Network Working Group K. Chowdhury
Internet-Draft Nortel Networks
Expires: February 15, 2005 P. Yegani
Cisco Systems
L. Madour
Ericsson
August 17, 2004
DHCPv4 Options for Broadcast and Multicast Control Servers
draft-chowdhury-dhc-bcmcv4-option-01.txt
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Copyright (C) The Internet Society (2004). All Rights Reserved.
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
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
network.
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 |
+------------+ +--------+
|
Control|
Info|
|
|
V
+----+ +------------+ +------------+
| | | | | |
| 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",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
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
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 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
US
Phone: +1 972-685-7788
EMail: chowdury@nortelnetworks.com
Parviz Yegani
Cisco Systems
3625 Cisco Way
San Jose, CA 95134
US
Phone: +1 408-832-5729
EMail: pyegani@cisco.com
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Lila Madour
Ericsson
8400, Decarie Blvd
Town of Mount Royal, Quebec H4P 2N2
CANADA
Phone: +1 514-345-7900
EMail: Lila.Madour@ericsson.com
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