One document matched: draft-ietf-mip6-bootstrapping-split-02.txt

Differences from draft-ietf-mip6-bootstrapping-split-01.txt



      
      
     MIP6 WG                                           G. Giaretta, Editor 
     Internet Draft                                         Telecom Italia 
     Expires: September 3, 2006                                   J. Kempf 
                                                           DoCoMo Labs USA 
                                                            V. Devarapalli 
                                                                     Nokia 
                                                             March 3, 2006 
                                         
      
                                          
                   Mobile IPv6 bootstrapping in split scenario 
                    draft-ietf-mip6-bootstrapping-split-02.txt 


     Status of this Memo 

        By submitting this Internet-Draft, each author represents that       
        any applicable patent or other IPR claims of which he or she is       
        aware have been or will be disclosed, and any of which he or she       
        becomes aware will be disclosed, in accordance with Section 6 of       
        BCP 79. 

        Internet-Drafts are working documents of the Internet Engineering 
        Task Force (IETF), its areas, and its working groups.  Note that 
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        Drafts. 

        Internet-Drafts are draft documents valid for a maximum of six 
        months and may be updated, replaced, or obsoleted by other 
        documents at any time.  It is inappropriate to use Internet-Drafts 
        as reference material or to cite them other than as "work in 
        progress." 

        The list of current Internet-Drafts can be accessed at 
             http://www.ietf.org/ietf/1id-abstracts.txt 

        The list of Internet-Draft Shadow Directories can be accessed at 
             http://www.ietf.org/shadow.html 

        This Internet-Draft will expire on August 3, 2006. 

     Copyright Notice 

        Copyright (C) The Internet Society (2006).  All Rights Reserved. 

     Abstract 

        A Mobile IPv6 node requires a Home Agent address, a home address, 
        and IPsec security associations with its Home Agent before it can 
        start utilizing Mobile IPv6 service. RFC 3775 requires that some 
        or all of these are statically configured. This document defines 
        how a Mobile IPv6 node can bootstrap this information from non-
      
      
      
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        topological information and security credentials preconfigured on 
        the Mobile Node. The solution defined in this document solves the 
        bootstrapping problem from draft-ietf-mip6-bootstrapping-ps-02 
        when the Mobile Node's mobility service is authorized by a 
        different service provider than basic network access, and is 
        therefore generically applicable to any bootstrapping case. 

     Conventions used in this document 

        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 RFC-2119 
        [1]. 

      




































      
      
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     Table of Contents 

        1. Introduction...................................................4 
        2. Terminology....................................................5 
        3. Split scenario.................................................6 
        4. Components of the solution.....................................9 
        5. Protocol Operations...........................................11 
           5.1. Home Agent Address Discovery.............................11 
              5.1.1. DNS lookup by Home Agent Name.......................11 
              5.1.2. DNS lookup by service name..........................12 
           5.2. IPsec Security Associations setup........................13 
           5.3. Home Address assignment..................................13 
              5.3.1. Home Address assignment by the Home Agent...........13 
              5.3.2. Home Address auto-configuration by the Mobile Node..13 
           5.4. Authorization and Authentication with MSA................15 
        6. Home Address registration in the DNS..........................17 
        7. Summary of Bootstrapping Protocol Flow........................19 
        8. Option and Attribute Format...................................21 
           8.1. DNS Update mobility option...............................21 
           8.2. MIP6_HOME_PREFIX attribute...............................22 
        9. Security Considerations.......................................23 
           9.1. HA Address Discovery.....................................23 
           9.2. Home Address Assignment through IKEv2....................24 
           9.3. SA Establishment Using EAP Through IKEv2.................25 
           9.4. Back End Security Between the HA and AAA Server..........25 
           9.5. Dynamic DNS Update.......................................25 
        10. IANA Considerations..........................................27 
        11. Contributors.................................................28 
        12. Acknowledgments..............................................29 
           12.1. Normative References....................................30 
           12.2. Informative References..................................30 
        Authors' Addresses...............................................32 
        Intellectual Property Statement..................................33 
        Disclaimer of Validity...........................................33 
        Copyright Statement..............................................33 
        Acknowledgment...................................................33 
      














      
      
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     1. Introduction 

        Mobile IPv6 [2] requires the Mobile Node to know its Home Agent 
        Address, its own Home Address and the cryptographic materials 
        (e.g. shared keys or certificates) needed to set up IPsec security 
        associations with the Home Agent in order to protect Mobile IPv6 
        signaling. This is generally referred to as the Mobile IPv6 
        bootstrapping problem [4]. 

        Mobile IPv6 base protocol does not specify any method to 
        automatically acquire this information, which means that network 
        administrators are normally required to manually set configuration 
        data on Mobile Nodes and HAs. However, in real deployments, manual 
        configuration does not scale as the Mobile Nodes increase in 
        number.  

        As discussed in [4], several bootstrapping scenarios can be 
        identified depending on the relationship between the network 
        operator that authenticates a mobile node for granting network 
        access service (Access Service Authorizer, ASA) and the service 
        provider that authorizes Mobile IPv6 service (Mobility Service 
        Authorizer, MSA). This document describes a solution to the 
        bootstrapping problem that is applicable in a scenario where the 
        MSA and the ASA are different entities (i.e. split scenario). 

         

























      
      
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     2. Terminology 

        General mobility terminology can be found in [8]. The following 
        additional terms are used here: 

        ASA 
            Access Service Authorizer. A network operator that 
            authenticates a mobile node and establishes the mobile node's 
            authorization to receive Internet service. 

        ASP 
            Access Service Provider. A network operator that provides 
            direct IP packet forwarding to and from the end host. 

        MSA 
            Mobility Service Authorizer. A service provider that 
            authorizes Mobile IPv6 service. 

        MSP 
            Mobility Service Provider. A service provider that provides 
            Mobile IPv6 service.  In order to obtain such service, the 
            mobile node must be authenticated and prove authorization to 
            obtain the service. 

        Split scenario 
            A scenario where mobility service and network access service 
            are authorized by different entities. This implies that MSA is 
            different from ASA. 
         






















      
      
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     3. Split scenario 

        In the problem statement description [4] there is a clear 
        assumption that mobility service and network access service can be 
        separate. This assumption implies that mobility service and 
        network access service may be authorized by different entities. As 
        an example, the service model defined in [4] allows an enterprise 
        network to deploy a Home Agent and offer Mobile IPv6 service to a 
        user, even if the user is accessing the Internet independent of 
        its enterprise account (e.g., by using his personal WiFi hotspot 
        account at a coffee shop). 

        Therefore, in this document it is assumed that network access and 
        mobility service are authorized by different entities, which means 
        that authentication and authorization for mobility service and 
        network access will be considered separately. This scenario is 
        called split scenario. 

        Moreover, the model defined in [4] separates the entity providing 
        the service from the entity that authenticates and authorizes the 
        user. This is similar to the roaming model for network access. 
        Therefore, in the split scenario, two different cases can be 
        identified depending on the relationship between the entity that 
        provides the mobility service (i.e. Mobility Service Provider, 
        MSP) and the entity that authenticates and authorizes the user 
        (i.e. Mobility Service Authorizer, MSA). 

        Figure 1 depicts the split scenario when the MSP and the MSA are 
        the       same entity. This means that the network operator that 
        provides the       Home Agent authenticates and authorizes the 
        user for mobility       service.. 

                                             Mobility Service                 
                                      Provider and Authorizer                 
                 +-------------------------------------------+                
                 |                                           |                
                 |  +-------------+                   +--+   |                
                 |  | MSA/MSP AAA |  <------------->  |HA|   |                
                 |  |   server    |    AAA protocol   +--+   |                
                 |  +-------------+                          |                
                 |                                           |                
                 +-------------------------------------------+                
                                                                              
                            +--+                                              
                            |MN|                                              
                            +--+                                              
                                                                              
                      Figure 1 - Split Scenario (MSA == MSP) 
         
        Figure 2 shows the split scenario in case the MSA and the MSP are 
        two different entities. This might happen if the Mobile Node is 
      
      
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        far from its MSA network and is assigned a closer HA to optimize 
        performance or if the MSA cannot provide any Home Agent and relies 
        on a third party (i.e. the MSP) to grant mobility service to its 
        users. Notice that the MSP might be or might not also be the 
        network operator that is providing network access (i.e. ASP, 
        Access Service Provider).  
         
                     Mobility Service                                         
                           Authorizer                                         
                    +-------------+                                           
                    |  MSA AAA    |                                           
                    |   server    |                                           
                    +-------------+                                           
                          ^                                                   
                          |                                                   
             AAA protocol |                                                   
                          |                  Mobility Service                 
                          |                          Provider                 
                 +--------|----------------------------------+                
                 |        V                                  |                
                 |  +-------------+                   +--+   |                
                 |  |  MSP AAA    |  <------------->  |HA|   |                
                 |  |   server    |    AAA protocol   +--+   |                
                 |  +-------------+                          |                
                 |                                           |                
                 +-------------------------------------------+                
                                                                              
                            +--+                                              
                            |MN|                                              
                            +--+                                              
                                                                              
                      Figure 2 - Split Scenario (MSA != MSP) 
                                                                              
        Note that Figure 1 and Figure 2 assume the use of an AAA protocol 
        to authenticate and authorize the Mobile Node for mobility 
        service. However, since IKEv2 allows EAP client authentication 
        only and the server authentication needs to be performed based on 
        certificates or public keys, the Mobile Node potentially requires 
        a certificate revocation list check (CTL check) even though an AAA 
        potocol is used to authenticate and authorize the Mobile Node for 
        mobility service. 

        If, instead, a PKI is used, the Mobile Node and HA exchange 
        certificates and there is no AAA server involved. This is 
        conceptually similar to Figure 1, since the MSP == MSA, except the 
        Home Agent, and potentially the Mobile Node, may require a 
        certificate revocation list check (CRL check) with the Certificate 
        Authority (CA). The CA may be either internal or external to the 
        MSP. Figure 3 illustrates. 

         
      
      
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                            Certificate                                      
                             Authority                                       
                           +-------------+                                   
                           |    CA       |                                   
                           |   server    |                                   
                           +-------------+                                   
                                 ^                                           
                                 |                                           
                    CRL Check    |                                           
                                 |       Mobility Service                    
                                 |    Provider and Authorizer                
                        +--------|----------+                                
                        |        V          |                                
                        |  +-------------+  |                                
                        |  |     HA      |  |                                
                        |  |             |  |                                
                        |  +-------------+  |                                
                        |                   |                                
                        +-------------------+                                
                                                                             
                                   +--+                                      
                                   |MN|                                      
                                   +--+                                      
      
                        Figure 3 - Split Scenario with PKI 

        The split scenario is the simplest model that can be identified, 
        since no assumptions about the access network are made. This 
        implies that the mobility service is bootstrapped independently 
        from the authentication protocol for network access used (e.g. 
        PANA, EAP). For this reason, the solution described in this 
        document and developed for this scenario could also be applied to 
        the integrated access network deployment model [4], even if it 
        might not be optimized. 









      
      
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     4. Components of the solution 

        The bootstrapping problem is composed of different sub-problems 
        that can be solved independently in a modular way. The components 
        identified and a brief overview of their solution follow. 

        o  HA address discovery. The Mobile Node needs to discover the 
           address of its Home Agent. The main objective of a 
           bootstrapping solution is to minimize the data pre-configured 
           on the Mobile Node. For this reason, the DHAAD defined in [2] 
           may not be applicable in real deployments since it is required 
           that the Mobile Node is pre-configured with the home network 
           prefix and it does not allow an operator to load balance by 
           having Mobile Nodes dynamically assigned to Home Agents located 
           in different subnets. This document defines a solution for Home 
           Agent address discovery that is based on Domain Name Service 
           (DNS), introducing a new DNS SRV record [5]. The unique 
           information that needs to be pre-configured on the Mobile Node 
           is the domain name of the MSP. 

        o  IPsec Security Associations setup. Mobile IPv6 requires that a 
           Mobile Node and its Home Agent share an IPsec SA in order to 
           protect binding updates and other Mobile IPv6 signaling. This 
           document provides a solution that is based on IKEv2 and follows 
           what is specified in [6]. The IKEv2 peer authentication can be 
           performed both using certificates and using EAP, depending on 
           the network operator's deployment model. 

        o  Home Address (HoA) assignment. The Mobile Node needs to know 
           its Home Address in order to bootstrap Mobile IPv6 operation. 
           The Home Address is assigned by the Home Agent during the IKEv2 
           exchange (as described in [6]). The solution defined in this 
           document also allows the Mobile Node to auto-configure its Home 
           Address based on stateless auto-configuration ([20]), 
           Cryptographically Generated Addresses ([9]) or privacy 
           addresses ([10]). 

        o  Authentication and Authorization with MSA. The user must be 
           authenticated in order for the MSP to grant the service. Since 
           the user credentials can be verified only by the MSA, this 
           authorization step is performed by the MSA. Moreover, the 
           mobility service must be explicitly authorized by the MSA based 
           on the user's profile. These operations are performed in 
           different ways depending on the credentials used by the Mobile 
           Node during the IKEv2 peer authentication and on the backend 
           infrastructure (PKI or AAA).  

        An optional part of bootstrapping involves providing a way for the 
        Mobile Node to have its FQDN updated in the DNS with a dynamically 
        assigned home address. While not all applications will require 
        this service, many networking applications use the FQDN to obtain 
      
      
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        an address for a node prior to starting IP traffic with it. The 
        solution defined in this document specifies that the dynamic DNS 
        update is performed by the Home Agent or through the AAA 
        infrastructure, depending on the trust relationship in place.  















































      
      
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     5. Protocol Operations 

        This section describes in detail the procedures needed to perform 
        Mobile IPv6 bootstrapping based on the components identified in 
        the previous section.  

         

     5.1. Home Agent Address Discovery 

        Once a Mobile Node has obtained network access, it can perform 
        Mobile IPv6 bootstrapping. For this purpose, the Mobile Node 
        queries the DNS server to request information on Home Agent 
        service. As mentioned before in the document, the only information 
        that needs to be pre-configured on the Mobile Node is the domain 
        name of the Mobility Service Provider. 

        The Mobile Node needs to obtain the IP address of the DNS server 
        before it can send a DNS request. This can be pre-configured on 
        the Mobile Node or obtained through DHCPv6 from the visited link 
        [11]. In any case, it is assumed that there is some kind of 
        mechanism by which the Mobile Node is configured with a DNS server 
        since a DNS server is needed for many other reasons. 

        Two options for DNS lookup for a Home Agent address are identified 
        in this document: DNS lookup by Home Agent Name and DNS lookup by 
        service name.  

        This document does not provide a specific mechanism to load balance different 
        Mobile Nodes among Home Agents. It is possible for an MSP to achieve coarse-
        grained load balancing by dynamically updating the SRV RR priorities to reflect 
        the current load on the MSP's collection of Home Agents. Mobile Nodes then use 
        the priority mechanism to preferentially select the least loaded HA. The 
        effectiveness of this technique depends on how much of a load it will place on 
        the DNS servers, particularly if dynamic DNS is used for frequent updates.  

        While this document specifies a Home Agent Address Discovery 
        solution  based on DNS, when the ASP and the MSP are the same 
        entity DHCP may be used. See [15] for details. 

     5.1.1. DNS lookup by Home Agent Name 

        In this case, the Mobile Node is configured with the Fully 
        Qualified Domain Name of the Home Agent. As an example, the Mobile 
        Node could be configured with the name "ha1.example.com", where 
        "example.com" is the domain name of the MSP granting the mobility 
        service.  

        The Mobile Node constructs a DNS request, by setting the QNAME to 
        the name of the Home Agent. The request has QTYPE set to 'AAAA', 
        so that the DNS server sends the IPv6 address of the Home Agent. 
      
      
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        Once the DNS server replies to this query, the Mobile Node knows 
        its Home Agent address and can run IKEv2 in order to set up the 
        IPsec SAs and get a Home Address. 

        Additionally, the ability to provide a mobile node with a 
        localized home agent (e.g. on the visited link) can help to 
        optimize handover signaling and improve routing efficiency in bi-
        directional tunneling mode. There are a variety of ways this can 
        be achieved in an interoperable way. One way is to provision the 
        mobile node with an FQDN for a local home agent when it configures 
        for the local link. Another way is to specify an interoperable 
        naming convention for constructing home agent FQDNs based on 
        location. For example, an operator might assign the FQDN 
        "ha.locationA.operator.com" to the Home Agent located in "location 
        A" and the FQDN "ha.locationB.operator.com" to the Home Agent 
        located in "location B". If the Mobile Node wants to use a Home 
        Agent located in "location A", it will set the QNAME to 
        "ha.locationA.operator.com" in the DNS request. The exact way in 
        which localized Home Agents are configured is out of scope for 
        this draft.          

     5.1.2. DNS lookup by service name 

        RFC 2782 [5] defines the service resource record (SRV RR) that 
        allows an operator to use several servers for a single domain, to 
        move services from host to host, and to designate some hosts as 
        primary servers for a service and others as backups. Clients ask 
        for a specific service/protocol for a specific domain and get back 
        the names of any available servers. 

        RFC 2782[5] also describes the policies to choose a service agent 
        based on the preference and weight values. The DNS SRV record may 
        contain the preference and weight values for multiple Home Agents 
        available to the Mobile Node in addition to the Home Agent FQDNs. 
        If multiple Home Agents are available in the DNS SRV record then 
        Mobile Node is responsible for processing the information as per 
        policy and for picking one Home Agent. If the Home Agent of choice 
        does not respond for some reason or the IKEv2 authentication 
        fails, the Mobile Node SHOULD try other Home Agents on the list. 

        The service name for Mobile IPv6 Home Agent service as required by   
        RFC 2782 is "mip6" and the protocol name is "ipv6". Note that a   
        transport name cannot be used here because Mobile IPv6 does not 
        run over a transport protocol. 

        The SRV RR has a DNS type code of 33. As an example, the Mobile 
        constructs a request with QNAME set to "_mip6._ipv6.example.com" 
        and QTYPE to SRV. The reply contains the FQDNs of one or more 
        servers, that can then be resolved in a separate DNS transaction 
        to the IP addresses. However, if there is room in the SRV reply, 
        it is RECOMMENDED that the DNS server also return the IP addresses 
      
      
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        of the Home Agents in AAAA records as part of the additional data 
        section (in order to avoid requiring an additional DNS round trip 
        to resolve the FQDNs).  

         

     5.2. IPsec Security Associations setup 

        As soon as the Mobile Node has discovered the Home Agent Address, 
        it establishes an IPsec Security Association with the Home Agent 
        itself through IKEv2. The detailed description of this procedure 
        is provided in [6]. If the Mobile Node wants the HA to register 
        the Home Address in the DNS, it MUST use the FQDN as the initiator 
        identity in IKE_AUTH step of the IKEv2 exchange (IDi). This is 
        needed because the Mobile Node has to provide it is the owner of 
        the FQDN provided in the subsequent DNS Update Option. See section 
        6 and section 9 for a more detailed analysis on this issue.   

        The IKEv2 Mobile Node to Home Agent authentication can be 
        performed using either IKEv2 public key signatures or the 
        Extensible Authentication Protocol (EAP). The details about how to 
        use IKEv2 authentication are described in [6] and [7]. Choice of 
        an IKEv2 peer authentication method depends on the deployment. 
        However, IKEv2 restricts the Home Agent to Mobile Node 
        authentication to use public key signature-based authentication. 

         

     5.3. Home Address assignment 

        Home Address assignment is performed during the IKEv2 exchange. 
        The Home Address can be assigned directly by the Home Agent or can 
        be auto-configured by the Mobile Node. 

     5.3.1. Home Address assignment by the Home Agent 

        When the Mobile Node runs IKEv2 with its Home Agent, it can 
        request a HoA through the Configuration Payload in the IKE_AUTH 
        exchange by including an INTERNAL_IP6_ADDRESS attribute. When the 
        Home Agent processes the message, it allocates a HoA and sends it 
        a CFG_REPLY message. The Home Agent could consult a DHCP server on 
        the home link for the actual home address allocation. This is 
        explained in detail in [6]. 

     5.3.2. Home Address auto-configuration by the Mobile Node 

        With the type of assignment described in the previous section, the 
        Home Address cannot be generated based on Cryptographically 
        Generated Addresses (CGAs) [9] or based on the privacy extensions 
        for stateless auto-configuration [10]. However, the Mobile Node 
        might want to have an auto-configured HoA based on these 
      
      
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        mechanisms. It is worthwhile to mention that the auto-
        configuration procedure described in this section cannot be used 
        in some possible deployments, since the Home Agents might be 
        provisioned with pools of allowed Home Addresses.  

        In the simplest case, the Mobile Node is provided with a pre-
        configured home prefix and home prefix length. In this case the 
        Mobile Node creates a Home Address based on the pre-configured 
        prefix and sends it to the Home Agent including an 
        INTERNAL_IP6_ADDRESS attribute in a Configuration Payload of type 
        CFG_REQUEST. If the Home Address is valid, the Home Agent replies 
        with a CFG_REPLY, including an INTERNAL_IP6_ADDRESS with the same 
        address. If the Home Address provided by the Mobile Node is not 
        valid, the Home Agent assigns a different Home Address including 
        an INTERNAL_IP6_ADDRESS attribute with a new value. According to 
        [7] the Mobile Node MUST use the address sent by the Home Agent. 
        Later, if the Mobile Node wants to use an auto-configured Home 
        Address (e.g. based on CGA), it can run Mobile Prefix Discovery, 
        obtain a prefix, auto-configure a new Home Address and then 
        perform a new CREATE_CHILD_SA exchange.  

        If the Mobile Node is not provided with a pre-configured Home 
        Prefix, the Mobile cannot simply propose an auto-configured HoA in 
        the Configuration Payload since the Mobile Node does not know the 
        home prefix before the start of the IKEv2 exchange. The Mobile 
        Node must obtain the home prefix and the home prefix length before 
        it can configure a home address.  

        One simple solution would be for the Mobile Node to just assume 
        that the prefix length on the home link is 64 bits and extract the 
        home prefix from the Home Agent's address. The disadvantage with 
        this solution is that the home prefix cannot be anything other 
        than /64. Moreover, this ties the prefix on the home link and the 
        Home Agent's address, but, in general, a Home Agent with a 
        particular address should be able to serve a number of prefixes on 
        the home link, not just the prefix from which its address is 
        configured.  

        Another solution would be for the Mobile Node to assume that the 
        prefix length on the home link is 64 bits and send its interface 
        identifier to the Home Agent in the INTERNAL_IP6_ADDRESS attribute 
        within the CFG_REQ payload. Even though this approach does not tie 
        the prefix on the home link and the Home Agent's address, it still 
        requires that the home prefix length is 64 bits. 

        For this reason the Mobile Node needs to obtain the home link 
        prefixes through the IKEv2 exchange. In the Configuration Payload 
        during the IKE_AUTH exchange, the Mobile Node includes the 
        MIP6_HOME_PREFIX attribute in the CFG_REQUEST message.  The Home 
        Agent, when it processes this message, should include in the 
        CFG_REPLY payload prefix information for one prefix on the home 
      
      
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        link. This prefix information includes the prefix length (see 
        section 8.2). The Mobile Node auto-configures a Home Address from 
        the prefix returned in the CFG_REPLY message and runs a 
        CREATE_CHILD_SA exchange to create security associations for the 
        new Home Address.  

        As mentioned before in this document, there are deployments where 
        auto-configuration of the Home Address cannot be used. In this 
        case, when the Home Agent receives a CFG_REQUEST including a 
        MIP6_HOME_PREFIX attribute, in the subsequent IKE response it 
        includes a Notify Payload type "USE_ASSIGNED_HoA" and the related 
        Home Address in a INTERNAL_IP6_ADDRESS attribute. If the Mobile 
        Node gets a "USE_ASSIGNED_HoA" Notify Payload in response to the 
        Configuration Payload containing the MIP6_HOME_PREFIX attribute, 
        it looks for an INTERNAL_IP6_ADDRESS attribute and MUST use the 
        address contained in it in the subsequent CREATE_CHILD_SA 
        exchange. 

        When the Home Agent receives a Binding Update for the Mobile Node, 
        it performs proxy DAD for the auto-configured Home Address. If DAD 
        fails, the Home Agent rejects the Binding Update. If the Mobile 
        Node receives a Binding Acknowledgement with status 134 (DAD 
        failed), it MUST stop using the current Home Address, configure a 
        new HoA, and then run IKEv2 CREATE_CHILD_SA exchange to create 
        security associations based on the new HoA. The Mobile Node does 
        not need to run IKE_INIT and IKE_AUTH exchanges again. Once the 
        necessary security associations are created, the Mobile Node sends 
        a Binding Update for the new Home Address. 

        It is worth noting that with this mechanism, the prefix 
        information carried in MIP6_HOME_PREFIX attribute includes only 
        one prefix and does not carry all the information that is 
        typically present when received through a IPv6 router 
        advertisement. Mobile Prefix Discovery, specified in RFC 3775 [2], 
        is the mechanism through which the Mobile Node can get all 
        prefixes on the home link and all related information. That means 
        that MIP6_HOME_PREFIX attribute is only used for Home Address 
        auto-configuration and does not replace the usage of Mobile Prefix 
        Discovery for the purposes detailed in RFC 3775. 

         

     5.4. Authorization and Authentication with MSA 

        In a scenario where the Home Agent is discovered dynamically by 
        the Mobile Node, it is very likely that the Home Agent is not able 
        to verify by its own the credentials provided by the Mobile Node 
        during the IKEv2 exchange. Moreover, the mobility service needs to 
        be explicitly authorized based on the user's profile. As an 
        example, the Home Agent might not be aware of whether the mobility 

      
      
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        service can be granted at a particular time of the day or when the 
        credit of the Mobile Node is going to expire. 

        Due to all these reasons, the Home Agent may need to contact the 
        MSA in order to authenticate the Mobile Node and authorize 
        mobility service. This can be accomplished based on a Public Key 
        Infrastructure if certificates are used and a PKI is deployed by 
        the MSP and MSA. On the other hand, if the Mobile Node is provided 
        with other types of credentials, the AAA infrastructure must be 
        used. 

        The definition of this backend communication is out of the scope 
        of this document. In [12] a list of goals for such a communication 
        is provided. 

         



































      
      
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     6. Home Address registration in the DNS 

        In order that the Mobile Node is reachable through its dynamically 
        assigned Home Address, the DNS needs to be updated with the new 
        Home Address. Since applications make use of DNS lookups on FQDN 
        to find a node, the DNS update is essential for providing IP 
        reachability to the Mobile Node, which is the main purpose of the 
        Mobile IPv6 protocol. The need for DNS updating is not discussed 
        in RFC 3775 since it assumes that the Mobile Node is provisioned 
        with a static Home Address. However, when a dynamic Home Address 
        is assigned to the Mobile Node, any existing DNS entry becomes 
        invalid and the Mobile Node becomes unreachable unless a DNS 
        update is performed. 

        Since the DNS update must be performed securely in order to 
        prevent attacks or modifications from malicious nodes, the node 
        performing this update must share a security association with the 
        DNS server. Having all possible Mobile Nodes sharing a security 
        association with the DNS servers of the MSP might be cumbersome 
        from an administrative perspective. Moreover, even if a Mobile 
        Node has a security association with a DNS server of its MSP, an 
        address authorization issue comes into the picture. A detailed 
        analysis of possible threats against DNS update is provided in 
        section 9.5. 

        Therefore, due to security and administrative reasons, it is 
        RECOMMENDED that the Home Agent perform DNS entry updates for the 
        Mobile Node. For this purpose the Mobile Node MAY include a new 
        mobility option in the Binding Update, the DNS Update option, with 
        the flag R not set in the option. This option is defined in 
        section 8 and includes the FQDN that needs to be updated. After 
        receiving the Binding Update, the Home Agent MUST update the DNS 
        entry with the identifier provided by the Mobile Node and the Home 
        Address included in the Home Address Option. The procedure for 
        sending a dynamic DNS update message is specified in [14]. The 
        dynamic DNS update SHOULD be performed in a secure way; for this 
        reason, the usage of TKEY and TSEC or DNSSEC is recommended (see 
        section 9.5. for details). As soon as the Home Agent has updated 
        the DNS, it MUST send a Binding Acknowledgement message to the 
        Mobile Node including the DNS Update mobility option with the 
        correct value in the Status field (see section 8.1). 

        This procedure can be performed directly by the Home Agent if the 
        Home Agent has a security association with the domain specified in 
        the Mobile Node's FQDN.  

        On the other hand, if the Mobile Node wants to be reachable 
        through a FQDN that belongs to the MSA, the Home Agent and the DNS 
        server that must be updated belong to different administrative 
        domains. In this case the Home Agent may not share a security 
        association with the DNS server and the DNS entry update can be 
      
      
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        performed by the AAA server of the MSA. In order to accomplish 
        this, the Home Agent sends to the AAA server the FQDN-HoA pair 
        through the AAA protocol. This message is proxied by the AAA 
        infrastructure of the MSP and is received by the AAA server of the 
        MSA. The AAA server of the MSA perform the DNS update based on 
        [14]. Notice that, even in this case, the Home Agent is always 
        required to perform a DNS update for the reverse entry, since this 
        is always performed in the DNS server of the MSP. The detailed 
        description of the communication between Home Agent and AAA is out 
        of the scope of this document. More details are provided in [12]. 

        A mechanism to remove stale DNS entries is needed. A DNS entry 
        becomes stale when the related Home Address is no longer used by 
        the Mobile Node. To remove a DNS entry, the Mobile Node includes 
        in the Binding Update the DNS Update mobility option, with the 
        flag R set in the option. After receiving the Binding Update, the 
        Home Agent MUST remove the DNS entry identified by the FQDN 
        provided by the Mobile Node and the Home Address included in the 
        Home Address Option. The procedure for sending a dynamic DNS 
        update message is specified in [14]. As mentioned above, the 
        dynamic DNS update SHOULD be performed in a secure way; for this 
        reason, the usage of TKEY and TSEC or DNSSEC is recommended (see 
        section 9.5. for details).  

        This approach does not work if the Mobile Node stops using the 
        Home Address without sending a Binding Update message (e.g. in 
        case of crash). In this case, an additional mechanism to trigger 
        the DNS entry removal is needed. For this purpose, the Home Agent 
        has a timer related to the DNS entry of the Mobile Node. This 
        timer is initialized when the Mobile Node sends a Binding Update 
        with R==0 (i.e. when the Mobile Node asks the Home Agent to bind 
        the FQDN to the Home Address). The initial value of this timer is 
        configurable by the network operator. 

        If the Home Agent receives a Binding Update with R==1, it removes 
        the DNS entry as described in the previous paragraph and removes 
        the timer associated with that entry. If the timer expires without 
        receiving a Binding Update with R==1, the HA checks the Binding 
        Cache. If there is an existing Binding Cache entry for the HoA, 
        the HA does not remove the DNS entry and re-initialize the timer. 
        If there is not a Binding Cache entry, it sends a Neighbor 
        Solicitation message to check if the Mobile Node is at home and is 
        using the HoA. If the HA gets a Neighbor Advertisement message, it 
        does not remove the DNS entry and re-initialize the timer. If it 
        does not receive a NA, it removes the DNS entry and the timer 
        associated with it. 

          

      

      
      
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     7. Summary of Bootstrapping Protocol Flow 

        The message flow of the whole bootstrapping procedure when the 
        dynamic DNS update is performed by the Home Agent is depicted in 
        Figure 4. 

            +----+                  +----+              +-----+           
            | MN |                  | HA |              | DNS |           
            +----+                  +----+              +-----+           
                                                                          
                   IKEv2 exchange                                         
                (HoA configuration)                                   
               <======================>                                   
                                                                          
               BU (DNS update option)                                     
               ----------------------->                                   
                                             DNS update                   
                                       <------------------->              
                BA (DNS update option)                                    
               <-----------------------                                   
                                                                          
                                                                        
                     Figure 4 - Dynamic DNS update by the HA 

         

        Figure 5 shows the message flow of the whole bootstrapping 
        procedure when the dynamic DNS update is performed by the AAA 
        server of the MSA. 

         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
      
      
      
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          +----+                +----+         +---+         +---+     
          | MN |                | HA |         |AAA|         |DNS|     
          +----+                +----+         +---+         +---+     
                                                                       
                IKEv2 exchange                                         
              (HoA configuration)                                      
            <======================>                                   
                                                                       
            BU (DNS update option)                                     
            ----------------------->                                   
                                                                       
                                     AAA request                       
                                     (FQDN, HoA)                       
                                   <-------------->                    
                                                                       
                                                    DNS update         
                                                   <----------->       
                                     AAA answer                        
                                     (FQDN, HoA)                       
                                   <-------------->                    
              BA (DNS update option)                                   
            <-----------------------                                   
                                                                       
                                                                       
                     Figure 5 - Dynamic DNS update by the AAA 

        Notice that, even in this last case, the Home Agent is always 
        required to perform a DNS update for the reverse entry, since this 
        is always performed in the DNS server of the MSP. This is not 
        depicted in Figure 5. 

         



















      
      
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     8. Option and Attribute Format 

     8.1. DNS Update mobility 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 Type  | Option Length | 
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
        |   Status      |R|  Reserved   |     MN identity (FQDN) ...      
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
         

        o  Option Type - DNS-UPDATE-TYPE to be defined by IANA 

        o  Option Length - 8 bit unsigned integer indicating the length of 
           the option excluding the type and length fields 

        o  Status - 8 bit unsigned integer indicating the result of the 
           dynamic DNS update procedure. This field MUST be set to 0 and 
           ignored by the receiver when the DNS Update mobility option is 
           included in a Binding Update message. When the DNS Update 
           mobility option is included in the Binding Acknowledgement 
           message, values of the Status field less than 128 indicate that 
           the dynamic DNS update was performed successfully by the Home 
           Agent. Values greater than or equal to 128 indicate that the 
           dynamic DNS update was not completed by the HA. The following 
           Status values are currently defined: 

               0 DNS update performed 

               128 Reason unspecified 

               129 Administratively prohibited 

               130 DNS Update Failed 

        o  R flag - if set the Mobile Node is requesting the HA to remove 
           the DNS entry identified by the FQDN specified in this option 
           and the HoA of the Mobile Node. If not set, the Mobile Node is 
           requesting the HA to create or update a DNS entry with its HoA 
           and the FQDN specified in the option. 

        o  Reserved - these bits are reserved for future purposes and MUST 
           be set to 0. 

        o  MN identity - the identity of the Mobile Node to be used by the 
           Home Agent to send a Dynamic DNS update.  It is a variable 
           length field. 

         
      
      
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     8.2. MIP6_HOME_PREFIX attribute 

        The MIP6_HOME_PREFIX attribute is included in the IKEv2 
        CFG_REQUEST by the Mobile Node to ask the Home Agent for the home 
        prefix and is included in the CFG_REPLY by the Home Agent to 
        provide the Mobile Node with home prefix and home prefix length. 
        The format of this attribute is equal to the format of the 
        Configuration Attributes defined in [7] and is depicted below. 

                              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  
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
         |R|         Attribute Type      !            Length             | 
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
         |                                                               | 
         |                        home prefix                            | 
         |                                                               | 
         |                                                               | 
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
         |                     Prefix Lifetime                           | 
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
         | Prefix Length |                                                 
         +-+-+-+-+-+-+-+-+                                                 
         

        o  Reserved (1 bit) - This bit MUST be set to zero and MUST be 
           ignored on receipt. 

        o  Attribute Type (7 bits) - A unique identifier for the 
           MIP6_HOME_PREFIX attribute. To be assigned by IANA. 

        o  Length (2 octets) - Length in octets of Value field (home 
           prefix and Prefix Length). This is multi-valued and can be 0 or 
           17. 

        o  Home Prefix (16 octets) - The prefix of the home link through 
           which the Mobile Node must auto-configure its Home Address. 

        o  Prefix Lifetime (4 octets) -  

        o  Prefix Length (1 octet) - The length in bits of the home prefix 
           specified in the field Home Prefix. 

        When the MIP6_HOME_PREFIX attribute is included by the Mobile Node 
        in the CFG_REQUEST payload, the value of the Length field is 0. On 
        the other hand, when the MIP6_HOME_PREFIX attribute is included in 
        the CFG_REPLY payload by the Home Agent, the value of the Length 
        field is 17 and the attribute contains also the Home Prefix and 
        the Prefix Length fields. 

         
      
      
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     9. Security Considerations 

     9.1. HA Address Discovery 

        Use of DNS for address discovery carries certain security risks. 
        DNS transactions in the Internet are typically done without any 
        authentication of the DNS server by the client or of the client by 
        the server. There are two risks involved: 

        1) A legitimate client obtains a bogus Home Agent address from a 
        bogus DNS server. This is sometimes called a "pharming" attack, 

        2) An attacking client obtains a legitimate Home Agent address 
        from a legitimate server. 

        The risk in Case 1 is mitigated because the Mobile Node is 
        required to conduct an IKE transaction with the Home Agent prior 
        to performing a Binding Update to establish Mobile IPv6 service. 
        According to the IKEv2 specification [7], the responder must 
        present the initiator with a valid certificate containing the 
        responder's public key, and the responder to initiator IKE_AUTH 
        message must be protected with an authenticator calculated using 
        the public key in the certificate. Thus, an attacker would have to 
        set up both a bogus DNS server and a bogus Home Agent, and 
        provision the Home Agent with a certificate that a victim Mobile 
        Node could verify. If the Mobile Node can detect that the 
        certificate is not trustworthy, the attack will be foiled when the 
        Mobile Node attempts to set up the IKE SA. 

        The risk in Case 2 is limited for a single Mobile Node to Home 
        Agent transaction if the attacker does not possess proper 
        credentials to authenticate with the Home Agent. The IKE SA 
        establishment will fail when the attacking Mobile Node attempts to 
        authenticate itself with the Home Agent. Regardless of whether the 
        Home Agent utilizes EAP or host-side certificates to authenticate 
        the Mobile Node, the authentication will fail unless the Mobile 
        Node has valid credentials. 

        Another risk exists in Case 2 because the attacker may be 
        attempting to propagate a DoS attack on the Home Agent. In that 
        case, the attacker obtains the Home Agent address from the DNS, 
        then propagates the address to a network of attacking hosts that 
        bombard the Home Agent with traffic. This attack is not unique to 
        the bootstrapping solution, however, it is actually a risk that 
        any Mobile IPv6 Home Agent installation faces. In fact, the risk 
        is faced by any service in the Internet that distributes a unicast 
        globally routable address to clients. Since Mobile IPv6 requires 
        that the Mobile Node communicate through a globally routable 
        unicast address of a Home Agent, it is possible that the Home 
        Agent address could be propagated to an attacker by various means 
        (theft of the Mobile Node, malware installed on the Mobile Node, 
      
      
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        evil intent of the Mobile Node owner him/herself, etc.) even if 
        the home address is manually configured on the Mobile Node. 
        Consequently, every Mobile IPv6 Home Agent installation will 
        likely be required to mount anti-DoS measures. Such measures 
        include overprovisioning of links to and from Home Agents and of 
        Home Agent processing capacity, vigilant monitoring of traffic on 
        the Home Agent networks to detect when traffic volume increases 
        abnormally indicating a possible DoS attack, and hot spares that 
        can quickly be switched on in the event an attack is mounted on an 
        operating collection of Home Agents. DoS attacks of moderate 
        intensity should be foiled during the IKEv2 transaction. IKEv2 
        implementations are expected to generate their cookies without any 
        saved state, and to time out cookie generation parameters 
        frequently, with the timeout value increasing if a DoS attack is 
        suspected. This should prevent state depletion attacks, and should 
        assure continued service to legitimate clients until the practical 
        limits on the network bandwith and processing capacity of the Home 
        Agent network are reached. 

        Explicit security measures between the DNS server and host, such 
        DNSSEC [16] or TSIG/TKEY [17] [18] can mitigate the risk of 1) and 
        2), but these security measures are not widely deployed on end 
        nodes. These security measures are not sufficient to protect the 
        Home Agent address against DoS attack, however, because a node 
        having a legitimate security association with the DNS server could 
        nevertheless intentionally or inadvertently cause the Home Agent 
        address to become the target of DoS. 

        Finally notice that assignment of an home agent from the serving 
        network access provider's (local home agent) or a home agent from 
        a nearby network (nearby home agent) may set up the potential to 
        compromise a mobile node's location privacy. However, since a 
        standardized mechanism of assigning local or nearby home agents is 
        out of scope for this document, it is not possible to present 
        detailed security considerations. Please see other drafts that 
        contain detailed mechanisms for localized home agent assignment, 
        such as [15], for information on the location privacy properties 
        of particular home agent assignment mechanisms. 

        Security considerations for discovering HA using DHCP are covered 
        in draft-jang-dhc-haopt-01 [15]. 

     9.2. Home Address Assignment through IKEv2 

        Mobile IPv6 bootstrapping assigns the home address through the 
        IKEv2 transaction. The Mobile Node can either choose to request an 
        address, similar to DHCP, or the Mobile Node can request a prefix 
        on the home link then auto-configure an address. 

        RFC 3775 [2] and 3776 [3] require that a Home Agent check 
        authorization of a home address received during a Binding Update. 
      
      
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        The Home Agent MUST set up authorization by linking the home 
        address to the identity of the IPsec SAs used to authenticate the 
        Binding Update message. The linking MUST be done either during the 
        IKE_AUTH phase or CREATE_CHILD_SA phase when the IPsec SAs are 
        constructed.  

        If the address is auto-configured, RFC 3775 requires the Home 
        Agent to proxy-defend the address on the home link after the 
        Mobile Node performs the initial Binding Update. Since it is not 
        currently possible to securely proxy CGAs using SEND, attacks on 
        address resolution for Neighbor Discovery listed in RFC 3756 are 
        possible on dynamically assigned home addresses that are proxied 
        by the Home Agent. 

     9.3. SA Establishment Using EAP Through IKEv2 

        Security considerations for authentication of the IKE transaction 
        using EAP are covered in draft-ietf-mip6-ikev2-ipsec [6]. 

     9.4. Back End Security Between the HA and AAA Server 

        Some deployments of Mobile IPv6 bootstrapping may use an AAA 
        server to handle authorization for mobility service. This process 
        has its own security requirements, but the back end protocol for 
        Home Agent to AAA server interface is not covered in this draft. 
        Please see draft-ietf-mip6-aaa-ha-goals [12] for a discussion of 
        this interface. 

     9.5. Dynamic DNS Update 

        Mobile IPv6 bootstrapping recommends the Home Agent to update the 
        Mobile Node's FQDN with a dynamically assigned home address rather 
        than have the Mobile Node itself do it (see Section 6 above). This 
        choice was motivated by a concern for preventing redirection-based 
        flooding attacks (see draft-ietf-mip6-ro-sec [19] for more 
        information about redirection-based flooding attacks and the role 
        preventing them played in the design of Mobile IPv6 route 
        optimization security). Exactly as for route optimization, it is 
        possible for a node that is the legitimate owner of a DNS FQDN - 
        in the sense that it has a security association with the DNS 
        server allowing it to perform dynamic DNS update of its FQDN - to 
        bind its FQDN to the address of a victim, then redirect large 
        volumes of traffic at the victim. The attack may be propagated 
        without the owner's knowledge, for example, if the node is 
        compromised by malware, or it may be intentional if the node 
        itself is the attacker.  

        While it is possible to prevent redirection attacks through 
        ingress filtering on access routers, ISPs have little or no 
        incentive to deploy ingress filtering. In some cases, if an attack 
        could result in substantial financial gain, it is even possible 
      
      
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        that a corrupt ISP may have an incentive not to deploy ingress 
        filters such as has been the case for spam. Consequently, the 
        security for dynamic Mobile Node FQDN update has been assigned to 
        the Home Agent, where active network administration and vigilant 
        defense measures are more likely to (but are not assured of) 
        mitigating problems, and the owner of the Mobile Node is more 
        likely to detect a problem if it occurs. 

        If a Home Agent performs dynamic DNS update on behalf of the 
        Mobile Node directly with the DNS server, the Home Agent MUST have 
        a security association of some type with the DNS server. The 
        security association MAY be established either using DNSSEC [16] 
        or TSIG/TKEY [17][18]. A security association is required even if 
        the DNS server is in the same administrative domain as the Home 
        Agent. The security association SHOULD be separate from the 
        security associations used for other purposes, such as AAA. 

        In the case where the Mobility Service Provider is different from 
        the Mobility Service Authorizer, the network administrators may 
        want to limit the number of cross-administrative domain security 
        associations. If the Mobile Node's FQDN is in the Mobility Service 
        Authorizer's domain, since a security association for AAA 
        signaling involved in mobility service authorization is required 
        in any case, the Home Agent can send the Mobile Node's FQDN to the 
        AAA server under the HA-AAA server security association, and the 
        AAA server can perform the update. In that case, a security 
        association is required between the AAA server and DNS server for 
        the dynamic DNS update. See draft-ietf-mip6-aaa-ha-goals [12] for 
        a deeper discussion of the Home Agent to AAA server interface. 

        Regardless of whether the AAA server or Home Agent performs DNS 
        update, the authorization of the Mobile Node to update a FQDN MUST 
        be checked prior to the performance of the update. It is an 
        implementation issue as to how authorization is determined. 
        However, in order to allow this authorization step, the Mobile 
        Node MUST use a FQDN as the IDi in IKE_AUTH step of the IKEv2 
        exchange. The FQDN MUST be the same that will be provided by the 
        Mobile Node in the DNS Update Option. This allows the Home Agent 
        to get authorization information about the Mobile Node's FQDN via 
        the AAA back end communication performed during IKEv2 exchange. 
        The outcome of this step will give the Home Agent the necessary 
        information to authorize the DNS update request of the Mobile 
        Node. See draft-ietf-mip6-aaa-ha-goals [12] for details about the 
        communication between the AAA server and the Home Agent needed to 
        perform the authorization. Notice that if certificates are used in 
        IKEv2, the authorization information about the FQDN for DNS update 
        MUST be present in the certificate provided by the Mobile Node. 




      
      
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     10. IANA Considerations 

        This document defines a new Mobility Option and a new IKEv2 
        Configuration Attribute Type. 

        The following values should be assigned: 

        o  from "Mobility Option" namespace ([2]): DNS-UPDATE-TYPE 
           (section 8.1) 

        o  from "IKEv2 Configuration Payload Attribute Types" namespace 
           ([7]): MIP6_HOME_PREFIX attribute (section 8.2) 

        o  from "IKEv2 Notify Payload Error Types" namespace ([7]): 
           USE_ASSIGNED_HoA error type (section 5.3.2) 

         


































      
      
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     11. Contributors 

        This contribution is a joint effort of the bootstrapping solution 
        design team of the MIP6 WG.  The contributors include Basavaraj 
        Patil, Alpesh Patel, Jari Arkko, James Kempf, Yoshihiro Ohba, 
        Gopal Dommety, Alper Yegin, Junghoon Jee, Vijay Devarapalli, 
        Kuntal Chowdury, Julien Bournelle. 

        The design team members can be reached at: 

        Gerardo Giaretta  gerardo.giaretta@tilab.com 

        Basavaraj Patil   basavaraj.patil@nokia.com 

        Alpesh Patel      alpesh@cisco.com 

        Jari Arkko        jari.arkko@kolumbus.fi 

        James Kempf       kempf@docomolabs-usa.com 

        Yoshihiro Ohba    yohba@tari.toshiba.com 

        Gopal Dommety     gdommety@cisco.com 

        Alper Yegin       alper.yegin@samsung.com 

        Vijay Devarapalli vijayd@iprg.nokia.com 

        Kuntal Chowdury   kchowdury@starentnetworks.com 

        Junghoon Jee      jhjee@etri.re.kr 

        Julien Bournelle  julien.bournelle@int-evry.fr 


















      
      
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     12. Acknowledgments 

        The authors would like to thank Rafa Lopez, Francis Dupont, Jari 
        Arkko, Kilian Weniger, Vidya Narayanan, Ryuji Wakikawa for their 
        valuable comments. 

         












































      
      
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     13. References 

     13.1. Normative References 

        [1]   Bradner, S., "Key words for use in RFCs to Indicate 
              Requirement Levels", BCP 14, RFC 2119, March 1997. 

        [2]   Johnson, D., Perkins, C. and J. Arkko, "Mobility Support            
              in IPv6”, RFC 3775, June 2004. 

        [3]   Arkko, J., Devarapalli, V., Dupont, F., "Using IPsec to             
              Protect Mobile IPv6 Signaling between Mobile Nodes and             
              Home Agents", RFC 3776, June 2004 

        [4]   Patel, A., "Problem Statement for bootstrapping Mobile 
              IPv6", Internet-Draft draft-ietf-mip6-bootstrap-ps-04, 
              February 2006. 

        [5]   Gulbrandsen, A., Vixie, P. and L. Esibov, "A DNS RR for 
              specifying the location of services (DNS SRV)", RFC 2782,         
              February 2000. 

        [6]   Devarapalli, V., " Mobile IPv6 Operation with IKEv2 and the 
              revised IPsec Architecture", Internet-Draft draft-ietf-mip6-
              ikev2-ipsec-04, October 2005. 

        [7]   Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",        
              RFC 4306, December 2005. 

     13.2. Informative References 

        [8]   Manner, J., Kojo, M. "Mobility Related Terminology”, RFC 
              3753, June 2004. 

        [9]   Aura, T., "Cryptographically Generated Addresses (CGA)", RFC 
              3972, March 2005. 

        [10]  Narten, T., Draves, R., Krishnan, S., "Privacy Extensions 
              for Stateless Address Autoconfiguration in IPv6", Internet-
              Draft draft-ietf-ipv6-privacy-addrs-v2-04, May 2005. 

        [11]  Droms, R., Ed., "DNS Configuration options for Dynamic Host 
              Configuration Protocol for IPv6 (DHCPv6)", RFC 3646, 
              December 2003. 

        [12]  Giaretta, G., Ed. "Goals for AAA-HA interface", Internet-
              Draft draft-ietf-mip6-aaa-ha-goals-01, February 2006. 


      
      
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        [13]  Koodli, R., Devarapalli, V., Perkins, C., Flinck, H., 
              "Solutions for IP Address Location Privacy in the presence 
              of IP Mobility", Internet-Draft, draft-koodli-mip6-location-
              privacy-solutions-00, February 2005. 

        [14]  P. Vixie, Ed., S. Thomson, Y. Rekhter, and J. Bound.  
              "Dynamic Updates in the Domain Name System (DNS UPDATE)", 
              RFC 2136, April 1997. 

        [15]  Chowdhury, K., Yegin, A., Choi, J., "MIP6-bootstrapping via 
              DHCPv6 for the Integrated Scenario", Internet-Draft, draft-
              ietf-mip6-bootstrapping-integrated-dhc-00, October 2005. 

        [16]  Arends, R., Austein, R., Larson, M., Massey, D., Rose, S., 
              "DNS Security Introduction and Requirements", RFC 4033, 
              March 2005.  

        [17]  Vixie, P., Gudmundsson, O., Eastlake 3rd, D., Wellington, 
              B., "Secret Key Transaction Authentication for DNS (TSIG)", 
              RFC 2845, May 2000. 

        [18]  Eastlake 3rd, D., " Secret Key Establishment for DNS (TKEY 
              RR)", RFC 2930, September 2000. 

        [19]  Nikander, P., Arkko, J.,  Aura, T., Montenegro, G., 
              Nordmark, E., "Mobile IP version 6 Route Optimization 
              Security Design Background", Internet-Draft, draft-ietf-
              mip6-ro-sec-02, October 2004. 

        [20]  Narten, T., Nordmark, E., Simpson, W., Soliman, H., 
              "Neighbor Discovery for IP version 6 (IPv6)"`, Internet-
              Draft, draft-ietf-ipv6-2461bis-05, October 2005. 

      

















      
      
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     Authors' Addresses 

        Gerardo Giaretta 
        Telecom Italia Lab 
        via Reiss Romoli 274 
        10148 Torino 
        Italy 
            
        Phone: +39 011 228 6904 
        Email: gerardo.giaretta@telecomitalia.it 
         
         
         
        James Kempf 
        DoCoMo Labs USA 
        181 Metro Drive 
        Suite 300 
        San Jose, CA, 95110 
        USA 
         
        Phone: +1 408 451 4711 
        Email: kempf@docomolabs-usa.com 
         
         
         
        Vijay Devarapalli 
        Nokia Research Center 
        313 Fairchild Drive 
        Mountain View, CA  94043 
        USA 
         
        Email: vijay.devarapalli@nokia.com 
         

      
      
      
         













      
      
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