Network Working Group K. Chowdhury Internet-Draft Starent Networks Expires:
December 31, 2005February 2, 2006 P. Yegani Cisco Systems L. Madour Ericsson June 29,August 1, 2005 DHCP Options for Broadcast and Multicast Control Servers draft-ietf-dhc-bcmc-options-02.txtdraft-ietf-dhc-bcmc-options-03.txt 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 December 31, 2005.February 2, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This document defines new options to discover the Broadcast and Multicast Service (BCMCS) controller in an IP network. BCMCS is being developed for 3rd generation (3G) cellular telephone networks. Users of the service interact with a controller in the network via the Mobile Node (MN) to derive information required to receive broadcast and multicast service. Dynamic Host Configuration Protocol can be used to configure the MN to acccess a particular controller. 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 & Multicast Service Controller Options . . . . . . . 6 4.1 Broadcast & Multicast Service Controller Domain Name list for DHCPv4 . . . . . . . . . . . . . . . . . . . . . 6 4.2 Broadcast & Multicast Service Controller Domain Name List Option for DHCPv6 . . . . . . . . . . . . . . . . . . 7 4.3 Broadcast & Multicast Service Controller IPv4 address option for DHCPv4 . . . . . . . . . . . . . . . . . . . . 7 4.4 Broadcast & Multicast Service Controller IPv6 Address Option for DHCPv6 . . . . . . . . . . . . . . . . . . . . 8 4.5 Consideration for Client Operation . . . . . . . . . . . . 8 4.6 Consideration for Server Operation . . . . . . . . . . . . 98 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 8. Normative References . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . 14 1. Motivation Dynamic Host Configuration Protocol [RFC2131] and [RFC3315] 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 being standardized in various mobile wireless standard bodies such as 3GPP2, OMA, and 3GPP. A description of the BCMCS as defined in 3GPP2 can be found in [BCMCS]. While DHCP already defines many options for device configuration, no option exists for configuring a mobile device to use BCMCS. This memo defines extensions for both DHCPv4 and DHCPv6 so that DHCP can be used to provide necessary configuration information to a mobile device about the BCMCS controllers. DHCP is being used in 3GPP2, to assist mobile nodes (MN) with the discovery of the BCMCS Controller in a mobile operator's IP network. The BCMCS includes a controller component that is responsible for managing the service via interaction with the MN and other network entities. In this document we will call this a BCMCS controller. 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 MNs are required to know the IPv4 or the IPv6 address of the BCMCS controller entity so that they can download all the necessary information about a desired broadcast and/or a multicast program. In a roaming environment static configuration of the BCMCS controller's IP address becomes unrealistic. Therefore, DHCP is considered to be a method to dynamically configure the MNs with the IP address or the fully qualified domain name of the BCMCS controller in the 3G cellular telephone networks. In order to allow the MNs to discover the BCMCS controllers, the MNs request the appropriate option codes from the DHCP server using Parameter Request List option. The DHCP servers need to return the corresponding configuration options that carry either BCMCS controller's IP address or fully qualified domain name based on configuration. This document defines the necessary options and option codes. 2. Overview of the 3GPP2 BCMCS Network The Broadcast and Multicast Service architecture in a 3G cellular telephone network such as 3GPP2 has the following model: +------------+ +--------+ | BCMCS | | | | Controller | | DHCP | | | | Server | +------------+ +--------+ ^ Control| Info| | | V +----+ +------------+ +------------+ | | | | | | | MN/| bearer | Radio | | BCMCS | |User|<-------| Access |<---| Content | | | | Network | | Server | +----+ +------------+ +------------+ Note that this figure is shown here for a basic understanding of how Broadcast and Multicast service works in a 3G cellular telehone network. The network elements except MN/user and the DHCP server are not relevant to the text in this document. The MN interacts with the BCMCS Controller to request broadcast/ multicast program information from the network (e.g., scheduled time, multicast IP address, port numbers). The MN may also be authenticated by the BCMCS Controller while downloading the relevant program security related information (such as encryption key). These interactions may happen via HTTP and XML as defined in [BCMCS]. There may be more than one BCMCS controller in the network. The MN should discover the appropriate BCMCS controller to request the relevant program information. For details of Broadcast and Multicast Service operation in 3GPP2, see [BCMCS]. 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. 4. Broadcast & Multicast Service Controller Options This section defines the configuration option for the BCMCS controller of the broadcast and multicast service. 4.1 Broadcast & Multicast Service Controller Domain Name list for DHCPv4 The general format of the BCMCS Controller Domain list option for DHCPv4 is as follows: Code Len FQDN(s) of BCMCS Controller +-----+-----+-----+-----+-----+-----+-----+-- | TBD1| n | s1 | s2 | s3 | s4 | s5 | ... +-----+-----+-----+-----+-----+-----+-----+-- 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 MUSTcan try any or ALL of the records in the order listed, applying the mechanism described in [BCMCS] for each entry. The client only resolves the subsequentdomain names if attemptsto contact the first one failed or yielded no common transport protocols between the client andconstruct the BCMCS controller or denote a domain that is administratively prohibited by client's policy.SRV lookups. The uselist of multipledomain names is not meant to replace the SRV records, but rather to allow a single DHCPv4 server to indicateMAY conatin the BCMCS controllers indomain name of the wirelessaccess provider's network.provider and it's partner networks that also offer broadcast and multicast service. If the length of the domain list exceeds the maximum permissible length within a single option (254 octets), then the domain list MUST be represented in the DHCPv4 message as specified in [RFC3396] . An example case when two controller domain names, example.com and example.net are returned will be: +----+----+----+----+----+----+----+----+----+----+----+ |TBD1| 26 | 7 | 'e'| 'x'| 'a'| 'm'| 'p'| 'l'| 'e'| 3 | +----+----+----+----+----+----+----+----+----+----+----+ +----+----+----+----+----+----+----+----+----+----+----+ |'c' | 'o'||'o'| 'm'| 0 | 7 | 'e'| 'x'| 'a'| 'm'| 'p'| 'l'| 'e'|+----+----+----+----+----+----+----+----+----+----+----+ +----+----+----+----+----+----+ |'e' | 3 | 'n'| 'e'| 't'| 0 | 7 |+----+----+----+----+----+----+ 4.2 Broadcast & Multicast Service Controller Domain Name List Option for DHCPv6 The semantics and content of the DHCPv6 encoding of this option is exactly the same as the encoding described in the previous section, other than necessary differences between the way options are encoded in DHCPv4 and DHCPv6. Specifically, the DHCPv6 option for the BCMCS Control Server Domain Names has the following format: 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_BCMCS_SERVER_D | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BCMCS Control Server Domain Name List | | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code: OPTION_BCMCS_SERVER_D (TBD2). option-length: Length of the 'BCMCS Control Server Domain Name List' field in octets; variable. BCMCS Control Server Domain Name List: Identical content as in Section 4.1 (except the Code and Len fields). 4.3 Broadcast & Multicast Service Controller IPv4 address option for DHCPv4 The Length byte (Len) is followed by a list of IPv4 addresses indicating BCMCS controller IPv4 addresses. The BCMCS controllers MUST be listed in order of preference. Its minimum length is 4, and the length MUST be a multiple of 4. The DHCPv4 option for this encoding has the following format: Code Len Address 1 Address 2 +-----+-----+-----+-----+-----+-----+-----+-- |TBD3 | n | a1 | a2 | a3 | a4 | a1 | ... +-----+-----+-----+-----+-----+-----+-----+-- 4.4 Broadcast & Multicast Service Controller IPv6 Address Option for DHCPv6 This DHCPv6 option MUST carry one or more 128-bit IPv6 address(es) of the BCMCS Controller in a operator's network. 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_BCMCS_SERVER_A | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | BCMCS Control server-1 address (IPv6 address) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | BCMCS Control server-2 address (IPv6 address) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code: OPTION_BCMCS_SERVER_A (TBD4). option-length: Length of the 'BCMCS Control Server IPv6 address' field in octets; variable. 4.5 Consideration for Client Operation For DHCPv6, a client MAY request either or both of the BCMCS Controller Domain Name List and the IPv6 Address options in the Options Request Option (ORO) as described in [RFC3315]. If a client receives both the BCMCS Controller Domain Name List and IPv6 Address options, it SHOULD use the Domain Name List option. In this case, the client MAYSHOULD NOT use the BCMCS Controller IPv6 Address option only ifunless the servers in the BCMCS Controller Domain Name List can not be resolved or reached. 4.6 Consideration for Server Operation A server MAY send a client either the BCMCS Controller Domain Name List Option or the BCMCS Controller IPv6 Address/IPv4 Address options if the server is configured to do so. In case of DHCPv6, If a client requests both options and the server is configured with both types of information, the server MAY send the client only one of these options if it is configured to do so. In this case the server SHOULD send the BCMCS Controller Domain Name List option. A server configured with the BCMCS Controller IPv6 Address information MUST send a client the BCMCS Controller IPv6 Address option if that client requested only the BCMCS Controller IPv6 address option and not the BCMCS Controller Domain Name List option in the ORO [RFC3315]. If a client requests for the BCMCS Controller IPv6 option and the Server is configured only with the Domain Names, the Server MUST return the Domain Names List and vice versa. The DNS name(s) MUST be concatenated and encoded using the technique described in section 3.3 of "Domain Names - Implementation And Specification" [RFC1035]. DNS name compression MUST NOT be used. The following table summarizes the server's response for DHCPv6: Client sends in ORO Domain Name List IPv6 Address List __________________________________________________________________ Neither option SHOULD MAY Domain Name List MUST MAY IPv6 Address MAY MUST Both options SHOULD MAY 5. Security Considerations TheThis document does not introduce any new security considerationsconcerns beyond those specified in the basebasic DHCP spec[RFC2131] applies. An attacker may change information of the BCMCS Controller in packets that are in-tranist from DHCP server to the MN, if integrity protection is not in place.and DHCPv6 [RFC3315] specifications. In that event,the userabsence of message integrity protection for these options, an attacker could modify the Broadcast & Multicast service may be divertedoption values to a rogue BCMCS controller.frustrate or divert requests for broadcast service. 6. IANA Considerations The following option codes for Broadcast & Multicast Service Controller option must be assigned by IANA: 1. The BCMCS Controller Domain Name list (section 4.1) has been assigned a value of TBD1 from the DHCPv4 option space. 2. The BCMCS Controller Domain Name list (section 4.2) has been assigned a value of TBD2 from the DHCPv6 option space, and a name of OPTION_BCMCS_SERVER_D. 3. The BCMCS Controller IPv4 address option (section 4.3) has been assigned a value of TBD3 from the DHCPv4 option space. 4. The BCMCS Controller IPv6 address option (section 4.4) has been assigned a value of TBD4 from the DHCPv6 option space, and a name of OPTION_BCMCS_SERVER_A. The DHCP options should be registered in http://www.iana.org/assignments/bootp-dhcp-extensions The DHCPv6 options should be registered in http://www.iana.org/assignments/dhcpv6-parameters7. 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, Margaret Wasserman, andThomas Narten.Narten, Elwyn Davies, Pekka Savola, and Bert Wijnen. 8. Normative References [BCMCS] 3GPP2, www.3gpp2.org, ftp://ftp.3gpp2.org/TSGX/Projects/X.P0022 2ndV&V.zip, "X.S0022, Broadcast and Multicast Service in cdma2000 Wireless IP Network. (pending publication)", December 2004. [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [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 30 International Place Tewksbury, MA 01876 US Phone: +1 214-550-1416 Email: email@example.com Parviz Yegani Cisco Systems 3625 Cisco Way San Jose, CA 95134 US Phone: +1 408-832-5729 Email: firstname.lastname@example.org Lila Madour Ericsson 8400, Decarie Blvd Town of Mount Royal, Quebec H4P 2N2 CANADA Phone: +1 514-345-7900 Email: Lila.Madour@ericsson.com 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. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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