A Virtual Private Dial-up Network (VPDN) is a network that uses a distributed infrastructure to extend remote
access to a private network. VPDNs are based on Layer 2 tunneling and use the Layer 2 Forwarding (L2F), Layer 2 Tunneling Protocol (L2TP), and Point to Point Tunneling Protocol (PPTP) tunneling protocols. This method is used to extend network connections of a remote user over the network of an InternetService Provider (ISP). VPDNs provide a cost-effective alternative for a point-to-point connection over long distances between remote users and private networks.