draft-ietf-idr-ext-opt-param-04.txt		draft-ietf-idr-ext-opt-param-05.txt
	Internet Engineering Task Force E. Chen		Internet Engineering Task Force E. Chen
	Internet-Draft Cisco Systems		Internet-Draft Cisco Systems
	Intended status: Standards Track J. Scudder		Updates: 4271 (if approved) J. Scudder
	Expires: September 15, 2016 Juniper Networks		Intended status: Standards Track Juniper Networks
	March 14, 2016		Expires: December 30, 2016 June 28, 2016
	Extended Optional Parameters Length for BGP OPEN Message		Extended Optional Parameters Length for BGP OPEN Message
	draft-ietf-idr-ext-opt-param-04		draft-ietf-idr-ext-opt-param-05
	Abstract		Abstract
	The Optional Parameters in the BGP OPEN message as defined in the		The Optional Parameters in the BGP OPEN message as defined in the
	base BGP specification are limited to 255 octets due to a one-octet		base BGP specification are limited to 255 octets due to a one-octet
	length field. BGP Capabilities are carried in this field and may		length field. BGP Capabilities are carried in this field and may
	foreseeably exceed 255 octets in the future, leading to concern about		foreseeably exceed 255 octets in the future, leading to concern about
	this limitation.		this limitation.
	In this document we extend the BGP OPEN length field in a backward-		In this document we update RFC 4271 by extending the BGP OPEN length
	compatible manner. The Parameter Length field of individual Optional		field in a backward-compatible manner. The Parameter Length field of
	Parameters is similarly extended.		individual Optional Parameters is similarly extended.
	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.
	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 September 15, 2016.		This Internet-Draft will expire on December 30, 2016.
	Copyright Notice		Copyright Notice
	Copyright (c) 2016 IETF Trust and the persons identified as the		Copyright (c) 2016 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
	skipping to change at page 2, line 19 ¶		skipping to change at page 2, line 19 ¶
	1. Introduction		1. Introduction
	The Optional Parameters Length field in the BGP OPEN message is		The Optional Parameters Length field in the BGP OPEN message is
	defined in the base BGP specification [RFC4271] as one octet, thus		defined in the base BGP specification [RFC4271] as one octet, thus
	limiting the Optional Parameters field in the OPEN message to 255		limiting the Optional Parameters field in the OPEN message to 255
	octets. As BGP Capabilities [RFC5492] are carried in the Optional		octets. As BGP Capabilities [RFC5492] are carried in the Optional
	Parameters field, and new BGP capabilities continue to be introduced,		Parameters field, and new BGP capabilities continue to be introduced,
	the limitation is becoming a concern for BGP development.		the limitation is becoming a concern for BGP development.
	In this document we extend the BGP OPEN length field in a backward-		In this document we update [RFC4271] by extending the BGP OPEN length
	compatible manner. The Parameter Length field of individual Optional		field in a backward-compatible manner. The Parameter Length field of
	Parameters is similarly extended. This is done by using Optional		individual Optional Parameters is similarly extended. This is done
	Parameters Length of 255 combined with Optional Parameter Type 255 as		by using Optional Parameters Length of 255 combined with Optional
	a distinguished value pair, which indicates that an extended Optional		Parameter Type 255 as a distinguished value pair, which indicates
	Parameters Length field follows. In this case the Parameter Length		that an extended Optional Parameters Length field follows. In this
	field of the Optional Parameters in the BGP OPEN message is also		case the Parameter Length field of the Optional Parameters in the BGP
	extended.		OPEN message is also extended.
	1.1. Requirements Language		1.1. Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	2. Protocol Extensions		2. Protocol Extensions
	This document reserves Optional Parameter Type code 255 as the		This document reserves Optional Parameter Type code 255 as the
	"Extended Length" type code.		"Extended Length" type code.
	In the event that the length of Optional Parameters in the BGP OPEN		In the event that the length of Optional Parameters in the BGP OPEN
	message does not exceed 255, the encodings of the base BGP		message does not exceed 255, the encodings of the base BGP
	specification [RFC4271] MUST be used without alteration.		specification [RFC4271] MUST be used without alteration.
	However, if the length of Optional Parameters is greater than 255,		However, if the length of Optional Parameters is greater than 255, an
	four octets are used for the length field. Each of the first two		extended encoding is used. The (non-extended) length field is set to
	octets is set to 255, and the remaining two octets carry the actual		255, as is the subsequent octet that in the non-extended format would
	length. In addition, the "Parameter Length" field of each Optional		be the first Optional Parameter Type. The subsequent two octets
	Parameter is enlarged to two octets. Other than the larger sizes of		carry the actual length. In addition, the "Parameter Length" field
	the given fields, there is no change to the BGP OPEN message defined		of each Optional Parameter is enlarged to two octets. Other than the
	in [RFC4271].		larger sizes of the given fields, there is no change to the BGP OPEN
			message defined in [RFC4271].
			When receiving an OPEN, a BGP speaker determines the extended
			encoding is in use if the first Optional Parameter Type field is 255.
			In this case, the BGP speaker MUST ignore the non-extended Optional
			Parameters Length field, and must instead rely on the Extended
			Optional Parameters Length field.
	Accordingly, when the length of Optional Parameters in the BGP OPEN		Accordingly, when the length of Optional Parameters in the BGP OPEN
	message is greater than 255, the OPEN message format is modified to		message is greater than 255, the OPEN message format is modified as
	be the following:		follows, repurposing the Optional Parameters Length field as well as
			the first Optional Parameter Type field to indicate the use of the
			extended format:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	| Version |		| Version |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| My Autonomous System |		| My Autonomous System |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Hold Time |		| Hold Time |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| BGP Identifier |		| BGP Identifier |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| 0xFF | 0xFF | Extended Opt. Parm. Length |		|Non-Ext OP Len.|Non-Ext OP Type| Extended Opt. Parm. Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	| Optional Parameters (variable) |		| Optional Parameters (variable) |
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			The non-extended Optional Parameters Length field MUST be set to 255
			on transmission, and MUST be ignored on receipt once the use of the
			extended format is determined.
			The subsequent one-octet field, that in the non-extended format would
			be the first Optional Parameter Type field, MUST be set to 255 on
			transmission. On receipt, a value of 255 for this field is the
			indication that the extended format is in use.
			In this extended encoding, the subsequent two-octet field, termed the
			Extended Optional Parameters Length field, is an unsigned integer
			indicating the total length of the Optional Parameters field in
			octets. If the value of this field is zero, no Optional Parameters
			are present (this would never be expected to happen with the extended
			encoding, however).
	Likewise, in that situation the Optional Parameters encoding is		Likewise, in that situation the Optional Parameters encoding is
	modified to be the following:		modified to be the following:
	0 1 2		0 1 2
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Parm. Type | Parameter Length |		| Parm. Type | Parameter Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ Parameter Value (variable) ~		~ Parameter Value (variable) ~
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			The rules for encoding Optional Parameters are unchanged with respect
			to those given in [RFC4271] other than the extension of the Parameter
			Length field to be a two-octet unsigned integer.
	In parsing an OPEN message, a BGP speaker MUST use the value of the		In parsing an OPEN message, a BGP speaker MUST use the value of the
	one-octet "Optional Parameters Length" field and the value of the		one-octet "Optional Parameters Length" field and the value of the
	octet following it to determine the encoding of the Optional		octet following it to determine the encoding of the Optional
	Parameters length, as well as the size of the "Parameter Length"		Parameters length, as well as the size of the "Parameter Length"
	field of the Optional Parameters. If both values are 255, then the		field of the Optional Parameters. If both values are 255, then the
	four-octet encoding described above is used for the Optional		four-octet encoding described above is used for the Optional
	Parameters length. Otherwise the encoding defined in [RFC4271] is		Parameters length. Otherwise the encoding defined in [RFC4271] is
	used.		used.
	This encoding is chosen for backward compatibility reasons -- a BGP		This encoding is chosen for backward compatibility reasons -- a BGP
	skipping to change at page 4, line 32 ¶		skipping to change at page 5, line 11 ¶
	impossible that the old speaker might detect some other error first,		impossible that the old speaker might detect some other error first,
	such as a length error, depending on the details of the		such as a length error, depending on the details of the
	implementation. In no case would the peering be expected to		implementation. In no case would the peering be expected to
	establish successfully; the only question is which NOTIFICATION would		establish successfully; the only question is which NOTIFICATION would
	be generated.		be generated.
	We note that in any case, such a peering could not succeed, since by		We note that in any case, such a peering could not succeed, since by
	definition the extended length encoding would not be used by the new		definition the extended length encoding would not be used by the new
	speaker unless the basic encoding was insufficient.		speaker unless the basic encoding was insufficient.
			Although the Optional Parameter Type code 255 is used in this
			specification as the indication that the extended encoding is in use,
			it is not a bonafide Optional Parameter Type in the usual sense, and
			MUST NOT be used other than as described above. If encountered as an
			actual Optional Parameter Type code, it MUST be treated as an
			unrecognized Optional Parameter and handled according to [RFC4271]
			Section 6.2.
	4. IANA Considerations		4. IANA Considerations
	IANA is requested to designate BGP OPEN Optional Parameter Type code		IANA is requested to designate BGP OPEN Optional Parameter Type code
	255 as the Extended Length type code.		255 as the Extended Length type code.
	5. Security Considerations		5. Security Considerations
	This extension to BGP does not change the underlying security issues.		This extension to BGP does not change the underlying security issues
			inherent in the existing BGP [RFC4272].
	6. Acknowledgements		6. Acknowledgements
	The authors would like to thank Yakov Rekhter and Srihari Sangli for		The authors would like to thank Yakov Rekhter and Srihari Sangli for
	discussing various options to enlarge the Optional Parameters field.		discussing various options to enlarge the Optional Parameters field.
	We would also like to thank Pradosh Mohapatra, Keyur Patel and Hannes		We would also like to thank Matthew Bocci, Jakob Heitz, Pradosh
	Gredler for their valuable comments.		Mohapatra, Keyur Patel and Hannes Gredler for their valuable
			comments.
	7. References		7. References
	7.1. Normative References		7.1. 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,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<http://www.rfc-editor.org/info/rfc2119>.		<http://www.rfc-editor.org/info/rfc2119>.
	[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A		[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
	Border Gateway Protocol 4 (BGP-4)", RFC 4271,		Border Gateway Protocol 4 (BGP-4)", RFC 4271,
	DOI 10.17487/RFC4271, January 2006,		DOI 10.17487/RFC4271, January 2006,
	<http://www.rfc-editor.org/info/rfc4271>.		<http://www.rfc-editor.org/info/rfc4271>.
	7.2. Informative References		7.2. Informative References
			[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
			RFC 4272, DOI 10.17487/RFC4272, January 2006,
			<http://www.rfc-editor.org/info/rfc4272>.
	[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement		[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
	with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February		with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February
	2009, <http://www.rfc-editor.org/info/rfc5492>.		2009, <http://www.rfc-editor.org/info/rfc5492>.
	Authors' Addresses		Authors' Addresses
	Enke Chen		Enke Chen
	Cisco Systems		Cisco Systems
	Email: enkechen@cisco.com		Email: enkechen@cisco.com
End of changes. 14 change blocks.
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