| 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 (*1) | | | | | 6.(no reply) | | | | | | <---- | | | | 7.Binding Update (*1) | | | | | 8.(no reply) | | | | | | <---- | | | | 9.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) 8. (no reply) 9. Receive Binding Update. (NUTX -> HA0) Packet Format is: 11. 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. - Timeout period is doubled upon each retransmission. - Transmit until the retransmission interval becomes MAX_BINDACK_TIMEOUT.
(draft-ietf-mobileip-ipv6-24.txt) 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 indefinitely. 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  times the default value of DupAddrDetectTransmits .