MN-2-1-1-1-011 - Retransmissions (Use InitialBindackTimeoutFirstReg as the initial retransmission timer)




                                  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
    - Binding Update retransmit (home registration): YES
 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.(no reply)
        |       |       |       |        |
        | <---- |       |       |        | 7.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. (no reply)
        7. Receive Binding Update. (NUTX -> HA0)
        Packet Format is:
          7. Binding Update


 (*1) PASS: HA0 receives the retransmission of Binding Update.
            Then, check whether this packet fills all of the following,
            - Sequence Number value greater than that used.
            - The initial retransmission timer is set to InitialBindackTimeoutFirstReg.


11.8 Retransmissions and Rate Limiting
   The mobile node is responsible for retransmissions and rate limiting
   in the return routability procedure, registrations, and in solicited
   prefix discovery.
   When the mobile node sends a Mobile Prefix Solicitation, Home Test
   Init, Care-of Test Init or Binding Update for which it expects a
   response, the mobile node has to determine a value for the initial
   retransmission timer:
   o  If the mobile node is sending a Mobile Prefix Solicitation, it
      SHOULD use an initial retransmission interval of
      INITIAL_SOLICIT_TIMER (see Section 12).
   o  If the mobile node is sending a Binding Update and it does not
      have an existing binding at the home agent, it SHOULD use
      InitialBindackTimeoutFirstReg (see Section 13) as a value for the
      initial retransmission timer.  This long retransmission interval
      will allow the home agent to complete the Duplicate Address
      Detection procedure which is mandated in this case, as detailed in
      Section 11.7.1.
   o  Otherwise, the mobile node should use the specified value of
      INITIAL_BINDACK_TIMEOUT for the initial retransmission timer.
   If the mobile node fails to receive a valid, matching response within
   the selected initial retransmission interval, the mobile node SHOULD
   retransmit the message, until a response is received.
   The retransmissions by the mobile node MUST use an exponential
   back-off process, in which the timeout period is doubled upon each
   retransmission until either the node receives a response or the
   timeout period reaches the value MAX_BINDACK_TIMEOUT.  The mobile
   node MAY continue to send these messages at this slower rate
   The mobile node SHOULD start a separate back-off process for
   different message types, different home addresses and different
   care-of addresses.  However, in addition an overall rate limitation
   applies for messages sent to a particular correspondent node.  This
   ensures that the correspondent node has sufficient amount of time to
   answer when bindings for multiple home addresses are registered, for
   instance.  The mobile node MUST NOT send Mobility Header messages of
   a particular type to a particular correspondent node more than
   MAX_UPDATE_RATE times within a second.
   Retransmitted Binding Updates MUST use a Sequence Number value
   greater than that used for the previous transmission of this Binding
   Update.  Retransmitted Home Test Init and Care-of Test Init messages
   MUST use new cookie values.
13. Protocol Configuration Variables
    MaxMobPfxAdvInterval            Default: 86,400 seconds
    MinDelayBetweenRAs              Default: 3 seconds,
                                    Min: 0.03 seconds
    MinMobPfxAdvInterval            Default: 600 seconds
    InitialBindackTimeoutFirstReg   Default: 1.5 seconds
   Home agents MUST allow the first three variables to be configured by
   system management, and mobile nodes MUST allow the last variable to
   be configured by system management.
   The default value for InitialBindackTimeoutFirstReg has been
   calculated as 1.5 times the default value of RetransTimer [12] times
   the default value of DupAddrDetectTransmits [13].