How do you contact a mobile node?

• Mobile node moves from network to network
• Correspondents want to send packets to mobile node

Two approaches:

1. Indirect routing: Communication from correspondent to mobile node goes through home agent
2. Direct routing: Correspondent gets foreign address of mobile, sends directly to mobile

• Home network: Permanent home of mobile
• Permanent address: address in home network, can always be used to reach mobile
• Home agent: entity that will perform mobility functions on behalf of mobile, when mobile is remote
• Visited Network: Network in which mobile currently resides
• Care of address: Address in visited network
• Foreign agent: Entity in visited network that performs mobility functions on behalf of mobile

Registration:

• mobile contacts foreign agent on entering visited network
• foreign agent contacts home agent
• Foreign agent knows about mobile
• Home agent knows about mobile

Mobility using Indirect routing:

• Correspondent contacts the permanent address
• Home agent intercepts the packets and forwards them to foreign agent