Network Working Group J. Jeong, Ed.
Request for Comments: 5006 ETRI/University of Minnesota
Category: Experimental S. Park
SAMSUNG Electronics
L. Beloeil
France Telecom R&D
S. Madanapalli
Ordyn Technologies
September 2007
IPv6 Router Advertisement Option for DNS Configuration
Status of This Memo
This memo defines an Experimental Protocol for the Internet
community. It does not specify an Internet standard of any kind.
Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
Abstract
This document specifies a new IPv6 Router Advertisement option to
allow IPv6 routers to advertise DNS recursive server addresses to
IPv6 hosts.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Applicability Statements . . . . . . . . . . . . . . . . . 2
1.2. Coexistence of RDNSS Option and DHCP Option . . . . . . . 2
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Neighbor Discovery Extension . . . . . . . . . . . . . . . . . 4
5.1. Recursive DNS Server Option . . . . . . . . . . . . . . . 4
5.2. Procedure of DNS Configuration . . . . . . . . . . . . . . 5
5.2.1. Procedure in IPv6 Host . . . . . . . . . . . . . . . . 5
6. Implementation Considerations . . . . . . . . . . . . . . . . 6
6.1. DNS Server List Management . . . . . . . . . . . . . . . . 6
6.2. Synchronization between DNS Server List and Resolver
Repository . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.1. Normative References . . . . . . . . . . . . . . . . . . . 9
10.2. Informative References . . . . . . . . . . . . . . . . . . 9
Jeong, et al. Experimental [Page 1]RFC 5006 IPv6 RA Option for DNS Configuration September 20071. Introduction
Neighbor Discovery (ND) for IP Version 6 and IPv6 Stateless Address
Autoconfiguration provide ways to configure either fixed or mobile
nodes with one or more IPv6 addresses, default routers and some other
parameters [2][3]. To support the access to additional services in
the Internet that are identified by a DNS name, such as a web server,
the configuration of at least one recursive DNS server is also needed
for DNS name resolution.
It is infeasible for nomadic hosts, such as laptops, to be configured
manually with a DNS resolver each time they connect to a different
wireless LAN (WLAN) such as IEEE 802.11 a/b/g [12]-[15]. Normally,
DHCP [6]-[8] is used to locate such resolvers. This document
provides an alternate, experimental mechanism which uses a new IPv6
Router Advertisement (RA) option to allow IPv6 routers to advertise
DNS recursive server addresses to IPv6 hosts.
1.1. Applicability Statements
The only standards-track DNS configuration mechanism in the IETF is
DHCP, and its support in hosts and routers is necessary for reasons
of interoperability.
RA-based DNS configuration is a useful, optional alternative in
networks where an IPv6 host's address is autoconfigured through IPv6
stateless address autoconfiguration, and where the delays in
acquiring server addresses and communicating with the servers are
critical. RA-based DNS configuration allows the host to acquire the
nearest server addresses on every link. Furthermore, it learns these
addresses from the same RA message that provides configuration
information for the link, thereby avoiding an additional protocol
run. This can be beneficial in some mobile environments, such as
with Mobile IPv6 [10].
The advantages and disadvantages of the RA-based approach are
discussed in [9] along with other approaches, such as the DHCP and
well-known anycast addresses approaches.
1.2. Coexistence of RDNSS Option and DHCP Option
datatracker.ietf.org