IPv6 Group R. Droms
Internet-Draft Cisco Systems, Inc.
Expires: March 5, 2006 D. Evans
ARRIS International, Inc.
September 1, 2005
Time Protocol Servers Option for IPv6 DHCP
draft-droms-dhc-dhcpv6-rfc868-servers-00.txt
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Copyright (C) The Internet Society (2005).
Abstract
The Time Protocol Servers option for IPv6 DHCP (RFC 3315) carries the
IPv6 addresses of servers that a host should use for the Time
Protocol (RFC 868).
1. Introduction
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The Time Protocol [1] can be used to obtain the current time from a
server. The Time Protocol Servers option defined in this document
provides an option to provide the IPv6 addresses of Time Protocol
servers to a host through DHCP [2].
The option defined in this document is based on the IPv4 DHCP [3]
Time Server option [4]. This document has no effect on IPv4 DHCP,
which will continue to use the Time Server option to provide the IPv4
addresses of RFC 868 Time Protocol servers to clients.
2. Terminology
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 [5].
Throughout this document, unless indicated otherwise for clarity, the
acronym "DHCP" refers to "Dynamic Host Configuration Protocol for
IPv6" [2].
3. Format of the Time Protocol Servers option
The Time Protocol Servers option defines a list of Time Protocol
servers available to the DHCP client. The IPv6 address of each
server is included in the option. The addresses SHOULD be listed in
order of preference. The addresses MUST be unicast or anycast
addresses.
The Time Protocol Servers option has the following format:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_RFC868_SERVER | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| server-address1 |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| server-address2 |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| server-addressN |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_RFC868_SERVERS (TBD).
option-len 16 * N.
server-address1-N The IPv6 addresses of the Time Protocol servers.
4. Security Considerations
A server could use this option to return invalid or incorrect
addresses or valid addresses of malicious Time Protocol servers to
the client.
Authentication of DHCP messages [2] can be used to ensure that the
contents of this option are not altered in transit between the DHCP
server and client.
5. IANA Considerations
IANA is requested to assign an option code from the IPv6 DHCP options
registry to OPTION_RFC868_SERVER.
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6. Normative References
[1] Postel, J. and K. Harrenstien, "Time Protocol", STD 26, RFC 868,
May 1983.
[2] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M.
Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 3315, July 2003.
[3] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
March 1997.
[4] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997.
[5] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
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Authors' Addresses
Ralph Droms
Cisco Systems, Inc.
1414 Massachusetts Avenue
Boxborough, MA 01719
USA
Phone: +1 978.936.1674
Email: rdroms@cisco.com
D. R. Evans
ARRIS International, Inc.
7912 Fairview Road
Boulder, CO 80303
USA
Phone: +1 303.494.0394
Email: N7DR@arrisi.com
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Internet-Draft IPv6 DHCP Time Protocol Servers Option September 2005
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