draft-ietf-grow-large-communities-usage-03.txt		draft-ietf-grow-large-communities-usage-04.txt
	Global Routing Operations J. Snijders		Global Routing Operations J. Snijders
	Internet-Draft J. Heasley		Internet-Draft J. Heasley
	Intended status: Informational NTT		Intended status: Informational NTT
	Expires: September 13, 2017 M. Schmidt		Expires: September 14, 2017 M. Schmidt
	i3D.net		i3D.net
	March 12, 2017		March 13, 2017
	Usage of BGP Large Communities		Use of BGP Large Communities
	draft-ietf-grow-large-communities-usage-03		draft-ietf-grow-large-communities-usage-04
	Abstract		Abstract
	Examples and inspiration for operators for the use of BGP Large		Examples and inspiration for operators to use BGP Large Communities.
	Communities.
	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 http://datatracker.ietf.org/drafts/current/.		Drafts is at http://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 13, 2017.		This Internet-Draft will expire on September 14, 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2017 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://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 13 ¶		skipping to change at page 2, line 13 ¶
	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. The Design Overview . . . . . . . . . . . . . . . . . . . . . 2		2. The Design Overview . . . . . . . . . . . . . . . . . . . . . 2
	2.1. Informational Communities . . . . . . . . . . . . . . . . 4		2.1. Informational Communities . . . . . . . . . . . . . . . . 4
	2.2. Action Communities . . . . . . . . . . . . . . . . . . . 4		2.2. Action Communities . . . . . . . . . . . . . . . . . . . 4
	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 . . . . . . . . . . . 5
	3.1.2. A UN M.49 Region function . . . . . . . . . . . . . . 5		3.1.2. A UN M.49 Region Function . . . . . . . . . . . . . . 5
	3.2. Relation Function . . . . . . . . . . . . . . . . . . . . 6		3.2. Relation Function . . . . . . . . . . . . . . . . . . . . 6
	3.3. Combining Informational Communities . . . . . . . . . . . 6		3.3. Combining Informational Communities . . . . . . . . . . . 6
	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 . . . . . . . . . . . . 7
	4.1.2. Location Based Selective NO_EXPORT . . . . . . . . . 7		4.1.2. Location Based Selective NO_EXPORT . . . . . . . . . 7
	4.2. Selective AS_PATH Prepending . . . . . . . . . . . . . . 8		4.2. Selective AS_PATH Prepending . . . . . . . . . . . . . . 8
	4.2.1. ASN Based Selective AS_PATH Prepending . . . . . . . 8		4.2.1. ASN Based Selective AS_PATH Prepending . . . . . . . 8
	4.2.2. Location Based Selective AS_PATH Prepending . . . . . 9		4.2.2. Location Based Selective AS_PATH Prepending . . . . . 9
	4.3. Manipulation of the LOCAL_PREF attribute . . . . . . . . 9		4.3. Manipulation of the LOCAL_PREF Attribute . . . . . . . . 9
	4.3.1. Global Manipulation of LOCAL_PREF . . . . . . . . . . 10		4.3.1. Global Manipulation of LOCAL_PREF . . . . . . . . . . 10
	4.3.2. Location Based Manipulation of LOCAL_PREF . . . . . . 10		4.3.2. Location Based Manipulation of LOCAL_PREF . . . . . . 10
	4.3.3. Note of Caution for LOCAL_PREF Functions . . . . . . 11		4.3.3. Note of Caution for LOCAL_PREF Functions . . . . . . 11
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 11		4.4. Route Server Prefix Distribution Control . . . . . . . . 11
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11		5. Security Considerations . . . . . . . . . . . . . . . . . . . 12
	7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12		7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
	8.1. Normative References . . . . . . . . . . . . . . . . . . 12		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
	8.2. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 12		8.1. Normative References . . . . . . . . . . . . . . . . . . 13
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12		8.2. Informative References . . . . . . . . . . . . . . . . . 13
			8.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 13
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
	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. This document presents		information between Autonomous Systems (ASs). This document presents
	examples of how operators might utilise BGP Large Communities to		examples of how operators might utilize BGP Large Communities to
	achieve various goals. This document draws from experience of		achieve various goals. This document draws on the experience of
	operational communities such as NANOG [1] and NLNOG [2].		operator communities such as NANOG [1] and NLNOG [2].
	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 Autonomous System (AS) that has		Autonomous System Number (ASN) of the AS that has defined the meaning
	defined the meaning of the remaining two 4-octet fields, known as		of the remaining two 4-octet fields, known as "Local Data Part 1" and
	"Local Data Part 1" and "Local Data Part 2". This document describes		"Local Data Part 2". This document describes an approach where the
	an approach where the "Local Data Part 1" field contains a function		"Local Data Part 1" field contains a function identifier and the
	identifier and the "Local Data Part 2" contains a parameter value.		"Local Data Part 2" contains a parameter value. Using the canonical
			notation this format can be summarized as "ASN:Function:Parameter".
	Using the canonical notation the above 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 usage of fields in BGP Large Communities		A mapping table on the use of fields in BGP Large Communities between
	between [RFC8092] and this document.		[RFC8092] and this document.
	Table 1: Field mapping		Table 1: Field Mapping
	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, the function of a community can be divided into
	two categories:		two categories:
	o Informational Communities		o Informational Communities
	o Action Communities		o Action Communities
	Throughout the document a topology of four Autonomous Systems is used		Throughout the document a topology of four ASs is used to illustrate
	to illustrate the usage of Communities in the following		the use of communities in the following configuration:
	configuration:
	AS 65551		AS 65551
	|		|
	^		^
	|		|
	AS 64497		AS 64497
	/ \		/ \
	^ \		^ \
	/ ^		/ ^
	AS 64498 \		AS 64498 \
	| |		| |
	`<->- AS 64499		`<->- AS 64499
	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
	32-bit 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 products. Operators are		deployment of new features or changes to their routing policy that
	encouraged to publicly publish and maintain documentation of the		perform an action. Operators are encouraged to publicly publish and
	purpose of each BGP Large Community, both informational and action,		maintain documentation on the purpose of each BGP Large Community,
	that they support or are visible in BGP RIBs.		both informational and action, that they support or are visible 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		EBGP neighbor or the intended propagation audience. Informational
	Communities can also assist in providing valuable information for		Communities can also assist in providing valuable information for
	day-to-day network operations such as debugging or capacity planning.		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 which labels the
	routes with the Informational Communities. For example, AS 64497		routes with the Informational Communities. For example, AS 64497
	might add a community with the GA 64497 to a route accepted from an		might add a community with the GA 64497 to a route accepted from an
	IBGP or EBGP neighbor as a means of signaling that it was imported in		IBGP or EBGP neighbor as a means of signaling that it was imported in
	a certain geographical region.		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		downstream networks and the Global Administrator itself, but any AS
	Autonomous System could benefit from receiving these communities.		could benefit from receiving these communities.
	2.2. Action Communities		2.2. Action Communities
	Action Communities are added as a label to request non-default		Action Communities are added as a label to request that a route be
	treatment of a route within an AS. The operator of that AS defines		treated in a particular way within an AS. The operator of the AS
	routing policy which, based upon the communities, adjusts route		defines a routing policy that adjusts path attributes based on the
	attributes such as its propagation characteristics, the LOCAL_PREF		community. For example, the route's propagation characteristics, the
	(local preference), the next-hop, or the number of AS_PATH prepends		LOCAL_PREF (local preference), the next-hop, or the number of AS_PATH
	to be added upon reception or propagation.		prepends to be added when it is received or propagated can be
			changed.
	The Global Administrator field is set to the ASN which has defined		The Global Administrator field is set to the ASN which has defined
	the functionality of that BGP Large Community and is therefore the		the functionality of that BGP Large Community and is the ASN that is
	ASN that is expected to perform the action. For instance, AS 64499		expected to perform the action. For example, AS 64499 might label a
	might label a route with a BGP Large Community containing GA 64497 to		route with a BGP Large Community containing GA 64497 to request that
	request that AS 64497 perform a pre-defined action upon that route.		AS 64497 perform a pre-defined 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 Global
	Administrator itself, but any AS could take action if they chose and		Administrator itself, but any AS could take action if they choose and
	any AS could add an action community with the GA of a non-adjacent		any AS could add an Action Community with the GA of a non-adjacent
	ASN. However, note that an Action Community could also be		ASN. However, note that an Action Community could also be
	informational. Its presence is an indicator that the GA may have		informational. Its presence is an indicator that the GA may have
	performed the action and that an AS in the AS_PATH requested it.		performed the action and that an AS in the AS_PATH requested it.
			Operators are recommended to publish the relative order in which
			Action Communities (both BGP Communities and BGP Large Communities)
			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 thereof.		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 [3] numeric
	country identifier.		country identifier.
	+---------------------+---------------------------------------------+		+---------------------+---------------------------------------------+
	| 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		Example documentation for Informational Communities deployed by AS
	64497 to describe the location where a route was imported using ISO		64497 to describe the location where a route was imported using ISO
	3166-1 numeric identifiers.		3166-1 numeric identifiers.
	Table 2: Information: ISO 3166-1		Table 2: Information: ISO 3166-1
	3.1.2. A 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) [4] for macro
	geographical (continental) regions, geographical sub-regions, or		geographical (continental) regions, geographical sub-regions, or
	selected economic and other groupings.		selected economic and other groupings.
	+---------------------+-------------------------------+		+---------------------+-------------------------------+
	| BGP Large Community | Description |		| BGP Large Community | Description |
	+---------------------+-------------------------------+		+---------------------+-------------------------------+
	skipping to change at page 7, line 42 ¶		skipping to change at page 7, line 42 ¶
	the propagation of routes to the neighboring ASN specified in the		the propagation of routes to the neighboring ASN specified in the
	Parameter field.		Parameter field.
	Table 5: Action: ASN NO_EXPORT		Table 5: Action: ASN NO_EXPORT
	4.1.2. Location Based Selective NO_EXPORT		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 thereby		neighbors from learning that route in another country and making it
	making it available in the country specified by the BGP Large		available in the country specified by the BGP Large Community.
	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 |
	skipping to change at page 8, line 34 ¶		skipping to change at page 8, line 34 ¶
	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 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 upon 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 |
	+---------------------+------------------------------------------+		+---------------------+------------------------------------------+
	skipping to change at page 9, line 10 ¶		skipping to change at page 9, line 10 ¶
	the AS_PATH with AS 64497 when propagating the route to the specified		the AS_PATH with AS 64497 when propagating the route to the specified
	EBGP neighbor.		EBGP neighbor.
	Table 7: Action: Prepend to ASN		Table 7: Action: Prepend to ASN
	4.2.2. Location Based Selective AS_PATH Prepending		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 upon 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 United |
	skipping to change at page 9, line 32 ¶		skipping to change at page 9, line 32 ¶
	+------------------+------------------------------------------------+		+------------------+------------------------------------------------+
	Example documentation for Action Communities deployed by AS 64497 to		Example documentation for Action Communities deployed by AS 64497 to
	expose a BGP traffic engineering function which selectively prepends		expose a BGP traffic engineering function which selectively prepends
	the AS_PATH with AS 64497 when propagating the route to all EBGP		the AS_PATH with AS 64497 when propagating the route to all EBGP
	neighbors in the geographical region specified in the Parameter		neighbors in the geographical region specified in the Parameter
	field.		field.
	Table 8: Action: Prepend in Region		Table 8: Action: Prepend in Region
	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 non-
	transitive and therefore is not propagated to EBGP neighbors.		transitive and is not propagated to EBGP neighbors.
	The LOCAL_PREF value of routes are locally significant within each		The LOCAL_PREF value of routes are locally significant within each AS
	Autonomous System and therefore are impossible to list in this		and are impossible to list in this document. Instead, the typical
	document. Instead, the typical LOCAL_PREF values could be classified		LOCAL_PREF values could be classified as a hierarchy and a BGP Large
	as a hierarchy and a BGP Large Community function exposed allowing an		Community function exposed allowing an EBGP neighbor to affect the
	EBGP neighbor to affect the LOCAL_PREF value within the specified GA.		LOCAL_PREF value within the specified GA. The following example list
	The following non-exhaustive list defines the classes of routes in		defines the classes of routes in the order of descending LOCAL_PREF
	the order of descending LOCAL_PREF value and assigns a function		value and assigns a function identifier which could be used in the
	identifier which could be used in the Function field of a BGP Large		Function field of a BGP Large Community.
	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 |
	+----------+--------------------------------------------------------+		+----------+--------------------------------------------------------+
	Table 9: Action: Preference Function Identifiers		Table 9: Action: Preference Function Identifiers
	4.3.1. Global Manipulation of LOCAL_PREF		4.3.1. Global 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 set the value 0 in the		Function Identifiers in the Function field and set the value 0 in the
	Parameter field to designate that the LOCAL_PREF associated with that		Parameter field to designate that the LOCAL_PREF associated with that
	function identifier should be applied for that route throughout the		function identifier should be applied for that route throughout the
	whole Autonomous System.		whole AS.
	+---------------------+---------------------------------------------+		+---------------------+---------------------------------------------+
	| 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 |
	+---------------------+---------------------------------------------+		+---------------------+---------------------------------------------+
	skipping to change at page 11, line 28 ¶		skipping to change at page 11, line 28 ¶
	expose a BGP traffic engineering function which allows a BGP neighbor		expose a BGP traffic engineering function which allows a BGP neighbor
	to selectively manipulate the LOCAL_PREF attribute within AS 64497 in		to selectively manipulate the LOCAL_PREF attribute within AS 64497 in
	the geographical region specified in the Parameter field.		the geographical region specified in the Parameter field.
	Table 11: Action: Regional LOCAL_PREF Manipulation		Table 11: Action: Regional LOCAL_PREF Manipulation
	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.
	Therefore, Operators should take special care when using Action		Operators should take special care when using Action Communities that
	Communities that decrease the LOCAL_PREF value, and therefore the		decrease the LOCAL_PREF value, and the degree of preference, to a
	degree of preference, to a value below that of another route class.		value below that of another route class. Some of the unintended BGP
	Some of the unintended BGP states that might arise as a result of		states that might arise as a result of these traffic engineering
	these traffic engineering decisions are described as "BGP Wedgies" in		decisions are described as "BGP Wedgies" in [RFC4264].
	[RFC4264].
			4.4. Route Server Prefix Distribution Control
			Route Servers [RFC7947] use BGP to broker network reachability
			information among their clients. As not all route server clients may
			wish to interconnect with each other, the route server operator will
			usually implement a mechanism to allow each client to control the
			route server's export routing policy, as described in Section 4.6 of
			[RFC7948]. One widely-used mechanism is a route server specific
			adaption of "ASN Based Selective NO_EXPORT" (Section 4.1.1).
			An example BGP Large Communities policy which enables client-
			controlled prefix distribution for a route server operating as AS
			64497, is outlined as follows:
			+-------------------+-----------------------------------------------+
			| BGP Large | Description |
			| Community | |
			+-------------------+-----------------------------------------------+
			| 64497:0:peer-as | Explicitly prevent announcement of route to |
			| | peer-as |
			| 64497:1:peer-as | Explicitly announce route to peer-as |
			| 64497:0:0 | Do not announce route to any peers by default |
			| 64497:1:0 | Announce route to all peers by default |
			+-------------------+-----------------------------------------------+
			Table 12: Action: Route Server Prefix Distribution Control
			Multiple BGP Large Community values can be used together to implement
			fine-grained route distribution control. For example, route server
			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
			all their outbound routes to the route server with 64497:1:0 (to
			announce to all clients by default) and 64497:1:64510 (to prevent
			announcement to AS 64510).
			Alternatively, route server client AS 64501 may have a selective
			routing policy and may wish to interconnect with only AS 64505 and AS
			64506. This could be implemented by announcing routes labeled with
			64497:0:0 (blocking all distribution by default) and 64497:1:64505,
			64497:1:64506 to instruct the route server to force announcement to
			those two ASNs.
	5. Security Considerations		5. Security Considerations
	Network operators should note the recommendations in Section 11 of		Operators should note the recommendations in Section 11 of BGP
	BGP Operations and Security [RFC7454].		Operations and Security [RFC7454].
	6. IANA Considerations		6. IANA Considerations
	None.		None.
	7. Acknowledgments		7. Acknowledgments
	The authors would like to gratefully acknowledge the insightful		The authors would like to gratefully acknowledge the insightful
	comments, contributions, critique and support from Adam Chappell,		comments, contributions, critique and support from Adam Chappell,
	Jonathan Stewart, and Will Hargrave.		Jonathan Stewart, Greg Hankins, Nick Hilliard, Will Hargrave, and
			Randy Bush.
	8. References		8. References
	8.1. Normative References		8.1. 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>.
	[RFC4264] Griffin, T. and G. Huston, "BGP Wedgies", RFC 4264,
	DOI 10.17487/RFC4264, November 2005,
	<http://www.rfc-editor.org/info/rfc4264>.
	[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. URIs		8.2. Informative References
	[1] http://nanog.net		[RFC4264] Griffin, T. and G. Huston, "BGP Wedgies", RFC 4264,
			DOI 10.17487/RFC4264, November 2005,
			<http://www.rfc-editor.org/info/rfc4264>.
	[2] http://nlnog.net		[RFC7947] Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker,
			"Internet Exchange BGP Route Server", RFC 7947,
			DOI 10.17487/RFC7947, September 2016,
			<http://www.rfc-editor.org/info/rfc7947>.
			[RFC7948] Hilliard, N., Jasinska, E., Raszuk, R., and N. Bakker,
			"Internet Exchange BGP Route Server Operations", RFC 7948,
			DOI 10.17487/RFC7948, September 2016,
			<http://www.rfc-editor.org/info/rfc7948>.
			8.3. URIs
			[1] https://www.nanog.org
			[2] https://nlnog.net
	[3] https://www.iso.org/iso-3166-country-codes.html		[3] https://www.iso.org/iso-3166-country-codes.html
	[4] https://unstats.un.org/unsd/methodology/m49/		[4] https://unstats.un.org/unsd/methodology/m49/
	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
	John Heasley		John Heasley
	NTT Communications		NTT Communications
	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
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