DHC Working Group R. Yan Internet Draft Y. Jiang Expiration Date:
JuneAugust 2006 L. Gui Alcatel Shanghai Bell X. Duan China Mobile Domain Suffix Option for DHCPv6 <draft-ietf-dhc-dhcpv6-opt-dnsdomain-00.txt> September 26, 2005<draft-ietf-dhc-dhcpv6-opt-dnsdomain-01.txt> February 6, 2006 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on June 26,August 6, 2006. Copyright Notice Copyright (C) The Internet Society (2005).(2006). Abstract This document specifies a new DHCPv6 (DHCP for IPv6) option which is passed from a DHCPv6 server to a DHCPv6 client to specify the domain suffix name used to perform domain name update.name. 1. Introduction This document describes a new option for DHCPv6 [RFC3315] that provides a mechanism for the transfer of a domain suffix name.name suffix. Using this option, an IPv6 device, which works as athe DHCPv6 client,server can configurespecify the domain suffixname automatically. For example, a service provider could use this option to transfer a domainsuffix nameto 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 domain 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, e.g.the DHCPv6 Client FQDN Option [FQDNv6] provides a mechanism to exchange client's FQDN information during a stateful DHCPv6 session, and [RADNS] defines a DNS update mechanism for IPv6 stateless configuration.client. 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 [RFC2119]. This document should be read in conjunction with the DHCPv6 specification, [RFC3315]. Definitions for terms and acronyms used in this document are defined in [RFC3315] and [RFC3633].RFC3315. 2. Domain Suffix Option The domain suffix option for DHCPv6 is used to carry a domain suffix toby the DHCPv6 client, which will be usedserver to construct and updatetell the DHCPv6 client the domain name forsuffix that the hosts in local network.DHCPv6 server administrator has specified for that DHCPv6 client. The format of the domain 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Domain suffix ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: 16-bits identifier of the type of option (TBD). Length: Length of the "domain suffix" field in octets. Domain suffix: The specification of a domain suffix. The domain suffix in the 'domain suffix' field MUST include only one item, and MUST be encoded as specified in the section of RFC3315 titled "Representation and use of domain names" of [RFC3315].names". 2.1 Usage In stateful DHCPv6 [RFC3315], the DHCPv6 server MAY place a domain suffix option in the options field of IA_PD option [RFC3363] in an outgoing DHCPv6 message. The DHCPv6 server MUST NOT place a domain suffix option in any other portion of a stateful DHCPv6 message. In stateless DHCPv6 [RFC3736], the DHCPv6 server MAY place a domain suffix option in the main option buffer of any DHCPv6 message sent to a client.A DHCPv6 server may provide different values for the domain suffix option to different clients. This is useful to avoid domain name conflict in large-scale network.The mechanism for choosing which suffix to assign to which client is a matter of implementation and administrative policy, and is therefore not specified in this document. 3. Example +-------+ +------+ + CPE +-+ | Node +--+ +-------+ | +------+ | | | +-------+ | +------+ | + CPE +-+ | Node +--+ +-------+ | +----------+ +------+ | : | | : +-------+ | +------------------+ | ISP Core | +----+ CPE +-+--|Aggregation device|--| | +------+ | +-------+ +------------------+ | Network | | Node +--+ | | +------+ +----------+ \____________ __________/ \_________________ ________________/ \/ \/ Subscriber network ISP network The above figure shows a typical usage of the domain suffix option. In this model, ISP has the ISP level domain name suffix (e.g. example.com). CPE in subscriber network may include a DNS server for name resolution for local hosts. The CPE in the subscriber network, which acts as a requesting router, initiates a DHCPv6 session with the ISP's aggregation device, acting as a delegation route. During the DHCP session, an IPv6 prefix, along with the corresponding domain suffix name (i.e. example.com) will be transferred to the CPE. The domain suffix name can then be used to construct the domain name for the hosts in subscriber network, using mechanisms defined in [FQDNv6] or [RADNS]. To avoid frequent domain name conflicts, aggregation device might allocate different domain suffix name for the CPEs. An example way can be selection based on an external authority such as a RADIUS server, in which a unique domain suffix name prefix, called "home name", is negotiated between user and ISP when subscribing. For example, "user1.example.com" and "user2.example.com". 4.Security Considerations Security considerations in DHCP are described in section 23, "Security Considerations" of [RFC3315]. A rogue DHCP server can issue bogus domain 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 domain 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 [RFC3315] can be used. 5.RFC3315. 4. IANA Considerations IANA is requested to assign a DHCPv6 option code for the Domain Suffix Option. 6.5. Acknowledgements The authors thank Ralph Droms, Ted Lemon, Bernie Volz, Tatuya Jinmei, Joe Quanaim and Stefaan De Cnodder for valuable discussions and comments. 7.6. References 7.16.1 Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3315] 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. [RFC3363] O. Troan, R. Droms, "IPv6 prefix option for DHCPv6", RFC 3363, December 2003. 7.2 Informative References [FQDNv6] B. Volz, "The DHCPv6 Client FQDN Option", draft-ietf-dhc- dhcpv6-fqdn-00.txt, September, 2004. [RFC3736] R. Droms, "Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6", RFC 3736, April 2004. [RADNS] R. Yan, "DNS update in IPv6 stateless configuration", draft-yan-ipv6-ra-dns-01.txt, June 2005.Authors' Addresses 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, ext. 7169 Email: email@example.com Yinglan.firstname.lastname@example.org Luoning.email@example.com Xiaodong Duan Research & Development Center China Mobile Communications Corporation 53A, Xibianmennei Ave., Xuanwu District, Beijing, 100053 P.R. China Phone: +86 (10) 6600-6688, ext. 3062 Email: firstname.lastname@example.org Full Copyright Statement Copyright (C) The Internet Society (2005). 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 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. 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