(a) IP Packet Delivery in Mobile IP

When a mobile node (MN) moves to a different network, packets are forwarded using triangular routing:

  1. A correspondent node (CN) sends a packet to the MN's home address.

  2. The Home Agent (HA) intercepts the packet and encapsulates it in another IP packet.

  3. The encapsulated packet is sent to the Foreign Agent (FA) via a tunnel.

  4. The FA decapsulates the packet and delivers it to the MN.

For reverse communication, the MN can send packets directly to the CN, avoiding the HA. However, route optimization techniques reduce delays by allowing direct communication between MN and CN.

(b) Registration Process in Mobile IP

The registration process ensures that the MN's location is updated:

  1. Agent Discovery: The MN listens for advertisements from a nearby FA or sends a request.

  2. Registration Request: The MN sends a request to the FA, which forwards it to the HA.

  3. Authentication & Registration: The HA verifies the request, updates the MN’s location, and sends a reply back via the FA.

  4. Registration Reply: The FA informs the MN of successful registration.

This process allows the MN to receive packets at its new location without losing connectivity.