Policy-Based Networking: Architecture and Algorithms

VPN Support in the ISP Environment

The cheapest VPN would be obtained if the campus sites simply connected to the Internet and used encrypted tunnels to carry their traffic across the Internet. However, given the wide variety of threats that exist on the open network, as well as the wide performance fluctuations, it is much more likely that the VPN service would be offered on a private network physically separate from the one that the ISP uses for global Internet connectivity. A customer network would have access to both the public Internet and the ISP-private network. Several customers would be multiplexed on to the ISP-private network. This would reduce the overall cost to the ISP of maintaining its network, and the ISP would be able to offer ...