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<pre>Internet Engineering Task Force (IETF) H. Jang
Request for Comments: 6610 KISTI
Category: Standards Track A. Yegin
ISSN: 2070-1721 Samsung
K. Chowdhury
Radio Mobile Access, Inc.
J. Choi
Samsung
T. Lemon
Nominum
May 2012
<span class="h1">DHCP Options for Home Information Discovery in Mobile IPv6 (MIPv6)</span>
Abstract
This document defines a DHCP-based scheme to enable dynamic discovery
of Mobile IPv6 home network information. New DHCP options are
defined that allow a mobile node to request the home agent IP
address, Fully Qualified Domain Name (FQDN), or home network prefix
and obtain it via the DHCP response.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in <a href="./rfc5741#section-2">Section 2 of RFC 5741</a>.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
<a href="http://www.rfc-editor.org/info/rfc6610">http://www.rfc-editor.org/info/rfc6610</a>.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to <a href="https://www.rfc-editor.org/bcp/bcp78">BCP 78</a> and the IETF Trust's Legal
Provisions Relating to IETF Documents
(<a href="http://trustee.ietf.org/license-info">http://trustee.ietf.org/license-info</a>) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
<span class="grey">Jang, et al. Standards Track [Page 1]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-2" ></span>
<span class="grey"><a href="./rfc6610">RFC 6610</a> DHCPv6 for Home Info Discovery in MIPv6 May 2012</span>
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Table of Contents
<a href="#section-1">1</a>. Introduction ....................................................<a href="#page-3">3</a>
<a href="#section-2">2</a>. Terminology .....................................................<a href="#page-3">3</a>
<a href="#section-3">3</a>. DHCP Options for Home Network/Agent Dynamic Discovery ...........<a href="#page-4">4</a>
<a href="#section-3.1">3.1</a>. MIPv6 Home Network ID FQDN Option ..........................<a href="#page-4">4</a>
<a href="#section-3.2">3.2</a>. Home Network Information Options ...........................<a href="#page-5">5</a>
<a href="#section-3.2.1">3.2.1</a>. MIPv6 Visited Home Network Information Option .......<a href="#page-5">5</a>
<a href="#section-3.2.2">3.2.2</a>. MIPv6 Identified Home Network Information Option ....<a href="#page-6">6</a>
<a href="#section-3.2.3">3.2.3</a>. MIPv6 Unrestricted Home Network Information Option ..6
<a href="#section-3.3">3.3</a>. MIPv6 Home Network Prefix Option ...........................<a href="#page-7">7</a>
<a href="#section-3.4">3.4</a>. MIPv6 Home Agent Address Option ............................<a href="#page-7">7</a>
<a href="#section-3.5">3.5</a>. MIPv6 Home Agent FQDN Option ...............................<a href="#page-8">8</a>
<a href="#section-4">4</a>. Option Usage ....................................................<a href="#page-9">9</a>
<a href="#section-4.1">4.1</a>. Mobile Node Behavior .......................................<a href="#page-9">9</a>
<a href="#section-4.1.1">4.1.1</a>. Requesting MIPv6 Configuration ......................<a href="#page-9">9</a>
<a href="#section-4.1.2">4.1.2</a>. Processing MIPv6 Configuration Information .........<a href="#page-10">10</a>
<a href="#section-4.2">4.2</a>. Relay Agent Behavior ......................................<a href="#page-11">11</a>
<a href="#section-4.3">4.3</a>. DHCP Server Behavior ......................................<a href="#page-12">12</a>
<a href="#section-4.4">4.4</a>. Home Agent Discovery Using a Network Access Server ........<a href="#page-12">12</a>
<a href="#section-5">5</a>. Security Considerations ........................................<a href="#page-13">13</a>
<a href="#section-6">6</a>. IANA Considerations ............................................<a href="#page-14">14</a>
<a href="#section-7">7</a>. Acknowledgments ................................................<a href="#page-14">14</a>
<a href="#section-8">8</a>. References .....................................................<a href="#page-14">14</a>
<a href="#section-8.1">8.1</a>. Normative References ......................................<a href="#page-14">14</a>
<a href="#section-8.2">8.2</a>. Informative References ....................................<a href="#page-15">15</a>
<span class="grey">Jang, et al. Standards Track [Page 2]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-3" ></span>
<span class="grey"><a href="./rfc6610">RFC 6610</a> DHCPv6 for Home Info Discovery in MIPv6 May 2012</span>
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Introduction</span>
Before a mobile node can engage in Mobile IPv6 signaling with a home
agent, it should either know the IP address of the home agent via
pre-configuration or dynamically discover it. The Mobile IPv6
specification [<a href="./rfc6275" title=""Mobility Support in IPv6"">RFC6275</a>] describes how home agents can be dynamically
discovered by mobile nodes that know the home network prefix. This
scheme does not work when prefix information is not already available
to the mobile node. This document specifies extensions to DHCPv6
[<a href="./rfc3736" title=""Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6"">RFC3736</a>] [<a href="./rfc3315" title=""Dynamic Host Configuration Protocol for IPv6 (DHCPv6)"">RFC3315</a>] to deliver the home agent information to the
mobile node in the form of the IP address of the home agent or the
Fully Qualified Domain Name (FQDN) [<a href="./rfc1035" title=""Domain names - implementation and specification"">RFC1035</a>] of the home agent. The
information delivered to the mobile node may also include the home
prefix for the mobile node. The solution involves defining new DHCP
options to carry home network prefixes, home agent IP addresses, and
FQDN information. The mobile node MAY also use the home prefix to
discover the list of home agents serving the home prefix using the
Dynamic Home Agent Address Discovery mechanism specified in
[<a href="./rfc6275" title=""Mobility Support in IPv6"">RFC6275</a>].
As part of configuring the initial TCP/IP parameters, a mobile node
can find itself a suitable home agent. Such a home agent might
reside in the access network to which the mobile node connects or in
a home network with which the mobile node is associated. A mobile
node can indicate its home network identity when roaming to a visited
network in order to obtain the MIPv6 bootstrap parameters from the
home network. As an example, the visited network may determine the
home network of the mobile node based on the realm portion of the NAI
(Network Access Identifier) [<a href="./rfc4282" title=""The Network Access Identifier"">RFC4282</a>] used in access authentication
[<a href="./rfc5447" title=""Diameter Mobile IPv6: Support for Network Access Server to Diameter Server Interaction"">RFC5447</a>].
The mobile node may or may not be connected to the "home" network
when it attempts to learn Mobile IPv6 home network information. This
allows operators to centrally deploy home agents while being able to
bootstrap mobile nodes that are already roaming. This scenario also
occurs when Hierarchical Mobile IPv6 (HMIPv6) [<a href="./rfc5380" title=""Hierarchical Mobile IPv6 (HMIPv6) Mobility Management"">RFC5380</a>] is used,
where the mobile node is required to discover the MAP (a special home
agent) that is located multiple hops away from the mobile node's
attachment point.
<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Terminology</span>
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 [<a href="./rfc2119" title=""Key words for use in RFCs to Indicate Requirement Levels"">RFC2119</a>].
<span class="grey">Jang, et al. Standards Track [Page 3]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-4" ></span>
<span class="grey"><a href="./rfc6610">RFC 6610</a> DHCPv6 for Home Info Discovery in MIPv6 May 2012</span>
General mobility terminology can be found in [<a href="./rfc3753" title=""Mobility Related Terminology"">RFC3753</a>]. The
following additional terms, as defined in [<a href="./rfc4640" title=""Problem Statement for bootstrapping Mobile IPv6 (MIPv6)"">RFC4640</a>], are used in this
document:
Access Service Provider (ASP): A network operator that provides
direct IP packet forwarding to and from the mobile node.
Mobility Service Provider (MSP): A service provider that provides
Mobile IPv6 service. In order to obtain such service, the mobile
node must be authenticated and authorized to use the Mobile IPv6
service.
Mobility Service Authorizer (MSA): A service provider that
authorizes Mobile IPv6 service.
<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. DHCP Options for Home Network/Agent Dynamic Discovery</span>
This section introduces new DHCP options that are used for dynamic
discovery of the home agent's IPv6 address, IPv6 home network prefix,
or FQDN information in Mobile IPv6. Transport to a home agent over
IPv4 is also supported by specifying an IPv4-Embedded IPv6 address.
The detailed procedures are described in <a href="#section-2.3.2">Section 2.3.2</a> of "Mobile
IPv6 Support for Dual Stack Hosts and Routers" [<a href="./rfc5555" title=""Mobile IPv6 Support for Dual Stack Hosts and Routers"">RFC5555</a>].
The names of options listed in this section all start with MIPv6, in
order to differentiate them from other DHCP options that might have
similar names. However, throughout the rest of this document, the
options are referred to by name without the MIPv6 prefix, for
brevity.
<span class="h3"><a class="selflink" id="section-3.1" href="#section-3.1">3.1</a>. MIPv6 Home Network ID FQDN Option</span>
This option is used by mobile nodes to communicate to the DHCP server
an FQDN that identifies the target home network for which the client
is requesting configuration information. When the mobile node
requests configuration for more than one target home network, this
option is also used by the server to identify the target home network
for each Identified Home Network Information option returned.
When a mobile node sends this option to request information about a
specific home network, the option is simply included in the DHCP
message from the mobile node. When a server responds with an
Identified Home Network Information option, this option MUST be
encapsulated in the Identified Home Network Information option that
it identifies.
<span class="grey">Jang, et al. Standards Track [Page 4]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-5" ></span>
<span class="grey"><a href="./rfc6610">RFC 6610</a> DHCPv6 for Home Info Discovery in MIPv6 May 2012</span>
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_MIP6_HNIDF | Option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Home Network Identifier FQDN |
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code: OPTION_MIP6_HNIDF (49)
Option-len: Length of option, per <a href="./rfc3315">RFC 3315</a>
Home Network Identifier FQDN: A Fully Qualified Domain Name (FQDN)
that identifies a mobile IP home network for which the client is
seeking configuration information. This is encoded in accordance
with <a href="./rfc3315#section-8">RFC 3315, Section 8</a>, "Representation and Use of Domain
Names".
<span class="h3"><a class="selflink" id="section-3.2" href="#section-3.2">3.2</a>. Home Network Information Options</span>
There are three different options that specify home network
information. Which of these options is used depends on what kind of
home network information the client needs. Each of these options is
used to encapsulate options containing prefix and home agent
information about the home network for which configuration
information was requested.
<span class="h4"><a class="selflink" id="section-3.2.1" href="#section-3.2.1">3.2.1</a>. MIPv6 Visited Home Network Information Option</span>
This option is used by relay agents and DHCP servers to provide
information about the local home 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_MIP6_VDINF | Option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Options |
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
<span class="grey">Jang, et al. Standards Track [Page 5]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-6" ></span>
<span class="grey"><a href="./rfc6610">RFC 6610</a> DHCPv6 for Home Info Discovery in MIPv6 May 2012</span>
Option-code: OPTION_MIP6_VDINF (50)
Option-len: Length of option, per <a href="./rfc3315">RFC 3315</a>
Options: One or more options, specifying information about the local
ASP (visited domain).
<span class="h4"><a class="selflink" id="section-3.2.2" href="#section-3.2.2">3.2.2</a>. MIPv6 Identified Home Network Information Option</span>
This option is used by relay agents and DHCP servers to provide
information about the home network identified by a Home Network
Identifier FQDN option.
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_MIP6_IDINF | Option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Options |
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code: OPTION_MIP6_IDINF (69)
Option-len: Length of option, per <a href="./rfc3315">RFC 3315</a>
Options: One or more options, specifying information about the home
network identified by a Home Network Identifier FQDN option
sent by a mobile node.
<span class="h4"><a class="selflink" id="section-3.2.3" href="#section-3.2.3">3.2.3</a>. MIPv6 Unrestricted Home Network Information Option</span>
This option is used by relay agents and DHCP servers to provide
information about the a home network specified by the DHCP server
administrator.
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_MIP6_UDINF | Option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Options |
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
<span class="grey">Jang, et al. Standards Track [Page 6]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-7" ></span>
<span class="grey"><a href="./rfc6610">RFC 6610</a> DHCPv6 for Home Info Discovery in MIPv6 May 2012</span>
Option-code: OPTION_MIP6_UDINF (70)
Option-len: Length of option, per <a href="./rfc3315">RFC 3315</a>
Options: One or more options, specifying information about some home
network as specified by the DHCP server administrator.
<span class="h3"><a class="selflink" id="section-3.3" href="#section-3.3">3.3</a>. MIPv6 Home Network Prefix Option</span>
This option is used by DHCP servers and relay agents to define the
prefix for a home network. This option should only appear in one of
the Home Network Information options.
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_MIP6_HNP | Option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix-len | |
+-+-+-+-+-+-+-+-+ +
| |
| Prefix |
| |
| +-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code: OPTION_MIP6_HNP (71)
Option-len: Length of option, per <a href="./rfc3315">RFC 3315</a>
Prefix-len: Length of prefix
Prefix: Home Network Prefix
<span class="h3"><a class="selflink" id="section-3.4" href="#section-3.4">3.4</a>. MIPv6 Home Agent Address Option</span>
This option is used by DHCP servers and relay agents to specify the
home agent IP address. In cases where the home agent must be
contacted over an IPv4-only infrastructure, the IPv4 address is
specified as an IPv4-Embedded IPv6 address using the "Well-Known
Prefix" [<a href="./rfc6052" title=""IPv6 Addressing of IPv4/IPv6 Translators"">RFC6052</a>]. This option should only appear in one of the Home
Network Information options.
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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_MIP6_HAA | Option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code: OPTION_MIP6_HAA (72)
Option-len: Length of option, per <a href="./rfc3315">RFC 3315</a>
Address: IP Address of home agent
<span class="h3"><a class="selflink" id="section-3.5" href="#section-3.5">3.5</a>. MIPv6 Home Agent FQDN Option</span>
This option is used by DHCP servers and relay agents to specify the
home agent FQDN. This FQDN is used to look up one or more A or AAAA
records containing IPv4 or IPv6 addresses for the home agent, as
needed. This option should only appear in one of the Home Network
Information options.
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_MIP6_HAF | Option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| FQDN |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code: OPTION_MIP6_HAF (73)
Option-len: Length of option, per <a href="./rfc3315">RFC 3315</a>
Address: FQDN resolving to one or more IPv4 and/or IPv6 addresses
for the home agent. This is encoded in accordance with <a href="./rfc3315">RFC</a>
<a href="./rfc3315">3315</a>, <a href="#section-8">Section 8</a>, "Representation and Use of Domain Names".
<span class="grey">Jang, et al. Standards Track [Page 8]</span></pre>
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<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Option Usage</span>
The requesting and sending of the proposed DHCP options follow the
rules for DHCPv6 options in [<a href="./rfc3315" title=""Dynamic Host Configuration Protocol for IPv6 (DHCPv6)"">RFC3315</a>].
<span class="h3"><a class="selflink" id="section-4.1" href="#section-4.1">4.1</a>. Mobile Node Behavior</span>
Mobile nodes MAY obtain MIPv6 configuration information during either
a stateful configuration exchange [<a href="./rfc3315" title=""Dynamic Host Configuration Protocol for IPv6 (DHCPv6)"">RFC3315</a>] or a stateless
configuration exchange [<a href="./rfc3736" title=""Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6"">RFC3736</a>].
Mobile nodes that obtain MIPv6 configuration information using a
stateful configuration exchange SHOULD include the same options in
every message they send to the DHCP server.
Mobile nodes that obtain MIPv6 configuration using a stateless
exchange MAY omit MIPv6 configuration from some exchanges, but SHOULD
reconfigure whenever a change in the attached network is detected.
If the DHCP server responds to a MIPv6-related stateless
configuration request with an Information Request Timer option, the
mobile node SHOULD attempt to reconfigure when the IRT expires.
A mobile node using stateless configuration may try to perform home
network information discovery when it lacks home network information
for MIPv6 or needs to change the home agent for some reason. For
example, this may be necessary to recover from the failure of an
existing home agent or to use the local home agent located in the
network where the mobile node is currently attached. Note that
despite the home information discovery procedure, the mobile node may
continue to use the old home agent, in order to avoid losing current
sessions.
<span class="h4"><a class="selflink" id="section-4.1.1" href="#section-4.1.1">4.1.1</a>. Requesting MIPv6 Configuration</span>
Mobile nodes signal that they are interested in being configured with
MIPv6 home agent information by requesting one or more of the three
Home Network Information options: the Visited Home Network
Information option, the Identified Home Network Information option,
or the Unrestricted Home Network Information option. To request
these options, the client lists them in the Option Request Option
(ORO). A client that requests any of these three options in the ORO
MUST also request the Home Network Identifier FQDN option, the Home
Network Prefix option, the Home Agent Address option, and the Home
Agent FQDN option.
If the mobile node requests the Visited Home Network Information
option, this indicates that it is interested in learning the home
<span class="grey">Jang, et al. Standards Track [Page 9]</span></pre>
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network information that pertains to the currently visited network.
This type can be used to discover local home agents in the local ASP.
If the mobile node requests the Identified Home Network Information
option, this indicates that it is interested in learning the home
network information that pertains to a specified realm. This type
can be used to discover home agents that are hosted by a user's home
domain or by any target domain. A mobile node requesting the
Identified Home Network Information option MUST include a Client Home
Network ID FQDN option identifying the MSP being identified. The
target MSP can be a mobile node's home MSP or any MSP that has a
trusted roaming relationship with the mobile node's MSA.
If the mobile node has no preference as to the home network with
which it should be configured, it SHOULD request the Unrestricted
Home Network Information option, and SHOULD NOT request either the
Visited Home Network Information option or the Identified Home
Network Information option.
A client that wishes to be configured with both the Visited Home
Network Information option and the Identified Home Network
Information option may request both options in the Option Request
Option. A client may request information about more than one
identified domain by requesting the Identified Home Network
Information option in the ORO and including more than one Home
Network ID FQDN option. A client that sends more than one Home
Network ID FQDN option MUST request the Home Network ID option in the
ORO.
<span class="h4"><a class="selflink" id="section-4.1.2" href="#section-4.1.2">4.1.2</a>. Processing MIPv6 Configuration Information</span>
DHCP Clients on mobile nodes should be prepared to receive any MIPv6
Home Network Information options they request. If more than one Home
Network ID FQDN option was sent, the client should be prepared to
handle zero or more Identified Home Network Information options in
response; the DHCP server may not have configuration information for
all targeted domains, or, indeed, for any. If a misconfigured server
returns an Identified Home Network Information option that does not
contain a Home Network ID FQDN option corresponding to one that the
client requested, the client MUST silently discard that Identified
Home Network Information option.
If any of the three Home Network Information options is returned,
configuration information will be included within it. The client
must be prepared to handle home agent addresses in the form of either
the Home Agent Address option or the Home Agent FQDN option.
<span class="grey">Jang, et al. Standards Track [Page 10]</span></pre>
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If the client finds an IPv4-Embedded IPv6 address in a Home Agent
Address option, it may only use this address to communicate over
IPv4. If a Home Network Information option does not contain complete
configuration information, the client MUST silently discard that Home
Network Information option.
If the client receives any Home Network ID FQDN options, Home Network
Prefix options, Home Agent Address options, or Home Agent FQDN
options that are not encapsulated in one of the three types of Home
Network Information options, it MUST silently discard these options.
The DHCP client must pass whatever configuration information it
receives to the appropriate mobile IP implementation on the mobile
node. How this is done, and what the mobile IP implementation on the
mobile node does with this information, is outside the scope of this
document.
As described later in this section, servers may provide more than one
Home Network Information option or multiple Home Agent Prefix, Home
Agent Address, or Home Agent FQDN options. When provided with
multiple Visited Home Network Information options or Unrestricted
Home Network Information options of the same type, or with multiple
sub-options within such an option, the mobile node SHOULD choose the
first one that it can employ.
If the DHCP client on a mobile node receives any Home Network Prefix
options, Home Agent Address option, or Home Agent FQDN option that
are not contained within Home Network Information options, the DHCP
client MUST silently discard these options.
<span class="h3"><a class="selflink" id="section-4.2" href="#section-4.2">4.2</a>. Relay Agent Behavior</span>
In some cases, DHCP relay agents may have access to configuration
information for the mobile node. In such cases, relay agents MAY
send Visited Home Network Information options, Identified Home
Network Information options, and/or Unrestricted Home Network
Information options to the DHCP server. To do so, the relay agent
MUST encapsulate these options in a Relay-Supplied Options option
[<a href="./rfc6422" title=""Relay-Supplied DHCP Options"">RFC6422</a>]. If the DHCP relay agent includes any Identified Home
Network Information options, these options MUST correspond to home
networks identified in Home Network ID FQDN options in the client
request. In addition, each Identified Home Network Information
option must contain a Home Network ID FQDN option identical to the
one sent by the client, to identify the network to the client.
No special handling is required when processing relay-reply messages.
<span class="grey">Jang, et al. Standards Track [Page 11]</span></pre>
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<span class="h3"><a class="selflink" id="section-4.3" href="#section-4.3">4.3</a>. DHCP Server Behavior</span>
Generally, DHCP servers can simply be configured with Visited Home
Network Information options, Identified Home Network Information
options, and Unrestricted Home Network Information options. In the
case of Visited Home Network Information options and Unrestricted
Home Network Information options, which clients get what options
depends on operator configuration.
A DHCP server MAY maintain a table of Home Network ID FQDNs. For
each such FQDN, a server that maintains such a table SHOULD include
an Identified Home Network Information option. Such a server would
look up the FQDN from any Home Network ID FQDN options provided by
the client in its table, and for each match, include the Identified
Home Network Information option configured in the table entry for
that FQDN.
If a DHCP server does not implement the Home Network ID FQDN table,
or some similar functionality, it is an error for the operator to
configure it with any Identified Home Network Information options.
These options could be erroneously forwarded to the client, which
would have no use for them, and is required to discard them.
DHCP servers that implement the Home Network ID FQDN table must, when
sending an Identified Home Network Information option to the client,
include a Home Network ID option within the Identified Home Network
Information option that identifies the home network for which
configuration information is being sent.
Aside from the Home Network ID FQDN table, the actual behavior of the
DHCP server with respect to MIPv6 configuration is simply in
accordance with the DHCPv6 protocol specification [<a href="./rfc3315" title=""Dynamic Host Configuration Protocol for IPv6 (DHCPv6)"">RFC3315</a>] and
depends on operator configuration. No special processing is required
for Visited Home Network Information options or Unrestricted Home
Network Information options.
<span class="h3"><a class="selflink" id="section-4.4" href="#section-4.4">4.4</a>. Home Agent Discovery Using a Network Access Server</span>
[<a id="ref-RFC5447">RFC5447</a>] describes the complete procedure for home agent assignment
among the mobile node, NAS (Network Access Server), DHCP, and
Authentication, Authorization, and Accounting (AAA) entities for the
bootstrapping procedure in the integrated scenario.
A NAS is assumed to be co-located with a DHCP relay agent or a DHCP
server in this solution. In a network where the NAS is not
co-located with a DHCP relay or a server, the server may not be
provided with the home network information from the NAS; therefore,
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it may either fail to provide information or provide home information
that has been pre-configured by the administrator or that is acquired
through a mechanism that is not described in this document.
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. Security Considerations</span>
Secure delivery of home agent and home network information from a
DHCP server to the mobile node (DHCP client) relies on the same
security as DHCP. The particular option defined in this document
does not have additional impact on DHCP security.
Aside from the DHCP client-to-server interaction, an operator must
also ensure secure delivery of mobile IP information to the DHCP
server. This is outside the scope of DHCP and the newly defined
options.
The mechanisms in this specification could be used by attackers to
learn the addresses of home agents in the home network or to feed
incorrect information to mobile nodes.
The ability to learn addresses of nodes may be useful to attackers
because brute-force scanning of the address space is not practical
with IPv6. Thus, they could benefit from any means that make mapping
the networks easier. For example, if a security threat targeted at
routers or even home agents is discovered, having a simple mechanism
to easily find out possible targets may prove to be an additional
security risk.
Apart from discovering the address(es) of home agents, attackers will
not be able to learn much from this information, and mobile nodes
cannot be tricked into using wrong home agents, as the actual
communication with the home agents employs mutual authentication.
The mechanisms from this specification may also leak interesting
information about network topology and prefixes to attackers, and
where there is no security to protect DHCP, even modify this
information. Again, the mobile nodes and home agents employ end-to-
end security when they communicate with each other. The authentic
source of all information is that communication, not the information
from DHCP.
However, attacks against the information carried in DHCP may lead to
denial of service if mobile nodes are unable to connect to any home
agent, or choose a home agent that is not the most preferred one.
<span class="grey">Jang, et al. Standards Track [Page 13]</span></pre>
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<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. IANA Considerations</span>
IANA has assigned the following new DHCPv6 Option Codes in the
registry maintained in
<a href="http://www.iana">http://www.iana</a>.org/assignments/dhcpv6-parameters:
49: OPTION_MIP6_HNIDF for the Home Network ID FQDN option
50: OPTION_MIP6_VDINF for the Visited Home Network Information
option
69: OPTION_MIP6_IDINF for the Identified Home Network Information
option
70: OPTION_MIP6_UDINF for the Unrestricted Home Network
Information option
71: OPTION_MIP6_HNP for the Home Network Prefix option
72: OPTION_MIP6_HAA for the Home Agent Address option
73: OPTION_MIP6_HAF for the Home Agent FQDN option
<span class="h2"><a class="selflink" id="section-7" href="#section-7">7</a>. Acknowledgments</span>
The authors would like to thank Kilian Weniger, Domagoj Premec,
Basavaraj Patil, Vijay Devarapalli, Gerardo Giaretta, Bernie Volz,
David W. Hankins, Behcet Sarikaya, Vidya Narayanan, Francis Dupont,
Sam Weiler, Jari Arkko, Alfred Hoenes, Suresh Krishnan, and Miguel A.
Diaz for their valuable feedback.
<span class="h2"><a class="selflink" id="section-8" href="#section-8">8</a>. References</span>
<span class="h3"><a class="selflink" id="section-8.1" href="#section-8.1">8.1</a>. Normative References</span>
[<a id="ref-RFC1035">RFC1035</a>] Mockapetris, P., "Domain names - implementation and
specification", STD 13, <a href="./rfc1035">RFC 1035</a>, November 1987.
[<a id="ref-RFC2119">RFC2119</a>] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", <a href="https://www.rfc-editor.org/bcp/bcp14">BCP 14</a>, <a href="./rfc2119">RFC 2119</a>, March 1997.
[<a id="ref-RFC3315">RFC3315</a>] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", <a href="./rfc3315">RFC 3315</a>, July 2003.
[<a id="ref-RFC3736">RFC3736</a>] Droms, R., "Stateless Dynamic Host Configuration Protocol
(DHCP) Service for IPv6", <a href="./rfc3736">RFC 3736</a>, April 2004.
<span class="grey">Jang, et al. Standards Track [Page 14]</span></pre>
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[<a id="ref-RFC4282">RFC4282</a>] Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The
Network Access Identifier", <a href="./rfc4282">RFC 4282</a>, December 2005.
[<a id="ref-RFC5555">RFC5555</a>] Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and
Routers", <a href="./rfc5555">RFC 5555</a>, June 2009.
[<a id="ref-RFC6052">RFC6052</a>] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", <a href="./rfc6052">RFC 6052</a>,
October 2010.
[<a id="ref-RFC6275">RFC6275</a>] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", <a href="./rfc6275">RFC 6275</a>, July 2011.
[<a id="ref-RFC6422">RFC6422</a>] Lemon, T. and Q. Wu, "Relay-Supplied DHCP Options",
<a href="./rfc6422">RFC 6422</a>, December 2011.
<span class="h3"><a class="selflink" id="section-8.2" href="#section-8.2">8.2</a>. Informative References</span>
[<a id="ref-RFC3753">RFC3753</a>] Manner, J. and M. Kojo, "Mobility Related Terminology",
<a href="./rfc3753">RFC 3753</a>, June 2004.
[<a id="ref-RFC4640">RFC4640</a>] Patel, A. and G. Giaretta, "Problem Statement for
bootstrapping Mobile IPv6 (MIPv6)", <a href="./rfc4640">RFC 4640</a>,
September 2006.
[<a id="ref-RFC5380">RFC5380</a>] Soliman, H., Castelluccia, C., ElMalki, K., and L.
Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility
Management", <a href="./rfc5380">RFC 5380</a>, October 2008.
[<a id="ref-RFC5447">RFC5447</a>] Korhonen, J., Bournelle, J., Tschofenig, H., Perkins, C.,
and K. Chowdhury, "Diameter Mobile IPv6: Support for
Network Access Server to Diameter Server Interaction",
<a href="./rfc5447">RFC 5447</a>, February 2009.
<span class="grey">Jang, et al. Standards Track [Page 15]</span></pre>
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Authors' Addresses
Heejin Jang
Korea Institute of Science and Technology Information (KISTI)
245 Daehak-ro, Yuseong-gu
Daejeon 305-806
Korea
EMail: heejin.jang@gmail.com
Alper E. Yegin
Samsung Electronics
Istanbul
Turkey
EMail: alper.yegin@yegin.org
Kuntal Chowdhury
Radio Mobile Access, Inc.
100 Ames Pond Dr.
Tewksbury, MA 01876
US
EMail: kc@radiomobiles.com
JinHyeock Choi
Samsung Advanced Institute of Technology
P.O. Box 111
Suwon 440-600
Korea
EMail: jinchoe@gmail.com
Ted Lemon
Nominum
2000 Seaport Blvd
Redwood City, CA 94063
USA
Phone: +1 650 381 6000
EMail: Ted.Lemon@nominum.com
Jang, et al. Standards Track [Page 16]
</pre>
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