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Network Working Group                                       K. Chowdhury
Internet-Draft                                           Nortel Networks
Expires: February 15, 2005                                     P. Yegani
                                                           Cisco Systems
                                                               L. Madour
                                                         August 17, 2004

       DHCPv4 Options for Broadcast and Multicast Control Servers

Status of this Memo

   By submitting this Internet-Draft, I certify that any applicable
   patent or other IPR claims of which I am aware have been disclosed,
   and any of which I become aware will be disclosed, in accordance with
   RFC 3668.

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Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.


   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
   required to receive broadcast service.  Dynamic Host Configuration
   Protocol can be used to configure the controller IPv4 addresses or

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   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 . . . . . . . . . . . . . . . . . . . . . . . . . . .  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

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1.  Motivation

   Dynamic Host Configuration Protocol 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

   In 3G wirelesss network standards body such as 3GPP2 (www.3gpp2.org),
   broadcast and multicast service is being developed [BCMCS].  The
   service includes a controller component that is responsible for
   managing the service via interaction with the users and other network
   entities.  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, DHC is considered to be a
   method to dynamically configure 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 need to request for appropriate option codes from the DHC
   servers using Option-Request-Option and the DHC servers need to
   return corresponding configuration options that carry the broadcast
   and multicast service controller IPv4 address or fully qualified
   domain name.  The motivation for this document is to define the
   necessary options and option codes.

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2.  Overview

   The Broadcast and Multicast Service architecture in a 3G wireless
   network such as 3GPP2 has the following model:

                              +------------+   +--------+
                              |            |   |        |
                              | Controller |   |  DHCP  |
                              |            |   | Server |
                              +------------+   +--------+
   +----+        +------------+    +------------+
   |    |        |            |    |            |
   | MN/| bearer |   Radio    |    | Broadcast  |
   |User|<-------|   Access   |<---| Content    |
   |    |        |   Network  |    | Server     |
   +----+        +------------+    +------------+

   Note that this inforamtive figure is shown here for broad
   understanding of how Broadcast and Multicast service works in a 3G
   radio 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.  For details of Broadcast and
   Multicast Service operation in 3GPP2, see [BCMCS].  There may be more
   than one controller in the network.  The user should discover the
   appropriate controller to request the relevant program information.

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3.  Terminology

   The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   this document are to be interpreted as described in RFC 2119.

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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

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

   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 cleint'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:

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       |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  |  ...

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5.  Security Considerations

   The security considerations in the base DHCPv6 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.

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6.  IANA Considerations

   The option codes for Broadcast Service Controller Domain Name list
   and the IPv4 address Must be assigned by IANA.

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7.  Acknowledgements

   Thanks to the follwoing indivduals for their review and constructive
   comments during the development of this document:

   AC Mahendran, Jun Wang, Raymond Hsu, Jayshree Bharatia, Ralph Dorms,
   Ted Lemon.

8  Normative References

   [BCMCS]    3GPP2, www.3gpp2.org, "X.P0022, Broadcast and Multicast
              Service in cdma2000 Wireless IP Network.", October 2003.

   [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
   Nortel Networks
   2221 Lakeside Blvd.
   Richardson, TX  75082

   Phone: +1 972-685-7788
   EMail: chowdury@nortelnetworks.com

   Parviz Yegani
   Cisco Systems
   3625 Cisco Way
   San Jose, CA  95134

   Phone: +1 408-832-5729
   EMail: pyegani@cisco.com

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   Lila Madour
   8400, Decarie Blvd
   Town of Mount Royal, Quebec  H4P 2N2

   Phone: +1 514-345-7900
   EMail: Lila.Madour@ericsson.com

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