MN-2-1-2-1-004 - Sending BU (before the expiration of home registration)




                                  R       CN0
                                  |        |
                     -----+-------+--------+---------------- LinkZ
                          R2                      NUTY
                          |                         |
                     -----+-------+-----------------+------- LinkY
                                  R1              NUTX
                                  |                 |
                     -----+-------+-----------------+------- LinkX
                         HA0             Node0    NUT0
                          |               |         |
    ----------------------+---------------+---------+------- Link0
Link0 3ffe:501:ffff:100::/64 home link
LinkX 3ffe:501:ffff:102::/64  
LinkY 3ffe:501:ffff:103::/64  
LinkZ 3ffe:501:ffff:104::/64  
HA0(Link0) 3ffe:501:ffff:100:200:ff:fe00:a0a0  
Node0(Link0) 3ffe:501:ffff:100:200:ff:fe00:a3a3  
R1(LinkX) 3ffe:501:ffff:102:200:ff:fe00:a4a4  
R2(LinkY) 3ffe:501:ffff:103:200:ff:fe00:a6a6  
CN0(LinkZ) 3ffe:501:ffff:104:200:ff:fe00:a8a8  


 1. Selection Option
    - none
 2. Position of Mobile Node
    - none


       HA0     NUT0     R1      R2      CN0
        |       |       |       |        |
        | ----> |       |       |        | 1.Router Advertisement
        |       |       |       |        |
        |      NUTX     |       |        |
        |       |       |       |        |
        |       | <---- |       |        | 2.Router Advertisement
        |       |       |       |        |
        | <---- |       |       |        | 3.Neighbor Solicitations(NUD)
        |       |       |       |        | 4.(no reply)
        |       |       |       |        |
        | <---- |       |       |        | 5.Binding Update
        | ----> |       |       |        | 6.Binding Acknowledgement
        |       |       |       |        | 7.(wait)
        |       |       |       |        |
        | <---- |       |       |        | 8.Binding Update (*1)
        |       |       |       |        |
        1. Send Router Advertisement. (HA0 -> HA0_allnode_multi)
        2. Send Router Advertisement. (R1 -> R1_allnode_multi)
        3. Receive Neighbor Solicitations(NUD). (NUT0 -> HA0)
        4. (no reply)
            # Wait during a maximum of 3 seconds(RFC2461).
        5. Receive Binding Update. (NUTX -> HA0)
        6. Send Binding Acknowledgement. (HA0 -> NUTX)
        7. (wait)
            # Wait during a maximum of the lifetime value in the Binding Update[5].
        8. Receive Binding Update. (NUTX -> HA0)
        Packet Format is:
          8. Binding Update


 (*1) PASS: HA0 receives Binding Update before the expiration of the following
             - The remaining lifetime of the home registration.
            Then, check whether this packet fills all of the following,
             - The Sequence Number is set more than that in the previous Binding Update.
             - The Alternate Care-of Address mobility option is included, and,
                - The Care-of Address field is set to the care-of address.


11.7.1 Sending Binding Updates to the Home Agent
   Also, if the mobile node wants the services of the home agent beyond
   the current registration period, the mobile node should send a new
   Binding Update to it well before the expiration of this period, even
   if it is not changing its primary care-of address.  However, if the
   home agent returned a Binding Acknowledgement for the current
   registration with Status field set to 1 (accepted but prefix
   discovery necessary), the mobile node should not try to register
   again before it has learned the validity of its home prefixes through
   mobile prefix discovery.  This is typically necessary every time this
   Status value is received, because information learned earlier may
   have changed.
   To register a care-of address or to extend the lifetime of an
   existing registration, the mobile node sends a packet to its home
   agent containing a Binding Update, with the packet constructed as
   o  The Home Registration (H) bit MUST be set in the Binding Update.
   o  The Acknowledge (A) bit MUST be set in the Binding Update.
   o  The packet MUST contain a Home Address destination option, giving
      the mobile node's home address for the binding.
   o  The care-of address for the binding MUST be used as the Source
      Address in the packet's IPv6 header, unless an Alternate Care-of
      Address mobility option is included in the Binding Update.  This
      option MUST be included in all home registrations, as the ESP
      protocol will not be able to protect care-of addresses in the IPv6
      header.  (Mobile IPv6 implementations that know they are using
      IPsec AH to protect a particular message might avoid this option.
      For brevity the usage of AH is not discussed in this document.)
   o  If the mobile node's link-local address has the same interface
      identifier as the home address for which it is supplying a new
      care-of address, then the mobile node SHOULD set the Link-Local
      Address Compatibility (L) bit.
   o  If the home address was generated using RFC 3041 [18], then the
      link local address is unlikely to have a compatible interface
      identifier.  In this case, the mobile node MUST clear the
      Link-Local Address Compatibility (L) bit.
   o  If the IPsec security associations between the mobile node and the
      home agent have been established dynamically, and the mobile node
      has the capability to update its endpoint in the used key
      management protocol to the new care-of address every time it
      moves, the mobile node SHOULD set the Key Management Mobility
      Capability (K) bit in the Binding Update.  Otherwise, the mobile
      node MUST clear the bit.
   o  The value specified in the Lifetime field SHOULD be less than or
      equal to the remaining valid lifetime of the home address and the
      care-of address specified for the binding.
      Mobile nodes that use dynamic home agent address discovery should
      be careful with long lifetimes.  If the mobile node loses the
      knowledge of its binding with a specific home agent, registering a
      new binding with another home agent may be impossible as the
      previous home agent is still defending the existing binding.
      Therefore, mobile nodes that use home agent address discovery
      SHOULD ensure information about their bindings is not lost,
      de-register before losing this information, or use small
11.1 Conceptual Data Structures
   Each Binding Update List entry conceptually contains the following
   o  The IP address of the node to which a Binding Update was sent.
   o  The home address for which that Binding Update was sent.
   o  The care-of address sent in that Binding Update.  This value is
      necessary for the mobile node to determine if it has sent a
      Binding Update giving its new care-of address to this destination
      after changing its care-of address.
   o  The initial value of the Lifetime field sent in that Binding
   o  The remaining lifetime of that binding.  This lifetime is
      initialized from the Lifetime value sent in the Binding Update and
      is decremented until it reaches zero, at which time this entry
      MUST be deleted from the Binding Update List.
   o  The maximum value of the Sequence Number field sent in previous
      Binding Updates to this destination.  The Sequence Number field is
      16 bits long, and all comparisons between Sequence Number values
      MUST be performed modulo 2**16 (see Section 9.5.1).
   o  The time at which a Binding Update was last sent to this
      destination, as needed to implement the rate limiting restriction
      for sending Binding Updates.
   o  The state of any retransmissions needed for this Binding Update.
      This state includes the time remaining until the next
      retransmission attempt for the Binding Update, and the current
      state of the exponential back-off mechanism for retransmissions.
   o  A flag specifying whether or not future Binding Updates should be
      sent to this destination.  The mobile node sets this flag in the
      Binding Update List entry when it receives an ICMP Parameter
      Problem, Code 1, error message in response to a return routability
      message or Binding Update sent to that destination, as described
      in Section 11.3.5.