Selecting Labels for Use with Conventional DNS and Other Resolution Systems in DNS-Based Service Discovery
RFC 8222
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Type |
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RFC - Informational
(September 2017; No errata)
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Last updated |
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2017-09-21
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Replaces |
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draft-sullivan-dnssd-mdns-dns-interop
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Stream |
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IETF
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Formats |
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plain text
pdf
html
bibtex
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Reviews |
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TSVART,
OPSDIR
will not review this version
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WG state
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Submitted to IESG for Publication
(wg milestones:
Mar 2014 - Adopt Informational ...,
Sep 2015 - Submit the zeroconf ...
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Document shepherd |
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Suzanne Woolf
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Shepherd write-up |
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Show
(last changed 2017-02-22)
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| IESG |
IESG state |
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RFC 8222 (Informational)
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Consensus Boilerplate |
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Yes
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Telechat date |
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Responsible AD |
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Terry Manderson
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Send notices to |
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"Suzanne Woolf" <suzworldwide@gmail.com>
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| IANA |
IANA review state |
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IANA OK - No Actions Needed
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IANA action state |
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No IC
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Internet Engineering Task Force (IETF) A. Sullivan
Request for Comments: 8222 Oracle
Category: Informational September 2017
ISSN: 2070-1721
Selecting Labels for Use with Conventional DNS and
Other Resolution Systems in DNS-Based Service Discovery
Abstract
Despite its name, DNS-Based Service Discovery (DNS-SD) can use naming
systems other than DNS when looking for services. Moreover, when it
uses DNS, DNS-SD uses the full capability of DNS, rather than using a
subset of available octets. This is of particular relevance where
some environments use DNS labels that conform to Internationalized
Domain Names for Applications (IDNA), and other environments use
labels containing Unicode characters (such as containing octets
corresponding to characters encoded as UTF-8). In order for DNS-SD
to be used effectively in environments where multiple different name
systems and conventions for their operation are in use, it is
important to attend to differences in the underlying technology and
operational environment. This memo presents an outline of the
requirements for the selection of labels for conventional DNS and
other resolution systems when they are expected to interoperate in
this manner.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8222.
Sullivan Informational [Page 1]
RFC 8222 DNS-SD Label Selection September 2017
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions and Terms Used in This Document . . . . . . . 3
2. Why There Could Be a Problem at All . . . . . . . . . . . . . 4
3. Requirements for a Profile for Label Interoperation . . . . . 5
4. DNS-SD Portions . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. The <Instance> Portion of the Service Instance Name . . . 6
4.2. The <Service> Portion of the Service
Instance Name . . . . . . . . . . . . . . . . . . . . . . 7
4.3. The <Domain> Portion of the Service Instance Name . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. Informative References . . . . . . . . . . . . . . . . . . . 9
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
DNS-Based Service Discovery (DNS-SD, [RFC6763]) specifies a mechanism
for discovering services using queries to DNS ([RFC1034] and
[RFC1035]) and to any other system that uses domain names, such as
Multicast DNS (mDNS, [RFC6762]). Many applications that use DNS
follow "Internet hostname" syntax [RFC952] for labels -- the
so-called LDH (letters, digits, and hyphen) rule. That convention is
the reason behind the development of Internationalized Domain Names
for Applications (IDNA2008, [RFC5890], [RFC5891], [RFC5892],
[RFC5893], [RFC5894], and [RFC5895]). It is worth noting that the
LDH rule is a convention, and not a rule of the DNS; this is made
entirely plain by Section 11 of [RFC2181], and discussed further in
Section 3 of [RFC6055]. Nevertheless, there is a widespread belief
that in many circumstances domain names cannot be used in the DNS
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