Features of this implementation

Basically fully compliant with RFC 2002 (except an ARP feature¹).
It enforces security. Registrations MUST be routed through the FA.
All the implementation is installed at user space.
It does not overload the kernel.
Transparent to the user.
Encapsulation and decapsulation at kernel space.
Authentication between mobile node and foreign agents and foreign agents and home agents.
The agent module can be foreign agent and home agent at the same time.
Multicast/broadcast advertisements/solicitations.
Small programs (30 - 40 KB).
Platform independent. This version of Mobile IP could be moved easily to different platforms because kernel changes are not required.

¹ Due to the implementation is working at user space, one of the constrains we have found is the impossibility of answering to the foreign agent's ARP request. ARP answers have been disable. In order to avoid the problem of answering FA's ARP requests, the Mobile Node issues periodically and ARP reply addressed to the FA. With this, the FA updates its ARP entry (associated with the MN) and it does not issue any ARP request.