draft-ietf-idr-bgp-dpa-04.txt		draft-ietf-idr-bgp-dpa-05.txt
	INTERNET-DRAFT Enke Chen		INTERNET-DRAFT Enke Chen
	<draft-ietf-idr-bgp-dpa-04.txt> Tony Bates		<draft-ietf-idr-bgp-dpa-05.txt> Tony Bates
	Expires in six months MCI		Expires September 1996 MCI
	January 1996		March 1996
	Destination Preference Attribute for BGP		Destination Preference Attribute for BGP
	<draft-ietf-idr-bgp-dpa-04.txt>		<draft-ietf-idr-bgp-dpa-05.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 32		skipping to change at page 2, line 32
	This document proposes the DPA path attribute, which is an optional		This document proposes the DPA path attribute, which is an optional
	transitive attribute of fixed length. The attribute is represented		transitive attribute of fixed length. The attribute is represented
	by a pair <AS#, DPA value>. The AS# is a two octet non-negative		by a pair <AS#, DPA value>. The AS# is a two octet non-negative
	integer, which denotes the AS that specifies the preference. The DPA		integer, which denotes the AS that specifies the preference. The DPA
	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 shall be used as a route selection criteria, after		A router may use DPA to influence the degree of preference [1]
	the "LOCAL_PREF" attribute is evaluated, and before the evaluation of		assigned to a route.
	the AS path length and the multi-exit-discriminator (MED) attribute.
	However, if a route contains both MED and DPA attributes from the
	same neighboring AS, the MED values shall be favored over DPA values
	for route selection.
	The higher the DPA attribute value, the more preferred the route.
	A route with missing DPA attribute must be treated as having an DPA		DPA influence on the computation of degree of preference is a local
	attribute with value zero.		matter. In general, a route with a higher DPA indicates a higher
			preference by the originator of the DPA attribute.
	Operation		Operation
	The AS that sets this attribute must include its AS number in the		The AS that sets this attribute must include its AS number in the
	attribute. A BGP speaker may use the "LOCAL_PREF" attribute to		attribute. A BGP speaker may use the "LOCAL_PREF" attribute to
	select a different path other than the one specified by the DPA		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 value. This does not preclude an AS from re-setting this
	attribute. However, coordination with the upstream and/or downstream		attribute. However, coordination with the upstream and/or downstream
	neighbors is strongly recommended.		neighbors is strongly recommended.
	To make sure that the MED attribute and not the DPA attribute is used
	in the selection of routes from multiple peers of the same
	neighboring AS, the DPA value, if set, must be identical for all
	peers with the same neighboring AS. It is an operational matter to
	ensure the correct setting of the DPA value for multiple peers to the
	same neighboring AS.
	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
	It is noted that this new BGP attribute is simple and requires little		It is noted that this new BGP attribute is simple and requires little
	skipping to change at page 4, line 9		skipping to change at page 3, line 47
	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. We also acknowledge Ramesh		insightful comments and suggestions. We also acknowledge Ramesh
	Govindan (ISI) and Ravi Chandra (cisco) for their helpful comments.		Govindan (ISI), Paul Traina (cisco), 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
End of changes.
This html diff was produced by rfcdiff 1.23, available from http://www.levkowetz.com/ietf/tools/rfcdiff/