On Interoperation of Labels Between mDNS and DNS
draft-ietf-dnssd-mdns-dns-interop-00

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DNSSD                                                        A. Sullivan
Internet-Draft                                                       Dyn
Intended status: Informational                             March 4, 2015
Expires: September 5, 2015

            On Interoperation of Labels Between mDNS and DNS
                  draft-ietf-dnssd-mdns-dns-interop-00

Abstract

   Despite its name, DNS-Based Service Discovery can use naming systems
   other than the Domain Name System when looking for services.
   Different name systems use different conventions for the characters
   allowed in any name.  In order for DNS-SD to be used effectively in
   environments where multiple different name systems are in use, it is
   important to attend to differences in the underlying technology.
   This memo presents an outline of the requirements for selection of
   labels for mDNS and DNS when they are expected to interoperate in
   this manner.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on September 5, 2015.

Copyright Notice

   Copyright (c) 2015 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
   (http://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

Sullivan                Expires September 5, 2015               [Page 1]
Internet-Draft            mDNS and DNS Interop                March 2015

   to this document.  Code Components extracted from this document must
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions and terms used in this document . . . . . . .   3
   2.  Requirements for a profile for label interoperation . . . . .   3
   3.  DNS-SD portions . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  The <Instance> Portion of the Service     Instance Name .   4
     3.2.  The <Service> Portion of the Service     Instance Name  .   5
     3.3.  The <Domain> Portion of the     Service Instance Name . .   5
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  Informative References  . . . . . . . . . . . . . . . . . . .   7
   Appendix A.  Change History . . . . . . . . . . . . . . . . . . .   8
     A.1.  draft-ietf-dnssd-mdns-dns-interop-00  . . . . . . . . . .   8
     A.2.  draft-sullivan-dnssd-mdns-dns-interop-01  . . . . . . . .   8
     A.3.  draft-sullivan-dnssd-mdns-dns-interop-00  . . . . . . . .   8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   DNS-Based Service Discovery (DNS-SD, [RFC6763]) specifies a mechanism
   for discovering services using queries both to the Domain Name System
   (DNS, [RFC1034], [RFC1035]) and to Multicast DNS (mDNS, [RFC6762]).
   Conventional use of the DNS generally follows the host name rules
   [RFC0952] for labels -- the so-called LDH rule.  That convention is
   the reason behind the development of Internationalized Domain Names
   for Applications (IDNA2008, [RFC5890], [RFC5891], [RFC5892],
   [RFC5893], [RFC5894], [RFC5895]).  It is worth noting that the LDH
   rule is a convention, and not a strict rule of the DNS.  It is
   assumed to be true widely enough, however, that in many circumstances
   names cannot be used unless they cleave to the LDH rule.

   At the same time, mDNS requires that labels be encoded in UTF-8, and
   permits a range of characters in labels that are not permitted by
   IDNA2008 or the LDH rule.  For example, mDNS encourages the use of
   spaces and punctuation in mDNS names (see [RFC6763], section 4.1.3).
   It does not restrict which Unicode code points may be used in those
   labels, so long as the code points are UTF-8 in Net-Unicode [RFC5198]
   format.

   Users of applications are, of course, frequently unconcerned with
   (not to say oblivious to) the name-resolution system(s) in service at
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