draft-ietf-idr-bgp-dpa-02.txt		draft-ietf-idr-bgp-dpa-03.txt
	INTERNET-DRAFT Enke Chen		INTERNET-DRAFT Enke Chen
	<draft-ietf-idr-bgp-dpa-02.txt> Tony Bates		<draft-ietf-idr-bgp-dpa-03.txt> Tony Bates
	MCI		MCI
	July 1995		November 1995
	Destination Preference Attribute for BGP		Destination Preference Attribute for BGP
	<draft-ietf-idr-bgp-dpa-02.txt>		<draft-ietf-idr-bgp-dpa-03.txt>
	Status of this Memo		Status of this Memo
	This document is an Internet Draft. Internet Drafts are working		This document is an Internet Draft. Internet Drafts are working
	documents of the Internet Engineering Task Force (IETF), its Areas,		documents of the Internet Engineering Task Force (IETF), its Areas,
	and its Working Groups. Note that other groups may also distribute		and its Working Groups. Note that other groups may also distribute
	working documents as Internet Drafts.		working documents as Internet Drafts.
	Internet Drafts are draft documents valid for a maximum of six		Internet Drafts are draft documents valid for a maximum of six
	months. Internet Drafts may be updated, replaced, or obsoleted by		months. Internet Drafts may be updated, replaced, or obsoleted by
	skipping to change at page 2, line 36		skipping to change at page 2, line 36
	value is a four octet non-negative integer.		value is a four octet non-negative integer.
	The DPA attribute has Type Code 11.		The DPA attribute has Type Code 11.
	Route Selection Process		Route Selection Process
	The DPA attributes are considered comparable only if the DPA		The DPA attributes are considered comparable only if the DPA
	attributes are present in all the routes being compared and are set		attributes are present in all the routes being compared and are set
	by the same AS.		by the same AS.
	The comparable DPA attributes shall be used as a selection criteria,		The comparable DPA attributes shall be used as a route selection
	after the "local_pref" attribute is evaluated, and before the		criteria, after the "local_pref" attribute is evaluated, and before
	evaluation of the AS path length and the multi-exit-discriminator		the evaluation of the AS path length and the multi-exit-discriminator
	(MED). Non-comparable DPA attributes shall not be used in the route		(MED) attribute. However, if a route contains both MED and comparable
			DPA attributes from the same neighboring AS, the MED values shall be
			favored over DPA values for route selection.
			Non-comparable DPA attributes shall not be used in the route
	selection process.		selection process.
	The higher the DPA attribute value, the more preferred the route.		The higher the DPA attribute value, the more preferred the route.
	Operation		Operation
	The DPA attribute should not be used as a replacement for MED. MED		The AS that sets this attribute must include its AS number in the
	should still be used when an AS has multiple connections to a single		attribute. A BGP speaker may use the "local_pref" attribute to
	neighboring AS.		select a different path other than the one specified by the DPA
			attribute value. This does not preclude an AS from re-setting this
			attribute. However, coordination with the upstream and/or downstream
			neighbors is strongly recommended.
	The DPA attribute should only be set when needed. The AS that sets		To make sure that the MED attribute and not the DPA attribute is used
	this preference must include its AS number in the attribute. A BGP		in the selection of routes from multiple peers of the same
	speaker may use the "local_pref" attribute to prefer a different path		neighboring AS, the DPA value, if set, must be identical for all
	other than the one specified by the DPA attribute value. This does		peers with the same neighboring AS. It is an operational matter to
	not preclude an AS from re-setting this attribute. However,		ensure the correct setting of the DPA value for multiple peers to the
	coordination with the upstream and/or downstream neighbors is		same neighboring AS.
	strongly recommended.
	Aggregation		Aggregation
	If aggregation is done, the resultant aggregate shall be treated as a		If aggregation is done, the resultant aggregate shall be treated as a
	new NLRI. No DPA attribute shall be derived from more specific NLRIs		new NLRI. No DPA attribute shall be derived from more specific NLRIs
	which formed the aggregate. The resultant aggregate is free to have		which formed the aggregate. The resultant aggregate is free to have
	the DPA attribute set if so desired.		the DPA attribute set if so desired.
	Remarks		Remarks
	skipping to change at page 3, line 44		skipping to change at page 4, line 7
	The DPA path attribute may be used with BGP version 4 and all		The DPA path attribute may be used with BGP version 4 and all
	subsequent versions of BGP unless specifically noted otherwise.		subsequent versions of BGP unless specifically noted otherwise.
	Security Considerations		Security Considerations
	Security considerations are not discussed in this memo.		Security considerations are not discussed in this memo.
	Acknowledgments		Acknowledgments
	The authors would like to thank Yakov Rekhter of Cisco for his		The authors would like to thank Yakov Rekhter of cisco for his
	insightful comments and suggestions.		insightful comments and suggestions. We also acknowledge Ramesh
			Govindan (ISI) and Ravi Chandra (cisco) for their helpful comments.
	References		References
	[1] Rekhter, Y., and Li, T., "A Border Gateway Protocol 4 (BGP-4)",		[1] Rekhter, Y., and Li, T., "A Border Gateway Protocol 4 (BGP-4)",
	RFC1771, March 1995.		RFC1771, March 1995.
	[2] Y. Rekhter, and P. Gross, "Application of the Border Gateway		[2] Y. Rekhter, and P. Gross, "Application of the Border Gateway
	Protocol in the Internet", RFC1772, March 1995.		Protocol in the Internet", RFC1772, March 1995.
	[3] Chen, E., and Bates, T., "Current Practice of Implementing		[3] Chen, E., and Bates, T., "Current Practice of Implementing
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