Network Working Group K. Chowdhury Internet-Draft Starent Networks Expires: June 27, 2005 P. Yegani Cisco Systems L. Madour Ericsson December 27, 2004 DHCPv4 Options for Broadcast and Multicast Control Servers draft-ietf-dhc-bcmcv4-option-00.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. 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 become aware will be disclosed, in accordance with RFC 3668. 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 27, 2005. Copyright Notice Copyright (C) The Internet Society (2004). Abstract This document defines new options for Broadcast and Multicast Service controller discovery in an IP network. Broadcast service is being developed for 3G wireless networks. Users of the service interact with a controller in the network to derive informations that are Chowdhury, et al. Expires June 27, 2005 [Page 1] Internet-Draft December 2004 required to receive broadcast service. Dynamic Host Configuration Protocol can be used to configure the controller IPv4 addresses or fully qualified domain names in the user's devices. This document defines the related options and option codes. Table of Contents 1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Overview of the 3GPP2 BCMCS Network . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Broadcast Service Controller Options . . . . . . . . . . . . . 6 4.1 Broadcast Service Controller Domain Name list . . . . . . 6 4.2 Broadcast Service Controller IPv4 address option . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 8. Normative References . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 10 Intellectual Property and Copyright Statements . . . . . . . . 12 Chowdhury, et al. Expires June 27, 2005 [Page 2] Internet-Draft December 2004 1. Motivation Dynamic Host Configuration Protocol [RFC2131] can be used to configure various non-IP address type of parameters. These parameters are required for normal operation of various services that are offered over an IP network. Broadcast and multicast service (BCMCS) is one such service that is currently being standardized in various mobile wireless standard bodies such as 3GPP, 3GPP2 and OMA. A description of the BCMCS, for example, in 3GPP2 can be found in [BCMCS]. While DHCP offers necessary mechanisms for device configuration, it lacks the information elements required to configure a mobile device to support BCMCS. This memo is an effort to define the extensions needed for DHCP to provide necessary configuration information to a mobile device in a BCMCS network. DHCP is being used in 3GPP2, for example, to assist with the discovery of the BCMCS Controller in a mobile operators IP network. The BCMCS includes a controller component that is responsible for managing the service via interaction with the users and other network entities. An overview of the 3GPP2 BCMCS architecture is given in the next section. It provides enough information to understand the basics of the 3GPP2 BCMCS operation. Readers are encouraged to find a more detailed description in [BCMCS]. As described in [BCMCS], the users of the service are required to know the IPv4 address of the controller entity so that they can download all the necessary information about a desired broadcast program. In a roaming environment static configuration of the controller IPv4 address becomes unrealistic. Therefore, DHCP is considered to be a method to dynamically configure the controller IPv4 address or the fully qualified domain name of the controller in the 3G wireless networks. In order to allow the users to discover the broadcast controllers, the clients request for appropriate option codes from the DHCP servers using Parameter Request List option. The DHCP servers need to return the corresponding configuration options that carry either broadcast and multicast service controller IPv4 address or fully qualified domain name based on configuration. The motivation for this document is to define the necessary option and option code. Chowdhury, et al. Expires June 27, 2005 [Page 3] Internet-Draft December 2004 2. Overview of the 3GPP2 BCMCS Network The Broadcast and Multicast Service architecture in a 3G wireless network such as 3GPP2 has the following model: +------------+ +--------+ | | | | | Controller | | DHCP | | | | Server | +------------+ +--------+ ^ Control| Info| | | V +----+ +------------+ +------------+ | | | | | | | MN/| bearer | Radio | | Broadcast | |User|<-------| Access |<---| Content | | | | Network | | Server | +----+ +------------+ +------------+ Note that this figure is shown here for broad understanding of how Broadcast and Multicast service works in a 3G mobile wireless IP network. The network elements except MN/user and the DHCP server are not relevant to the text in this document. The user interacts with the Controller to request for broadcast/multicast program information from the network (e.g., scheduled time, multicast IP address, port numbers). The User may also be authenticated by the Controller while downloading the relevant program security related information (such as encryption key). These interactions happen via HTTP and XML. There may be more than one controller in the network. The user should discover the appropriate controller to request the relevant program information. For details of Broadcast and Multicast Service operation in 3GPP2, see [BCMCS] Chowdhury, et al. Expires June 27, 2005 [Page 4] Internet-Draft December 2004 3. Terminology The keywords "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. Chowdhury, et al. Expires June 27, 2005 [Page 5] Internet-Draft December 2004 4. Broadcast Service Controller Options This section defines the configuration option for the controller of Broadcast Service. The Configuration Option contains the IPv4 address or the fully qualified domain names of the broadcast service controller. 4.1 Broadcast Service Controller Domain Name list If the 'enc' byte has a value of 0, the encoding byte is followed by a sequence of labels, encoded according to Section 3.1 of RFC 1035 [RFC1035]. The option MAY contain multiple domain names, but these domain names SHOULD be used to construct SRV lookups as specified in [BCMCS], rather than querying for different A records. The client MUST try the records in the order listed, applying the mechanism described in [BCMCS] for each entry. The client only resolves the subsequent domain names if attempts to contact the first one failed or yielded no common transport protocols between the client and the controller or denote a domain administratively prohibited by client's policy. Use of multiple domain names is not meant to replace the SRV records, but rather to allow a single DHCP server to indicate the broadcast controllers in the access provider's network. Clients MUST support compression according to the encoding in Section 4.1.4 of "Domain Names - Implementation And Specification [RFC1035]. Since the domain names are supposed to be different domains, compression will likely have little effect, however. If the length of the domain list exceeds the maximum permissible within a single option (254 octets), then the domain list MUST be represented in the DHCP message as specified in [RFC3396] . The DHCP option for this encoding has the following format: Code Len enc FQDN(s) of Broadcast Controller +-----+-----+-----+-----+-----+-----+-----+-----+-- | TBD | n | 0 | s1 | s2 | s3 | s4 | s5 | ... +-----+-----+-----+-----+-----+-----+-----+-----+-- An example case when two controller domain names e.g. bcmc1.carrier1.com, bcmc2.carrier1.com are returned will be: Chowdhury, et al. Expires June 27, 2005 [Page 6] Internet-Draft December 2004 +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |TBD|38 | 5 |'b'|'c'|'m'|'c'|'1'| 8 |'c'|'a'|'r'|'r'|'i'|'e'|'r'| +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |'1'| 3 |'c'|'o'|'m'| 5 |'b'|'c'|'m'|'c'|'2'| 8 |'c'|'a'|'r'|'r'| +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+ |'i'|'e'|'r'|'1'| 3 |'c'|'o'|'m'| +---+---+---+---+---+---+---+---+ 4.2 Broadcast Service Controller IPv4 address option If the 'enc' byte has a value of 1, the encoding byte is followed by a list of IPv4 addresses indicating broadcast controller IPv4 addresses. The controllers MUST be listed in order of preference. Its minimum length is 5, and the length MUST be a multiple of 4 plus one. The DHCP option for this encoding has the following format: Code Len enc Address 1 Address 2 +-----+-----+-----+-----+-----+-----+-----+-----+-- | TBD | n | 1 | a1 | a2 | a3 | a4 | a1 | ... +-----+-----+-----+-----+-----+-----+-----+-----+-- Chowdhury, et al. Expires June 27, 2005 [Page 7] Internet-Draft December 2004 5. Security Considerations The security considerations in the base DHCP spec [RFC2131] applies. An attacker may change information of the Broadcast Service Controller in packets that are in-tranist from DHCP server to the MN, if integrity protection is not in place. In that event, the user of the Broadcast service may be diverted to a rogue broadcast service controller. In the absence of a mutual authentication procedure between MN and the Broadcast controller, the MN may receive wrong or fraudulent information about Broadcast Service. Chowdhury, et al. Expires June 27, 2005 [Page 8] Internet-Draft December 2004 6. IANA Considerations The option code for Broadcast Service Controller option must be assigned by IANA. Chowdhury, et al. Expires June 27, 2005 [Page 9] Internet-Draft December 2004 7. Acknowledgements Thanks to the following indivduals for their review and constructive comments during the development of this document: AC Mahendran, Jun Wang, Raymond Hsu, Jayshree Bharatia, Ralph Droms, Ted Lemon. 8 Normative References [BCMCS] 3GPP2, www.3gpp2.org, "X.S0022, Broadcast and Multicast Service in cdma2000 Wireless IP Network.", February 2005. [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC3396] Lemon, T. and S. Cheshire, "Encoding Long Options in the Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396, November 2002. Authors' Addresses Kuntal Chowdhury Starent Networks 2540 Coolwater Dr. Plano, TX 75025 US Phone: +1 214-550-1416 EMail: kchowdhury@starentnetworks.com Parviz Yegani Cisco Systems 3625 Cisco Way San Jose, CA 95134 US Phone: +1 408-832-5729 EMail: pyegani@cisco.com Chowdhury, et al. Expires June 27, 2005 [Page 10] Internet-Draft December 2004 Lila Madour Ericsson 8400, Decarie Blvd Town of Mount Royal, Quebec H4P 2N2 CANADA Phone: +1 514-345-7900 EMail: Lila.Madour@ericsson.com Chowdhury, et al. Expires June 27, 2005 [Page 11] Internet-Draft December 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. 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Disclaimer of Validity 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. Copyright Statement 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Chowdhury, et al. Expires June 27, 2005 [Page 12]