Virtual Private Networks, Second Edition

Central Office

The central office is the natural source of information about products and operations. Security is critical. Besides the VPN, several other Internet services are centralized here, including the corporate web, email, and FTP servers. The company web- based Intranet is also centralized at the main office.

Network Connections

The central office maintains two T1 connections through two separate national Internet providers. This provides redundancy and gives other connecting sites a variety of network paths over which they can reach the central office. The T1 connections allow enough bandwidth for all sites to connect to the central network with adequate response time over the VPN, in addition to supporting these other services.

Hardware and Operating System

Routing traffic from the T1, the company has a Cisco 4500 Internet router. This is a robust and expandable router that can handle up to four T1s for a large network. Likewise, it can encapsulate and route a variety of protocols, from IP to AppleTalk. For broad coverage of VPN solutions, the main office is running PPTP on Windows NT servers. Secondarily, there is a Unix server and an Ascend MAX remote access hub, both running PPTP.

VPN Package

The central office must run three VPN servers to give their connecting networks a variety of solutions. The large branch offices require a stable and fast network-to- network VPN. For this high-bandwidth task, the Cisco PIX firewall was chosen. In addition to being a robust firewall ...