draft-ietf-idr-bgp-confed-00.txt		rfc1965.txt
	Internet Engineering Task Force Paul Traina		Network Working Group P. Traina
	INTERNET DRAFT cisco Systems		Request for Comments: 1965 cisco Systems
	<draft-ietf-idr-bgp-confed-00.txt> March 27, 1996		Category: Experimental June 1996
	Autonomous System Confederations for BGP		Autonomous System Confederations for BGP
	Status of this Memo		Status of this Memo
	This memo provides information for the Internet community. It does
	not specify an Internet standard. Distribution of this memo is
	unlimited.
	This document is an Internet Draft. Internet Drafts are working
	documents of the Internet Engineering Task Force (IETF), its Areas,
	and its Working Groups. Note that other groups may also distribute
	working documents as Internet Drafts.
	Internet Drafts are draft documents valid for a maximum of six
	months. Internet Drafts may be updated, replaced, or obsoleted by
	other documents at any time. It is not appropriate to use Internet
	Drafts as reference material or to cite them other than as a "working
	draft" or "work in progress."
	Please check the I-D abstract listing contained in each Internet		This memo defines an Experimental Protocol for the Internet
	Draft directory to learn the current status of this or any other		community. This memo does not specify an Internet standard of any
	Internet Draft.		kind. Discussion and suggestions for improvement are requested.
			Distribution of this memo is unlimited.
	Abstract		Abstract
	Border Gateway Protocol [1] is an inter-autonomous system routing		Border Gateway Protocol [1] is an inter-autonomous system routing
	protocol designed for TCP/IP networks.		protocol designed for TCP/IP networks.
	This document describes an extension to BGP which may be used to		This document describes an extension to BGP which may be used to
	create a confederation of autonomous systems which is represented as		create a confederation of autonomous systems which is represented as
	one single autonomous system to BGP peers external to the		one single autonomous system to BGP peers external to the
	confederation.		confederation.
	skipping to change at page 4, line 44		skipping to change at page 4, line 21
	Section 5.1.2 of [1] is replaced with the following text.		Section 5.1.2 of [1] is replaced with the following text.
	When a BGP speaker propagates a route which it has learned from		When a BGP speaker propagates a route which it has learned from
	another BGP speaker's UPDATE message, it shall modify the route's		another BGP speaker's UPDATE message, it shall modify the route's
	AS_PATH attribute based on the location of the BGP speaker to which		AS_PATH attribute based on the location of the BGP speaker to which
	the route will be sent:		the route will be sent:
	a) When a given BGP speaker advertises the route to another BGP		a) When a given BGP speaker advertises the route to another BGP
	speaker located in its own autonomous system, the advertising		speaker located in its own autonomous system, the advertising
	speaker shall not modify the AS_PATH attribute associated with the		speaker shall not modify the AS_PATH attribute associated with
	route.		the route.
	b) When a given BGP speaker advertises the route to a BGP speaker		b) When a given BGP speaker advertises the route to a BGP
	located in a neighboring autonomous system that is a member of the		speaker located in a neighboring autonomous system that is a
	local autonomous system confederation, then the advertising		member of the local autonomous system confederation, then the
	speaker shall update the AS_PATH attribute as follows:		advertising speaker shall update the AS_PATH attribute as
			follows:
	1) if the first path segment of the AS_PATH is of type		1) if the first path segment of the AS_PATH is of type
	AS_CONFED_SEQUENCE, the local system shall prepend its own AS		AS_CONFED_SEQUENCE, the local system shall prepend its own AS
	number as the last element of the sequence (put it in the		number as the last element of the sequence (put it in the
	leftmost position).		leftmost position).
	2) if the first path segment of the AS_PATH is not of type		2) if the first path segment of the AS_PATH is not of type
	AS_CONFED_SEQUENCE the local system shall prepend a new path		AS_CONFED_SEQUENCE the local system shall prepend a new path
	segment of type AS_CONFED_SEQUENCE to the AS_PATH, including		segment of type AS_CONFED_SEQUENCE to the AS_PATH, including
	its own confederation identifier in that segment.		its own confederation identifier in that segment.
	c) When a given BGP speaker advertises the route to a BGP speaker		c) When a given BGP speaker advertises the route to a BGP
	located in a neighboring autonomous system that is not a member of		speaker located in a neighboring autonomous system that is not a
	the current routing domain confederation, then the advertising		member of the current routing domain confederation, then the
	speaker shall update the AS_PATH attribute as follows:		advertising speaker shall update the AS_PATH attribute as
			follows:
	1) if the first path segment of the AS_PATH is of type		1) if the first path segment of the AS_PATH is of type
	AS_CONFED_SEQUENCE, that segment and any immediately following		AS_CONFED_SEQUENCE, that segment and any immediately
	segments of the type AS_CONFED_SET are removed from the AS_PATH		following segments of the type AS_CONFED_SET are removed from
	attribute, leaving the sanitized AS_PATH attribute to be		the AS_PATH attribute, leaving the sanitized AS_PATH
	operated on by steps 2, or 3.		attribute to be operated on by steps 2, or 3.
	2) if the first path segment of the remaining AS_PATH is of		2) if the first path segment of the remaining AS_PATH is of
	type AS_SEQUENCE, the local system shall prepend its own		type AS_SEQUENCE, the local system shall prepend its own
	confederation identifier as the last element of the sequence		confederation identifier as the last element of the sequence
	(put it in the leftmost position).		(put it in the leftmost position).
	3) if there are no path segments following the removal of the		3) if there are no path segments following the removal of the
	first AS_CONFED_SET/AS_CONFED_SEQUENCE segments, or if the		first AS_CONFED_SET/AS_CONFED_SEQUENCE segments, or if the
	first path segment of the remaining AS_PATH is of type AS_SET		first path segment of the remaining AS_PATH is of type AS_SET
	the local system shall prepend a new path segment of type		the local system shall prepend a new path segment of type
	skipping to change at page 5, line 47		skipping to change at page 5, line 25
	identifier in that segment.		identifier in that segment.
	When a BGP speaker originates a route:		When a BGP speaker originates a route:
	a) the originating speaker shall include an empty AS_PATH		a) the originating speaker shall include an empty AS_PATH
	attribute in all UPDATE messages sent to BGP speakers located in		attribute in all UPDATE messages sent to BGP speakers located in
	its own autonomous system. (An empty AS_PATH attribute is one		its own autonomous system. (An empty AS_PATH attribute is one
	whose length field contains the value zero).		whose length field contains the value zero).
	b) the originating speaker shall include its own AS number in an		b) the originating speaker shall include its own AS number in an
	AS_CONFED_SEQUENCE segment of the AS_PATH attribute of all UPDATE		AS_CONFED_SEQUENCE segment of the AS_PATH attribute of all
	messages sent to BGP speakers located in neighboring autonomous		UPDATE messages sent to BGP speakers located in neighboring
	systems that are members of the local confederation. (In this		autonomous systems that are members of the local confederation.
	case, the AS number of the originating speaker's member autonomous		(In this case, the AS number of the originating speaker's member
	system number will be the only entry in the AS_PATH attribute).		autonomous system number will be the only entry in the AS_PATH
			attribute).
	c) the originating speaker shall include its own confederation		c) the originating speaker shall include its own confederation
	identifier in a AS_SEQUENCE segment of the AS_PATH attribute of		identifier in a AS_SEQUENCE segment of the AS_PATH attribute of
	all UPDATE messages sent to BGP speakers located in neighboring		all UPDATE messages sent to BGP speakers located in neighboring
	autonomous systems that are not members of the local		autonomous systems that are not members of the local
	confederation. (In this case, the confederation identifier of the		confederation. (In this case, the confederation identifier of
	originating speaker's member confederation will be the only entry		the originating speaker's member confederation will be the only
	in the AS_PATH attribute).		entry in the AS_PATH attribute).
	Common Administration Issues		Common Administration Issues
	It is reasonable for member ASs of a confederation to share a common		It is reasonable for member ASs of a confederation to share a common
	administration and IGP information for the entire confederation.		administration and IGP information for the entire confederation.
	It shall be legal for a BGP speaker to advertise an unchanged		It shall be legal for a BGP speaker to advertise an unchanged
	NEXT_HOP and MULTI_EXIT_DISCRIMINATOR attribute to peers in a		NEXT_HOP and MULTI_EXIT_DISCRIMINATOR attribute to peers in a
	neighboring AS within the same confederation. In addition, the		neighboring AS within the same confederation. In addition, the
	restriction against sending the LOCAL_PREFERENCE attribute to peers		restriction against sending the LOCAL_PREFERENCE attribute to peers
	skipping to change at page 7, line 11		skipping to change at page 6, line 34
	requirement that all BGP speakers participating in a confederation to		requirement that all BGP speakers participating in a confederation to
	allow the use of legacy units provided they have no external (i.e.		allow the use of legacy units provided they have no external (i.e.
	neither inter-AS nor intra-confederation) connectivity.		neither inter-AS nor intra-confederation) connectivity.
	At the time of this writing, an implementation of this extension as		At the time of this writing, an implementation of this extension as
	documented is widely deployed throughout the Internet, therefore the		documented is widely deployed throughout the Internet, therefore the
	value of any change that is incompatible with this document must be		value of any change that is incompatible with this document must be
	weighed against the benefit gained from a relaxation of this		weighed against the benefit gained from a relaxation of this
	restriction.		restriction.
			References
			[1] Rekhter, Y., and T. Li, "A Border Gateway Protocol 4 (BGP-4)",
			RFC 1771, March 1995.
			[2] Kunzinger, C. Editor, "Inter-Domain Routing Protocol", ISO/IEC
			10747, October 1993.
	Security Considerations		Security Considerations
	Security considerations are not discussed in this memo.		Security issues are not discussed in this memo.
	Acknowledgments		Acknowledgments
	Ravi Chandra and Yakov Rekhter reviewed this document and provided		Ravi Chandra and Yakov Rekhter reviewed this document and provided
	constructive and valuable comments.		constructive and valuable comments.
	Author's Address:		Author's Address
	Paul Traina		Paul Traina
	cisco Systems, Inc.		cisco Systems, Inc.
	170 W. Tasman Dr.		170 W. Tasman Dr.
	San Jose, CA 95134		San Jose, CA 95134
	pst@cisco.com
	References
	[1] RFC1771
	Rekhter, Y., and Li, T., "A Border Gateway Protocol 4 (BGP-4)", March
	1995.
	[2] ISO/IEC 10747		EMail: pst@cisco.com
	Kunzinger, C. Editor, "Inter-Domain Routing Protocol", October 1993
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