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 -
How to Configure Site to Site IPSec VPN Tunnel in Cisco IOS Router - Tech Support
Configuring IPSec Router-to-Router with NAT Overload and Cisco Secure VPN Client - Cisco
How To Configure IPsec Site-to-Site VPN On Cisco Router? – GetLabsDone
IPSec Tunnel between Cisco ASA Firewall and Cisco Router