Example for Configuring the Headquarters (Cisco Router) to Manage Branches Using Efficient VPN and Establishing IPSec Tunnels - AR100, AR120, AR150, AR160, AR200, AR1200, AR2200, AR3200, and AR3600 CLI-based Typical Configuration Examples -
Configure an IPSec Tunnel Between a Checkpoint NG and Router - Cisco
Configuring IPSec Router-to-Router Hub and Spoke with Communication Between the Spokes - Cisco
BOVPN Virtual Interface for Dynamic Routing to Cisco
8.4.1.3 Lab – Configuring a Site-to-Site VPN Using Cisco IOS (Instructor Version)
Cisco IOS VPN Configuration Guide - Site-to-Site and Extranet VPN Business Scenarios [Cisco 7200 Series Routers] - Cisco
Multiple Site to Site VPN Tunnels on One Cisco Router