In particular and in the same respect as BGP Communities [RFC1997],
	operators should be congnizant that any Large Community can be		operators should be cognizant that any Large Community can be carried
	carried in a BGP UPDATE. Operators should recognize that BGP		in a BGP UPDATE. Operators should recognize that BGP neighbors,
	neighbors, particularly customers and customers of customers, may		particularly customers and customers of customers, may utilize
	utilize communities defined by other BGP neighbors of the operator.		communities defined by other BGP neighbors of the operator. They may
	They may wish to send routes with action communities and receive		wish to send routes with Action Communities and receive routes with
	routes with informational communities to or from these other		Informational Communities to or from these other neighbors, and it is
	neighbors and it is beneficial to all to permit this.		beneficial to all to permit this.
	6. IANA Considerations		6. IANA Considerations
	None.		This document does not require any IANA actions.
	7. Acknowledgments
	The authors would like to gratefully acknowledge the insightful
	comments, contributions, critique and support from Adam Chappell,
	Jonathan Stewart, Greg Hankins, Nick Hilliard, Will Hargrave, Randy
	Bush, Shawn Morris, Jay Borkenhagen and Stewart Bryant.
	8. References		7. References
	8.1. Normative References		7.1. Normative References
	[RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities		[RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities
	Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,		Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,
	<http://www.rfc-editor.org/info/rfc1997>.		<http://www.rfc-editor.org/info/rfc1997>.
	[RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations		[RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations
	and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454,		and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454,
	February 2015, <http://www.rfc-editor.org/info/rfc7454>.		February 2015, <http://www.rfc-editor.org/info/rfc7454>.
	[RFC8092] Heitz, J., Ed., Snijders, J., Ed., Patel, K., Bagdonas,		[RFC8092] Heitz, J., Ed., Snijders, J., Ed., Patel, K., Bagdonas,
	I., and N. Hilliard, "BGP Large Communities Attribute",		I., and N. Hilliard, "BGP Large Communities Attribute",
	RFC 8092, DOI 10.17487/RFC8092, February 2017,		RFC 8092, DOI 10.17487/RFC8092, February 2017,
	<http://www.rfc-editor.org/info/rfc8092>.		<http://www.rfc-editor.org/info/rfc8092>.
	8.2. Informative References		7.2. Informative References
	[RFC1998] Chen, E. and T. Bates, "An Application of the BGP		[RFC1998] Chen, E. and T. Bates, "An Application of the BGP
	Community Attribute in Multi-home Routing", RFC 1998,		Community Attribute in Multi-home Routing", RFC 1998,
	DOI 10.17487/RFC1998, August 1996,		DOI 10.17487/RFC1998, August 1996,
	<http://www.rfc-editor.org/info/rfc1998>.		<http://www.rfc-editor.org/info/rfc1998>.
	[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,
	<http://www.rfc-editor.org/info/rfc4264>.		<http://www.rfc-editor.org/info/rfc4264>.
	[RFC7947] Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker,		[RFC7947] Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker,
	"Internet Exchange BGP Route Server", RFC 7947,		"Internet Exchange BGP Route Server", RFC 7947,
	DOI 10.17487/RFC7947, September 2016,		DOI 10.17487/RFC7947, September 2016,
	<http://www.rfc-editor.org/info/rfc7947>.		<http://www.rfc-editor.org/info/rfc7947>.
	[RFC7948] Hilliard, N., Jasinska, E., Raszuk, R., and N. Bakker,		[RFC7948] Hilliard, N., Jasinska, E., Raszuk, R., and N. Bakker,
	"Internet Exchange BGP Route Server Operations", RFC 7948,		"Internet Exchange BGP Route Server Operations", RFC 7948,
	DOI 10.17487/RFC7948, September 2016,		DOI 10.17487/RFC7948, September 2016,
	<http://www.rfc-editor.org/info/rfc7948>.		<http://www.rfc-editor.org/info/rfc7948>.
	8.3. URIs		Acknowledgments
	[1] https://www.nanog.org
	[2] https://nlnog.net
	[3] https://www.iso.org/iso-3166-country-codes.html
	[4] https://unstats.un.org/unsd/methodology/m49/		The authors would like to gratefully acknowledge the insightful
			comments, contributions, critique, and support from Adam Chappell,
			Jonathan Stewart, Greg Hankins, Nick Hilliard, Will Hargrave, Randy
			Bush, Shawn Morris, Jay Borkenhagen, and Stewart Bryant.
	Authors' Addresses		Authors' Addresses
	Job Snijders		Job Snijders
	NTT Communications		NTT Communications
	Theodorus Majofskistraat 100		Theodorus Majofskistraat 100
	Amsterdam 1065 SZ		Amsterdam 1065 SZ
	The Netherlands		The Netherlands
	Email: job@ntt.net		Email: job@ntt.net
	skipping to change at page 14, line 37 ¶		skipping to change at page 15, line 34 ¶
	1111 NW 53rd Drive		1111 NW 53rd Drive
	Portland, OR 97210		Portland, OR 97210
	United States of America		United States of America
	Email: heas@shrubbery.net		Email: heas@shrubbery.net
	Martijn Schmidt		Martijn Schmidt
	i3D.net		i3D.net
	Rivium 1e Straat 1		Rivium 1e Straat 1
	Capelle aan den IJssel 2909 LE		Capelle aan den IJssel 2909 LE
	NL		The Netherlands
	Email: martijnschmidt@i3d.net		Email: martijnschmidt@i3d.net
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