Operation

Reminder

Mobile Node (MN): mobile host that changes access point.
Home Agent (HA) : MN’s home network router.
Foreign Agent (FA) : visited network’s main router.
Correspondent Node (CN) : any node in a network, fixed or mobile.
Home Address (HoA): the mobile node’s home address.
Care-of address (CoA): current node’s address.
Access router (AR): current router that provides access point to the network.

In Mobile IPv6 there is no FA. Indeed this mobile protocol requires every mobile node to support IPv6 decapsulation, address autoconfiguration and neighbor discovery. The CN uses IPv6 routing header and not IP encapsulation. It naturally supports Route Optimization.

Specific internal functions

Binding Update: allows an MN to let its HA or any other CN know about its new care-of address.
Binding Acknowledgement: acknowledgement of the receipt of a BU.
Binding Request: any node can use it to request an MN to send a BU with its care-of address.

The global scheme of a Mobile IPv6 communication is the same as the one described on the Mobile IP part. We now focus on packets exchanges process illustrated by the figure above. Those packets exchanges occur after a movement from the MN.

The movement detection is automatic thanks to the standard IPv6 auto-configuration mechanism (RFC 4862).

This connection to a new network associates a new CoA to the MN with the prefix of the AR.

Then a BU is sent to its HA in order to update its new binding information such as its HoA and CoA.

The HA sets up an IPv6 tunnel between itself and the MN. This action fills up its Binding Cache (data structure) with mapping information linking its HoA to its CoA. Home Agent sends back a BA to confirm the achievement of the binding phase.

Finally the MN sends an ICMPv6 Echo request to the CN; this message is sent through the tunnel to its HA which decapsulates the message and forwards it to the CN. The correspondent answers to the MN by an ICMPv6 Echo Reply through the HA and the tunnel too.