Virtual private networks: a model for assessing alternatives

Many companies are beginning to see the importance of virtual private networks (VPNs) as a corporate networking solution primarily because of the access, flexibility, cost and level of security these networks can offer. Rather than using dedicated leased lines or frame relay networking services, public internet based virtual private networks establish local internet connections through an internet service provider and rely on that provider to ensure that the organisation's packets are properly routed to the appropriate destination. VPN offers a great combination of characteristics that allow connections to be secure, high-speed, flexible and cheaper compared to alternatives. The primary appeal of VPNs to IT managers is their ability to offer access to corporate IT resources to geographically dispersed users with minimal operational costs and an adequate level of security. This paper will present a model to determine the appropriateness of VPN for an organisation and to identify potential roadblocks to successful implementation. First, an overview of virtual private networking is given including some general definitions, functions, characteristics and properties of VPNs. Second, the costs and benefits of VPNs relative to current alternatives are discussed. Third, there follows a discussion of the implicit requirements for VPNs used as an organisational resource. Fourth, various ways that have been used to classify VPNs are presented and discussed. Fifth, aspects of VPN feasibility for organisations are discussed. Sixth, a model for assessing VPN technology is presented. Finally, the future implications of virtual private networks will be considered.