Network Working Group J. Abley Internet-Draft Dyn, Inc. Intended status: BCP October 18, 2013 Expires: April 21, 2014 DNS Reverse Mapping for Multicast Addresses draft-jabley-multicast-ptr-00 Abstract The mapping of IPv4 and IPv6 addresses to names using the Domain Name System (DNS) is colloquially known as "Reverse Mapping". Reverse Mapping support for registered multicast address assignments in IPv4 is currently incomplete and ad-hoc; in IPv6 there is no support at all. This document describes procedures to be followed that will result in more systematic and predictable support for Reverse Mapping for IPv4 multicast address assignments, and introduces analogous support for IPv6. 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." This Internet-Draft will expire on April 21, 2014. Copyright Notice Copyright (c) 2013 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 Abley Expires April 21, 2014 [Page 1] Internet-Draft Reverse Mapping for Multicast October 2013 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. General Approach . . . . . . . . . . . . . . . . . . . . . . . 4 3. Naming Scheme . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. IPv4 Multicast Addresses . . . . . . . . . . . . . . . . . 5 3.2. IPv6 Multicast Addresses . . . . . . . . . . . . . . . . . 5 4. Use of MCAST.ARPA . . . . . . . . . . . . . . . . . . . . . . 6 5. IAB Considerations . . . . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6.1. Registry Changes . . . . . . . . . . . . . . . . . . . . . 8 6.1.1. IPv6 Multicast Scope Registry . . . . . . . . . . . . 8 6.1.2. IPv4 Multicast Address Space Registries . . . . . . . 8 6.1.3. IPv6 Multicast Address Space Registries . . . . . . . 9 6.2. Delegation of MCAST.ARPA and MCAST6.ARPA . . . . . . . . . 9 6.3. Initial Zone Contents . . . . . . . . . . . . . . . . . . 9 6.4. Process Changes . . . . . . . . . . . . . . . . . . . . . 11 6.5. Ongoing Support for MCAST.NET . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 9.1. Normative References . . . . . . . . . . . . . . . . . . . 15 9.2. Informative References . . . . . . . . . . . . . . . . . . 15 Appendix A. Editorial Notes . . . . . . . . . . . . . . . . . . . 16 A.1. Change History . . . . . . . . . . . . . . . . . . . . . . 16 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 17 Abley Expires April 21, 2014 [Page 2] Internet-Draft Reverse Mapping for Multicast October 2013 1. Introduction The Domain Name System (DNS), as originally specified in [RFC1034] and [RFC1035], provides support for the mapping of IPv4 addresses to names using a namespace convention within the IN-ADDR.ARPR domain and the PTR resoure record type. The analogous mapping of IPv6 address to names is specified in [RFC3596], adopting a similar namespace convention within the IP6.ARPA domain. Multicast addresses are assigned by the IANA, and assignments are documented in various IANA registries. For IPv4, Reverse Mapping of assigned multicast addresses to names has historically been provided in an ad-hoc and incomplete fashion, without tight coordination with IANA multicast address assignment processes. Names assigned to IPv4 multicast addresses have been chosen somewhat arbitrarily within the MCAST.NET domain. For IPv6, no Reverse Mapping is provided. This document describes procedures to be followed by the IANA to support predictable and consistent Reverse Mapping for registered multicast addresses in IPv4 and IPv6. Abley Expires April 21, 2014 [Page 3] Internet-Draft Reverse Mapping for Multicast October 2013 2. General Approach This document specifies extensions to existing IPv4 and IPv6 multicast registries to include a mandatory column "DNS Label". This field is required to be popluated with a unique, valid DNS label for all future multicast address assignments except in the case where reverse mapping for an address is explicitly not desirable. The procedures at the IANA relating to multicast address assignment are extended to include the provisioning of appropriate changes in the DNS at the time of registration or de-registration of any multicast addresses. Specific actions requested of the IANA are described in Section 6. Names for multicast addresses are assigned under MCAST.ARPA for IPv4 addresses, and MCAST6.ARPA for IPv6 addresses. The naming schemes to bs used in each case are described in Section 3. The use of MCAST.ARPA rather than MCAST.NET is discussed in Section 4. Abley Expires April 21, 2014 [Page 4] Internet-Draft Reverse Mapping for Multicast October 2013 3. Naming Scheme 3.1. IPv4 Multicast Addresses Each assigned IPv4 multicast address has an accompanying DNS Label. The name associated with an IPv4 multicast address with DNS Label SOMENAME is SOMENAME.MCAST.ARPA. For example, suppose the assigned IPv4 multicast address 224.0.1.1 has the DNS Label "NTP". The address 224.0.1.1 maps to the name "NTP.MCAST.ARPA"; the name "NTP.MCAST.ARPA" maps to the address 224.0.1.1. 3.2. IPv6 Multicast Addresses Each assigned IPv6 multicast address has an accompanying DNS Label ("Address Label"). IPv6 multicast addresses may be of fixed or variable scope. The naming scheme for these addresses incorporates a scope identifier using an additional DNS label ("Scope Label"), specified in a dedicated registry (see Section 6.1.1). Both fixed and variable scope multicast addresses use the same naming scheme. The name associated with an IPv6 multicast address with Scope Label SCOPE and Address Label SOMENAME is SOMENAME.SCOPE.MCAST6.ARPA. For example, suppose ff01::1 is an assigned IPv6 multicast address with Scope Label "NODE-LOCAL" and Address Label "ALL-NODES". The address ff01::1 maps to the name "ALL-NODES.NODES-LOCAL.MCAST6.ARPA"; the name "ALL-NODES.NODES-LOCAL.MCAST6.ARPA" maps to the address ff01::1. The variable-scope multicast address ff0x::fb will have different Reverse Mapping depending on the scope specified in the address (i.e. the value of x), although the Address Label in each case will be the same ("MDNSV6"). The Site-Local address ff05::fb has an associated Scope Label "SITE-LOCAL", and is therefore named MDNSV6.SITE- LOCAL.MCAST6.ARPA. The Link-Local address ff02::fb has an associated Scope Label "LINK-LOCAL" and hence is named MDNSV6.LINK- LOCAL.MCAST6.ARPA. Abley Expires April 21, 2014 [Page 5] Internet-Draft Reverse Mapping for Multicast October 2013 4. Use of MCAST.ARPA Use of the MCAST.ARPA domain rather than MCAST.NET for IPv4 multicast addresses is specified for the same reasons that led IP6.INT to be superceded by "IP6.ARPA" [RFC3152]. It is prudent to assume that hard-coded assumptions about names in MCAST.NET exist, and will persist for some time. This document specifies that names in the MCAST.ARPA domain also be available in the MCAST.NET domain, to provide support for software with those assumptions. Ongoing support for the MCAST.NET zone is described in Section 6.5. It is possible that in the future empirical measurement will confirm that the use of names under MCAST.NET is no longer required and that provisioning of the MCAST.NET domain can safely cease. This document provides no such measurement and makes no such recommendation, however. Abley Expires April 21, 2014 [Page 6] Internet-Draft Reverse Mapping for Multicast October 2013 5. IAB Considerations This document proposes a delegation within the ARPA domain, and, in accordance with [RFC3172], IAB review and approval of the delegation of MCAST.ARPA and MCAST6.ARPA as described in Section 6.2 is required. Once IAB approval has been obtained, this section may be removed prior to publication or updated to include text that confirms the IAB's decision, at the IAB's discretion. Abley Expires April 21, 2014 [Page 7] Internet-Draft Reverse Mapping for Multicast October 2013 6. IANA Considerations 6.1. Registry Changes 6.1.1. IPv6 Multicast Scope Registry The IANA is directed to create a new registry as follows: Registry Name: IPv6 Multicast Address Scopes Registration Procedure: Standards Action Reference: This document Schema: See initial contents, below. Note that the Scope Value and DNS Label fields are mandatory for all rows, and that values chosen for future DNS Label fields are required to be unique within this registry. The initial contents of this new registry should be: +-------------+-------------+--------------------------+-----------+ | Scope Value | DNS Label | Scope Name | Reference | +-------------+-------------+--------------------------+-----------+ | 0x0 | (none) | Reserved | [RFC4291] | | | | | | | 0x1 | NODE-LOCAL | Node-Local Scope | [RFC4291] | | | | | | | 0x2 | LINK-LOCAL | Link-Local Scope | [RFC4291] | | | | | | | 0x3 | (none) | Reserved | [RFC4291] | | | | | | | 0x4 | ADMIN-LOCAL | Admin-Local Scope | [RFC4291] | | | | | | | 0x5 | SITE-LOCAL | Site-Local Scope | [RFC4291] | | | | | | | 0x8 | ORG-LOCAL | Organisation-Local Scope | [RFC4291] | | | | | | | 0xE | GLOBAL | Global Scope | [RFC4291] | +-------------+-------------+--------------------------+-----------+ The IANA may add "Date Registered" and "Last Revised" columns to the schema at its discretion. 6.1.2. IPv4 Multicast Address Space Registries The IANA is directed to add a mandatory "DNS Label" column to all IPv4 Multicast Address Space registries. The initial contents of the Abley Expires April 21, 2014 [Page 8] Internet-Draft Reverse Mapping for Multicast October 2013 DNS Label field for each row should be taken from the corresponding MCAST.NET zone owner names where available; addresses with no existing mapping in MCAST.NET should have DNS Labels assigned by the IANA at their discretion. All existing assignments should have a DNS Label assigned. A DNS Label should be mandatory for all future registrations. DNS Labels are required to be unique for all IPv4 multicast address assignments. 6.1.3. IPv6 Multicast Address Space Registries The IANA is directed to add a mandatory "DNS Label" column to all IPv6 Multicast Address Space registries. The initial contents of the DNS Label field for each row should be assigned by the IANA at their discretion. All existing assignments should have a DNS Label assigned. A DNS Label should be mandatory for all future registrations. DNS Labels are required to be unique for all IPv6 multicast address assignments. 6.2. Delegation of MCAST.ARPA and MCAST6.ARPA The IANA is directed to create and host the MCAST.ARPA and MCAST6.ARPA zones on name servers of their choosing. The MCAST.ARPA and MCAST6.ARPA zones should be signed using DNSSEC, with DNSSEC parameters chosen by the IANA. The initial zone contents should be as described in Section 6.3. The IANA is directed to provision secure delegations for the MCAST.ARPA and MCAST6.ARPA zones from the ARPA zone (i.e. delegations with accompanying DS RRSets). 6.3. Initial Zone Contents The IANA is directed to populate the MCAST.ARPA and MCAST6.ARPA zones, and the corresponding reverse mapping zones under IN-ADDR.ARPA and IP6.ARPA, directly from the IPv4 and IPv6 Multicast Address Registries, amended as described in Section 6.1. As an example, if the IPv6 Variable Scope Multicast Addresses sub- registry contained the following entry: +-------------+-------------+-----------+ | Address(es) | Description | DNS Label | +-------------+-------------+-----------+ | FF0X::FB | mDNSv6 | MDNSV6 | +-------------+-------------+-----------+ Abley Expires April 21, 2014 [Page 9] Internet-Draft Reverse Mapping for Multicast October 2013 then the following DNS records would be required: $ORIGIN MCAST6.ARPA. ; ; all scoped addresses for mDNSv6 ; MDNSV6.NODE-LOCAL AAAA FF01::FB MDNSV6.LINK-LOCAL AAAA FF02::FB MDNSV6.ADMIN-LOCAL AAAA FF04::FB MDNSV6.SITE-LOCAL AAAA FF05::FB MDNSV6.ORG-LOCAL AAAA FF08::FB MDNSV6.GLOBAL AAAA FF0E::FB $ORIGIN 0.F.F.IP6.ARPA. ; ; all scoped addresses for mDNSv6 (split across lines for clarity) ; B.F.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1 \ PTR MDNSV6.NODE-LOCAL.MCAST6.ARPA. B.F.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2 \ PTR MDNSV6.LINK-LOCAL.MCAST6.ARPA. B.F.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.4 \ PTR MDNSV6.ADMIN-LOCAL.MCAST6.ARPA. B.F.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.5 \ PTR MDNSV6.SITE-LOCAL.MCAST6.ARPA. B.F.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8 \ PTR MDNSV6.ORG-LOCAL.MCAST6.ARPA. B.F.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.E \ PTR MDNSV6.GLOBAL.MCAST6.ARPA. As a further example, if the IPv4 Internetwork Control Block Multicast Address Registry contained the following entry: +-------------+--------------+-----------+ | Address(es) | Description | DNS Label | +-------------+--------------+-----------+ | 224.0.1.2 | SGI-Dogfight | SGI-DOG | +-------------+--------------+-----------+ then the following DNS records would be required: Abley Expires April 21, 2014 [Page 10] Internet-Draft Reverse Mapping for Multicast October 2013 $ORIGIN MCAST.ARPA. ; ; SGI-Dogfight address ; SGI-DOG A 224.0.1.2 $ORIGIN 224.IN-ADDR.ARPA. ; ; SGI-Dogfight address ; 2.1.0 PTR SGI-DOG.MCAST.ARPA. 6.4. Process Changes The IANA is directed to require a valid and unique DNS Label to be specified within the existing processes of multicast address assignment in IPv4 and IPv6. The IANA is further directed to maintain the MCAST.ARPA, MCAST6.ARPA and related domains under IP6.ARPA and IN-ADDR.ARPA such that any additions, changes or deletions from the corresponding address registries are reflected accurately in the DNS. 6.5. Ongoing Support for MCAST.NET IANA is directed to remove all non-apex resource records from the MCAST.NET zone and to add an apex DNAME [RFC6672] with target MCAST.ARPA. The intention is to provide backwards compatibility for software that has hard-coded assumptions about naming conventions for IPv4 multicast addresses. For example, the following describes the result of this change for MCAST.NET SOA serial 2012123836, with DNSSEC resource records omitted for clarity: Abley Expires April 21, 2014 [Page 11] Internet-Draft Reverse Mapping for Multicast October 2013 $ORIGIN MCAST.NET. ; beginning of zone @ SOA SNS.DNS.ICANN.ORG. NOC.DNS.ICANN.ORG. ( 2012123836 7200 3600 604800 3600 ) NS A.IANA-SERVERS.NET. NS B.IANA-SERVERS.NET. NS C.IANA-SERVERS.NET. NS NS.ICANN.ORG. DNAME MCAST.ARPA. ; end of zone Abley Expires April 21, 2014 [Page 12] Internet-Draft Reverse Mapping for Multicast October 2013 7. Security Considerations This document presents no known additional security concerns to the Internet. Abley Expires April 21, 2014 [Page 13] Internet-Draft Reverse Mapping for Multicast October 2013 8. Acknowledgements Your name here, etc. Abley Expires April 21, 2014 [Page 14] Internet-Draft Reverse Mapping for Multicast October 2013 9. References 9.1. Normative References [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, November 1987. [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. [RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, "DNS Extensions to Support IP Version 6", RFC 3596, October 2003. [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006. 9.2. Informative References [RFC3152] Bush, R., "Delegation of IP6.ARPA", BCP 49, RFC 3152, August 2001. [RFC3172] Huston, G., "Management Guidelines & Operational Requirements for the Address and Routing Parameter Area Domain ("arpa")", BCP 52, RFC 3172, September 2001. [RFC6672] Rose, S. and W. Wijngaards, "DNAME Redirection in the DNS", RFC 6672, June 2012. Abley Expires April 21, 2014 [Page 15] Internet-Draft Reverse Mapping for Multicast October 2013 Appendix A. Editorial Notes This section (and sub-sections) to be removed prior to publication. A.1. Change History 00 Initial draft, circulated for the purposes of entertainment. Abley Expires April 21, 2014 [Page 16] Internet-Draft Reverse Mapping for Multicast October 2013 Author's Address Joe Abley Dyn, Inc. 470 Moore Street London, ON N6C 2C2 Canada Phone: +1 519 670 9327 Email: jabley@dyn.com Abley Expires April 21, 2014 [Page 17]