Network Time Protocol (NTP) Server Option for DHCPv6
RFC 5908
Internet Engineering Task Force (IETF) R. Gayraud
Request for Comments: 5908 Unaffiliated
Category: Standards Track B. Lourdelet
ISSN: 2070-1721 Cisco Systems, Inc.
June 2010
Network Time Protocol (NTP) Server Option for DHCPv6
Abstract
The NTP Server Option for Dynamic Host Configuration Protocol for
IPv6 (DHCPv6) provides NTPv4 (Network Time Protocol version 4) server
location information to DHCPv6 hosts.
Status of This Memo
This is an Internet Standards Track document.
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). Further information on
Internet Standards is available in 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/rfc5908.
Copyright Notice
Copyright (c) 2010 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
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.
Gayraud & Lourdelet Standards Track [Page 1]
RFC 5908 NTP Server Option for DHCPv6 June 2010
Table of Contents
1. Introduction ....................................................2
2. Requirements Notation ...........................................2
3. Related Work and Usage Model ....................................2
4. NTP Server Option for DHCPv6 ....................................3
4.1. NTP Server Address Suboption ...............................4
4.2. NTP Multicast Address Suboption ............................5
4.3. NTP Server FQDN Suboption ..................................6
5. Appearance of This Option .......................................6
6. Security Considerations .........................................7
7. RFC 4075 Deprecation ............................................7
8. IANA Considerations .............................................7
9. References ......................................................8
9.1. Normative References .......................................8
9.2. Informative References .....................................8
1. Introduction
This document defines a DHCPv6 option and associated suboptions to
provide Network Time Protocol version 4 [RFC5905] or greater server
location information to DHCPv6 hosts.
2. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Related Work and Usage Model
The NTP service is publicly offered on the Internet by a number of
organizations. Those servers can be used but should not be abused,
so any method that is tasked to disseminate locations of NTP servers
must act responsibly in a manner that does not lead to public server
overloading. When using DHCPv6 to offer NTP server location, and if
there is a need to distribute a host with a hardcoded configuration,
this configuration MUST NOT include server location that is not part
of the organization that distributes this device. Typical usage of
this option is to specify an NTP server that is part of the
organization that operates the DHCPv6 server.
The location of the NTP service, like any other Internet service, can
be specified by an IP address or a Fully Qualified Domain Name
(FQDN). By design, DHCP offers information to multiple devices and
is prone to amplification of mistakes, so great care must be taken to
define its configuration. Specification of the NTP service by FQDN
offers a level of indirection that works as a possible mitigation
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RFC 5908 NTP Server Option for DHCPv6 June 2010
tool in case of misconfiguration. DNS can be used to redirect
misconfigured clients to an IPv6 address that is not configured on
any host instead of having to change the address of the NTP server
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