 CNA The mobile node then implements the direct transfer procedure, initially initializing the Return Routability procedure. It then transmits the Binding Update message to the correspondent node to create the link between the CoA and HoA (Figure 9.4). Foreign network network Agent Tunnel 1 - IP packets transferred by the home agent 2 - Binding Update 3 Binding Mobile Acknowledgment 4 - IP packets transferred directly Correspondent Figure 9.4. Data transfer The transfer of packets between the correspondent node and the mobile node can then be carried out directly (Figure 9.4). Packets from the correspondent node to the mobile node carry the following addresses: Packet source address: CNA Packet destination address: CoA Routing (type 2) extension: HoA Packets from the mobile node to the correspondent node carry the following addresses: Packet source packet: CoA Packet destination address: CNA Destination extension: HoA 174 Wi-Fi Integration to the 4G Mobile Network 9.1.3.3. Local network change When the mobile node communicating with the correspondent node changes a foreign network, it repeats the procedure in order to build its new CoA, through the messages Router Solicitation and Router Advertisement (Figure 9.5). New foreign network network Agent 1 - Router Solicitation 2 Router Advertisement 3 - Binding Update 4 Binding Acknowledgment 5 Binding Update Mobile 6 - Binding Acknowledgment Correspondent Figure 9.5. Network change of the mobile node The mobile node resumes the operation of registering its CoA with its home agent by the messages Binding Update and Binding Acknowledgment (Figure 9.5) When the mobile node has registered with its home agent, it triggers a registration at the correspondent node to update the CoA by the messages Binding Update and Binding Acknowledgment. This registration is preceded by the Return Routability procedure (Figure 9.5). 9.1.3.4. Return of the mobile node to the host network A mobile node detects that it has returned to its home network when it detects its prefix in a Router A