draft-ietf-grow-bgp-med-considerations-02.txt		draft-ietf-grow-bgp-med-considerations-03.txt
	INTERNET-DRAFT Danny McPherson		INTERNET-DRAFT Danny McPherson
	Arbor Networks, Inc.		Arbor Networks, Inc.
	Vijay Gill		Vijay Gill
	AOL		AOL
	Category Informational		Category Informational
	Expires: January 2005 July 2004		Expires: September 2005 March 2005
	BGP MED Considerations		BGP MED Considerations
	<draft-ietf-grow-bgp-med-considerations-02.txt>		<draft-ietf-grow-bgp-med-considerations-03.txt>
	Status of this Document		Status of this Memo
	This document is an Internet-Draft and is in full conformance with		Status of this Memo
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	The key words "MUST"", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		This Internet-Draft will expire on August 28, 2005.
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC 2119].
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	and should be addressed to the author(s).
	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2004). All Rights Reserved.		Copyright (C) The Internet Society (2005). All Rights Reserved.
	Abstract		Abstract
	The BGP MED attribute provides a mechanism for BGP speakers to convey		The BGP MED attribute provides a mechanism for BGP speakers to convey
	to an adjacent AS the optimal entry point into the local AS. While		to an adjacent AS the optimal entry point into the local AS. While
	BGP MEDs function correctly in many scenarios, there are a number of		BGP MEDs function correctly in many scenarios, there are a number of
	issues which may arise when utilizing MEDs in dynamic or complex		issues which may arise when utilizing MEDs in dynamic or complex
	topologies.		topologies.
	This document discusses implementation and deployment considerations		This document discusses implementation and deployment considerations
	regarding BGP MEDs and provides information which implementors and		regarding BGP MEDs and provides information which implementors and
	network operators should be familiar with.		network operators should be familiar with.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
	1.1. About the MULTI_EXIT_DISC (MED) Attribute . . . . . . . . . 4		1.1. About the MULTI_EXIT_DISC (MED) Attribute . . . . . . . . . 4
	1.2. MEDs and Potatoes . . . . . . . . . . . . . . . . . . . . . 5		1.2. MEDs and Potatos. . . . . . . . . . . . . . . . . . . . . . 5
	2. Implementation and Protocol Considerations . . . . . . . . . . 6		2. Implementation and Protocol Considerations . . . . . . . . . . 6
	2.1. MULTI_EXIT_DISC is a Optional Non-Transitive		2.1. MULTI_EXIT_DISC is a Optional Non-Transitive
	Attribute. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7		Attribute. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
	2.2. MED Values and Preferences. . . . . . . . . . . . . . . . . 7		2.2. MED Values and Preferences. . . . . . . . . . . . . . . . . 7
	2.3. Comparing MEDs Between Different Autonomous		2.3. Comparing MEDs Between Different Autonomous
	Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8		Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
	2.4. MEDs, Route Reflection and AS Confederations		2.4. MEDs, Route Reflection and AS Confederations
	for BGP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8		for BGP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
	2.5. Route Flap Damping and MED Churn. . . . . . . . . . . . . . 9		2.5. Route Flap Damping and MED Churn. . . . . . . . . . . . . . 9
	2.6. Effects of MEDs on Update Packing Efficiency. . . . . . . . 9		2.6. Effects of MEDs on Update Packing Efficiency. . . . . . . . 9
	2.7. Temporal Route Selection. . . . . . . . . . . . . . . . . . 10		2.7. Temporal Route Selection. . . . . . . . . . . . . . . . . . 10
	3. Deployment Considerations. . . . . . . . . . . . . . . . . . . 10		3. Deployment Considerations. . . . . . . . . . . . . . . . . . . 10
	3.1. Comparing MEDs Between Different Autonomous		3.1. Comparing MEDs Between Different Autonomous
	Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11		Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
	3.2. Effects of Aggregation on MEDs` . . . . . . . . . . . . . . 11		3.2. Effects of Aggregation on MEDs` . . . . . . . . . . . . . . 11
	4. Security Considerations. . . . . . . . . . . . . . . . . . . . 12		4. Security Considerations. . . . . . . . . . . . . . . . . . . . 12
	4.1. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 12		4.1. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 12
	5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13		5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
	6. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 13		5.1. Normative References. . . . . . . . . . . . . . . . . . . . 14
	7. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 13		5.2. Informative References. . . . . . . . . . . . . . . . . . . 15
			6. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 15
	1. Introduction		1. Introduction
	The BGP MED attribute provides a mechanism for BGP speakers to convey		The BGP MED attribute provides a mechanism for BGP speakers to convey
	to an adjacent AS the optimal entry point into the local AS. While		to an adjacent AS the optimal entry point into the local AS. While
	BGP MEDs function correctly in many scenarios, there are a number of		BGP MEDs function correctly in many scenarios, there are a number of
	issues which may arise when utilizing MEDs in dynamic or complex		issues which may arise when utilizing MEDs in dynamic or complex
	topologies.		topologies.
	This document discusses implementation and deployment considerations		This document discusses implementation and deployment considerations
	regarding BGP MEDs and provides information which implementors and		regarding BGP MEDs and provides information which implementors and
	network operators should be familiar with.		network operators should be familiar with.
	1.1. About the MULTI_EXIT_DISC (MED) Attribute		1.1. About the MULTI_EXIT_DISC (MED) Attribute
	The BGP MUTLI_EXIT_DISC (MED) attribute, formerly known as the		The BGP MULTI_EXIT_DISC (MED) attribute, formerly known as the
	INTER_AS_METRIC, is currently defined in section 5.1.4 of [BGP4], as		INTER_AS_METRIC, is currently defined in section 5.1.4 of [BGP4], as
	follows:		follows:
	MULTI_EXIT_DISC is an optional non-transitive attribute which is		The MULTI_EXIT_DISC is an optional non-transitive attribute which
	intended to be used on external (inter-AS) links to discriminate		is intended to be used on external (inter-AS) links to discriminate
	among multiple exit or entry points to the same neighboring AS.		among multiple exit or entry points to the same neighboring AS.
	The MULTI_EXIT_DISC attribute is a four octet unsigned number which		The value of the MULTI_EXIT_DISC attribute is a four octet unsigned
	is called a metric. All other factors being equal, the exit point		number which is called a metric. All other factors being equal, the
	with lower metric SHOULD be preferred. If received over EBGP, the		exit point with lower metric SHOULD be preferred. If received over
	MULTI_EXIT_DISC attribute MAY be propagated over IBGP to other BGP		EBGP, the MULTI_EXIT_DISC attribute MAY be propagated over IBGP to
	speakers within the same AS. An MED attribute received from a		other BGP speakers within the same AS (see also 9.1.2.2). The
	neighboring AS MUST NOT be propagated to other neighboring		MULTI_EXIT_DISC attribute received from a neighboring AS MUST NOT
	autonomous systems.		be propagated to other neighboring ASs.
	A BGP speaker MUST IMPLEMENT a mechanism based on local		A BGP speaker MUST implement a mechanism based on local
	configuration which allows the MULTI_EXIT_DISC attribute to be		configuration which allows the MULTI_EXIT_DISC attribute to be
	removed from a route. This MAY be done prior to determining the		removed from a route. If a BGP speaker is configured to remove the
	degree of preference of the route and performing route selection		MULTI_EXIT_DISC attribute from a route, then this removal MUST be
	(decision process phases 1 and 2).		done prior to determining the degree of preference of the route and
			performing route selection (Decision Process phases 1 and 2).
	An implementation MAY also (based on local configuration) alter the		An implementation MAY also (based on local configuration) alter the
	value of the MULTI_EXIT_DISC attribute received over EBGP. This		value of the MULTI_EXIT_DISC attribute received over EBGP. If a
	MAY be done prior to determining the degree of preference of the		BGP speaker is configured to alter the value of the MULTI_EXIT_DISC
	route and performing route selection (decision process phases 1 and		attribute received over EBGP, then altering the value MUST be done
	2).		prior to determining the degree of preference of the route and
			performing route selection (Decision Process phases 1 and 2). See
			Section 9.1.2.2 of BGP4] for necessary restrictions on this.
	Section 9.1.2.2 (c) of [BGP4] defines the following route selection		Section 9.1.2.2 (c) of [BGP4] defines the following route selection
	criteria regarding MEDs:		criteria regarding MEDs:
	Remove from consideration routes with less-preferred		c) Remove from consideration routes with less-preferred
	MULTI_EXIT_DISC attributes. MULTI_EXIT_DISC is only comparable		MULTI_EXIT_DISC attributes. MULTI_EXIT_DISC is only comparable
	between routes learned from the same neighboring AS (the		between routes learned from the same neighboring AS (the neighbor-
	neighboring AS is determined from the AS_PATH attribute). Routes		ing AS is determined from the AS_PATH attribute). Routes which do
	which do not have the MULTI_EXIT_DISC attribute are considered to		not have the MULTI_EXIT_DISC attribute are considered to have the
	have the lowest possible MULTI_EXIT_DISC value.		lowest possible MULTI_EXIT_DISC value.
	This is also described in the following procedure:		This is also described in the following procedure:
	for m = all routes still under consideration		for m = all routes still under consideration
	for n = all routes still under consideration		for n = all routes still under consideration
	if (neighborAS(m) == neighborAS(n)) and (MED(n) < MED(m))		if (neighborAS(m) == neighborAS(n)) and (MED(n) < MED(m))
	remove route m from consideration		remove route m from consideration
	In the pseudo-code above, MED(n) is a function which returns the		In the pseudo-code above, MED(n) is a function which returns the
	value of route n's MULTI_EXIT_DISC attribute. If route n has no		value of route n's MULTI_EXIT_DISC attribute. If route n has no
	MULTI_EXIT_DISC attribute, the function returns the lowest possible		MULTI_EXIT_DISC attribute, the function returns the lowest possi-
	MULTI_EXIT_DISC value, i.e. 0.		ble MULTI_EXIT_DISC value, i.e. 0.
	If a MULTI_EXIT_DISC attribute is removed before re- advertising a		If a MULTI_EXIT_DISC attribute is removed before re- advertising a
	route into IBGP, then comparison based on the received EBGP		route into IBGP, then comparison based on the received EBGP
	MULTI_EXIT_DISC attribute MAY still be performed. If an		MULTI_EXIT_DISC attribute MAY still be performed. If an
	implementation chooses to remove MULTI_EXIT_DISC, then the optional		implementation chooses to remove MULTI_EXIT_DISC, then the optional
	comparison on MULTI_EXIT_DISC if performed at all MUST be performed		comparison on MULTI_EXIT_DISC if performed at all MUST be performed
	only among EBGP learned routes. The best EBGP learned route may		only among EBGP learned routes. The best EBGP learned route may
	then be compared with IBGP learned routes after the removal of the		then be compared with IBGP learned routes after the removal of the
	MULTI_EXIT_DISC attribute. If MULTI_EXIT_DISC is removed from a		MULTI_EXIT_DISC attribute. If MULTI_EXIT_DISC is removed from a
	subset of EBGP learned routes and the selected "best" EBGP learned		subset of EBGP learned routes and the selected "best" EBGP learned
	route will not have MULTI_EXIT_DISC removed, then the		route will not have MULTI_EXIT_DISC removed, then the
	MULTI_EXIT_DISC must be used in the comparison with IBGP learned		MULTI_EXIT_DISC must be used in the comparison with IBGP learned
	routes. For IBGP learned routes the MULTI_EXIT_DISC MUST be used in		routes. For IBGP learned routes the MULTI_EXIT_DISC MUST be used in
	route comparisons which reach this step in the decision process.		route comparisons which reach this step in the Decision Process.
	Including the MULTI_EXIT_DISC of an EBGP learned route in the		Including the MULTI_EXIT_DISC of an EBGP learned route in the
	comparison with an IBGP learned route, then removing the		comparison with an IBGP learned route, then removing the
	MULTI_EXIT_DISC attribute and advertising the route has been proven		MULTI_EXIT_DISC attribute and advertising the route has been proven
	to cause route loops.		to cause route loops.
	Routes that have different MULTI_EXIT_DISC attribute SHALL NOT be		1.2. MEDs and Potatos
	aggregated.
	1.2. MEDs and Potatoes
	In a situation where traffic flows between a pair of hosts, each		In a situation where traffic flows between a pair of hosts, each
	connected to different transit networks, which are themselves		connected to different transit networks, which are themselves
	interconnected at two or more locations, each transit network has the		interconnected at two or more locations, each transit network has the
	choice of either sending traffic to the closest peering to the		choice of either sending traffic to the closest peering to the
	adjacent transit network or passing traffic to the interconnection		adjacent transit network or passing traffic to the interconnection
	location which advertises the least cost path to the destination		location which advertises the least cost path to the destination
	host.		host.
	The former method is called "hot potato routing" (or closest-exit)		The former method is called "hot potato routing" (or closest-exit)
	skipping to change at page 6, line 38		skipping to change at page 6, line 38
	In some cases a provider may use hot potato routing for some		In some cases a provider may use hot potato routing for some
	destinations for a given peer AS and cold potato routing for others.		destinations for a given peer AS and cold potato routing for others.
	An example of this is the different treatment of commercial and		An example of this is the different treatment of commercial and
	research traffic in the NSFNET in the mid 1990s. Today many		research traffic in the NSFNET in the mid 1990s. Today many
	commercial networks exchange MEDs with customers but not bilateral		commercial networks exchange MEDs with customers but not bilateral
	peers. However, commercial use of MEDs varies widely, from		peers. However, commercial use of MEDs varies widely, from
	ubiquitous use of MEDs to no use of MEDs at all.		ubiquitous use of MEDs to no use of MEDs at all.
	In addition, many deployments of MEDs today are likely behaving		In addition, many deployments of MEDs today are likely behaving
	differently (e.g., resulting is sub-optimal routing) than the network		differently (e.g., resulting is sub-optimal routing) than the network
	operator intended, thereby resulting not in hot or cold potatoes, but		operator intended, thereby resulting not in hot or cold potatos, but
	mashed potatoes! More information on unintended behavior resulting		mashed potatos! More information on unintended behavior resulting
	from MEDs is provided throughout this document.		from MEDs is provided throughout this document.
	2. Implementation and Protocol Considerations		2. Implementation and Protocol Considerations
	There are a number of implementation and protocol peculiarities		There are a number of implementation and protocol peculiarities
	relating to MEDs that have been discovered that may affect network		relating to MEDs that have been discovered that may affect network
	behavior. The following sections provide information on these		behavior. The following sections provide information on these
	issues.		issues.
	2.1. MULTI_EXIT_DISC is a Optional Non-Transitive Attribute		2.1. MULTI_EXIT_DISC is a Optional Non-Transitive Attribute
	skipping to change at page 8, line 40		skipping to change at page 8, line 40
	Given current practices, we see the problem most frequently manifest		Given current practices, we see the problem most frequently manifest
	itself in the context of MED + route reflectors or confederations.		itself in the context of MED + route reflectors or confederations.
	One potential way to avoid this is by configuring inter-Member-AS or		One potential way to avoid this is by configuring inter-Member-AS or
	inter-cluster IGP metrics higher than intra-Member-AS IGP metrics		inter-cluster IGP metrics higher than intra-Member-AS IGP metrics
	and/or using other tie breaking policies to avoid BGP route selection		and/or using other tie breaking policies to avoid BGP route selection
	based on incomparable MEDs. Of course, IGP metric constraints may be		based on incomparable MEDs. Of course, IGP metric constraints may be
	unreasonably onerous for some applications.		unreasonably onerous for some applications.
	Comparing MEDs between differing adjacent autonomous systems (which		Comparing MEDs between differing adjacent autonomous systems (which
	will be discussed in later sections), or not utilizing MEDs at all,		is discussed in other sections), or not utilizing MEDs at all,
	significantly decreases the probability of introducing potential		significantly decreases the probability of introducing potential
	route oscillation conditions into the network.		route oscillation conditions into the network.
	Although perhaps "legal" as far as current specifications are		Although perhaps "legal" as far as current specifications are
	concerned, modifying MED attributes received on any type of IBGP		concerned, modifying MED attributes received on any type of IBGP
	session (e.g., standard IBGP, AS confederations EIBGP, route		session (e.g., standard IBGP, AS confederations EIBGP, route
	reflection, etc..) is NOT recommended.		reflection, etc..) is NOT recommended.
	2.5. Route Flap Damping and MED Churn		2.5. Route Flap Damping and MED Churn
	skipping to change at page 9, line 36		skipping to change at page 9, line 36
	Many implementations don't have a practical problem with IGP		Many implementations don't have a practical problem with IGP
	flapping, they either latch their IGP metric upon first advertisement		flapping, they either latch their IGP metric upon first advertisement
	or they employ some internal suppression mechanism. Some		or they employ some internal suppression mechanism. Some
	implementations regard BGP attribute changes as less significant than		implementations regard BGP attribute changes as less significant than
	route withdrawals and announcements to attempt to mitigate the impact		route withdrawals and announcements to attempt to mitigate the impact
	of this type of event.		of this type of event.
	2.6. Effects of MEDs on Update Packing Efficiency		2.6. Effects of MEDs on Update Packing Efficiency
	Multiple unfeasible routes can be advertised in a single BGP Update		Multiple unfeasible routes can be advertised in a single BGP Update
	message. In addition, one or more feasible routes can be advertised		message. The BGP4 protocol also permits advertisement of multiple
	in a single Update message so long as all prefixes share a common		prefixes with a common set of path attributes to be advertised in a
	attribute set.		single update message, this is commonly referred to as "update
			packing". When possible, update packing is recommended as it
	The BGP4 protocol permits advertisement of multiple prefixes with a		provides a mechanism for more efficient behavior in a number of
	common set of path attributes to be advertised in a single update		areas, to include:
	message, this is commonly referred to as "update packing". When
	possible, update packing is recommended as it provides a mechanism
	for more efficient behavior in a number of areas, to include:
	o Reduction in system overhead due to generation or receipt of		o Reduction in system overhead due to generation or receipt of
	fewer Update messages.		fewer Update messages.
	o Reduction in network overhead as a result of fewer packets and		o Reduction in network overhead as a result of fewer packets and
	lower bandwidth consumption.		lower bandwidth consumption.
	o Allows processing of path attributes and searches for matching		o Allows processing of path attributes and searches for matching
	sets in your AS_PATH database (if you have one) less frequently.		sets in your AS_PATH database (if you have one) less frequently.
	Consistent ordering of the path attributes allows for ease of		Consistent ordering of the path attributes allows for ease of
	skipping to change at page 10, line 36		skipping to change at page 10, line 33
	earlier implementations that cause non-deterministic behavior on		earlier implementations that cause non-deterministic behavior on
	whether the oldest route would truly be selected or not.		whether the oldest route would truly be selected or not.
	The reasoning for this is that "older" paths are presumably more		The reasoning for this is that "older" paths are presumably more
	stable, and thus more preferable. However, temporal behavior in		stable, and thus more preferable. However, temporal behavior in
	route selection results in non-deterministic behavior, and as such,		route selection results in non-deterministic behavior, and as such,
	is often undesirable.		is often undesirable.
	3. Deployment Considerations		3. Deployment Considerations
	Empirical data [MFN/Ixia Monitoring Project] has shown that accepting		It has been discussed that accepting MEDs from other autonomous
	MEDs from other autonomous systems have the potential to cause		systems have the potential to cause traffic flow churns in the
	traffic flow churns in the network. Some implementations only		network. Some implementations only ratchet down the MED and never
	ratchet down the MED and never move it back up to prevent excessive		move it back up to prevent excessive churn.
	churn.
	However, if that session is reset, the MEDs being advertised have the		However, if a session is reset, the MEDs being advertised have the
	potential of changing. If an network is relying on received MEDs to		potential of changing. If an network is relying on received MEDs to
	route traffic properly, the traffic patterns have the potential for		route traffic properly, the traffic patterns have the potential for
	changing dramatically, potentially resulting in congestion on the		changing dramatically, potentially resulting in congestion on the
	network. Essentially, accepting and routing traffic based on MEDs		network. Essentially, accepting and routing traffic based on MEDs
	allows other people to traffic engineer your network. This may or may		allows other people to traffic engineer your network. This may or may
	not be acceptable to you.		not be acceptable to you.
	As previously discussed, many network operators choose to reset MED		As previously discussed, many network operators choose to reset MED
	values on ingress. In addition, many operators explicitly do not		values on ingress. In addition, many operators explicitly do not
	employ MED values of 0 or 2^32-1 in order to avoid inconsistencies		employ MED values of 0 or 2^32-1 in order to avoid inconsistencies
	with implementations and various revisions of the BGP specification.		with implementations and various revisions of the BGP specification.
	3.1. Comparing MEDs Between Different Autonomous Systems		3.1. Comparing MEDs Between Different Autonomous Systems
	Although the MED was meant to only be used when comparing paths		Although the MED was meant to only be used when comparing paths
	received from different external peers in the same AS, many		received from different external peers in the same AS, many
	implementations provide the capability to compare MEDs between		implementations provide the capability to compare MEDs between
	different autonomous systems as well.		different autonomous systems as well. AS operators often use
			LOCAL_PREF to select the external preferences (primary, secondary
			upstreams, peers, customers, etc.), using MED instead of LOCAL_PREF
			would possibility lead to an inconsistent distribution of best routes
			as MED is compared only after the AS_PATH length.
	Though this may seem a fine idea for some configurations, care must		Though this may seem a fine idea for some configurations, care must
	be taken when comparing MEDs between different autonomous systems.		be taken when comparing MEDs between different autonomous systems.
	BGP speakers often derive MED values by obtaining the IGP metric		BGP speakers often derive MED values by obtaining the IGP metric
	associated with reaching a given BGP NEXT_HOP within the local AS.		associated with reaching a given BGP NEXT_HOP within the local AS.
	This allows MEDs to reasonably reflect IGP topologies when		This allows MEDs to reasonably reflect IGP topologies when
	advertising routes to peers. While this is fine when comparing MEDs		advertising routes to peers. While this is fine when comparing MEDs
	between multiple paths learned from a single AS, it can result in		between multiple paths learned from a single AS, it can result in
	potentially "weighted" decisions when comparing MEDs between		potentially "weighted" decisions when comparing MEDs between
	different autonomous systems. This is most typically the case when		different autonomous systems. This is most typically the case when
	skipping to change at page 12, line 19		skipping to change at page 12, line 19
	group was concerned that any metric specified by a remote operator		group was concerned that any metric specified by a remote operator
	would only affect routing in a local AS IF no other preference was		would only affect routing in a local AS IF no other preference was
	specified. A paramount goal of the design of the MED was to ensure		specified. A paramount goal of the design of the MED was to ensure
	that peers could not "shed" or "absorb" traffic for networks that		that peers could not "shed" or "absorb" traffic for networks that
	they advertise. As such, accepting MEDs from peers may in some sense		they advertise. As such, accepting MEDs from peers may in some sense
	increase a network's susceptibility to exploitation by peers.		increase a network's susceptibility to exploitation by peers.
	4.1. Acknowledgments		4.1. Acknowledgments
	Thanks to John Scudder for applying his usual keen eye and		Thanks to John Scudder for applying his usual keen eye and
	constructive insight. Also, thanks to Curtis Villamizar and JR		constructive insight. Also, thanks to Curtis Villamizar, JR Mitchell
	Mitchell.		and Pekka Savola for their valuable feedback.
	Others to be supplied.
	5. References		5. References
			5.1. Normative References
	[RFC 1519] Fuller, V., Li. T., Yu J., and K. Varadhan, "Classless		[RFC 1519] Fuller, V., Li. T., Yu J., and K. Varadhan, "Classless
	Inter-Domain Routing (CIDR): an Address Assignment and		Inter-Domain Routing (CIDR): an Address Assignment and
	Aggregation Strategy", RFC 1519, September 1993.		Aggregation Strategy", RFC 1519, September 1993.
	[RFC 1771] Rekhter, Y., and T. Li, "A Border Gateway Protocol 4		[RFC 1771] Rekhter, Y., and T. Li, "A Border Gateway Protocol 4
	(BGP-4)", RFC 1771, March 1995.		(BGP-4)", RFC 1771, March 1995.
	[RFC 2439] Villamizar, C. and Chandra, R., "BGP Route Flap Damping",
	RFC 2439, November 1998.
	[RFC 2796] Bates, T., Chandra, R., Chen, E., "BGP Route Reflection		[RFC 2796] Bates, T., Chandra, R., Chen, E., "BGP Route Reflection
	- An Alternative to Full Mesh IBGP", RFC 2796, April		- An Alternative to Full Mesh IBGP", RFC 2796, April
	2000.		2000.
	[RFC 3065] Traina, P., McPherson, D., Scudder, J.. "Autonomous System		[RFC 3065] Traina, P., McPherson, D., Scudder, J.. "Autonomous System
	Confederations for BGP", RFC 3065, February 2001.		Confederations for BGP", RFC 3065, February 2001.
	[RFC 3345] McPherson, D., Gill, V., Walton, D., and Retana, A, "BGP
	Persistent Route Oscillation Condition", RFC 3345,
	August 2002.
	[BGP4] Rekhter, Y., T. Li., and Hares. S, Editors, "A Border		[BGP4] Rekhter, Y., T. Li., and Hares. S, Editors, "A Border
	Gateway Protocol 4 (BGP-4)", BGP Draft, Work in Progress.		Gateway Protocol 4 (BGP-4)", BGP Draft, Work in Progress.
	[MFN/Ixia Monitoring Project] Vijay to Provide Pointer.		5.2. Informative References
			[RFC 2439] Villamizar, C. and Chandra, R., "BGP Route Flap Damping",
			RFC 2439, November 1998.
			[RFC 3345] McPherson, D., Gill, V., Walton, D., and Retana, A, "BGP
			Persistent Route Oscillation Condition", RFC 3345,
			August 2002.
	6. Authors' Addresses		6. Authors' Addresses
	Danny McPherson		Danny McPherson
	Arbor Networks		Arbor Networks
	Email: danny@arbor.net		Email: danny@arbor.net
	Vijay Gill		Vijay Gill
	AOL		AOL
	Email: VijayGill9@aol.com		Email: VijayGill9@aol.com
	7. Full Copyright Statement		Intellectual Property Statement
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End of changes.
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