The IP address of the remote user whether its static or dynamic is actually irrelevant when connecting to a VPN. When you connect to a VPN via a client (such as Cisco VPN client) you are creating a secure tunnel.
The IP address of the remote user connects them to the Internet, the VPN client will create the secure tunnel. A specified IP address will be assigned within the VPN connection.
A configured VPN client specified for your work or home gives you the capability to connect to that network securely from anywhere in the world, providing you have an Internet connection.
Quick, concise overview of how VPN's work.
Link:
www.howstuffworks.com/vpn.htm
Cheers,
ZiPPy
