< draft-sweet-uri-zoneid-00.txt		draft-sweet-uri-zoneid-01.txt >
	Internet Engineering Task Force M. Sweet, Ed.		Internet Engineering Task Force M. Sweet, Ed.
	Internet-Draft Apple Inc.		Internet-Draft Apple Inc.
	Intended status: Standards Track B. Carpenter		Intended status: Informational November 22, 2013
	Expires: February 28, 2014 University of Auckland		Expires: May 26, 2014
	S. Cheshire
	Apple Inc.
	R. Hinden
	Check Point Software Technologies, Inc.
	August 27, 2013
	Representing IPv6 Zone Identifiers in Address Literals and Uniform		An IPvFuture Syntax for IPv6 Link-Local Addresses
	Resource Identifiers		draft-sweet-uri-zoneid-01
	draft-sweet-uri-zoneid-00
	Abstract		Abstract
	This document describes how the zone identifier of an IPv6 scoped		This document describes how the zone identifier of an IPv6 scoped
	address, defined as <zone_id> in the IPv6 Scoped Address Architecture		address, defined as <zone_id> in the IPv6 Scoped Address Architecture
	(RFC 4007), can be represented in a literal IPv6 address and in a		(RFC 4007), can be represented in a literal IPv6 address and in a
	Uniform Resource Identifier that includes such a literal address. It		Uniform Resource Identifier that includes such a literal address. It
	updates the URI Generic Syntax specification (RFC 3986) accordingly.		documents a long-standing usage of the IPvFuture extension point
			provided in the Uniform Resource Identifier (URI) syntax
			specification [RFC3986].
	[ Editor's note: This draft adds the IPvFuture format used by CUPS		[ Editor's note: This draft documents the IPvFuture format originally
	since 2005, addresses some misconceptions of how zoneid's are not		defined in [LITERAL-ZONE] and used by CUPS since 2005. A separate,
	useful to HTTP servers, and is intended to replace RFC 6874. ]		incompatible format was defined and published in RFC 6874. ]
	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 February 28, 2014.		This Internet-Draft will expire on May 26, 2014.
	Copyright Notice		Copyright Notice
	Copyright (c) 2013 IETF Trust and the persons identified as the		Copyright (c) 2013 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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3		1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
	2. Specification . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Specification . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Web Browsers . . . . . . . . . . . . . . . . . . . . . . . . 5		3. HTTP Requirements . . . . . . . . . . . . . . . . . . . . . . 4
	4. Security Consideration . . . . . . . . . . . . . . . . . . . 6		4. Security Consideration . . . . . . . . . . . . . . . . . . . 5
	5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7		5. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
	6. References . . . . . . . . . . . . . . . . . . . . . . . . . 7		5.1. Normative References . . . . . . . . . . . . . . . . . . 5
	6.1. Normative References . . . . . . . . . . . . . . . . . . 7		5.2. Informative References . . . . . . . . . . . . . . . . . 6
	6.2. Informative References . . . . . . . . . . . . . . . . . 7		Appendix A. Change History . . . . . . . . . . . . . . . . . . . 6
	Appendix A. Options Considered . . . . . . . . . . . . . . . . . 8		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
	Appendix B. Change History . . . . . . . . . . . . . . . . . . . 9
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
	1. Introduction		1. Introduction
	The Uniform Resource Identifier (URI) syntax specification [RFC3986]		The Uniform Resource Identifier (URI) syntax specification [RFC3986]
	defined how a literal IPv6 address can be represented in the "host"		defines how a literal IPv6 address can be represented in the "host"
	part of a URI. Two months later, the IPv6 Scoped Address		part of a URI. However, it does not define how zone identifiers (see
	Architecture specification [RFC4007] extended the text representation		IPv6 Scoped Address Architecture specification [RFC4007]) are
	of limited-scope IPv6 addresses such that a zone identifier may be		represented, which has lead to the development and deployment of two
	concatenated to a literal address, for purposes described in that		incompatible URI syntax extensions. The first syntax, "A Format for
	specification. Zone identifiers are especially useful in contexts in		IPv6 Scope Zone Identifiers in Literal URIs" [LITERAL-ZONE], was
	which literal addresses are typically used, for example, during fault		originally proposed in 2005 and used the IPvFuture rule that was
	diagnosis, when it may be essential to specify which interface is		defined for future address extensions in URIs. While this draft was
	used for sending to a link-local address. It should be noted that		ultimately never published, the syntax was adopted by the CUPS [CUPS]
	zone identifiers have purely local meaning within the node in which		software in 2005 and is now widely deployed in clients and printers.
	they are defined, often being the same as IPv6 interface names. They		The second syntax, "Representing IPv6 Zone Identifiers in Address
	are completely meaningless for any other node. Today, they are		Literals and Uniform Resource Identifiers" [RFC6874], was published
	meaningful only when attached to addresses with less than global		in February 2013 and incompatibly extends the URI syntax with a new
	scope, but it is possible that other uses might be defined in the		IPv6addrz rule. This document describes the first syntax and
	future.		provides additional implementation guidelines for its use.
	The IPv6 Scoped Address Architecture specification [RFC4007] does not
	specify how zone identifiers are to be represented in URIs.
	Practical experience has shown that this feature is useful, in
	particular when using a web browser for debugging with link-local
	addresses, but because it is undefined, it is not implemented
	consistently in URI parsers or in browsers.
	Some versions of some browsers directly accept the IPv6 Scoped
	Address syntax [RFC4007] for scoped IPv6 addresses embedded in URIs,
	i.e., they have been coded to interpret a "%" sign following the
	literal address as introducing a zone identifier [RFC4007], instead
	of introducing two hexadecimal characters representing some percent-
	encoded octet [RFC3986]. Clearly, interpreting the "%" sign as
	introducing a zone identifier is very convenient for users, although
	it formally breaches the established URI syntax [RFC3986]. This
	document defines an alternative approach that respects and extends
	the rules of URI syntax, and IPv6 literals in general, to be
	consistent.
	Thus, this document updates the URI syntax specification [RFC3986] by
	adding two syntaxes that allow a zone identifier to be included in a
	literal IPv6 address within a URI. The first extends the ABNF
	[RFC5234] syntax to allow for a direct inclusion of the zone ID while
	the second is backwards-compatible with the original syntax defined
	in RFC 3986.
	It should be noted that in contexts other than a user interface, a
	zone identifier is mapped into a numeric zone index or interface
	number. The MIB textual convention InetZoneIndex [RFC4001] and the
	socket interface [RFC3493] define this as a 32-bit unsigned integer.
	The mapping between the human-readable zone identifier string and the
	numeric value is a host-specific function that varies between
	operating systems. The present document is concerned only with the
	human-readable string.
	Several alternative solutions were considered while this document was		[ Editor's note: Would it be appropriate to provide adoption numbers
	developed. Appendix A briefly describes the various options and		here (hundreds of millions of devices)? ]
	their advantages and disadvantages.
	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 "Key words for use in		document are to be interpreted as described in "Key words for use in
	RFCs to Indicate Requirement Levels" [RFC2119].		RFCs to Indicate Requirement Levels" [RFC2119].
	2. Specification		2. Specification
	skipping to change at page 4, line 25 ¶		skipping to change at page 3, line 32 ¶
	be percent-encoded and represented in the form "%25". Thus, the		be percent-encoded and represented in the form "%25". Thus, the
	scoped address fe80::a%en1 would appear in a URI as http://		scoped address fe80::a%en1 would appear in a URI as http://
	[fe80::a%25en1].		[fe80::a%25en1].
	However, since parsers based on the ABNF [RFC5234] in the URI syntax		However, since parsers based on the ABNF [RFC5234] in the URI syntax
	specification [RFC3986] will not allow a URI of that form, an		specification [RFC3986] will not allow a URI of that form, an
	alternate format based on the IPvFuture rule [LITERAL-ZONE] can be		alternate format based on the IPvFuture rule [LITERAL-ZONE] can be
	used where the address is prefixed with "v1." and the "+" character		used where the address is prefixed with "v1." and the "+" character
	is used as the separator between the address and <zone_id>. Thus,		is used as the separator between the address and <zone_id>. Thus,
	the alternate form of the scoped address fe80::a%en1 would appear in		the alternate form of the scoped address fe80::a%en1 would appear in
	a URI as http://[v1.fe80::a+en1]. Note: This format, originally		a URI as http://[v1.fe80::a+en1].
	proposed in 2005, was adopted by CUPS [CUPS] and has subsequently
	become widely implemented for printing.
	[ Editor's note: Would it be appropriate to provide adoption numbers
	here (hundreds of millions of devices)? ]
	A <zone_id> SHOULD contain only ASCII characters classified as		A <zone_id> SHOULD contain only ASCII characters classified as
	"unreserved" for use in URIs [RFC3986]. This excludes characters		"unreserved" for use in URIs [RFC3986]. This excludes characters
	such as "]" or even "%" that would complicate parsing. However, the		such as "]" or even "%" that would complicate parsing. However, the
	syntax described below does allow such characters to be percent-		syntax described below does allow such characters to be percent-
	encoded, for compatibility with existing devices that use them.		encoded, for compatibility with existing devices that use them.
	If an operating system uses any other characters in zone or interface		If an operating system uses any other characters in zone or interface
	identifiers that are not in the "unreserved" character set, they MUST		identifiers that are not in the "unreserved" character set, they MUST
	be represented using percent encoding [RFC3986].		be represented using percent encoding [RFC3986].
	skipping to change at page 5, line 8 ¶		skipping to change at page 4, line 8 ¶
	literal format in ABNF [RFC5234] by the following rule:		literal format in ABNF [RFC5234] by the following rule:
	IP-literal = "[" ( IPv6address / IPvFuture ) "]"		IP-literal = "[" ( IPv6address / IPvFuture ) "]"
	To provide support for a zone identifier, the existing syntax of		To provide support for a zone identifier, the existing syntax of
	IPv6address is retained, and a zone identifier may be added		IPv6address is retained, and a zone identifier may be added
	optionally to any literal address. This syntax allows flexibility		optionally to any literal address. This syntax allows flexibility
	for unknown future uses. The rule quoted above from the previous URI		for unknown future uses. The rule quoted above from the previous URI
	syntax specification [RFC3986] is replaced by three rules:		syntax specification [RFC3986] is replaced by three rules:
	IP-literal = "[" ( IPv6address / IPv6addrz / IPvFuture ) "]"		IP-literal = "[" ( IPv6address / IPvFuture /
			"v1." IPv6address "+" ZoneID ) "]"
	ZoneID = 1*( unreserved / pct-encoded )		ZoneID = 1*( unreserved / pct-encoded )
	IPv6addrz = IPv6address "%25" ZoneID / "v1." IPv6address "+" ZoneID
	This syntax fills the gap that is described at the end of		This syntax fills the gap that is described at the end of
	Section 11.7 of the IPv6 Scoped Address Architecture specification		Section 11.7 of the IPv6 Scoped Address Architecture specification
	[RFC4007].		[RFC4007].
	The established rules for textual representation of IPv6 addresses		The established rules for textual representation of IPv6 addresses
	[RFC5952] SHOULD be applied in producing URIs.		[RFC5952] SHOULD be applied in producing URIs.
	The URI syntax specification [RFC3986] states that URIs have a global		The URI syntax specification [RFC3986] states that URIs have a global
	scope, but that in some cases their interpretation depends on the		scope, but that in some cases their interpretation depends on the
	end-user's context. URIs including a ZoneID are to be interpreted		end-user's context. URIs including a ZoneID are to be interpreted
	only in the context of the host at which they originate, since the		only in the context of the host at which they originate, since the
	ZoneID is of local significance only.		ZoneID is of local significance only.
	The IPv6 Scoped Address Architecture specification [RFC4007] offers		The IPv6 Scoped Address Architecture specification [RFC4007] offers
	guidance on how the ZoneID affects interface/address selection inside		guidance on how the ZoneID affects interface/address selection inside
	the IPv6 stack. Note that the behaviour of an IPv6 stack, if it is		the IPv6 stack. Note that the behaviour of an IPv6 stack, if it is
	passed a non-null zone index for an address other than link-local, is		passed a non-null zone index for an address other than link-local, is
	undefined.		undefined.
	3. Web Browsers		3. HTTP Requirements
	This section discusses how web browsers might handle this syntax
	extension. Unfortunately, there is no formal distinction between the
	syntax allowed in a browser's input dialogue box and the syntax
	allowed in URIs. For this reason, no normative statements are made
	in this section.
	Due to the lack of defined syntax, web browsers have been
	inconsistent in providing for ZoneIDs. Many have no support, but
	there are examples of ad hoc support. For example, some versions of
	Firefox allowed the use of a ZoneID preceded by a bare "%" character,
	but this feature was removed for consistency with established syntax
	[RFC3986]. As another example, some versions of Internet Explorer
	allow use of a ZoneID preceded by a "%" character encoded as "%25",
	still beyond the syntax allowed by the established rules [RFC3986].
	This syntax extension is in fact used internally in the Windows
	operating system and some of its APIs.
	It is desirable for all browsers to recognise a ZoneID preceded by a
	percent-encoded "%". In the spirit of "be liberal with what you
	accept", we also suggest that URI parsers accept bare "%" signs when
	possible (i.e., a "%" not followed by two valid and meaningful
	hexadecimal characters). This would make it possible for a user to
	copy and paste a string such as "fe80::a%en1" from the output of a
	"ping" command and have it work. On the other hand, "%ee1" would
	need to be manually rewritten to "fe80::a%25ee1" to avoid any risk of
	misinterpretation.
	Such bare "%" signs are for user interface convenience, and need to		The Hypertext Transfer Protocol -- HTTP/1.1 [RFC2616] requires the
	be turned into properly encoded characters (where "%25" encodes "%")		client to supply the host and URI used to access the server. While a
	before the URI is used in any protocol or HTML document. And while		ZoneID is only significant to the HTTP client, many HTTP server
	URIs including a ZoneID have no meaning outside the originating node,		solutions, including IPP [RFC2911], generate absolute URIs to server-
	the address values can be used to construct subsequent valid URIs on		resident resources in response to a client's request. If the
	behalf of the originating node. It is therefore highly desirable for		client's ZoneID is not sent to the server, the server will not be
	a browser to retain the ZoneID in any URI included in an HTTP		able to provide absolute URIs that can be directly used by the
	request.		client. However, the server cannot use the provided ZoneID for any
			local address comparisons since the client and server likely have
			different ZoneID's for the same IPv6 link-local address.
	[ Editor's note: Reworded the previous paragraph from RFC 6874 to		HTTP clients SHOULD include the client-specific ZoneID in the HTTP
	indicate a preference for including the ZoneID. ]		Host: header and (if applicable) the HTTP Request-URI.
	The normal diagnostic usage for the ZoneID syntax will cause it to be		HTTP servers MUST support Host: and Request-URI values containing
	entered in the browser's input dialogue box. Thus, URIs including a		client-specific ZoneID's, MUST use the full address (including
	ZoneID are unlikely to be encountered in HTML documents. However, if		ZoneID) when generating absolute URIs for a response to the client,
	they do (for example, in a diagnostic script coded in HTML), it would		and MUST NOT use the ZoneID in any local (server) address
	be appropriate to treat them exactly as above.		comparisons.
	4. Security Consideration		4. Security Consideration
	The security considerations from the URI syntax specification		The security considerations from the URI syntax specification
	[RFC3986] and the IPv6 Scoped Address Architecture specification		[RFC3986] and the IPv6 Scoped Address Architecture specification
	[RFC4007] apply. In particular, this URI format creates a specific		[RFC4007] apply. In particular, this URI format creates a specific
	pathway by which a deceitful zone index might be communicated, as		pathway by which a deceitful zone index might be communicated, as
	mentioned in the final security consideration of the Scoped Address		mentioned in the final security consideration of the Scoped Address
	Architecture specification. It is emphasised that the format is		Architecture specification. It is emphasised that the format is
	intended only for debugging purposes, but of course this intention		intended only for local access purposes, but of course this intention
	does not prevent misuse.		does not prevent misuse.
	To limit this risk, implementations MUST NOT allow use of this format		To limit this risk, implementations MUST NOT allow use of this format
	except for well-defined usages, such as sending to link-local		except for well-defined usages, such as sending to link-local
	addresses under prefix fe80::/10. At the time of writing, this is		addresses under prefix fe80::/10. At the time of writing, this is
	the only well-defined usage known.		the only well-defined usage known.
	An HTTP client, proxy, or other intermediary MUST NOT remove any		5. References
	ZoneID attached to an outgoing URI so that URIs generated by the
	receiving host for the sending host retain the sending host's ZoneID
	information
	[ Editor's note: The previous paragraph has the opposite conformance
	requirement from RFC 6874. ]
	5. Acknowledgements
	The lack of this format was first pointed out by Margaret Wasserman
	some years ago, and more recently by Kerry Lynn. A previous draft
	document by Martin Duerst and Bill Fenner [LITERAL-ZONE] discussed
	this topic but was not finalised.
	Valuable comments and contributions were made by Karl Auer, Carsten
	Bormann, Benoit Claise, Stephen Farrell, Brian Haberman, Ted Hardie,
	Tatuya Jinmei, Yves Lafon, Barry Leiba, Radia Perlman, Tom Petch,
	Tomoyuki Sahara, Juergen Schoenwaelder, Dave Thaler, Martin Thomson,
	and Ole Troan.
	Brian Carpenter was a visitor at the Computer Laboratory, Cambridge
	University during part of this work.
	6. References
	6.1. Normative References		5.1. 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, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
			[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
			Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
			Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
			[RFC2911] Hastings, T., Herriot, R., deBry, R., Isaacson, S., and P.
			Powell, "Internet Printing Protocol/1.1: Model and
			Semantics", RFC 2911, September 2000.
	[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform		[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
	Resource Identifier (URI): Generic Syntax", STD 66, RFC		Resource Identifier (URI): Generic Syntax", STD 66, RFC
	3986, January 2005.		3986, January 2005.
	[RFC4007] Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and		[RFC4007] Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and
	B. Zill, "IPv6 Scoped Address Architecture", RFC 4007,		B. Zill, "IPv6 Scoped Address Architecture", RFC 4007,
	March 2005.		March 2005.
	[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax		[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
	Specifications: ABNF", STD 68, RFC 5234, January 2008.		Specifications: ABNF", STD 68, RFC 5234, January 2008.
	[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6		[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
	Address Text Representation", RFC 5952, August 2010.		Address Text Representation", RFC 5952, August 2010.
	6.2. Informative References		5.2. Informative References
	[CUPS] Sweet, M., "CUPS software", October 2005.		[CUPS] Sweet, M., "CUPS software", October 2005.
	[LITERAL-ZONE]		[LITERAL-ZONE]
	Fenner, B. and M. Duerst, "A Format for IPv6 Scope Zone		Fenner, B. and M. Duerst, "A Format for IPv6 Scope Zone
	Identifiers in Literal URIs", October 2005.		Identifiers in Literal URIs", October 2005.
	[RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.		[RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.
	Stevens, "Basic Socket Interface Extensions for IPv6", RFC		Stevens, "Basic Socket Interface Extensions for IPv6", RFC
	3493, February 2003.		3493, February 2003.
	[RFC4001] Daniele, M., Haberman, B., Routhier, S., and J.		[RFC4001] Daniele, M., Haberman, B., Routhier, S., and J.
	Schoenwaelder, "Textual Conventions for Internet Network		Schoenwaelder, "Textual Conventions for Internet Network
	Addresses", RFC 4001, February 2005.		Addresses", RFC 4001, February 2005.
	Appendix A. Options Considered		[RFC6874] Carpenter, B., Cheshire, S., and R. Hinden, "Representing
			IPv6 Zone Identifiers in Address Literals and Uniform
	The syntax defined above allows a ZoneID to be added to any IPv6		Resource Identifiers", RFC 6874, February 2013.
	address. The 6man WG discussed and rejected an alternative in which
	the existing syntax of IPv6address would be extended by an option to
	add the ZoneID only for the case of link-local addresses. It was
	felt that the solution presented in this document offers more
	flexibility for future uses and is more straightforward to implement.
	The various syntax options considered are now briefly described.
	[ Editor's note: I reversed items 4 and 5 from RFC 6874 and adjusted
	the example to match the alternate syntax used in CUPS. ]
	1. Leave the problem unsolved.
	This would mean that per-interface diagnostics would still have to
	be performed using ping or ping6:
	ping fe80::a%en1
	Advantage: works today.
	Disadvantage: less convenient than using a browser.
	2. Simply use the percent character:
	http://[fe80::a%en1]
	Advantage: allows use of browser; allows cut and paste.
	Disadvantage: invalid syntax under RFC 3986; not acceptable to URI
	community.
	3. Simply use an alternative separator:
	http://[fe80::a-en1]
	Advantage: allows use of browser; simple syntax.
	Disadvantage: Requires all IPv6 address literal parsers and
	generators to be updated in order to allow simple cut and paste;
	inconsistent with existing tools and practice.
	Note: The initial proposal for this choice was to use an
	underscore as the separator, but it was noted that this becomes
	effectively invisible when a user interface automatically
	underlines URLs.
	4. Retain the percent character already specified for introducing
	zone identifiers for IPv6 Scoped Addresses [RFC4007], and then
	percent-encode it when it appears in a URI, according to the
	already-established URI syntax rules [RFC 3986]:
	http://[fe80::a%25en1]
	Advantage: allows use of browser; consistent with general URI
	syntax.
	Disadvantage: somewhat ugly and confusing; doesn't allow simple		Appendix A. Change History
	cut and paste.
	This is the primary format chosen for standardization.		[ RFC Editor: This section to be deleted before RFC publication ]
	5. Simply use the "IPvFuture" syntax left open in RFC 3986:		November 22, 2013 - draft-sweet-uri-zoneid-01
	http://[v1.fe80::a+en1]		o Changed to informative draft to document what CUPS has been using
			since 2005.
	Advantage: allows use of browser, compatible with RFC 3986-based		o Section 1: Rewritten to document the two incompatible syntaxes.
	URI parsers.
	Disadvantage: ugly; doesn't allow simple cut and paste.		o Section 2: Dropped 6874 syntax and added the v1. syntax to the
			main address rule.
	This is the alternate format chosen for standardization.		o Section 3: Changed to HTTP Requirements, explained why this is
			necessary, provided conformance requirements.
	Appendix B. Change History		o Section 4: Cleaned up now that we are no longer obsoleting 6874.
	[ RFC Editor: This section to be deleted before RFC publication ]		o Deleted unused sections/appendices
	August 27, 2013 - draft-sweet-uri-zoneid-00		August 27, 2013 - draft-sweet-uri-zoneid-00
	[ Changes are from published RFC 6874 text ]		[ Changes are from published RFC 6874 text ]
	o Abstract: Added editor's note explaining why we need to update RFC		o Abstract: Added editor's note explaining why we need to update RFC
	6874		6874
	o Section 1: Update to talk about having two formats.		o Section 1: Update to talk about having two formats.
	o Section 2: Provide example and define IPvFuture format as an		o Section 2: Provide example and define IPvFuture format as an
	alternate, RFC 3986-compatible encoding.		alternate, RFC 3986-compatible encoding.
	o Section 3: Reword to encourage browsers to retain the ZoneID as an		o Section 3: Reword to encourage browsers to retain the ZoneID as an
	aid for getting usable server-generated URIs.		aid for getting usable server-generated URIs.
	o Section 4: Change conformance to MUST NOT remove ZoneID.		o Section 4: Change conformance to MUST NOT remove ZoneID.
	o Section 6.2: Add reference to CUPS.		o Section 6.2: Add reference to CUPS.
	o Appendix A: Put the IPvFuture example at the end, make it match		o Appendix A: Put the IPvFuture example at the end, make it match
	the correct IPvFuture format, and note it at the alternate syntax.		the correct IPvFuture format, and note it at the alternate syntax.
	Authors' Addresses		Author's Address
	Michael Sweet (editor)		Michael Sweet (editor)
	Apple Inc.		Apple Inc.
	1 Infinite Loop		1 Infinite Loop
	Cupertino, California 95014		Cupertino, California 95014
	United States		United States
	Email: msweet@apple.com		Email: msweet@apple.com
	Brian Carpenter
	University of Auckland
	Department of Computer Science
	Auckland, PB 92019 1142
	New Zealand
	Email: brian.e.carpenter@gmail.com
	Stuart Cheshire
	Apple Inc.
	1 Infinite Loop
	Cupertino, California 95014
	United States
	Email: cheshire@apple.com
	Robert M. Hinden
	Check Point Software Technologies, Inc.
	800 Bridge Parkway
	Redwood City, California 94065
	United States
	Email: bob.hinden@gmail.com
End of changes. 34 change blocks.
	229 lines changed or deleted		85 lines changed or added
This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/