Users want assurances that their VPNs are private and that their applications and communications are isolated and confidential. Where security is critical, such as in the banking industry, users can choose to encrypt their frame relay traffic. IP VPNs make use of encryption and tunneling to provide secure transmissions. While networking equipment utilizing IPSec has helped ease the fears of users and network managers about the security of information traversing the public Internet, scalable and secure enterprise networks based solely on IP may be some years ahead. Large institutions running mission-critical traffic across their network are not likely to make the move to a pure IP VPN model until security is an integral part of protocol support.
Network topology is another key factor in defining an appropriate VPN strategy.
Topology requirements often depend on who needs access to the network, what information they need to access and where they are located. In some networks, traffic from remote sites travel through the central site in what is commonly called a hub and spoke topology. Since the cost of frame relay services is distance-insensitive and virtual circuits are software configurable, a frame relay VPN is well suited to both topologies. Today, more and more companies need to extend their networks to mobile users and telecommuters. Extranets use web-based services, and network managers often install firewalls and encryption devices to keep certain data private.