draft-ietf-ipngwg-icmp-name-lookups-04.txt   draft-ietf-ipngwg-icmp-name-lookups-05.txt 
IPng Working Group Matt Crawford IPng Working Group Matt Crawford
Internet Draft Fermilab Internet Draft Fermilab
June 21, 1999 October 22, 1999
IPv6 Node Information Queries IPv6 Node Information Queries
<draft-ietf-ipngwg-icmp-name-lookups-04.txt> <draft-ietf-ipngwg-icmp-name-lookups-05.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 1. Abstract
This document describes an experimental protocol for asking an IPv6 This document describes an experimental protocol for asking an IPv6
node to supply certain network information, such as its fully- node to supply certain network information, such as its fully-
qualified domain name. IPv6 implementation experience has shown qualified domain name. IPv6 implementation experience has shown
that direct queries for FQDN are useful, and a direct query that direct queries for a DNS name are useful, and a direct query
mechanism for other information has been requested. mechanism for other information has been requested.
2. Terminology 2. 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 an 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.
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fields: Fields:
Type 139 - NI Query. Type 139 - NI Query.
140 - NI Reply. 140 - NI Reply.
Code For NI Query: Code For NI Query:
0 Indicates that the Data field contains an IPv6 0 Indicates that the Data field contains an IPv6
address which is the subject of this Query. address which is the Subject of this Query.
1 Indicates that the Data field contains a domain name 1 Indicates that the Data field contains a domain name
which is the subject of this Query which is the Subject of this Query
2 Indicates that the Data field contains an IPv4
address which is the Subject of this Query.
For NI Reply: For NI Reply:
0 Indicates a successful reply. 0 Indicates a successful reply. The Reply Data field
may or may not be empty.
1 Indicates that the Responder refuses to supply the 1 Indicates that the Responder refuses to supply the
answer. The Reply Data field will be absent. answer. The Reply Data field will be absent.
2 Indicates that the Qtype of the Query is unknown to 2 Indicates that the Qtype of the Query is unknown to
the Responder. The Reply Data field will be absent. the Responder. The Reply Data field will be absent.
Checksum The ICMPv6 checksum. Checksum The ICMPv6 checksum.
Qtype A 16-bit field which designates the type if information Qtype A 16-bit field which designates the type if information
requested in a Query or supplied in a Reply. Its value requested in a Query or supplied in a Reply. Its value
in a Reply is always copied from the corresponding Query in a Reply is always copied from the corresponding Query
by the Responder. Four values of Qtype are specified in by the Responder. Five values of Qtype are specified in
this document. this document.
Flags Qtype-specific flags which may be defined for certain Flags Qtype-specific flags which may be defined for certain
Query types and their Replies. Flags not defined for a Query types and their Replies. Flags not defined for a
given Qtype must be zero on transmission and ignored on given Qtype must be zero on transmission and ignored on
reception, and must not be copied from a Query to a reception, and must not be copied from a Query to a
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 Type
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] and from the IPv6 header's Payload Length field [2460], the
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
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.
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
name, including the terminating zero-length label, or a single DNS
label followed by two zero-length labels.
4. Message Processing 4. 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.
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 by appending to the prefix multicast address formed in the following way. The Subject Name is
FF02:0:0:0:0:2::/96 the CRC-32 checksum [IS3309] of the first converted to canonical form, as defined by DNS Security [2065],
component of the subject domain name -- the portion up to, but which is uncompressed with all alphabetic characters in lower case.
excluding, the first period. (If additional DNS label types for host names are defined, the rules
for canonicalizing those labels will be found in the defining
specification.) Compute the MD5 hash [1321] of the first label of
the Subject Name -- the portion beginning with the first one-octet
length field and up to, but excluding, any subsequent length field.
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
the "NI Group Address" for the name.
The Nonce should be a random or good pseudo-random value to foil The Nonce should be a random or good pseudo-random value to foil
spoofed replies. An implementation which allows multiple spoofed replies. An implementation which allows multiple
independent processes to send NI queries MAY use the Nonce value to independent processes to send NI queries MAY use the Nonce value to
deliver Replies to the correct process. Nonetheless, such processes deliver Replies to the correct process. Nonetheless, such processes
MUST check the received Nonce and ignore extraneous Replies. MUST check the received Nonce and ignore extraneous Replies.
If true communication security is required, IPsec [2401] must be If true communication security is required, IPsec [2401] must be
used. used.
Upon receiving an NI Query, the Responder must check the Query's Upon receiving a NI Query, the Responder must check the Query's IPv6
IPv6 destination address and discard the Query without further destination address and discard the Query without further processing
processing if it is not one of the Responder's unicast or anycast unless it is one of the Responder's unicast or anycast addresses, a
addresses. A Responder must also silently discard a Query whose NI Group Address for a name belonging to the Responder, or a NI
subject address or name (in the Data field) does belong to that Group Address for a name for which the Responder is providing proxy
node. service. 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 is providing proxy service for that Subject. A
single-component Subject Name matches any fully-qualified name whose
first label matches the Subject. All name matching is done in a
case-independent manner.
Next, if Qtype is unknown to the Responder, it must return an 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 Type = 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 an NI Reply with ICMPv6 Type = 1 and refused, the Responder may send a NI Reply with ICMPv6 Type = 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 address. If the Queried
Address was anycast, the source address for the Reply SHOULD be one Address was anycast, the source address for the Reply SHOULD be one
belonging to the interface on which the Query was received. 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 5. Defined Qtypes
The following four Qtypes are defined and must be supported by any The following five Qtypes are defined. The first four (number 0 to
implementation of this protocol. 3) MUST be supported by any implementation of this protocol. The
last one SHOULD be supported by any implementation on an IPv4/IPv6
dual-stack node and MAY be supported on an IPv6-only node.
0 NOOP. 0 NOOP.
1 Supported Qtypes. 1 Supported Qtypes.
2 FQDN. 2 DNS Name.
3 Node Addresses. 3 Node Addresses.
4 IPv4 Addresses.
5.1. NOOP 5.1. 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 an 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. Address was an anycast address.
5.2. Supported Qtypes 5.2. 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.
A 1-valued bit indicates support for the corresponding Qtype. The A 1-valued bit indicates support for the corresponding Qtype. The
lowest-order four bits in the first 32-bit word must be set to 1, lowest-order four bits in the first 32-bit word must be set to 1,
showing support for the four Qtypes defined in this specification. showing support for the four mandatory Qtypes defined in this
Thus the Data field of an NI Supported Qtypes Reply from a Responder specification. Thus the Data field of a NI Supported Qtypes Reply
implementing only the 4 Qtypes defined here will contain 32 bits in from a Responder implementing only the mandatory Qtypes will contain
the following form: 32 bits in the following form:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 . . . 0 0 0 1 1 1 1| |0 0 0 . . . 0 0 0 1 1 1 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The compressed form of the Reply Data consists of a sequence of The compressed form of the Reply Data consists of a sequence of
blocks, each block consisting of two 16-bit unsigned integers, nWord blocks, each block consisting of two 16-bit unsigned integers, nWord
and nSkip, followed by nWord 32-bit bitmasks describing the and nSkip, followed by nWord 32-bit bitmasks describing the
Responder's support for 32 consecutive Qtypes. nSkip is a count of Responder's support for 32 consecutive Qtypes. nSkip is a count of
32-bit words which would have been all-zero and have been 32-bit words following the included words which would have been
suppressed. The last block MUST have nSkip = 0. As an example, a all-zero and have been suppressed. The last block MUST have nSkip =
Responder supporting Qtypes 0, 1, 2, 3, 60, and 4097 could express 0. As an example, a Responder supporting Qtypes 0, 1, 2, 3, 60, and
that information with the following Reply Data (nWord and nSkip 4097 could express that information with the following Reply Data
fields are written in decimal for easier reading): (nWord and nSkip fields are written in decimal for easier reading):
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 2 | 126 | | 2 | 126 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 . . . 0 0 0 1 1 1 1| |0 0 0 . . . 0 0 0 1 1 1 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1 0 0 0 . . . 0 0 0| |0 0 0 1 0 0 0 . . . 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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 of the Reply or save significant space in the avoid fragmentation or save significant space in the Reply.
Reply.
5.3. FQDN 5.3. DNS Name
The NI FQDN Query requests the fully-qualified domain name The NI DNS Name Query requests the fully-qualified or single-
corresponding to the subject Address or Name. The Reply Data has component name corresponding to the Subject Address or Name. The
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NameLen | FQDN ... | | DNS Names ... |
+-+-+-+-+-+-+-+-+ + + +
/ / / /
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TTL The number of seconds that the name may be cached. For TTL The number of seconds that the name may be cached. For
compatibility with DNS [1035], this is a 32-bit signed, compatibility with DNS [1035], this is a 32-bit signed,
2's-complement number, which must not be negative. 2's-complement number, which must not be negative.
NameLen The length in octets of the FQDN, as an 8-bit unsigned DNS Names The fully-qualified or single-component name or names of
integer. the Responder which correspond(s) to the Subject Address
or Name, in DNS wire format [1035]. Each name MUST be
FQDN The fully-qualified domain name of the Responder which fully-qualified if the responder knows the domain
corresponds to the Subject Address or Name, as a suffix, and a single DNS label followed by two zero-
sequence of NameLen US-ASCII octets, with periods length labels otherwise.
between the labels, and no period after the last label.
The Responder must fill in the TTL field of the Reply with a The Responder must fill in the TTL field of the Reply with a
meaningful value if possible. That value should be one of the meaningful value if possible. That value should be one of the
following. following.
The remaining lifetime of a DHCP lease on the Subject Address; The remaining lifetime of a DHCP lease on the Subject Address;
The remaining Valid Lifetime of a prefix from which the Subject The remaining Valid Lifetime of a prefix from which the Subject
Address was derived through Stateless Autoconfiguration [2461, Address was derived through Stateless Autoconfiguration [2461,
2462]; 2462];
The TTL of an existing AAAA or A6 record which associates the The TTL of an existing AAAA or A6 record which associates the
Subject Address with the FQDN being returned. Subject Address with the DNS Name being returned.
If the Responder knows its hostname but not its domain, it MUST send If the Responder returns multiple names but considers one name to be
its one-component name with no periods. It may still be possible to official or canonical, that name MUST be placed immediately after
return a meaningful TTL based on a DHCP lease or autoconfigured the TTL.
prefix.
Only one TTL is included in the reply. If the Responder considers
different names to be cacheable for different times, the TTL field
must be set no larger than the minimum of those times.
If the Responder does not know its name at all it MUST send a Reply If the Responder does not know its name at all it MUST send a Reply
with TTL=0, NameLen=0 and no FQDN. with TTL=0 and no DNS Names. The Querier will be able to determine
from the packet length that the Data field contains only a TTL.
One Flag bit is defined, in the Reply only. One Flag bit is defined, in the Reply only.
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=2 | unused |T| | Qtype=2 | unused |T|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A T-flag set to 1 in an NI FQDN Reply indicates that the TTL field A T-flag set to 1 in a NI DNS Name Reply indicates that the TTL
contains a meaningful value. If the T-flag is 0, the TTL SHOULD be field contains a meaningful value. If the T-flag is 0, the TTL
set to zero by the Responder and MUST be ignored by the Querier. SHOULD be set to zero by the Responder and MUST be ignored by the
Querier.
If a name rather than an address was the Subject of the Query, the If a name rather than an address was the Subject of the Query, the
T-flag MUST be zero and the TTL SHOULD be zero. T-flag MUST be zero and the TTL SHOULD be zero.
The information in an NI FQDN Reply with T-flag 1 may be cached and The information in a NI DNS Name Reply with T-flag 1 may be cached
used for the period indicated by that TTL. If a Reply has no TTL and used for the period indicated by that TTL. If a Reply has no
(T-flag 0), the information in that Reply must not be used more than TTL (T-flag 0), the information in that Reply must not be used more
once. If the Query was sent by a DNS server on behalf of a DNS than once. If 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 client, the result may be returned to that client as a DNS response
with TTL zero. However, if the server has the matching AAAA record, with TTL zero. However, if the server has the matching AAAA record,
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 FQDN Reply and the record may be used as the missing TTL of the NI DNS Name Reply and
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 FQDN 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 FQDN Query. that caused the DNS Name Query.
5.3.1. Discussion 5.3.1. Discussion
Because a node can only answer a FQDN 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 FQDN messages to achieve greater trust in IPsec can be applied to NI DNS Name messages to achieve greater
the information obtained, but such a need may be obviated by trust in the information obtained, but such a need may be obviated
applying IPsec directly to some other communication which is going by applying IPsec directly to some other communication which is
on (or contemplated) between the Querier and Responder. going on (or contemplated) between the Querier and Responder.
5.4. Node Addresses 5.4. 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
unicast addresses. The Reply Data is a sequence of 128-bit IPv6 IPv6 unicast addresses. The Reply Data is a sequence of 128-bit
addresses, with Preferred addresses listed before Deprecated IPv6 addresses, each address preceded by separate a 32-bit TTL
addresses [2461], but otherwise in no special order. Four flag bits value, with Preferred addresses listed before Deprecated addresses
are defined in the Query, and five in the Reply. [2461], but otherwise in no special order. Five flag bits are
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Qtype=3 | unused |T|A|G|S|L| | Qtype=3 | unused |G|S|L|C|A|T|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
T Defined in a Reply only, indicates that the set of addresses is G If set to 1, Global-scope addresses [2374] are requested.
incomplete for space reasons.
S If set to 1, Site-local addresses [2374] are requested.
L If set to 1, Link-local addresses [2374] are requested.
C If set to 1, IPv4-compatible and IPv4-mapped addresses [2373]
are requested.
A If set to 1, all the Responder's unicast addresses (of the A If set to 1, all the Responder's unicast addresses (of the
specified scope(s))are requested. If 0, only those addresses specified scope(s))are requested. If 0, only those addresses
are requested which belong to the interface (or any one are requested which belong to the interface (or any one
interface) which has the Subject Address. interface) which has the Subject Address, or which are
associated with the Subject Name.
G If set to 1, Global-scope addresses [2374] are requested. T Defined in a Reply only, indicates that the set of addresses is
incomplete for space reasons.
S If set to 1, Site-local addresses [2374] are requested. Flags G, S, L, C and A are copied from a Query to the corresponding
Reply.
L If set to 1, Link-local addresses [2374] are requested. The TTL associated with each address are to be determined by the
rules in section 5.3, applied to the returned address rather than
the Subject. If no meaningful caching time can be given for an
address, the corresponding TTL field MUST be zero.
Flags A, G, S and L are copied from a Query to the corresponding Each address with non-zero TTL in a NI Node Address Reply may be
Reply. 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
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
zero.
IPv4-mapped addresses can only be returned by a Node Information
proxy, since they represent addresses of IPv4-only nodes, which
perforce do not implement this protocol.
5.5. IPv4 Addresses
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
addresses, each address preceded by a 32-bit TTL value. One flag
bit is defined in the Query, and two in the Reply.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Qtype=3 | unused |A|T|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A If set to 1, all the Responder's unicast addresses are
requested. If 0, only those addresses are requested which
belong to the interface (or any one interface) which has the
Subject Address.
T Defined in a Reply only, indicates that the set of addresses is
incomplete for space reasons.
Flag A is copied from a Query to the corresponding Reply.
The TTL associated with each address are to be determined by the
rules in section 5.3, applied to the returned address rather than
the Subject, excluding the autoconfiguration Valid Lifetime. If no
meaningful caching time can be given for an address, the
corresponding TTL field MUST be zero.
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
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
result may be returned to that client as a DNS response with TTL
zero.
5.5.1. Discussion
It is possible that a node may treat IPv4 interfaces and IPv6
interfaces as distinct, even though they are associated with the
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
Query has the A flag set to 0, it SHOULD consider IP interfaces,
other than tunnels, associated with the same hardware as being the
same interface.
6. IANA Considerations 6. 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 four values of Qtype, numbers 0 through 3. 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 [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 4 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 for of the Reply Data is used.
The multicast address formation of section has not yet been Assignment of the multicast address prefix FF02:0:0:0:0:2::/96 used
discussed in the IPNG working group and is not yet requested or in section 4 as a destination for IPv6 Node Information Queries is
assigned for this use. requested.
7. Security Considerations 7. 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 [2065] 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
skipping to change at page 10, line 36 skipping to change at page 12, line 37
Alain Durand contributed to this specification. This document is Alain Durand contributed to this specification. This document is
not the first proposal of a direct query mechanism for address-to- not the first proposal of a direct query mechanism for address-to-
name translation. The idea had been discussed briefly in the IPng name translation. The idea had been discussed briefly in the IPng
working group and an experimental RFC [1788] describes such a working group and an experimental RFC [1788] describes such a
mechanism for IPv4. mechanism for IPv4.
9. References 9. References
[1035] P. Mockapetris, "Domain Names - Implementation and [1035] P. Mockapetris, "Domain Names - Implementation and
Specification", RFC 1035, STD 13. Specification", RFC 1035, STD 13, November 1987.
[1788] W. Simpson, "ICMP Domain Name Messages", RFC 1788. [1321] R. Rivest, "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[2119] Bradner, S., "Key words for use in RFCs to Indicate [1788] W. Simpson, "ICMP Domain Name Messages", RFC 1788, April
Requirement Levels," RFC 2119. 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
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. 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
IANA Considerations Section in RFCs", RFC 2434. IANA Considerations Section in RFCs", RFC 2434, October 1998.
[2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[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.
[IS3309] International Organization for Standardization, "ISO
Information Processing Systems - Data Communication High-Level
Data Link Control Procedure - Frame Structure", IS 3309, October
1984, 3rd Edition.
10. Author's Address 10. 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
 End of changes. 

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