draft-ietf-ipngwg-icmp-name-lookups-06.txt		draft-ietf-ipngwg-icmp-name-lookups-07.txt
	IPng Working Group Matt Crawford		IPng Working Group Matt Crawford
	Internet Draft Fermilab		Internet Draft Fermilab
	July 14, 2000		August 28, 2000
	IPv6 Node Information Queries		IPv6 Node Information Queries
	<draft-ietf-ipngwg-icmp-name-lookups-06.txt>		<draft-ietf-ipngwg-icmp-name-lookups-07.txt>
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is in full conformance with		This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC2026. Internet-Drafts are working		all provisions of Section 10 of RFC2026. 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 and may be updated, replaced, or obsoleted by other documents		months and may be updated, replaced, or obsoleted by other documents
	at any time. It is inappropriate to use Internet- Drafts as		at any time. It is inappropriate to use Internet- Drafts as
	reference material or to cite them other than as "work in progress."		reference material or to cite them other than as "work in progress."
	The list of current Internet-Drafts can be accessed at		To view the list Internet-Draft Shadow Directories, see
	http://www.ietf.org/ietf/1id-abstracts.txt
	The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	1. Abstract		Abstract
	This document describes an experimental protocol for asking an IPv6		This document describes a protocol for asking an IPv6 node to supply
	node to supply certain network information, such as its fully-		certain network information, such as its fully-qualified domain
	qualified domain name. IPv6 implementation experience has shown		name. IPv6 implementation experience has shown that direct queries
	that direct queries for a DNS name are useful, and a direct query		for a DNS name are useful, and a direct query mechanism for other
	mechanism for other information has been requested.		information has been requested.
	2. Terminology		1. Terminology
	A "Node Information (or NI) Query" message is sent by a "Querier"		A "Node Information (or NI) Query" message is sent by a "Querier"
	node to a "Responder" node in an ICMPv6 packet addressed to the		node to a "Responder" node in an ICMPv6 packet addressed to the
	"Queried Address." The Query concerns a "Subject Address" which may		"Queried Address." The Query concerns a "Subject Address" which may
	differ from the Queried Address, or a "Subject Name". The Responder		differ from the Queried Address, or a "Subject Name". The Responder
	sends a "Node Information Reply" to the Querier, containing		sends a "Node Information Reply" to the Querier, containing
	information associated with the node at the Queries address. A node		information associated with the node at the Queries address. A node
	receiving a NI Query will be termed a Responder even if it does not		receiving a NI Query will be termed a Responder even if it does not
	send a Reply.		send a Reply.
	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 [2119].		document are to be interpreted as described in [2119].
	Packet fields marked "unused" must be zero on transmission and,		Packet fields marked "unused" must be zero on transmission and,
	aside from inclusion in checksums or message integrity checks,		aside from inclusion in checksums or message integrity checks,
	ignored on reception.		ignored on reception.
	3. Node Information Messages		2. Node Information Messages
	Two types of Node Information messages, the NI Query and the NI		Two types of Node Information messages, the NI Query and the NI
	Reply, are carried in ICMPv6 [2463] packets. They have the same		Reply, are carried in ICMPv6 [2463] packets. They have the same
	format.		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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Code | Checksum |		| Type | Code | Checksum |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 3, line 36		skipping to change at page 3, line 36
	Reply unless so specified in the definition of the		Reply unless so specified in the definition of the
	Qtype.		Qtype.
	Nonce An opaque 64-bit field to help avoid spoofing and/or to		Nonce An opaque 64-bit field to help avoid spoofing and/or to
	aid in matching Replies with Queries. Its value in a		aid in matching Replies with Queries. Its value in a
	Query is chosen by the Querier. Its value in a Reply is		Query is chosen by the Querier. Its value in a Reply is
	always copied from the corresponding Request by the		always copied from the corresponding Request by the
	Responder.		Responder.
	Data In a Query, the Subject Address or Name. In a Reply,		Data In a Query, the Subject Address or Name. In a Reply,
	Qtype-specific data present only when the ICMPv6 Type		Qtype-specific data present only when the ICMPv6 Code
	field is zero. The length of the Data may be inferred		field is zero. The length of the Data may be inferred
	from the IPv6 header's Payload Length field [2460], the		from the IPv6 header's Payload Length field [2460], the
	length of the fixed portion of the NI packet and the		length of the fixed portion of the NI packet and the
	lengths of the ICMPv6 header and intervening extension		lengths of the ICMPv6 header and intervening extension
	headers.		headers.
	Note that the type of information present in the Data field of a		Note that the type of information present in the Data field of a
	Query is inferred from the ICMP Code, while the type of information,		Query is inferred from the ICMP Code, while the type of information,
	if any, in the Data field of a Reply is inferred from the Qtype.		if any, in the Data field of a Reply is inferred from the Qtype.
	When the Subject of a Query is a name, the name MUST be in DNS wire		When the Subject of a Query is a name, the name MUST be in DNS wire
	format [1035]. The name may be either a fully-qualified domain		format [1035]. The name may be either a fully-qualified domain
	name, including the terminating zero-length label, or a single DNS		name, including the terminating zero-length label, or a single DNS
	label followed by two zero-length labels. Since a Query contains at		label followed by two zero-length labels. Since a Query contains at
	most one DNS name, DNS compression will not be used.		most one DNS name, DNS compression will not be used.
	4. Message Processing		3. Message Processing
	The Querier constructs an ICMP NI Query and sends it to the address		The Querier constructs an ICMP NI Query and sends it to the address
	from which information is wanted. When the Subject of the Query is		from which information is wanted. When the Subject of the Query is
	an IPv6 address, that address will normally be used as the IPv6		an IPv6 address, that address will normally be used as the IPv6
	destination address of the Query, but need not be if the Querier has		destination address of the Query, but need not be if the Querier has
	useful a priori information about the addresses of the target node.		useful a priori information about the addresses of the target node.
	An NI Query may also be sent to a multicast address of link-local		An NI Query may also be sent to a multicast address of link-local
	scope [2373].		scope [2373].
	When the Subject is a domain name, either fully-qualified or		When the Subject is a domain name, either fully-qualified or
	single-component, and the Querier does not have a unicast address		single-component, and the Querier does not have a unicast address
	for the target node, the query MUST be sent to a link-scope		for the target node, the query MUST be sent to a link-scope
	multicast address formed in the following way. The Subject Name is		multicast address formed in the following way. The Subject Name is
	converted to canonical form, as defined by DNS Security [2065],		converted to canonical form, as defined by DNS Security [2535],
	which is uncompressed with all alphabetic characters in lower case.		which is uncompressed with all alphabetic characters in lower case.
	(If additional DNS label types for host names are defined, the rules		(If additional DNS label types for host names are defined, the rules
	for canonicalizing those labels will be found in the defining		for canonicalizing those labels will be found in the defining
	specification.) Compute the MD5 hash [1321] of the first label of		specification.) Compute the MD5 hash [1321] of the first label of
	the Subject Name -- the portion beginning with the first one-octet		the Subject Name -- the portion beginning with the first one-octet
	length field and up to, but excluding, any subsequent length field.		length field and up to, but excluding, any subsequent length field.
	Append the first 32 bits of that 128-bit hash to the prefix		Append the first 32 bits of that 128-bit hash to the prefix
	FF02:0:0:0:0:2::/96. The resulting multicast address will be termed		FF02:0:0:0:0:2::/96. The resulting multicast address will be termed
	the "NI Group Address" for the name.		the "NI Group Address" for the name.
	skipping to change at page 5, line 7		skipping to change at page 5, line 7
	discard NI Queries to multicast addresses other than its NI Group		discard NI Queries to multicast addresses other than its NI Group
	Address(es) but if so, the default configuration MUST be not to		Address(es) but if so, the default configuration MUST be not to
	discard them.		discard them.
	A Responder must also silently discard a Query whose Subject Address		A Responder must also silently discard a Query whose Subject Address
	or Name (in the Data field) does not belong to that node, unless it		or Name (in the Data field) does not belong to that node, unless it
	is providing proxy service for that Subject. A single-component		is providing proxy service for that Subject. A single-component
	Subject Name matches any fully-qualified name whose first label		Subject Name matches any fully-qualified name whose first label
	matches the Subject. All name matching is done in a case-		matches the Subject. All name matching is done in a case-
	independent manner consistent with DNSSEC name canonicalization		independent manner consistent with DNSSEC name canonicalization
	[2065].		[2535].
	Next, if Qtype is unknown to the Responder, it must return a NI		Next, if Qtype is unknown to the Responder, it must return a NI
	Reply with ICMPv6 Type = 2 and no Reply Data. The Responder should		Reply with ICMPv6 Code = 2 and no Reply Data. The Responder should
	rate-limit such replies as it would ICMPv6 error replies [2463,		rate-limit such replies as it would ICMPv6 error replies [2463,
	2.4(f)].		2.4(f)].
	Next, the Responder should decide whether to refuse an answer, based		Next, the Responder should decide whether to refuse an answer, based
	on local policy not addressed in this document. If an answer is		on local policy not addressed in this document. If an answer is
	refused, the Responder may send a NI Reply with ICMPv6 Type = 1 and		refused, the Responder may send a NI Reply with ICMPv6 Code = 1 and
	no Reply Data. Again, the Responder should rate-limit such replies		no Reply Data. Again, the Responder should rate-limit such replies
	as it would ICMPv6 error replies [2463, 2.4(f)].		as it would ICMPv6 error replies [2463, 2.4(f)].
	Finally, if the Qtype is known and the response is allowed by local		Finally, if the Qtype is known and the response is allowed by local
	policy, the Responder must fill in the Flags and Reply Data of the		policy, the Responder must fill in the Flags and Reply Data of the
	NI Reply in accordance with the definition of the Qtype and transmit		NI Reply in accordance with the definition of the Qtype and transmit
	the NI Reply with an ICMPv6 source address equal to the Queried		the NI Reply with an ICMPv6 source address equal to the Queried
	Address, unless that address was an anycast address. If the Queried		Address, unless that address was an anycast or a multicast address.
	Address was anycast, the source address for the Reply SHOULD be one		If the Queried Address was anycast or multicast, the source address
	belonging to the interface on which the Query was received.		for the Reply SHOULD be one belonging to the interface on which the
			Query was received.
	If the Query was sent to an anycast or multicast address,		If the Query was sent to an anycast or multicast address,
	transmission of the Reply MUST be delayed by a random interval		transmission of the Reply MUST be delayed by a random interval
	between zero and MAX_ANYCAST_DELAY_TIME, as defined by IPv6 Neighbor		between zero and MAX_ANYCAST_DELAY_TIME, as defined by IPv6 Neighbor
	Discovery [2461].		Discovery [2461].
	5. Defined Qtypes		4. Defined Qtypes
	The following five Qtypes are defined. The first four (number 0 to		The following five Qtypes are defined. The first four (number 0 to
	3) MUST be supported by any implementation of this protocol. The		3) MUST be supported by any implementation of this protocol. The
	last one SHOULD be supported by any implementation on an IPv4/IPv6		last one SHOULD be supported by any implementation on an IPv4/IPv6
	dual-stack node and MAY be supported on an IPv6-only node.		dual-stack node and MAY be supported on an IPv6-only node.
	0 NOOP.		0 NOOP.
	1 Supported Qtypes.		1 Supported Qtypes.
	2 DNS Name.		2 DNS Name.
	3 Node Addresses.		3 Node Addresses.
	4 IPv4 Addresses.		4 IPv4 Addresses.
	5.1. NOOP		4.1. NOOP
	This NI type has no defined flags and never has a Data field. A		This NI type has no defined flags and never has a Data field. A
	Reply to a NI NOOP Query tells the Querier that a node with the		Reply to a NI NOOP Query tells the Querier that a node with the
	Queried Address is up and reachable, implements the Node Information		Queried Address is up and reachable, implements the Node Information
	protocol, and incidentally happens to reveal whether the Queried		protocol, and incidentally happens to reveal whether the Queried
	Address was an anycast address. On transmission, the ICMPv6 Code in		Address was an anycast address. On transmission, the ICMPv6 Code in
	a NOOP Query must be set to 1 and the Code in a NOOP Reply must be		a NOOP Query must be set to 1 and the Code in a NOOP Reply must be
	0. On reception of a NOOP Query or Reply, the Code must be ignored.		0. On reception of a NOOP Query or Reply, the Code must be ignored.
	5.2. Supported Qtypes		4.2. Supported Qtypes
	This Query contains no Data field. The Reply Data is a bit-vector		This Query contains no Data field. The Reply Data is a bit-vector
	showing which Qtypes are supported by the Responder. The Reply Data		showing which Qtypes are supported by the Responder. The Reply Data
	has two variant forms: uncompressed and compressed. The		has two variant forms: uncompressed and compressed. The
	uncompressed Data format is one or more complete 32-bit words, each		uncompressed Data format is one or more complete 32-bit words, each
	word a bitmask with the low-order bit in each word corresponding to		word a bitmask with the low-order bit in each word corresponding to
	the lowest numbered Qtype in a group of 32. The first word		the lowest numbered Qtype in a group of 32. The first word
	describes the Responder's support for Qtypes 0 to 31, the second		describes the Responder's support for Qtypes 0 to 31, the second
	word 32 to 63, and so on.		word 32 to 63, and so on.
	skipping to change at page 7, line 37		skipping to change at page 7, line 37
	In a Query, a C-flag set to 1 indicates that the Querier will accept		In a Query, a C-flag set to 1 indicates that the Querier will accept
	the compressed form of the Reply Data. In a Reply, a C-flag set to		the compressed form of the Reply Data. In a Reply, a C-flag set to
	1 indicates that the Reply Data is compressed. The compressed form		1 indicates that the Reply Data is compressed. The compressed form
	MAY be used in a Reply only if the Query had the C-flag set.		MAY be used in a Reply only if the Query had the C-flag set.
	Implementations of this specification SHOULD support the compressed		Implementations of this specification SHOULD support the compressed
	form and if they do, SHOULD set the C-flag in all Supported Qtypes		form and if they do, SHOULD set the C-flag in all Supported Qtypes
	Queries and SHOULD use the compressed form in Supported Qtypes		Queries and SHOULD use the compressed form in Supported Qtypes
	Replies (when allowed by the C-flag in the query) if doing so would		Replies (when allowed by the C-flag in the query) if doing so would
	avoid fragmentation or save significant space in the Reply.		avoid fragmentation or save significant space in the Reply.
	5.3. DNS Name		4.3. DNS Name
	The NI DNS Name Query requests the fully-qualified or single-		The NI DNS Name Query requests the fully-qualified or single-
	component name corresponding to the Subject Address or Name. The		component name corresponding to the Subject Address or Name. The
	Reply Data has the following format.		Reply Data has the following 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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| TTL |		| TTL |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 9, line 45		skipping to change at page 9, line 45
	either in cache or in an authoritative zone, then the TTL of that		either in cache or in an authoritative zone, then the TTL of that
	record may be used as the missing TTL of the NI DNS Name Reply and		record may be used as the missing TTL of the NI DNS Name Reply and
	the information in the reply may be cached and used for that period.		the information in the reply may be cached and used for that period.
	It would be an implementation choice for a server to perform a DNS		It would be an implementation choice for a server to perform a DNS
	query for the AAAA or A6 record that matches a received NI DNS Name		query for the AAAA or A6 record that matches a received NI DNS Name
	Reply. This might be done to obtain a TTL to make the Reply		Reply. This might be done to obtain a TTL to make the Reply
	cacheable or in anticipation of such a AAAA query from the client		cacheable or in anticipation of such a AAAA query from the client
	that caused the DNS Name Query.		that caused the DNS Name Query.
	5.3.1. Discussion		4.3.1. Discussion
	Because a node can only answer a DNS Name Request when it is up and		Because a node can only answer a DNS Name Request when it is up and
	reachable, it may be useful to create a proxy responder for a group		reachable, it may be useful to create a proxy responder for a group
	of nodes, for example a subnet or a site. Such a mechanism is not		of nodes, for example a subnet or a site. Such a mechanism is not
	addressed here.		addressed here.
	IPsec can be applied to NI DNS Name messages to achieve greater		IPsec can be applied to NI DNS Name messages to achieve greater
	trust in the information obtained, but such a need may be obviated		trust in the information obtained, but such a need may be obviated
	by applying IPsec directly to some other communication which is		by applying IPsec directly to some other communication which is
	going on (or contemplated) between the Querier and Responder.		going on (or contemplated) between the Querier and Responder.
	5.4. Node Addresses		4.4. Node Addresses
	The NI Node Addresses Query requests some set of the Responder's		The NI Node Addresses Query requests some set of the Responder's
	IPv6 unicast addresses. The Reply Data is a sequence of 128-bit		IPv6 unicast addresses. The Reply Data is a sequence of 128-bit
	IPv6 addresses, each address preceded by separate a 32-bit TTL		IPv6 addresses, each address preceded by separate a 32-bit TTL
	value, with Preferred addresses listed before Deprecated addresses		value, with Preferred addresses listed before Deprecated addresses
	[2461], but otherwise in no special order. Five flag bits are		[2461], but otherwise in no special order. Five flag bits are
	defined in the Query, and six in the Reply.		defined in the Query, and six in the Reply.
	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
	skipping to change at page 10, line 47		skipping to change at page 10, line 47
	interface) which has the Subject Address, or which are		interface) which has the Subject Address, or which are
	associated with the Subject Name.		associated with the Subject Name.
	T Defined in a Reply only, indicates that the set of addresses is		T Defined in a Reply only, indicates that the set of addresses is
	incomplete for space reasons.		incomplete for space reasons.
	Flags G, S, L, C and A are copied from a Query to the corresponding		Flags G, S, L, C and A are copied from a Query to the corresponding
	Reply.		Reply.
	The TTL associated with each address are to be determined by the		The TTL associated with each address are to be determined by the
	rules in section 5.3, applied to the returned address rather than		rules in section 4.3, applied to the returned address rather than
	the Subject. If no meaningful caching time can be given for an		the Subject. If no meaningful caching time can be given for an
	address, the corresponding TTL field MUST be zero.		address, the corresponding TTL field MUST be zero.
	Each address with non-zero TTL in a NI Node Address Reply may be		Each address with non-zero TTL in a NI Node Address Reply may be
	cached and used for the period indicated by that TTL. If the TTL is		cached and used for the period indicated by that TTL. If the TTL is
	zero, the corresponding address must not be used more than once. If		zero, the corresponding address must not be used more than once. If
	the Query was sent by a DNS server on behalf of a DNS client, the		the Query was sent by a DNS server on behalf of a DNS client, the
	result may be returned to that client as a DNS response with TTL		result may be returned to that client as a DNS response with TTL
	zero.		zero.
	IPv4-mapped addresses can only be returned by a Node Information		IPv4-mapped addresses can only be returned by a Node Information
	proxy, since they represent addresses of IPv4-only nodes, which		proxy, since they represent addresses of IPv4-only nodes, which
	perforce do not implement this protocol.		perforce do not implement this protocol.
	5.5. IPv4 Addresses		4.5. IPv4 Addresses
	The NI IPv4 Addresses Query requests some set of the Responder's		The NI IPv4 Addresses Query requests some set of the Responder's
	IPv4 unicast addresses. The Reply Data is a sequence of 32-bit IPv4		IPv4 unicast addresses. The Reply Data is a sequence of 32-bit IPv4
	addresses, each address preceded by a 32-bit TTL value. One flag		addresses, each address preceded by a 32-bit TTL value. One flag
	bit is defined in the Query, and two in the Reply.		bit is defined in the Query, and two in the Reply.
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Qtype=3 | unused |A|T|		| Qtype=4 | unused |A|T|
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	A If set to 1, all the Responder's unicast addresses are		A If set to 1, all the Responder's unicast addresses are
	requested. If 0, only those addresses are requested which		requested. If 0, only those addresses are requested which
	belong to the interface (or any one interface) which has the		belong to the interface (or any one interface) which has the
	Subject Address.		Subject Address.
	T Defined in a Reply only, indicates that the set of addresses is		T Defined in a Reply only, indicates that the set of addresses is
	incomplete for space reasons.		incomplete for space reasons.
	Flag A is copied from a Query to the corresponding Reply.		Flag A is copied from a Query to the corresponding Reply.
	The TTL associated with each address are to be determined by the		The TTL associated with each address are to be determined by the
	rules in section 5.3, applied to the returned address rather than		rules in section 4.3, applied to the returned address rather than
	the Subject, excluding the autoconfiguration Valid Lifetime. If no		the Subject, excluding the autoconfiguration Valid Lifetime. If no
	meaningful caching time can be given for an address, the		meaningful caching time can be given for an address, the
	corresponding TTL field MUST be zero.		corresponding TTL field MUST be zero.
	Each address with non-zero TTL in a NI IPv4 Address Reply may be		Each address with non-zero TTL in a NI IPv4 Address Reply may be
	cached and used for the period indicated by that TTL. If the TTL is		cached and used for the period indicated by that TTL. If the TTL is
	zero, the corresponding address must not be used more than once. If		zero, the corresponding address must not be used more than once. If
	the Query was sent by a DNS server on behalf of a DNS client, the		the Query was sent by a DNS server on behalf of a DNS client, the
	result may be returned to that client as a DNS response with TTL		result may be returned to that client as a DNS response with TTL
	zero.		zero.
	5.5.1. Discussion		4.5.1. Discussion
	It is possible that a node may treat IPv4 interfaces and IPv6		It is possible that a node may treat IPv4 interfaces and IPv6
	interfaces as distinct, even though they are associated with the		interfaces as distinct, even though they are associated with the
	same hardware. When such a node is responding to a NI Query having		same hardware. When such a node is responding to a NI Query having
	a Subject Address of one type requesting the other type, and the		a Subject Address of one type requesting the other type, and the
	Query has the A flag set to 0, it SHOULD consider IP interfaces,		Query has the A flag set to 0, it SHOULD consider IP interfaces,
	other than tunnels, associated with the same hardware as being the		other than tunnels, associated with the same hardware as being the
	same interface.		same interface.
	6. IANA Considerations		5. IANA Considerations
	ICMPv6 type values 139 and 140 have been assigned by IANA for this		ICMPv6 type values 139 and 140 have been assigned by IANA for this
	protocol.		protocol. This document defines three values of the ICMPv6 Code
			field for each of these ICMPv6 Type values. Additional Code values
			may be defined only by IETF Consensus [2434].
	This document defines five values of Qtype, numbers 0 through 4.		This document defines five values of Qtype, numbers 0 through 4.
	Following the policies outlined in [2434], new values, and their		Following the policies outlined in "Guidelines for Writing an IANA
			Considerations Section in RFCs" [2434], new values, and their
	associated Flags and Reply Data, may be defined as follows.		associated Flags and Reply Data, may be defined as follows.
	Qtypes 5 through 255, by IETF Consensus.		Qtypes 5 through 255, by IETF Consensus.
	Qtypes 256 through 1023, Specification Required.		Qtypes 256 through 1023, Specification Required.
	Qtypes 1024 through 4095, First Come First Served.		Qtypes 1024 through 4095, First Come First Served.
	Qtypes 4096 through 65535, Private Use.		Qtypes 4096 through 65535, Private Use.
	Users of Private Use values should note that values above 8000 to		Users of Private Use values should note that values above 8000 to
	9000 are likely to lead to fragmentation of "Supported Qtypes"		9000 are likely to lead to fragmentation of "Supported Qtypes"
	Replies unless the compressed for of the Reply Data is used.		Replies unless the compressed form of the Reply Data is used.
	Assignment of the multicast address prefix FF02:0:0:0:0:2::/96 used		Assignment of the multicast address prefix FF02:0:0:0:0:2::/96 used
	in section 4 as a destination for IPv6 Node Information Queries is		in section 3 as a destination for IPv6 Node Information Queries is
	requested.		requested.
	7. Security Considerations		6. Security Considerations
	The anti-spoofing Nonce does not give any protection from spoofers		The anti-spoofing Nonce does not give any protection from spoofers
	who can snoop the Query or the Reply.		who can snoop the Query or the Reply.
	In a large Internet with relatively frequent renumbering, the		In a large Internet with relatively frequent renumbering, the
	maintenance of of KEY and SIG records [2065] in the zones used for		maintenance of of KEY and SIG records [2535] in the zones used for
	address-to-name translations will be no easier than the maintenance		address-to-name translations will be no easier than the maintenance
	of the NS, SOA and PTR records themselves, which already appears to		of the NS, SOA and PTR records themselves, which already appears to
	be difficult in many cases. The author expects, therefore, that		be difficult in many cases. The author expects, therefore, that
	address-to-name mappings, either through the original DNS mechanism		address-to-name mappings, either through the original DNS mechanism
	or through this new mechanism, will generally be used as only a hint		or through this new mechanism, will generally be used as only a hint
	to find more trustworthy information using the returned name as an		to find more trustworthy information using the returned name as an
	index.		index.
	8. Acknowledgments		7. Acknowledgments
	Alain Durand contributed to this specification and valuable feedback		Alain Durand contributed to this specification and valuable feedback
	and implementation experience was provided by Jun-Ichiro Hagino and		and implementation experience was provided by Jun-Ichiro Hagino and
	Tatuya Jinmei. This document is not the first proposal of a direct		Tatuya Jinmei. This document is not the first proposal of a direct
	query mechanism for address-to-name translation. The idea had been		query mechanism for address-to-name translation. The idea had been
	discussed briefly in the IPng working group and an experimental RFC		discussed briefly in the IPng working group and RFC 1788 [1788]
	[1788] describes such a mechanism for IPv4.		describes such a mechanism for IPv4.
	9. References		8. References
	[1035] P. Mockapetris, "Domain Names - Implementation and		[1035] P. Mockapetris, "Domain Names - Implementation and
	Specification", RFC 1035, STD 13, November 1987.		Specification", RFC 1035, STD 13, November 1987.
	[1321] R. Rivest, "The MD5 Message-Digest Algorithm", RFC 1321,		[1321] R. Rivest, "The MD5 Message-Digest Algorithm", RFC 1321,
	April 1992.		April 1992.
	[1788] W. Simpson, "ICMP Domain Name Messages", RFC 1788, April		[1788] W. Simpson, "ICMP Domain Name Messages", RFC 1788, April
	1995.		1995.
	[2065] Eastlake 3rd, D. and C. Kaufman, "Domain Name System Security
	Extensions", RFC 2065, January 1997.
	[2119] S. Bradner, "Key words for use in RFCs to Indicate		[2119] S. Bradner, "Key words for use in RFCs to Indicate
	Requirement Levels," RFC 2119, March 1997.		Requirement Levels," RFC 2119, March 1997.
	[2373] Hinden, R. and S. Deering, "IP Version 6 Addressing		[2373] Hinden, R. and S. Deering, "IP Version 6 Addressing
	Architecture", RFC 2373, July 1998.		Architecture", RFC 2373, July 1998.
	[2401] Kent, S. and R. Atkinson, "Security Architecture for the		[2401] Kent, S. and R. Atkinson, "Security Architecture for the
	Internet Protocol", RFC 2401, November 1998.		Internet Protocol", RFC 2401, November 1998.
	[2434] Narten, T. and H. T. Alvestrand, "Guidelines for Writing an		[2434] Narten, T. and H. T. Alvestrand, "Guidelines for Writing an
	skipping to change at page 14, line 12		skipping to change at page 14, line 12
	[2461] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery		[2461] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery
	for IP Version 6 (IPv6)", RFC 2461, December 1998.		for IP Version 6 (IPv6)", RFC 2461, December 1998.
	[2462] Thomson, S. and T. Narten, "IPv6 Stateless Address		[2462] Thomson, S. and T. Narten, "IPv6 Stateless Address
	Autoconfiguration", RFC 2462, December 1998.		Autoconfiguration", RFC 2462, December 1998.
	[2463] Conta, A. and S. Deering, "Internet Control Message Protocol		[2463] Conta, A. and S. Deering, "Internet Control Message Protocol
	(ICMPv6) for the Internet Protocol Version 6 (IPv6)		(ICMPv6) for the Internet Protocol Version 6 (IPv6)
	Specification", RFC 2463, December 1998.		Specification", RFC 2463, December 1998.
	10. Author's Address		[2535] D. Eastlake 3rd, "Domain Name System Security Extensions",
			RFC 2535, March 1999.
			9. Author's Address
	Matt Crawford		Matt Crawford
	Fermilab MS 368		Fermilab MS 368
	PO Box 500		PO Box 500
	Batavia, IL 60510		Batavia, IL 60510
	USA		USA
	Phone: +1 630 840 3461		Phone: +1 630 840 3461
	Email: crawdad@fnal.gov		Email: crawdad@fnal.gov
End of changes.
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