Requirements for Scalable DNS-Based Service Discovery (DNS-SD) / Multicast DNS (mDNS) Extensions
RFC 7558
Internet Engineering Task Force (IETF) K. Lynn
Request for Comments: 7558 Verizon Labs
Category: Informational S. Cheshire
ISSN: 2070-1721 Apple, Inc.
M. Blanchet
Viagenie
D. Migault
Ericsson
July 2015
Requirements for Scalable DNS-Based Service
Discovery (DNS-SD) / Multicast DNS (mDNS) Extensions
Abstract
DNS-based Service Discovery (DNS-SD) over Multicast DNS (mDNS) is
widely used today for discovery and resolution of services and names
on a local link, but there are use cases to extend DNS-SD/mDNS to
enable service discovery beyond the local link. This document
provides a problem statement and a list of requirements for scalable
DNS-SD.
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 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7558.
Lynn, et al. Informational [Page 1]
RFC 7558 Scalable DNS-SD Requirements July 2015
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4
3. Basic Use Cases . . . . . . . . . . . . . . . . . . . . . . . 6
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Namespace Considerations . . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
Acknowedgements . . . . . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
DNS-based Service Discovery [DNS-SD] in combination with its
companion technology Multicast DNS [mDNS] is widely used today for
discovery and resolution of services and names on a local link. As
users move to multi-link home or campus networks, however, they find
that mDNS (by design) does not work across routers. DNS-SD can also
be used in conjunction with conventional unicast DNS to enable
wide-area service discovery, but this capability is not yet widely
deployed. This disconnect between customer needs and current
practice has led to calls for improvement, such as the Educause
petition [EP].
In response to this and similar evidence of market demand, several
products now enable service discovery beyond the local link using
different ad hoc techniques. As of yet, no consensus has emerged
regarding which approach represents the best long-term direction for
DNS-based Service Discovery protocol development.
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RFC 7558 Scalable DNS-SD Requirements July 2015
Multicast DNS in its present form is also not optimized for network
technologies where multicast transmissions are relatively expensive.
Wireless networks such as Wi-Fi [IEEE.802.11] may be adversely
affected by excessive mDNS traffic due to the higher network overhead
of multicast transmissions. Wireless mesh networks such as IPv6 over
Low-Power Wireless Personal Area Network (6LoWPAN) [RFC4944] are
effectively multi-link subnets [RFC4903] where multicasts must be
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