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re: [dhcwg] dhcpv6 'zone suffix' option
Hi, all,
According to the discussion before, I revised the draft based on the common opinions.
Any question or suggestion will be appreciated.
-Yan
Internet Engineering Task Force Renxiang Yan
Internet Draft Yinglan Jiang
Expiration: May 2005 Luoning Gui
File: draft-yan-dhc-dhcpv6-opt-dnszone-02.txt Alcatel Shanghai Bell
Zone Suffix Option for DHCPv6
<Draft-yan-dhc-dhcpv6-opt-dnszone-02.txt>
December 24, 2004
Status of this Memo
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patent or other IPR claims of which I am aware have been disclosed,
or will be disclosed, and any of which I become aware will be
disclosed, in accordance with RFC 3668.
This document is an Internet-Draft and is in full conformance with
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Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This document specifies a new DHCPv6 (DHCP for IPv6) option which is
passed from an DHCPv6 server to an DHCPv6 client to specify the
zone suffix name used to construct and perform domain name update.
Yan, et. al. [Page 1]
Internet-Draft zone suffix option for DHCPv6 December 2004
1.0 Introduction
This document describes a new option for DHCPv6 [2] that provides a
mechanism for the transfer of a zone suffix name. Using this option,
an IPv6 device, which works as a DHCPv6 client, can configure the
zone suffix name automatically.
For example, a service provider would use this option to transfer a
zone suffix name to a Customer Premise Equipment (CPE) device acting
as a router between the subscriber's internal network and the service
provider's core network.
The configured zone suffix name is intended to be used by the IPv6
device to perform DNS update for the hosts inside its local network.
The DNS update can be realized by several methods. The DHCPv6 Client
FQDN Option [6] provides a mechanism to exchange client's FQDN
information during a stateful DHCPv6 session. DNS update mechanism
for IPv6 stateless configuration can be defined in the future.
1.1 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 RFC 2119 [4].
This document should be read in conjunction with the DHCPv6
specification, RFC 3315 [2]. Definitions for terms and acronyms used
in this document are defined in RFC 3315 and RFC 3633 [3].
2.0 Zone Suffix Option
The zone suffix option is used to carry a zone suffix to the DHCPv6
client, which will be used to construct and update the domain name
for the hosts in local network.
The format of the zone suffix option is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | zone suffix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ zone suffix (cont.) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: 8-bit identifier of the type of option (TBD).
Yan, et. al. [Page 2]
Internet-Draft zone suffix option for DHCPv6 December 2004
Length: Length of the "zone suffix" field in octets.
zone suffix: The specification of a zone suffix.
The zone suffix in the 'zone suffix' MUST include only one item, and
MUST be encoded as specified in section "Representation and use of
domain names" of RFC3315.
2.1 Usage
The zone suffix option MUST only appear in IA_PD-options field of
IA_PD option (see [3]) and apply to all prefixes for that binding.
One IA_PD-options field MUST include none or only one zone suffix
option.
A DHCPv6 client which needs a zone suffix name MUST include a zone
suffix option when sending DHCP Solicit message.
DHCPv6 server may allocate different zone suffix name to different
clients. This can avoid frequent domain name conflicts when
performing DNS update in large network. The mechanism through which
the server selects different zone suffix name for client is not
specified in this document.
3.0 Example and applicability
+------+
| Node +--+
+------+ |
|
+------+ |
| Node +--+ +----------+
+------+ | | |
: +-------+ +------------------+ | ISP Core |
+--+ CPE +----|Aggregation device|--| |
: +-------+ +------------------+ | Network |
+------+ | | |
| Node +--+ +----------+
+------+
\___________ __________/ \_________________ __________________/
\/ \/
Subscriber network ISP network
Yan, et. al. [Page 3]
Internet-Draft zone suffix option for DHCPv6 December 2004
The above figure shows a typical usage of the zone suffix option.
In this model, ISP has the ISP level domain name suffix (e.g.
example.com).
The CPE in the subscriber network, which acts as a requesting
router, initiates a DHCP session with the router in ISP network. An
IPv6 prefix, along with the corresponding zone suffix name (i.e.
example.com) will be transferred to the CPE.
The zone suffix name can then be used to construct can update domain
name for the hosts in subscriber network, by an embedded DHCPv6
server in CPE or by other means of DNS update mechanism for stateless
IPv6 configuration.
To avoid frequent domain name conflicts, aggregation device might
allocate different zone suffix name for the CPE. An example way can
be selection based on an external authority such as a RADIUS server,
in which an unique zone suffix name prefix, called "home name", are
negotiated between user and ISP when subscribing. For example,
"user1.example.com" and "user2.example.com".
4.0 Security Considerations
Security considerations in DHCP are described in section 23,
"Security Considerations" of RFC 3315.
A rogue DHCP server can issue bogus zone suffix to a client. This
may cause wrong domain name update.
A malicious client may be able to mount a denial of service attack
by repeated DHCP requests for zone suffix, thus exhausts the DHCP
server's resource.
Currently, it is difficult for DHCP servers to develop much
confidence in the identities of its clients, given the absence of
entity authentication from the DHCP protocol itself. To guard against
attack, DHCP Authentication as described in section 21 of RFC 3315
can be used.
Copyright notice
Copyright (C) The Internet Society (2004). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
Yan, et. al. [Page 4]
Internet-Draft zone suffix option for DHCPv6 December 2004
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
References
[1] Deering, S. and R. Hiden, "Internet Protocol, Version 6 (IPv6)
Specification", RFC2460, December 1998.
[2] Bound, J., Carney, M., Perkins, C., Lemon, T., Volz, B. and R.
Droms (ed.), "Dynamic Host Configuration Protocol for IPv6
(DHCPv6)", RFC 3315, May 2003.
[3] O. Troan, R. Droms, "IPv6 prefix option for DHCPv6", RFC3363,
December 2003.
[4] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[5] P. Vixie, S. Thomson, Y. Rekhter and J. Bound, "Dynamic Updates
in the Domain Name System (DNS UPDATE)", RFC2136, April 1997.
[6] B. Volz, "The DHCPv6 Client FQDN Option", draft-ietf-dhc-
dhcpv6-fqdn-00.txt, September, 2004.
[7] Wellington, B., "Secure Domain Name System (DNS) Dynamic
Update", RFC 3007, November 2000.
[8] Mockapetris, P., "Domain names - concepts and facilities", STD
13, RFC 1034, November 1987.
Author Information:
Renxiang Yan
Yinglan Jiang
Luoning Gui
Research & Innovation Center
Alcatel Shanghai Bell Co., Ltd.
388#, NingQiao Road, Pudong Jinqiao
Shanghai 201206 P.R. China
Phone: +86 (21) 5854-1240
Email: renxiang.yan at alcatel-sbell.com.cn
Yinglan.jiang at alcatel-sbell.com.cn
Luoning.gui at alcatel-sbell.com.cn
Yan, et. al. [Page 5]
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