In order to allow for secure transmission of data across the network which may be wired or wireless, we feel it is necessary to use a mechanism known as VPN, which stands for Virtual Private Network. A Virtual Private Network typically uses the Internet as the transport backbone to establish secure links hosts which maybe wired or mobile. VPNs serve as private network overlays on public IP network infrastructures such as the Internet. It uses strong cryptography to provide both authentication and encryption services. Authentication ensures that packets are from the right sender and have not been altered in transit.
Encryption prevents unauthorized reading of packet contents.
These services allow one to build secure tunnels through untrusted networks. This is a network, which is effectively private even though it includes machines at several different sites connected by the insecure Internet. Another quite realistic way of implementing a mobile IP infrastructure is to use Lucent Wavelan cards' capability of transparent address mapping when moving between different wireless networks. This solution is likely not going to require any changes to routers and wireless clients other than installing Wavelan cards with drivers. V. Typical User Scenario 1.