draft-ietf-idr-aigp-14.txt		draft-ietf-idr-aigp-15.txt
	Network Working Group Pradosh Mohapatra		Network Working Group Pradosh Mohapatra
	Internet Draft Cumulus Networks		Internet Draft Cumulus Networks
	Intended Status: Proposed Standard		Intended Status: Proposed Standard
	Expires: June 16, 2014 Rex Fernando		Expires: July 31, 2014 Rex Fernando
	Eric C. Rosen		Eric C. Rosen
	Cisco Systems, Inc.		Cisco Systems, Inc.
	James Uttaro		James Uttaro
	ATT		ATT
	December 16, 2013		January 31, 2014
	The Accumulated IGP Metric Attribute for BGP		The Accumulated IGP Metric Attribute for BGP
	draft-ietf-idr-aigp-14.txt		draft-ietf-idr-aigp-15.txt
	Abstract		Abstract
	Routing protocols that have been designed to run within a single		Routing protocols that have been designed to run within a single
	administrative domain ("IGPs") generally do so by assigning a metric		administrative domain ("IGPs") generally do so by assigning a metric
	to each link, and then choosing as the installed path between two		to each link, and then choosing as the installed path between two
	nodes the path for which the total distance (sum of the metric of		nodes the path for which the total distance (sum of the metric of
	each link along the path) is minimized. BGP, designed to provide		each link along the path) is minimized. BGP, designed to provide
	routing over a large number of independent administrative domains		routing over a large number of independent administrative domains
	("autonomous systems"), does not make its path selection decisions		("autonomous systems"), does not make its path selection decisions
	skipping to change at page 2, line 18		skipping to change at page 2, line 18
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt.		http://www.ietf.org/ietf/1id-abstracts.txt.
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	Copyright and License Notice		Copyright and License Notice
	Copyright (c) 2013 IETF Trust and the persons identified as the		Copyright (c) 2014 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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 3, line 23		skipping to change at page 3, line 23
	3.4 Creating and Modifying the AIGP Attribute ............. 7		3.4 Creating and Modifying the AIGP Attribute ............. 7
	3.4.1 Originating the AIGP Attribute ........................ 7		3.4.1 Originating the AIGP Attribute ........................ 7
	3.4.2 Modifications by the Originator ....................... 9		3.4.2 Modifications by the Originator ....................... 9
	3.4.3 Modifications by a Non-Originator ..................... 9		3.4.3 Modifications by a Non-Originator ..................... 9
	4 Decision Process ...................................... 11		4 Decision Process ...................................... 11
	4.1 When a Route has an AIGP Attribute .................... 11		4.1 When a Route has an AIGP Attribute .................... 11
	4.2 When the Route to the Next Hop has an AIGP attribute .. 12		4.2 When the Route to the Next Hop has an AIGP attribute .. 12
	5 Deployment Considerations ............................. 13		5 Deployment Considerations ............................. 13
	6 IANA Considerations ................................... 13		6 IANA Considerations ................................... 13
	7 Security Considerations ............................... 13		7 Security Considerations ............................... 13
	8 Acknowledgments ....................................... 13		8 Acknowledgments ....................................... 14
	9 Authors' Addresses .................................... 14		9 Authors' Addresses .................................... 14
	10 Normative References .................................. 14		10 Normative References .................................. 15
	11 Informative References ................................ 14		11 Informative References ................................ 15
	1. Specification of requirements		1. Specification of requirements
	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 [RFC2119].		document are to be interpreted as described in [RFC2119].
	2. Introduction		2. Introduction
	There are many routing protocols that have been designed to run		There are many routing protocols that have been designed to run
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	3.4.1. Originating the AIGP Attribute		3.4.1. Originating the AIGP Attribute
	An implementation that supports the AIGP attribute MUST support a		An implementation that supports the AIGP attribute MUST support a
	configuration item, AIGP_ORIGINATE, that enables or disables its		configuration item, AIGP_ORIGINATE, that enables or disables its
	creation and attachment to routes. The default value of		creation and attachment to routes. The default value of
	AIGP_ORIGINATE MUST be "disabled".		AIGP_ORIGINATE MUST be "disabled".
	A BGP speaker MUST NOT add the AIGP attribute to any route whose path		A BGP speaker MUST NOT add the AIGP attribute to any route whose path
	leads outside the "AIGP administrative domain" to which the BGP		leads outside the "AIGP administrative domain" to which the BGP
	speaker belongs. It may be added only to routes that satisfy one of		speaker belongs. When the AIGP attribute is used, changes in IGP
			routing will directly impact BGP routing. Attaching the AIGP
			attribute to "customer routes", "Internet routes", or other routes
			whose paths lead outside the infrastructure of a particular AIGP
			administrative domain, could result in BGP scaling and/or thrashing
			problems.
			The AIGP attribute may be added only to routes that satisfy one of
	the following conditions:		the following conditions:
	- The route is a static route that is being redistributed into BGP;		- The route is a static route, not leading outside the AIGP
			administrative domain, that is being redistributed into BGP;
	- The route is an IGP route that is being redistributed into BGP;		- The route is an IGP route that is being redistributed into BGP;
	- The route is an IBGP-learned route whose AS_PATH attribute is		- The route is an IBGP-learned route whose AS_PATH attribute is
	empty;		empty;
	- The route is an EBGP-learned route whose AS_PATH contains only		- The route is an EBGP-learned route whose AS_PATH contains only
	ASes that are in the same AIGP Administrative Domain as the BGP		ASes that are in the same AIGP Administrative Domain as the BGP
	speaker.		speaker.
	skipping to change at page 13, line 24		skipping to change at page 13, line 25
	will tend to pass the paths for which the IGP distance from the Route		will tend to pass the paths for which the IGP distance from the Route
	Reflector itself to the next hop is smallest. This may result in a		Reflector itself to the next hop is smallest. This may result in a
	non-optimal choice by the clients.		non-optimal choice by the clients.
	6. IANA Considerations		6. IANA Considerations
	IANA has assigned the codepoint 26 in the "BGP Path Attributes"		IANA has assigned the codepoint 26 in the "BGP Path Attributes"
	registry to the AIGP attribute.		registry to the AIGP attribute.
	IANA shall create a registry for "BGP AIGP Attribute Types". The		IANA shall create a registry for "BGP AIGP Attribute Types". The
	type field consists of a single octet, with possible values from 0 to		type field consists of a single octet, with possible values from 1 to
	255. The allocation policy for this field is to be "Standards Action		255. (The value 0 is "reserved".) The allocation policy for this
	with Early Allocation". Type 1 should be defined as "AIGP", and		field is to be "Standards Action". Type 1 should be defined as
	should refer to this document.		"AIGP", and should refer to this document.
	7. Security Considerations		7. Security Considerations
	The spurious introduction, though error or malfeasance, of an AIGP		The spurious introduction, though error or malfeasance, of an AIGP
	attribute, could result in the selection of paths other than those		attribute, could result in the selection of paths other than those
	desired.		desired.
	Improper configuration on both ends of an EBGP connection could		Improper configuration on both ends of an EBGP connection could
	result in an AIGP attribute being passed from one service provider to		result in an AIGP attribute being passed from one service provider to
	another. This would likely result in an unsound selection of paths.		another. This would likely result in an unsound selection of paths.
	8. Acknowledgments		8. Acknowledgments
	The authors would like to thank Waqas Alam, Rajiv Asati, Bruno		The authors would like to thank Waqas Alam, Rajiv Asati, Ron Bonica,
	Decraene, Brian Dickson, Clarence Filsfils, Anoop Kapoor, Pratima		Bruno Decraene, Brian Dickson, Clarence Filsfils, Anoop Kapoor,
	Kini, Sue Hares, Thomas Mangin, Robert Raszuk, Yakov Rekhter, Eric		Pratima Kini, Sue Hares, Thomas Mangin, Robert Raszuk, Yakov Rekhter,
	Rosenberg, Samir Saad, John Scudder, Shyam Sethuram, and Ilya		Eric Rosenberg, Samir Saad, John Scudder, Shyam Sethuram, and Ilya
	Varlashkin for their input.		Varlashkin for their input.
	9. Authors' Addresses		9. Authors' Addresses
	Rex Fernando		Rex Fernando
	Cisco Systems, Inc.		Cisco Systems, Inc.
	170 Tasman Drive		170 Tasman Drive
	San Jose, CA 95134		San Jose, CA 95134
	Email: rex@cisco.com		Email: rex@cisco.com
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