Mobile IP Procedures Having Three Flow.
- Agent Discovery
Agent Discovery is the method by which a mobile node determines whether it is currently connected to its home network or to a foreign network, and by which a mobile node can detect when it has moved from one network to another.
When connected to a foreign network, the methods also allow the mobile node to determine the foreign agent care-of address being offered by each foreign agent on that network. Mobile IP extends ICMP Router Discovery as its primary mechanism for Agent Discovery. An Agent Advertisement is formed by including a Mobility Agent Advertisement Extension in an ICMP Router advertisement message
Agent Advertisements are transmitted by a mobility agent to advertise its services on a link. Mobile nodes use these advertisements to determine their current point of attachment to the Internet. An Agent Advertisement is an ICMP Router Advertisement that has been extended to also carry an Mobility Agent Advertisement Extension
Mobile IP registration provides a flexible mechanism for mobile nodes to communicate their current reachability information to their home agent. It is the method by which mobile nodes request forwarding services when visiting a foreign network, inform their home agent of their current care-of address, renew a registration which is due to expire, and/or deregister when they return home.
Two Types of Registration
Mobile IP defines two different registration procedures, one via a foreign agent that relays the registration to the mobile node’s home agent, one directly with the mobile node’s home agent (co-located care-of address). If a mobile node is registering a foreign agent care-of address, the mobile node must register via that foreign agent.
If a mobile node is using a co-located care-of address, and receives an Agent Advertisement from a foreign agent on the link on which it is using this care-of address, the mobile node should register via that foreign agent (or via another foreign agent on this link). If a mobile node is otherwise using a co-located care-of address, the mobile node must register directly with its home agent.