Site to Site IPSEC VPN Between Cisco Router and Juniper Security Gateway
Configuring IPSec Router-to-Router Hub and Spoke with Communication Between the Spokes - Cisco
Site-to-site IPSec VPN through NAT - Packet Pushers
Example for Configuring the Headquarters to Manage Branches (Cisco Routers) Using Efficient VPN and Establishing IPSec Tunnels - AR100, AR120, AR150, AR160, AR200, AR1200, AR2200, AR3200, and AR3600 CLI-based Typical Configuration Examples -
IPSec Tunnel between Cisco ASA Firewall and Cisco Router
Cisco IPsec Tunnel Mode Configuration
Configuring High Availability Features for Site-to-Site IPSec VPNs - Cisco