Virtual Privet Networks using Cisco Routers

الملخص

Virtual private Network (VPN), is a technology that provides a secure communications mechanism for data and control information transmitted between networks. It can be used over existing network such as data across public network. This is often less expensive than the alternatives such as dedicated private telecommunications lines between organization or branch offices, VPN uses many protocols that work together in various combinations to provide protection for communications. IPSec is flexible enough to meet many needs, because this it’s works in network layer. But there are other protocols such as (PPP, PPTP,L2TP, ….) that provide a better solution, Cisco, the largest manufacturer of IP routers, offers VPN-IPSec implementation in its routers. The purpose of this paper is to present and explain the steps necessary to configure tunnel mode IPSec between two Cisco routers. In order to provide a thorough understanding of the configuration.