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rfc:rfc6610

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
 DHCP Options for Home Information Discovery in Mobile IPv6 (MIPv6)

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 Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6610.

Copyright Notice

 Copyright (c) 2012 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) 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

Jang, et al. Standards Track [Page 1] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

 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

 1. Introduction ....................................................3
 2. Terminology .....................................................3
 3. DHCP Options for Home Network/Agent Dynamic Discovery ...........4
    3.1. MIPv6 Home Network ID FQDN Option ..........................4
    3.2. Home Network Information Options ...........................5
         3.2.1. MIPv6 Visited Home Network Information Option .......5
         3.2.2. MIPv6 Identified Home Network Information Option ....6
         3.2.3. MIPv6 Unrestricted Home Network Information Option ..6
    3.3. MIPv6 Home Network Prefix Option ...........................7
    3.4. MIPv6 Home Agent Address Option ............................7
    3.5. MIPv6 Home Agent FQDN Option ...............................8
 4. Option Usage ....................................................9
    4.1. Mobile Node Behavior .......................................9
         4.1.1. Requesting MIPv6 Configuration ......................9
         4.1.2. Processing MIPv6 Configuration Information .........10
    4.2. Relay Agent Behavior ......................................11
    4.3. DHCP Server Behavior ......................................12
    4.4. Home Agent Discovery Using a Network Access Server ........12
 5. Security Considerations ........................................13
 6. IANA Considerations ............................................14
 7. Acknowledgments ................................................14
 8. References .....................................................14
    8.1. Normative References ......................................14
    8.2. Informative References ....................................15

Jang, et al. Standards Track [Page 2] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

1. Introduction

 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 [RFC6275] 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
 [RFC3736] [RFC3315] 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) [RFC1035] 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
 [RFC6275].
 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) [RFC4282] used in access authentication
 [RFC5447].
 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) [RFC5380] 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.

2. Terminology

 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 [RFC2119].

Jang, et al. Standards Track [Page 3] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

 General mobility terminology can be found in [RFC3753].  The
 following additional terms, as defined in [RFC4640], 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.

3. DHCP Options for Home Network/Agent Dynamic Discovery

 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 Section 2.3.2 of "Mobile
 IPv6 Support for Dual Stack Hosts and Routers" [RFC5555].
 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.

3.1. MIPv6 Home Network ID FQDN Option

 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.

Jang, et al. Standards Track [Page 4] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

  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 RFC 3315
 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 RFC 3315, Section 8, "Representation and Use of Domain
    Names".

3.2. Home Network Information Options

 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.

3.2.1. MIPv6 Visited Home Network Information Option

 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                            |
 .                                                               .
 .                                                               .
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Jang, et al. Standards Track [Page 5] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

 Option-code:  OPTION_MIP6_VDINF (50)
 Option-len:  Length of option, per RFC 3315
 Options:  One or more options, specifying information about the local
           ASP (visited domain).

3.2.2. MIPv6 Identified Home Network Information Option

 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 RFC 3315
 Options:  One or more options, specifying information about the home
           network identified by a Home Network Identifier FQDN option
           sent by a mobile node.

3.2.3. MIPv6 Unrestricted Home Network Information Option

 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                            |
 .                                                               .
 .                                                               .
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Jang, et al. Standards Track [Page 6] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

 Option-code:  OPTION_MIP6_UDINF (70)
 Option-len:  Length of option, per RFC 3315
 Options:  One or more options, specifying information about some home
           network as specified by the DHCP server administrator.

3.3. MIPv6 Home Network Prefix Option

 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 RFC 3315
 Prefix-len:  Length of prefix
 Prefix:  Home Network Prefix

3.4. MIPv6 Home Agent Address Option

 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" [RFC6052].  This option should only appear in one of the Home
 Network Information options.

Jang, et al. Standards Track [Page 7] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

  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 RFC 3315
 Address:  IP Address of home agent

3.5. MIPv6 Home Agent FQDN Option

 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 RFC 3315
 Address:  FQDN resolving to one or more IPv4 and/or IPv6 addresses
           for the home agent.  This is encoded in accordance with RFC
           3315, Section 8, "Representation and Use of Domain Names".

Jang, et al. Standards Track [Page 8] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

4. Option Usage

 The requesting and sending of the proposed DHCP options follow the
 rules for DHCPv6 options in [RFC3315].

4.1. Mobile Node Behavior

 Mobile nodes MAY obtain MIPv6 configuration information during either
 a stateful configuration exchange [RFC3315] or a stateless
 configuration exchange [RFC3736].
 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.

4.1.1. Requesting MIPv6 Configuration

 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

Jang, et al. Standards Track [Page 9] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

 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.

4.1.2. Processing MIPv6 Configuration Information

 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.

Jang, et al. Standards Track [Page 10] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

 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.

4.2. Relay Agent Behavior

 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
 [RFC6422].  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.

Jang, et al. Standards Track [Page 11] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

4.3. DHCP Server Behavior

 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 [RFC3315] and
 depends on operator configuration.  No special processing is required
 for Visited Home Network Information options or Unrestricted Home
 Network Information options.

4.4. Home Agent Discovery Using a Network Access Server

 [RFC5447] 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,

Jang, et al. Standards Track [Page 12] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

 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.

5. Security Considerations

 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.

Jang, et al. Standards Track [Page 13] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

6. IANA Considerations

 IANA has assigned the following new DHCPv6 Option Codes in the
 registry maintained in
 http://www.iana.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

7. Acknowledgments

 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.

8. References

8.1. Normative References

 [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.
 [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.
 [RFC3736]  Droms, R., "Stateless Dynamic Host Configuration Protocol
            (DHCP) Service for IPv6", RFC 3736, April 2004.

Jang, et al. Standards Track [Page 14] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

 [RFC4282]  Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The
            Network Access Identifier", RFC 4282, December 2005.
 [RFC5555]  Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and
            Routers", RFC 5555, June 2009.
 [RFC6052]  Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
            Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
            October 2010.
 [RFC6275]  Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
            in IPv6", RFC 6275, July 2011.
 [RFC6422]  Lemon, T. and Q. Wu, "Relay-Supplied DHCP Options",
            RFC 6422, December 2011.

8.2. Informative References

 [RFC3753]  Manner, J. and M. Kojo, "Mobility Related Terminology",
            RFC 3753, June 2004.
 [RFC4640]  Patel, A. and G. Giaretta, "Problem Statement for
            bootstrapping Mobile IPv6 (MIPv6)", RFC 4640,
            September 2006.
 [RFC5380]  Soliman, H., Castelluccia, C., ElMalki, K., and L.
            Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility
            Management", RFC 5380, October 2008.
 [RFC5447]  Korhonen, J., Bournelle, J., Tschofenig, H., Perkins, C.,
            and K. Chowdhury, "Diameter Mobile IPv6: Support for
            Network Access Server to Diameter Server Interaction",
            RFC 5447, February 2009.

Jang, et al. Standards Track [Page 15] RFC 6610 DHCPv6 for Home Info Discovery in MIPv6 May 2012

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]

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