One document matched: draft-tsirtsis-v4v6-mipv4-00.txt


Personal                                                  G. Tsirtsis 
                                                          H. Soliman 
                                                          Flarion  
Internet Draft                                     
Document: draft-tsirtsis-v4v6-mipv4-00.txt                 
Expires: January 2003                                     August 2003 
                             
    
 
                          Dual Stack Mobile IPv4 
                     draft-tsirtsis-v4v6-mipv4-00.txt 
 
 
Status of this Memo 
    
   This document is an Internet-Draft and is in full conformance with 
   all provisions of Section 10 of RFC2026 [1].  
    
   Internet-Drafts are working documents of the Internet Engineering 
   Task Force (IETF), its areas, and its working groups. Note that 
   other groups may also distribute working documents as Internet-
   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. 
    
    
    
    
Abstract 
    
   This specification provides IPv6 extensions to the Mobile IPv4 
   [MIPv4] protocol. The extensions allow a dual stack node to use IPv4 
   and IPv6 home addresses as well as move between IPv4 and dual stack 
   network infrastructures.  
    
    
    
    
    
    
    
    
    
    
    
    
  
<Tsirtsis, Soliman>               1                                   
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
    
    
    
    
    
   INDEX 
    
1. Introduction.......................................................3 
2. Agent Advertisement................................................3 
2.1. Home Agent Considerations........................................4 
2.2. Foreign Agent Considerations.....................................4 
2.3. Mobile Client considerations.....................................4 
3. Extensions Headers.................................................5 
3.1. IPv6 Home Address Extension......................................5 
3.2. IPv6 Compatibility Extension.....................................5 
3.3. IPv6 Code Extension..............................................6 
4. Mobile IP Registrations............................................6 
4.1. Registration Requests............................................6 
4.2. Registration Reply...............................................7 
4.3. Home Agent Considerations........................................7 
4.4. Foreign Agent Considerations.....................................8 
4.5. Mobile Node considerations.......................................9 
4.5.1. Foreign Agent Assisted.........................................9 
4.5.2. Collocated care-of address....................................10 
4.6. Dynamic IPv6 home address.......................................10 
4.7. Deregistration of IPv6 home address.............................11 
4.8. Registration with a private CoA.................................11 
4.8.1. Dual Stack networks with Private IPv4.........................11 
5. Applicability and usage scenarios.................................11 
5.1. Example usage scenarios.........................................12 
5.1.1. Foreign agent with full IPv6 support..........................12 
5.1.2. Foreign agent with limited IPv6 support.......................13 
5.1.3. Foreign agent refuses to handle IPv6 for mobile...............14 
5.1.4. IPv4 only network with foreign agent support..................14 
5.1.5. IPv4 only network with no foreign agent support...............15 
5.2. Visiting IPv6 ONLY networks.....................................15 
6. Security Considerations...........................................16 
7. References........................................................16 
Author's Addresses...................................................16 
    
    












 
<Tsirtsis, Soliman>                                                  2 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
1. Introduction 
    
   Mobile IPv4 [MIPv4] allows a mobile node with an IPv4 address to 
   maintain communications while moving in an IPv4 network.  
    
   Extensions defined in this document allow a node that has IPv4 and 
   IPv6 [IPv6] addresses to maintain communications with either or both 
   of its addresses while moving in IPv4 or dual stack networks. 
    
   Essentially, this specification separates the Mobile IP signaling 
   version from the IP version of the traffic that it tunnels. Mobile 
   IPv4 with the present extensions becomes a signaling protocol that 
   runs over IPv4, and yet can set-up any combination of IPv4 and/or 
   IPv6 over IPv4 tunnels. 
    
   The aim is two-fold: 
    
   On one hand, Mobile IPv4 with the present extensions becomes a 
   powerful transition mechanism, allowing automatic but controlled 
   tunneling of IPv6 traffic over IPv4 tunnels. Dual stack nodes in 
   dual stack home networks can now roam to and from legacy IPv4 
   networks, while IPv4 mobile nodes and networks can migrate to IPv6 
   without changing mobility management, and without upgrading all 
   network nodes to IPv6 at once. 
    
   On the other hand, and maybe more importantly, it allows dual stack 
   mobile nodes and networks to utilize a single protocol for the 
   movement of both IPv4 and IPv6 stacks in the network topology. See 
   section 5 for applicability and usage scenarios. 
    
   Note that features like route optimization in Mobile IPv4 will not 
   be possible with this solution as it still relies on Mobile IPv4 
   signaling, which does not provide route optimization. 
    
    
2. Agent Advertisement 
    
   A new flag is added to indicate support for IPv6 
 
       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 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     Type      |    Length     |        Sequence Number        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |           Lifetime            |R|B|H|F|M|G|V|T|S|I|A|  rsrvd  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                  zero or more Care-of Addresses               | 
      |                              ...                              | 
 
    
      A        IP Version 6 extensions supported.   
    
    
 
<Tsirtsis, Soliman>                                                  3 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
    
2.1. Home Agent Considerations 
    
   Mobile IPv4 Home Agents that are prepared to support IPv6 for mobile 
   nodes SHOULD set the A flag. 
 
2.2. Foreign Agent Considerations 
    
   Foreign agents that are prepared to support mobile clients with IPv6 
   home addresses SHOULD set the A flag. 
 
2.3. Mobile Client considerations 
    
   A Mobile client that supports the IPv6 extensions described in this 
   specification should exhibit the following behavior depending on the 
   A flag setting in Foreign Agent advertisements (FAAs) and home agent 
   advertisements (HAAs)  
    
   A flag NOT SET in HA Advertisement 
   (HAA A=0, FAA A=0 or A=1) 
             Mobile clients that receive a home agent advertisement 
             with no A flag set SHOULD ignore IPv6 extensions in 
             foreign agent advertisements and SHOULD NOT attempt to use 
             the IPv6 extensions defined in this specification. 
    
    
   A flag SET in HA and FA advertisements 
   (HAA A=1, FAA A=1) 
    
             Mobile clients that receive a home agent advertisement 
             with an A flag set or they otherwise know their home agent 
             supports the extensions defined in this document and they 
             receive a foreign agent advertisement with an A flag set, 
             SHOULD attempt to use the extensions defined in this 
             specification. 
    
    
   A flag SET in HA advertisements but not in FA advertisements 
   (HAA A=1, FAA A=0) 
    
             Mobile clients that receive foreign agent advertisement 
             with no A flag set MAY attempt to use IPv6 extensions 
             described in this document provided the are prepared to 
             use end to end forward and reverse IPv4 tunneling for all 
             IPv6 traffic between their IPv4 HoA and the IPv4 HA 
             address. 
              
              
              
              
              
              
              
 
<Tsirtsis, Soliman>                                                  4 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
              
3. Extensions Headers 
 
    
3.1. IPv6 Home Address Extension 
    
   A new skippable extension to the Mobile IPv4 header in accordance to 
   the short extension format of [MIPv4] is defined here. 
    
        This extension contains the IPv6 Home Address of the mobile IP 
        client. 
    
    
   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 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |     Type      |   Length      |    Sub-Type   | IPv6 Address... 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Type = TBD 
   Length = 17 
   Sub-Type = 1 for IPv6 home address 
    
    
3.2. IPv6 Compatibility Extension 
 
   A new skippable extension to the Mobile IPv4 header in accordance to 
   the short extension format of [MIPv4] is defined here. 
    
        This extension indicates that the sender supports the IPv6 
        extensions specified in this document and defines whether 
        reverse tunneling is required for IPv6 traffic. 
    
   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 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |     Type      |   Length      |R|            Reserved         | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Type = TBD 
   Length = 2 
 
   R    If SET the FA mandates reverse tunnel for all IPv6 traffic. 
 
    
    
    
    
    
    
    
    
    
 
<Tsirtsis, Soliman>                                                  5 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
    
3.3. IPv6 Code Extension 
 
   A new skippable extension to the Mobile IPv4 header in accordance to 
   the short extension format of [MIPv4] is defined here. 
    
        This extension provides IPv6 error codes 
    
   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 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |     Type      |   Length      |     Code      |     Rsvd      | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Type = TBD 
   Length = 2 
    
    
   Code         A value indicating the result of the registration 
                request with respect to the IPv6 home address 
                registration 
    
   The following values are defined for use as a Code value in the 
   above extension 
    
       0 registration accepted IPv6 to be tunneled to CoA 
       2 registration accepted IPv6 to be tunneled to HoA 
    
     Registration denied by the foreign agent: 
    
      64 reason unspecified 
      65 administratively prohibited 
    
     Registration denied by the home agent: 
    
     128 reason unspecified 
     129 administratively prohibited 
    
   Note that a registration reply that does not include an IPv6 error 
   code extension indicates that the home agent does not support IPv6 
   extensions and thus has ignored such extensions in the registration 
   reply. 
    
    
4. Mobile IP Registrations 
    
    
4.1. Registration Requests 
    
   A mobile IP client MAY include an IPv6 home address extension 
   defined in this specification in a registration request. 
    

 
<Tsirtsis, Soliman>                                                  6 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
   When IPv6 home address extensions are used they MUST be placed after 
   the registration request header and before the mobile - home 
   authentication extension so they MUST be included in the computation 
   of any authentication extension. 
    
   A mobile client or foreign agent MAY include an IPv6 compatibility 
   extensions defined in the specification in a registration request. 
    
   When IPv6 compatibility extensions are used they MUST be placed 
   after the mobile - home authentication extensions and before the 
   foreign - home authentication extension so they MUST be included in 
   the computation of the foreign - home authentication extension when 
   on exists. 
 
    
4.2. Registration Reply 
 
   The mechanism described in the specification depends on skippable 
   extensions. For that reason a registration reply that does not 
   include an IPv6 code extension indicates that the home agent does 
   not support IPv6 extensions and has ignored the request. 
    
   If an IPv6 code extension in included in a registration reply then 
   said extension indicates the success code=0 or node code!=0 of the 
   IPv6 registration. The IPv6 code extension DOES NOT affect in any 
   way the code value in the registration reply header. 
    
   An IPv6 code extension is only required when:  
    
        - the code in the registration reply header indicates  
        successful IPv4 registration 
         
        - the code in the registration reply header indicates failure 
        but with a code other than 64, 65, 128, 129. This is done since 
        the rest of the error codes are independent from the home 
        address version registered. 
    
 
4.3. Home Agent Considerations 
    
   A dual stack home agent that supports the IPv6 extensions defined in 
   this specification, MUST keep track of the following IPv6 related 
   state for the mobile IP clients it supports in addition to what 
   state is defined in [MIPv4], section 3.8.1 
    
   - The mobile node's IPv6 home address 
   - Tunneling mode for IPv6 traffic: 
        - Tunnel to IPv4 HoA and accept IPv6 tunneled from IPv4 HoA 
        - Tunnel to CoA 
        - Tunnel to CoA and accept IPv6 tunneled from CoA 
         
   A home agent that supports this specification MUST be able to 
   intercept IPv4 and IPv6 packets destined to registered mobile nodes 
 
<Tsirtsis, Soliman>                                                  7 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
   according to mechanisms described in [MIPv4] and [MIPv6] 
   specifications. All intercepted traffic SHOULD be tunneled to the 
   registered care-of address or home address of the mobile client in 
   question according to T flag in the tunneling mode selected for IPv6 
   traffic. 
    
   Tunneling mode selection for IPv6 traffic depends on the following 
   parameters in a successful registration request: 
    
   1) Registration request was received with an IPv6 home address 
   extension but no IPv6 compatibility extension was included 
    
        The home agent MUST tunnel all IPv6 packets destined to the 
        registered IPv6 home address to the registered IPv4 home 
        address of the mobile. Additionally, the home agent MUST be 
        prepared to accept reverse tunneled packets from the IPv4 home 
        address of the mobile encapsulating IPv6 packets sent by the 
        mobile. Note that in this case the home agent MUST either 
        accept or reject both IPv4 and IPv6 home addresses. 
    
    
   2) Registration request was received with an IPv6 home address 
   extension and an IPv6 compatibility extension with R=0 
    
        In this case the home agent MUST tunnel all IPv6 packets 
        destined to the registered IPv6 home address to the registered 
        care-of address of the mobile.  
    
   3) Registration request was received with an IPv6 home address 
   extension and an IPv6 compatibility extension with R=1 
    
        In this case the home agent MUST tunnel all IPv6 packets 
        destined to the registered IPv6 home address to the registered 
        care-of address of the mobile. Additionally, the home agent 
        MUST be prepared to accept reverse tunneled packets from the 
        care-off address of the mobile encapsulating IPv6 packets sent 
        by the mobile. 
    
    
4.4. Foreign Agent Considerations 
    
   A dual stack foreign agent that supports the IPv6 extensions defined 
   in this specification, MUST keep track of the following IPv6 related 
   state for the mobile nodes it supports in addition to what state is 
   defined in [MIPv4], section 3.7.1. 
    
   - Mobile node's IPv6 home address 
   - Tunneling mode for IPv6 traffic: 
        - accept IPv6 encapsulated in IPv4 
        - accept IPv6 encapsulated in IPv4 and reverse tunnel IPv6 
    
   When a foreign agent receives a registration request with an IPv6 
   home address extension it has the following choices: 
 
<Tsirtsis, Soliman>                                                  8 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
    
   1) Ignore the extension. The registration request is forwarded as is 
   with no IPv6 compatibility extension to the home agent.  
    
        The foreign agent is not prepared to tunnel/de-tunnel IPv6  
        traffic for the mobile client and thus IPv6 traffic SHOLD be 
        tunneled to its IPv4 home address by the home agent as 
        described in home agent consideration section 4.3. 
         
   2) Attach an IPv6 Compatibility extension with R=0 to the 
   registration request sent to the home agent.  
    
        The foreign agent is prepared to decapsulate and deliver to the  
        mobile IPv6 packets tunneled to the care-off address. 
          
   4) Attach an IPv6 Compatibility extension with R=1 to the 
   registration request sent to the home agent.  
    
        The foreign agent is prepared to decapsulate and deliver to the  
        mobile IPv6 packets tunneled to the care-off address. The 
        foreign agent also instruct the home agent that all IPv6 
        traffic from the mobile will be reverse tunneled. 
    
    
4.5. Mobile Node considerations 
    
   A dual stack mobile node that supports the extensions described in 
   this document MAY use these extensions to maintain connectivity of 
   both its IPv4 and IPv6 home address while moving between access 
   routers. 
    
4.5.1. Foreign Agent Assisted 
    
   In this case the mobile client will receive a foreign agent 
   advertisement. According to the A flag setting in this advertisement 
   the mobile SHOULD exhibit the following behavior: 
    
   1) A flag is NOT SET 
    
        The mobile client SHOULD include an IPv6 home address extension 
        in the registration request. In this case the mobile MUST be 
        prepared to decapsulate IPv6 packets tunneled to its IPv4 home 
        address by the home agent. In addition it MUST reverse tunnel 
        all IPv6 traffic to its home agent using its IPv4 home address 
        as source address of the tunnel. 
         
    
   2) A flag is SET 
    
        The mobile client SHOULD include an IPv6 home address extension 
        in the registration request.  
    
    
 
<Tsirtsis, Soliman>                                                  9 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
4.5.2. Collocated care-of address 
    
   In this case the mobile client will not receive a foreign agent 
   advertisement and will use a collocated care-of address discovered 
   with the mechanisms outlined in [MIPv4]. Depending on IPv6 support 
   in the foreign network the mobile SHOULD exhibit the following 
   behavior (IPv4 support is always assumed in the foreign network): 
    
   1) mobile gets a local IPv6 address (native or via ngtrans tools) 
    
        The mobile client SHOULD include an IPv6 home address extension 
        in the registration request. The mobile SHOULD also include an 
        IPv6 compatibility extension with R=0 to indicate that no 
        reverse tunneling of IPv6 traffic is required.  
         
 
   2) mobile does not get a local IPv6 address 
    
        The mobile client SHOULD include an IPv6 home address extension 
        in the registration request. The mobile SHOULD also include an 
        IPv6 compatibility extension with R=1 to indicate that reverse 
        tunneling of IPv6 traffic is required. 
         
   If in either of the cases above the mobile does not include an IPv6 
   compatibility extension then it SHOULD be prepared to decapsulate 
   IPv6 packets tunneled to its IPv4 home address by the home agent and 
   it MUST reverse tunnel all IPv6 traffic to its home agent using its 
   IPv4 home address as source address of the tunnel. 
    
   Note that the local IPv6 address, when available, in the foreign 
   network is not used in this specification; it is merely an 
   indication that IPv6 traffic can be sent through the foreign 
   network. 
 
4.6. Dynamic IPv6 home address 
    
   The following options are supported: 
    
   -Mobile sends a zero IPv6 home address extension. The home agent 
   allocates a home address from its subnet and returns it in the same 
   extension. 
    
    
   -Mobile sends ::EUI64 in an IPv6 home address extension. The home 
   agent fills in its mobile network prefix and returns PREFIX::EUI64 
   or just PREFIX:: if it allocates a subnet. 
    
    
    
    
    
    
    
 
<Tsirtsis, Soliman>                                                 10 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
    
4.7. Deregistration of IPv6 home address 
    
   The mobile IP registration lifetime included in the registration 
   request header is valid for all binding created by the registration 
   request, which may include bindings for an IPv6 home address. 
    
   A registration request with a zero lifetime can be used to remove 
   all bindings from the home agent. 
    
    
4.8. Registration with a private CoA 
    
   If the care-of address is a private address then Mobile IP NAT 
   Traversal as described in [MIPNAT] MAY be used in combination with 
   the extensions described in this specification. 
    
4.8.1. Dual Stack networks with Private IPv4  
    
   This is a special case where the foreign network is dual stack but 
   it only supports private IPv4. 
    
   While in this case Mobile IP NAT traversal [MIPNAT] will also work 
   it should be possible to do something better. Since the scenario 
   offers the mobile with access to native IPv6, it should be possible 
   to further extend Mobile IPv4 to carry IPv6 care-of addresses.  
    
   In this case Mobile IP NAT Traversal could be used to send Mobile 
   IPv4 signaling but the resulting tunnel would be an IPv6 tunnel 
   (instead of UDP tunnel) between the HA and the mobile's IPv6 CoA 
   encapsulating both IPv4 and IPv6 traffic destined for the mobile. 
    
   While work on these issues could be beneficial, it is also separable 
   from the basic notion of IPv6 home address support in Mobile IPv4. 
   For that reason IPv6 care-of address extensions will be examined in 
   a separate document. 
    
5. Applicability and usage scenarios 
    
   This specification makes the following assumptions regarding IPv4 
   and IPv6 configuration of the various elements. 
    
   The home agent is IPv4/v6 dual stack. The home agent supports the 
   IPv6 extensions defined in this document and supports IPv4 and IPv6 
   address pools as home addresses. The home agent is able to intercept 
   and tunnel appropriately all IPv4 and IPv6 packets destined to 
   registered mobiles. 
    
   The mechanisms described in this specification can benefit from an 
   access routing supporting foreign agent functionality, the 
   extensions described in this document and being dual stack but they 
   do not depend on it. 
    
 
<Tsirtsis, Soliman>                                                 11 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
    
   Key for the following sections: 
   MN   Mobile Node 
   CN   Corresponding Node 
   FA   Foreign Agent 
   HA   Home Agent 
   HoA  Home Address 
   CoA  Care-off address 
   SA   Source Address 
   DA   Destination address 
   -->  Un-tunneled traffic 
   ==>  Tunneled traffic 
   ##>  Double-tunneled traffic  
    
 
5.1. Example usage scenarios 
    
   Some examples of how this specification may be used are provided in 
   this section. This is not an exhaustive list. 
    
   In all the examples it is assumed that the mobile and home agent 
   fully support the extensions described in this document and that the 
   mobile is dual stack with an IPv4 and an IPv6 home address. 
    
   The different examples below examine how the protocol should work 
   when the support for IPv6 and the extensions described in this 
   document varies in the access routers the mobile is visiting. 
    
5.1.1. Foreign agent with full IPv6 support 
    
   In this case the foreign agent in the foreign network supports IPv6 
   extensions and enjoys native IPv6 connectivity.  
    
   MN receives FAA with A=1 
   MN sends RREQ(HoA,CoA,IPv6HoA) 
   FA forwards RREQ(HoA,CoA,IPv6HoA,R=0) 
   HA returns RREP(Code=0, IPv6Code=0) 
    
   HA keeps binding: 
        IPv6HoA  -> IPv4CoA 
        IPv4HoA  -> IPv4CoA 
    
   MN sends IPv6 traffic natively 
         
        Header SA=IPv6HoA, DA=IPv6CN 
    
   FA forwards IPv6 traffic natively 
    
        Header SA=IPv6HoA, DA=IPv6CN 
    
   HA tunnels all IPv6 traffic to the CoA 
    
        Outer Header SA=IPv4HA, DA= IPv4CoA 
 
<Tsirtsis, Soliman>                                                 12 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
        Inner Header (SA=IPv6CN, DA=IPv6HoA) 
    
   FA decapsulates and delivers to the mobile. 
    
        Header SA=IPv6HoA, DA=IPv6CN 
    
    
        MN                      FA                      HA      CN 
        |    v6 native          |                       |        | 
        |------------------------------------------------------->| 
        |                       |                       |        | 
        |    v6 native          |   v6 over v4          |  IPv6  | 
        |<----------------------|<======================|<-------| 
    
 
    
5.1.2. Foreign agent with limited IPv6 support 
    
   In this case the foreign agent in the foreign network supports IPv6 
   extensions but does not have native IPv6 connectivity and is set up 
   to reverse all IPv6 traffic to the HA. 
    
    
   MN receives FAA with A=1 
   MN sends RREQ(HoA,CoA,IPv6HoA) 
   FA forwards RREQ(HoA,CoA,IPv6HoA,R=1) 
   HA returns RREP(Code=0, IPv6Code=0) 
    
   HA keeps binding: 
        IPv6HoA <=> IPv4CoA 
        IPv4HoA  -> IPv4CoA 
    
   MN sends IPv6 traffic natively 
         
        Header SA=IPv6HoA, DA=IPv6CN 
    
   FA reverse tunnels IPv6 traffic to HA 
    
        Outer Header SA=IPv4CoA, DA=IPv4HA 
        Inner Header (SA=IPv6HOA, DA=IPv6CN) 
    
   HA decapsulates and forwards to the CN 
    
        Header SA=IPv6HoA, DA=IPv6CN 
    
   HA tunnels all IPv6 traffic to the CoA 
    
        Outer Header SA=IPv4HA, DA=IPv4CoA 
        Inner Header (SA=IPv6CN, DA=IPv6HoA) 
    
   FA decapsulates and delivers to the mobile. 
    
        Header SA=IPv6HoA, DA=IPv6CN 
 
<Tsirtsis, Soliman>                                                 13 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
    
    
        MN                      FA                      HA      CN 
        |    v6 native          |   v6 over v4          |  IPv6  | 
        |---------------------->|======================>|------->| 
        |                       |                       |        | 
        |    v6 native          |   v6 over v4          |  IPv6  | 
        |<----------------------|<======================|<-------| 
    
    
5.1.3. Foreign agent refuses to handle IPv6 for mobile 
    
   In this case the foreign agent in the foreign network supports IPv6 
   extensions but is not prepared to handle IPv6 traffic for the 
   specific mobile due to policy or other reason. 
    
    
   MN receives FAA with A=1 
   MN sends RREQ(HoA,CoA,IPv6HoA) 
   FA forwards RREQ(HoA,CoA,IPv6HoA) 
   HA returns RREP(Code=0, IPv6Code=2) 
    
   This degenerates into the same packet from with case 5.1.4 below 
    
    
5.1.4. IPv4 only network with foreign agent support 
    
   In this case the foreign network is IPv4 ONLY and it does support 
   foreign agents but no IPv6 or support for IPv6 extensions. 
    
    
   MN receives FAA with A=0 
   MN sends RREQ(HoA,CoA,IPv6HoA) 
   FA forwards RREQ as is ignoring IPv6HoA 
    
   HA keeps binding: 
        IPv6HoA <=> IPv4HoA 
        IPv4HoA  -> IPv4CoA 
    
   MN tunnels all IPv6 traffic to the HA  
    
        Outer Header SA=IPv4HoA, DA=IPv4HA  
        Inner Header (SA=IPv6HoA, DA=IPv6CN)  
    
   HA tunnels all IPv6 traffic to the HoA 
    
        Outer Header SA=IPv4HA, DA=IPv4CoA 
        Inner Header (SA=IPv4HA, DA=IPv4HoA) 
        Second Inner Header ((SA=IPv6CN, DA=IPv6HoA)) 
    
   NOTE that this results in double-tunneling 
   FA decapsulates and delivers to the mobile. 
    
 
<Tsirtsis, Soliman>                                                 14 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
        Outer Header SA=IPv4HA, DA=IPv4HoA 
        Inner Header (SA=IPv6CN, DA=IPv6HoA) 
    
    
        MN                      FA                      HA      CN 
        |    v6 over v4         |                       |  IPv6  | 
        |==============================================>|------->| 
        |                       |                       |        | 
        |    v6 over v4         | v6 over v4 over v4    |  IPv6  | 
        |<======================|<######################|<-------| 
    
 
5.1.5. IPv4 only network with no foreign agent support 
    
   In this case the foreign network is IPv4 ONLY and it neither 
   supports foreign agents nor IPv6 extensions. 
    
   MN discovers collocated CoA 
   MN sends RREQ(HoA,CoA,IPv6HoA,R=1) 
    
   HA keeps binding: 
        IPv6HoA -> IPv4CoA 
        IPv4HoA -> IPv4CoA 
    
   MN tunnels all IPv6 traffic to the HA  
    
        Outer Header SA=IPv4HoA, DA=IPv4HA  
        Inner Header (SA=IPv6HoA, DA=IPv6CN)  
    
   HA tunnels all IPv6 traffic to the CoA 
    
        Outer Header SA=IPv4HA, DA=IPv4CoA 
        Inner Header (SA=IPv6CN, DA=IPv6HoA) 
    
        MN                      HA 
        |    IPv6 over IPv4     | 
        |======================>| 
        |<======================| 
        |                       | 
    
    
5.2. Visiting IPv6 ONLY networks 
    
   It is clear that the scheme presented in this specification does not 
   work when a mobile visits an IPv6 ONLY network since there is no way 
   to send Mobile IPv4 signaling packets. 
    
    
    
    
    
    
    
 
<Tsirtsis, Soliman>                                                 15 
                       <Dual Stack Mobile IPv4>        <August> <2003> 
 
 
6. Security Considerations 
    
   This specification operates in the security constraints and 
   requirements of [MIPv4]. It extends the operations defined in 
   [MIPv4] for IPv4 home addresses to cover IPv6 home addresses and 
   should provide the same level of security for both IP versions.  
    
   MN - HA security associations are normally based on the mobile's 
   home address. Since there are now two home addresses (one IPv4 and 
   IPv6)the NAI extension [NAI] MUST be included in all registration 
   requests that also include an IPv6 home address extension. The 
   mobile - home authenticator could then be calculated based on a 
   secret that is based on the mobile's NAI rather than any specific 
   home address. 
    
7. References 
 
   [AUTO]       S. Thomson, T. Narten, "IPv6 Stateless Address  
                Autoconfiguration", RFC2462 
     
   [IPv6]       S. Deering and B. Hinden, "Internet Protocol version 6  
                (IPv6) specification", RFC 2460  
    
   [KEYWORDS]   Bradner, S., "Key words for use in RFCs to Indicate 
                Requirement Levels", BCP 14, RFC 2119, March 1997. 
    
   [MIPNAT]     H. Levkowetz, S. Vaarala, " Mobile IP Traversal of 
                Network Address Translation (NAT) Devices", RFC3519 
    
   [MIPv4]      C. Perkins, "Mobility Support for IPv4", RFC3344 
    
   [MIPv6]      D. Johnson, C. Perkins and J. Arkko, "Mobility Support  
                in IPv6", draft-ietf-mobileip-ipv6-24.txt, June 2003. 
    
   [NAI]        P.Calhoun, C. Perkins, "Mobile IP Network Access  
                Identifier Extension for IPv4", RFC2794 
    
   [REVTUN]     G. Montenegro, "Reverse Tunneling for Mobile IP,  
                revised", RFC3024 
    
Author's Addresses 
    
   George Tsirtsis 
   Flarion Technologies 
   Phone: +44-20-88260073 
   Email1: G.Tsirtsis@Flarion.com 
   Email2: tsirtsisg@yahoo.com 
    
   Hesham Soliman 
   Flarion Technologies 
   Phone:  +61400500321 
   E-mail: H.Soliman@Flarion.com 

 
<Tsirtsis, Soliman>                                                 16 
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<Tsirtsis, Soliman>                                                 17 

PAFTECH AB 2003-20262026-04-23 16:08:00