Some other related posts:
- Troubleshooting Cisco IPSec Site to Site VPN - "reason: Unknown delete reason!" after Phase 1 Completed
- Troubleshooting Cisco IPSec Site to Site VPN - "IPSec policy invalidated proposal with error 32"
- Troubleshooting Cisco IPSec Site to Site VPN - "QM Rejected"
1. Enabled Debugging on Cisco IOS Router
vpn-R1#debug crypto ipsec
Crypto IPSEC debugging is on
vpn-R1#debug crypto isakmp
Crypto ISAKMP debugging is on
vpn-R1#debug crypto engine
Crypto Engine debugging is on
vpn-R1#terminal monitor