--- /dev/null
+
+
+DNSEXT Working Group Randy Bush (ed.)
+ Alain Durand (ed.)
+ Bob Fink (ed.)
+ Olafur Gudmundsson (ed.)
+ Tony Hain (ed.)
+INTERNET-DRAFT March 2002
+
+<draft-ietf-dnsext-ipv6-addresses-01.txt>
+
+Updates: RFC 1886, RFC 2673, RFC 2874
+
+
+
+ Representing IPv6 addresses in DNS.
+
+
+Status of this Memo
+
+ This document is an Internet-Draft and is in full conformance with
+ all provisions of Section 10 of RFC 2026.
+
+ Internet-Drafts are working documents of the Internet Engineering
+ Task Force (IETF), its areas, and its working groups. Note that
+ other groups may also distribute working documents as Internet-
+ Drafts.
+
+ Internet-Drafts are draft documents valid for a maximum of six months
+ and may be updated, replaced, or obsoleted by other documents at any
+ time. It is inappropriate to use Internet-Drafts as reference
+ material or to cite them other than as ``work in progress.''
+
+ The list of current Internet-Drafts can be accessed at
+ 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
+
+ Comments should be sent to the authors or the DNSEXT WG mailing list
+ namedroppers@ops.ietf.org
+
+ This draft expires on September 1, 2002.
+
+ Copyright Notice
+
+ Copyright (C) The Internet Society (2002). All rights reserved.
+
+
+
+
+
+
+Expires 1/September/2002 DNSEXT [Page 1]
+
+INTERNET-DRAFT Representation of IPv6 addresses in DNS. March 2002
+
+
+Abstract
+
+ This document clarifies and updates the standards status of RFCs that
+ define direct and reverse map of IPv6 addresses in DNS. This document
+ moves the A6 and Bit label specifications to experimental status.
+
+
+
+
+1 - Introduction
+
+ The IETF had begun the process of standardizing two different address
+ formats for IPv6 addresses AAAA[RFC1886] and A6[RFC2874] and both are
+ at proposed standard. This had led to confusion and conflicts on
+ which one to deploy. It is important for deployment that any
+ confusion in this area be cleared up, as there is a feeling in the
+ community that having more than one choice will lead to delays in the
+ deployment of IPv6. The goal of this document is to clarify the
+ situation.
+
+ This document is based on extensive technical discussion on various
+ relevant working groups mailing lists and a joint DNSEXT and NGTRANS
+ meeting at the 51st IETF in August 2001. This document attempts to
+ capture the sense of the discussions and reflect them in this
+ document to represent the consensus of the community.
+
+ The main arguments and the issues are covered in a separate
+ document[Tradeoff] that reflects the current understanding of the
+ issues. This document summarizes the outcome of these discussions.
+
+ The issue of the root of reverse IPv6 address map is outside the
+ scope of this document and is covered in a different
+ document[RFC3152].
+
+1.1 Standards action taken
+
+ This document changes the status of RFCs 2673 and 2874 from Proposed
+ Standard to Experimental.
+
+
+
+
+
+
+
+
+
+
+
+
+
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+
+2 - IPv6 addresses: AAAA RR vs A6 RR
+
+ Working group consensus as perceived by the chairs of the DNSEXT and
+ NGTRANS working groups is that:
+
+ a) AAAA records are preferable at the moment for production
+ deployment of IPv6, and
+
+ b) that A6 records have interesting properties that need to be
+ better understood before deployment.
+
+ c) It is not known if the benefits of A6 outweigh the costs and
+ risks.
+
+
+2.1 Rationale
+
+ There are several potential issues with A6 RRs that stem directly
+ from the feature that makes them different from AAAA RRs: the ability
+ to build up addresses via chaining.
+
+ Resolving a chain of A6 RRs involves resolving a series of what are
+ nearly-independent queries. Each of these sub-queries takes some
+ non-zero amount of time, unless the answer happens to be in the
+ resolver's local cache already. Other things being equal, we expect
+ that the time it takes to resolve an N-link chain of A6 RRs will be
+ roughly proportional to N. What data we have suggests that users are
+ already impatient with the length of time it takes to resolve A RRs
+ in the IPv4 Internet, which suggests that users are not likely to be
+ patient with significantly longer delays in the IPv6 Internet, but
+ terminating queries prematurely is both a waste of resources and
+ another source of user frustration. Thus, we are forced to conclude
+ that indiscriminate use of long A6 chains is likely to lead to
+ increased user frustration.
+
+ The probability of failure during the process of resolving an N-link
+ A6 chain also appears to be roughly proportional to N, since each of
+ the queries involved in resolving an A6 chain has roughly the same
+ probability of failure as a single AAAA query.
+
+ Last, several of the most interesting potential applications for A6
+ RRs involve situations where the prefix name field in the A6 RR
+ points to a target that is not only outside the DNS zone containing
+ the A6 RR, but is administered by a different organization entirely.
+ While pointers out of zone are not a problem per se, experience both
+ with glue RRs and with PTR RRs in the IN-ADDR.ARPA tree suggests that
+ pointers to other organizations are often not maintained properly,
+ perhaps because they're less susceptible to automation than pointers
+
+
+
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+
+ within a single organization would be.
+
+2.2 Recommended standard action
+
+ Based on the perceived consensus, this document recommend that RFC
+ 1886 stay on standards track and be advanced, while moving RFC 2874
+ to Experimental status.
+
+3 - Bitlabels in the reverse DNS tree
+
+ RFC 2673 defines a new DNS label type. This was the first new type
+ defined since RFC 1035[RFC1035]. Since the development of 2673 it has
+ been learned that deployment of a new type is difficult since DNS
+ servers that do not support bitlabels reject queries containing bit
+ labels as being malformed. The community has also indicated that this
+ new label type is not needed for mapping reverse addresses.
+
+3.1 Rationale
+
+ The hexadecimal text representation of IPv6 addresses appears to be
+ capable of expressing all of the delegation schemes that we expect to
+ be used in the DNS reverse tree.
+
+3.2 Recommended standard action
+
+ RFC 2673 standard status is to be changed from Proposed to
+ Experimental. Future standardization of these documents is to be done
+ by the DNSEXT working group or its successor.
+
+4 DNAME in IPv6 reverse tree
+
+ The issues for DNAME chaining in the reverse tree are substantially
+ identical to the issues for A6 chaining in the forward tree.
+ Therefore, in moving RFC 2874 to experimental, the intent of this
+ document is that use of DNAME RRs in the reverse tree be deprecated.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
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+
+5 Acknowledgments
+
+ This document is based on input from many members of the various IETF
+ working groups involved in this issues. Special thanks go to the
+ people that prepared reading material for the joint DNSEXT and
+ NGTRANS working group meeting at the 51st IETF in London, Rob
+ Austein, Dan Bernstein, Matt Crawford, Jun-ichiro itojun Hagino,
+ Christian Huitema. Number of other people have made number of
+ comments on mailing lists about this issue including Andrew W.
+ Barclay, Robert Elz, Johan Ihren, Edward Lewis, Bill Manning, Pekka
+ Savola, Paul Vixie.
+
+6 - Security Considerations:
+
+ As this document specifies a course of action, there are no direct
+ security considerations. There is an indirect security impact of the
+ choice, in that the relationship between A6 and DNSSEC is not well
+ understood throughout the community, while the choice of AAAA does
+ leads to a model for use of DNSSEC in IPv6 networks which parallels
+ current IPv4 practice.
+
+
+7 - IANA Considerations:
+
+ None.
+
+References:
+
+[RFC1035] P. Mockapetris, ``Domain Names - Implementation and
+ Specification'' STD 13, RFC 1035, November 1987.
+
+[RFC1886] S. Thompson, C. Huitema, ``DNS Extensions to support IP
+ version 6'', RFC 1886, December 1995.
+
+[RFC2673] M. Crawford ``Binary Labels in the Domain Name System``, RFC
+ 2673, August 1999.
+
+[RFC2874] M. Crawford, C. Huitema, ``DNS Extensions to Support IPv6
+ Address Aggregation and Renumbering'', RFC 2874, July 2000.
+
+[RFC3152] R. Bush, ``Delegation of IP6.ARPA'', RFC 3152 also BCP0049,
+ August 2001,
+
+[Tradeoff] R. Austein, ``Tradeoffs in DNS support for IPv6'', Work in
+ progress, draft-ietf-dnsext-ipv6-dns-tradeoffs-xx.txt, July
+ 2001.
+
+
+
+
+
+Expires 1/September/2002 DNSEXT [Page 5]
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+INTERNET-DRAFT Representation of IPv6 addresses in DNS. March 2002
+
+
+Editors Address
+
+ Randy Bush <randy@psg.com>
+ Alain Durand <alain.durand@sun.com>
+ Bob Fink <fink@es.net>
+ Olafur Gudmundsson <ogud@ogud.com>
+ Tony Hain <hain@tndh.net>
+
+Full Copyright Statement
+
+ Copyright (C) The Internet Society (2002). All Rights Reserved.
+
+ This document and translations of it may be copied and furnished to
+ others, and derivative works that comment on or otherwise explain it
+ or assist in its implementation may be prepared, copied, published
+ and distributed, in whole or in part, without restriction of any
+ kind, provided that the above copyright notice and this paragraph are
+ included on all such copies and derivative works. However, this
+ document itself may not be modified in any way, such as by removing
+ the copyright notice or references to the Internet Society or other
+ Internet organizations, except as needed for the purpose of
+ developing Internet standards in which case the procedures for
+ copyrights defined in the Internet Standards process must be
+ followed, or as required to translate it into languages other than
+ English.
+
+ The limited permissions granted above are perpetual and will not be
+ revoked by the Internet Society or its successors or assigns.
+
+ This document and the information contained herein is provided on an
+ "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
+ TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
+ BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
+ HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
+ MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
+
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projects / thirdparty / bind9.git / commitdiff
