draft-ietf-idr-aigp-02.txt		draft-ietf-idr-aigp-03.txt
	Network Working Group Pradosh Mohapatra		Network Working Group Pradosh Mohapatra
	Internet Draft Rex Fernando		Internet Draft Rex Fernando
	Intended Status: Proposed Standard Eric C. Rosen		Intended Status: Proposed Standard Eric C. Rosen
	Expires: October 2, 2010 Cisco Systems, Inc.		Expires: October 16, 2010 Cisco Systems, Inc.
	James Uttaro		James Uttaro
	ATT		ATT
	April 2, 2010		April 16, 2010
	The Accumulated IGP Metric Attribute for BGP		The Accumulated IGP Metric Attribute for BGP
	draft-ietf-idr-aigp-02.txt		draft-ietf-idr-aigp-03.txt
	Status of this Memo		Status of this Memo
	This Internet-Draft is submitted to IETF in full conformance with the		This Internet-Draft is submitted to IETF 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), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	other groups may also distribute working documents as Internet-		other groups may also distribute working documents as Internet-
	Drafts.		Drafts.
	skipping to change at page 3, line 17		skipping to change at page 3, line 17
	1 Specification of requirements ......................... 3		1 Specification of requirements ......................... 3
	2 Introduction .......................................... 3		2 Introduction .......................................... 3
	3 AIGP Attribute ........................................ 5		3 AIGP Attribute ........................................ 5
	3.1 Applicability Restrictions and Cautions ............... 6		3.1 Applicability Restrictions and Cautions ............... 6
	3.2 Restrictions on Sending/Receiving ..................... 6		3.2 Restrictions on Sending/Receiving ..................... 6
	3.3 Creating and Modifying the AIGP Attribute ............. 7		3.3 Creating and Modifying the AIGP Attribute ............. 7
	3.3.1 Originating the AIGP Attribute ........................ 7		3.3.1 Originating the AIGP Attribute ........................ 7
	3.3.2 Modifications by the Originator ....................... 7		3.3.2 Modifications by the Originator ....................... 7
	3.3.3 Modifications by a Non-Originator ..................... 8		3.3.3 Modifications by a Non-Originator ..................... 8
	4 Decision Process ...................................... 9		4 Decision Process ...................................... 9
	4.1 When a Route has an AIGP Attribute .................... 9		4.1 When a Route has an AIGP Attribute .................... 10
	4.2 When the Route to the Next Hop has an AIGP attribute .. 10		4.2 When the Route to the Next Hop has an AIGP attribute .. 10
	5 Deployment Considerations ............................. 11		5 Deployment Considerations ............................. 11
	6 IANA Considerations ................................... 11		6 IANA Considerations ................................... 11
	7 Security Considerations ............................... 11		7 Security Considerations ............................... 11
	8 Acknowledgments ....................................... 11		8 Acknowledgments ....................................... 12
	9 Authors' Addresses .................................... 12		9 Authors' Addresses .................................... 12
	10 Normative References .................................. 12		10 Normative References .................................. 13
	11 Informative References ................................ 13		11 Informative References ................................ 13
	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
	skipping to change at page 9, line 41		skipping to change at page 9, line 41
	some IS-IS), or if the meaning of the metrics is different in the		some IS-IS), or if the meaning of the metrics is different in the
	different IGPs (e.g., if the metric represents bandwidth in some IGP		different IGPs (e.g., if the metric represents bandwidth in some IGP
	domains but represents latency in others). These procedures also are		domains but represents latency in others). These procedures also are
	unlikely to give a sensible result if the metric assigned to inter-AS		unlikely to give a sensible result if the metric assigned to inter-AS
	BGP links (on which no IGP is running) or to static routes is not		BGP links (on which no IGP is running) or to static routes is not
	comparable to the IGP metrics. All such cases are outside the scope		comparable to the IGP metrics. All such cases are outside the scope
	of the current document.		of the current document.
	4. Decision Process		4. Decision Process
			Support for the AIGP attribute involves several modifications to the
			tie breaking procedures of the BGP "phase 2" decision described in
			[BGP], section 9.1.2.2. These modifications are described below in
			sections 4.1 and 4.2.
			In some cases, the BGP decision process may install a route without
			executing any tie breaking procedures. This may happen, e.g., if
			only one route to a given prefix has the highest degree of preference
			(as defined in [BGP] section 9.1.1). In this case, the AIGP
			attribute is not considered.
			In other cases, some routes may be eliminated before the tie breaking
			procedures are invoked, e.g., routes with AS-PATH attributes
			indicating a loop, or routes with unresolvable next hops. In these
			cases, the AIGP attributes of the eliminated routes are not
			considered.
	4.1. When a Route has an AIGP Attribute		4.1. When a Route has an AIGP Attribute
	Use of the AIGP attribute involves several modifications to the BGP		Assuming that the BGP decision process invokes the tie breaking
	"phase 2" decision process as described in [BGP], section 9.1.2.2.		procedures, the procedures in this section MUST be executed BEFORE
	The procedures defined in this section MUST be executed BEFORE any of		any of the tie breaking procedures described in [BGP] section 9.1.2.2
	the tie breaking procedures described therein are executed.		are executed.
	If any routes have an AIGP attribute, remove from consideration all		If any routes have an AIGP attribute, remove from consideration all
	routes that do not have an AIGP attribute.		routes that do not have an AIGP attribute.
	If router R is considering route T, where T has an AIGP attribute,		If router R is considering route T, where T has an AIGP attribute,
	- then R must compute the value A, defined as follows: set A to the		- then R must compute the value A, defined as follows: set A to the
	sum of (a) T's AIGP attribute value and (b) the IGP distance from		sum of (a) T's AIGP attribute value and (b) the IGP distance from
	R to T's next hop.		R to T's next hop.
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	8. Acknowledgments		8. Acknowledgments
	The authors would like to thank Rajiv Asati, Clarence Filsfils,		The authors would like to thank Rajiv Asati, Clarence Filsfils,
	Robert Raszuk, Yakov Rekhter, Samir Saad, and John Scudder for their		Robert Raszuk, Yakov Rekhter, Samir Saad, and John Scudder for their
	input.		input.
	9. Authors' Addresses		9. Authors' Addresses
	Rex Fernando		Rex Fernando
	Juniper Networks		Cisco Systems, Inc.
	1194 N. Mathilda Ave		170 Tasman Drive
	Sunnyvale, CA 94089		San Jose, CA 95134
	USA		Email: rex@cisco.com
	Email: rex@juniper.net
	Pradosh Mohapatra		Pradosh Mohapatra
	Cisco Systems, Inc.		Cisco Systems, Inc.
	170 Tasman Drive		170 Tasman Drive
	San Jose, CA 95134		San Jose, CA 95134
	Email: pmohapat@cisco.com		Email: pmohapat@cisco.com
	Eric C. Rosen		Eric C. Rosen
	Cisco Systems, Inc.		Cisco Systems, Inc.
	1414 Massachusetts Avenue		1414 Massachusetts Avenue
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