Hybrid Unicast/Multicast DNS-Based Service Discovery
draft-ietf-dnssd-hybrid-01

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Document Type Active Internet-Draft (dnssd WG)
Last updated 2015-10-19
Replaces draft-cheshire-dnssd-hybrid
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Internet Engineering Task Force                              S. Cheshire
Internet-Draft                                                Apple Inc.
Intended status: Standards Track                        October 19, 2015
Expires: April 21, 2016

          Hybrid Unicast/Multicast DNS-Based Service Discovery
                       draft-ietf-dnssd-hybrid-01

Abstract

   Performing DNS-Based Service Discovery using purely link-local
   Multicast DNS enables discovery of services that are on the local
   link, but not (without some kind of proxy or similar special support)
   discovery of services that are outside the local link.  Using a very
   large local link with thousands of hosts facilitates service
   discovery, but at the cost of large amounts of multicast traffic.

   Performing DNS-Based Service Discovery using purely Unicast DNS is
   more efficient and doesn't require excessively large multicast
   domains, but requires that the relevant data be available in the
   Unicast DNS namespace.  This can be achieved by manual DNS
   configuration (as has been done for many years at IETF meetings to
   advertise the IETF Terminal Room printer) but this is labor
   intensive, error prone, and requires a reasonable degree of DNS
   expertise.  The Unicast DNS namespace can be populated with the
   required data automatically by the devices themselves, but that
   requires configuration of DNS Update keys on the devices offering the
   services, which has proven onerous and impractical for simple devices
   like printers and network cameras.

   Hence a compromise is needed, that combines the ease-of-use of
   Multicast DNS with the efficiency and scalability of Unicast DNS.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

Cheshire                 Expires April 21, 2016                 [Page 1]
Internet-Draft     Hybrid uDNS/mDNS Service Discovery       October 2015

   This Internet-Draft will expire on April 21, 2016.

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
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   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.

Cheshire                 Expires April 21, 2016                 [Page 2]
Internet-Draft     Hybrid uDNS/mDNS Service Discovery       October 2015

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Conventions and Terminology Used in this Document  . . . . . .  5
   3.  Hybrid Proxy Operation . . . . . . . . . . . . . . . . . . . .  6
     3.1.  Delegated Subdomain for Service Discovery Records  . . . .  7
     3.2.  Domain Enumeration . . . . . . . . . . . . . . . . . . . .  8
       3.2.1.  Domain Enumeration via Unicast Queries . . . . . . . .  8
       3.2.2.  Domain Enumeration via Multicast Queries . . . . . . .  9
     3.3.  Delegated Subdomain for LDH Host Names . . . . . . . . . . 10
     3.4.  Delegated Subdomain for Reverse Mapping  . . . . . . . . . 12
     3.5.  Data Translation . . . . . . . . . . . . . . . . . . . . . 13
       3.5.1.  DNS TTL limiting . . . . . . . . . . . . . . . . . . . 13
       3.5.2.  Suppressing Unusable Records . . . . . . . . . . . . . 13
       3.5.3.  Application-Specific Data Translation  . . . . . . . . 14
     3.6.  Answer Aggregation . . . . . . . . . . . . . . . . . . . . 15
       3.6.1.  Discovery of LLQ or PUSH Notification Service  . . . . 17
   4.  Implementation Status  . . . . . . . . . . . . . . . . . . . . 18
     4.1.  Already Implemented and Deployed . . . . . . . . . . . . . 18
     4.2.  Partially Implemented  . . . . . . . . . . . . . . . . . . 18
     4.3.  Not Yet Implemented  . . . . . . . . . . . . . . . . . . . 19
   5.  IPv6 Considerations  . . . . . . . . . . . . . . . . . . . . . 19
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 20
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