draft-ietf-idr-link-bandwidth-05.txt		draft-ietf-idr-link-bandwidth-06.txt
	Network Working Group P. Mohapatra		Network Working Group P. Mohapatra
	Internet-Draft R. Fernando		Internet-Draft R. Fernando
	Intended status: Standards Track Cisco Systems		Intended status: Standards Track Cisco Systems
	Expires: May 9, 2013 November 5, 2012		Expires: July 26, 2013 January 22, 2013
	BGP Link Bandwidth Extended Community		BGP Link Bandwidth Extended Community
	draft-ietf-idr-link-bandwidth-05.txt		draft-ietf-idr-link-bandwidth-06.txt
	Abstract		Abstract
	This document describes an application of BGP extended communities		This document describes an application of BGP extended communities
	that allows a router to perform unequal cost load balancing.		that allows a router to perform unequal cost load balancing.
	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.
	skipping to change at page 1, line 31		skipping to change at page 1, line 31
	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 May 9, 2013.		This Internet-Draft will expire on July 26, 2013.
	Copyright Notice		Copyright Notice
	Copyright (c) 2012 IETF Trust and the persons identified as the		Copyright (c) 2013 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 2, line 21		skipping to change at page 2, line 21
	it for publication as an RFC or to translate it into languages other		it for publication as an RFC or to translate it into languages other
	than English.		than English.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3		1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3
	2. Link Bandwidth Extended Community . . . . . . . . . . . . . . . 3		2. Link Bandwidth Extended Community . . . . . . . . . . . . . . . 3
	3. Deployment Considerations . . . . . . . . . . . . . . . . . . . 3		3. Deployment Considerations . . . . . . . . . . . . . . . . . . . 3
	4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4		4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
	6. Security Considerations . . . . . . . . . . . . . . . . . . . . 4		6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
	7. Normative References . . . . . . . . . . . . . . . . . . . . . 4		7. Normative References . . . . . . . . . . . . . . . . . . . . . 5
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5
	1. Introduction		1. Introduction
	When a BGP speaker receives multiple paths from its internal peers,		When a BGP speaker receives multiple paths from its internal peers,
	it could select more than one path to send traffic to. In doing so,		it could select more than one path to send traffic to. In doing so,
	it might be useful to provide the speaker with information that would		it might be useful to provide the speaker with information that would
	help it distribute the traffic based on the bandwidth of the external		help it distribute the traffic based on the bandwidth of the external
	(DMZ) link. This document suggests that the external link bandwidth		(DMZ) link. This document suggests that the external link bandwidth
	be carried in the network using a new extended community [RFC4360] -		be carried in the network using a new extended community [RFC4360] -
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	route is received with link bandwidth extended community and the BGP		route is received with link bandwidth extended community and the BGP
	speaker sets itself as next-hop while announcing that route to other		speaker sets itself as next-hop while announcing that route to other
	peers, the link bandwidth extended community should be removed.		peers, the link bandwidth extended community should be removed.
	The extended community is optional non-transitive. The value of the		The extended community is optional non-transitive. The value of the
	high-order octet of the extended Type Field is 0x40. The value of		high-order octet of the extended Type Field is 0x40. The value of
	the low-order octet of the extended type field for this community is		the low-order octet of the extended type field for this community is
	0x04. The value of the Global Administrator subfield in the Value		0x04. The value of the Global Administrator subfield in the Value
	Field SHOULD represent the Autonomous System of the router that		Field SHOULD represent the Autonomous System of the router that
	attaches the Link Bandwidth Community. If four octet AS numbering		attaches the Link Bandwidth Community. If four octet AS numbering
	scheme is used [RFC4893], AS_TRANS should be used in the Global		scheme is used [RFC6793], AS_TRANS should be used in the Global
	Administrator subfield. The bandwidth of the link is expressed as 4		Administrator subfield. The bandwidth of the link is expressed as 4
	octets in IEEE floating point format, units being bytes (not bits!)		octets in IEEE floating point format, units being bytes (not bits!)
	per second. It is carried in the Local Administrator subfield of the		per second. It is carried in the Local Administrator subfield of the
	Value Field.		Value Field.
	3. Deployment Considerations		3. Deployment Considerations
	The usage of this community is restricted to the cases where BGP		The usage of this community is restricted to the cases where BGP
	multipath can be safely deployed. In other words, the IGP distance		multipath can be safely deployed. If the path between the load
	between the load balancing router and the exit points should be the		sharing router and the exit point is not tunneled, then the IGP
	same. Alternatively, the path between the load sharing router and		distance between the load balancing router and the exit points should
	the exit points could be tunneled. If there are multiple paths to		be the same.
	reach a destination and if only some of them have link bandwidth
	community, the receiver should not perform unequal cost load		If the path between the load sharing router and the exit point is
	balancing based on link bandwidths.		tunneled, then the choice to use this community is a purely local
			matter to the load sharing router.
			In the context of BGP/MPLS VPNs [RFC4364], link bandwidth community
			could be used to support inbound load balancing for multihomed sites,
			as follows. Consider a site that is connected to PE1 and PE2. Both
			PE1 and PE2 would advertise VPN-IP routes associated with the
			destinations within the site. One way to enable other PEs to receive
			all these routes is to require the RD of the routes advertised by PE1
			to be different from the RD of the routes advertised by PE2. The
			VPN-IP routes advertised by PE1 should carry the link bandwidth
			community; likewise for the VPN-IP routes advertised by PE2. The
			bandwidth value carried in the community could be locally determined
			by PE1 and PE2. Alternatively CEs of the site, when advertising IP
			routes to PE1 and PE2, could add the link bandwith community to these
			advertisements, in which case PE1 and PE2, when originating VPN-IP
			routes, would use the bandwidth value from the IP routes they
			received from the CEs to construct the link bandwidth community
			carried by these VPN-IP routes.
			An ingress PE, when sending traffic to destinations within the site,
			can use the bandwidth value carried in the community of the routes
			advertised by PE1 and PE2 to perform load sharing, where some of the
			traffic would go via PE1, while other traffic would go via PE2.
			If there are multiple paths to reach a destination and if only some
			of them have link bandwidth community, the load sharing router should
			not perform unequal cost load balancing based on link bandwidths.
	4. Acknowledgments		4. Acknowledgments
	The authors would like to thank Yakov Rekhter, Srihari Sangli and Dan		The authors would like to thank Yakov Rekhter, Srihari Sangli and Dan
	Tappan for proposing unequal cost load balancing as one possible		Tappan for proposing unequal cost load balancing as one possible
	application of the extended community attribute.		application of the extended community attribute.
	The authors would like to thank Bruno Decraene, Robert Raszuk, Joel		The authors would like to thank Bruno Decraene, Robert Raszuk, Joel
	Halpern, Aleksi Suhonen, and Randy Bush for their useful comments and		Halpern, Aleksi Suhonen, Randy Bush, and John Scudder for their
	discussions.		comments and contributions.
	5. IANA Considerations		5. IANA Considerations
	This document defines a specific application of the two-octet AS		This document defines a specific application of the two-octet AS
	specific extended community. IANA is requested to assign a sub- type		specific extended community. IANA is requested to assign a sub- type
	value of 0x04 for the link bandwidth extended community.		value of 0x04 for the link bandwidth extended community.
	Name Value		Name Value
	---- -----		---- -----
	non-transitive Link Bandwidth Ext. Community 0x4004		non-transitive Link Bandwidth Ext. Community 0x4004
	6. Security Considerations		6. Security Considerations
	There are no additional security risks introduced by this design.		There are no additional security risks introduced by this design.
	7. Normative References		7. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended		[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
	Communities Attribute", RFC 4360, February 2006.		Communities Attribute", RFC 4360, February 2006.
	[RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-octet AS		[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
	Number Space", RFC 4893, May 2007.		Networks (VPNs)", RFC 4364, February 2006.
			[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
			Autonomous System (AS) Number Space", RFC 6793,
			December 2012.
	Authors' Addresses		Authors' Addresses
	Pradosh Mohapatra		Pradosh Mohapatra
	Cisco Systems		Cisco Systems
	170 W. Tasman Drive		170 W. Tasman Drive
	San Jose, CA 95134		San Jose, CA 95134
	USA		USA
	Phone:		Phone:
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