Backup VPN tunnel flapping

[AndreyPokorskiy]

Hello Community,
The router C1111-8P Version 17.3.3 has two VPN tunnels configured with the same interface as the tunnel source.
The tunnel 21 is the primary tunnel where all the traffic passes through and Tunnel 22 is backup and there is no traffic
There's a problem... Tunnel 22 is fine, but Tunnel 21 keeps going up and down all the time.
The setup for both tunnels is identical, except for the destination IP address.
I'm here to ask the Community for help or thoughts on what might be causing the backup tunnel to constantly flap.

Regards,
Andrey P.

[MHM Cisco World]

Did you use shared keyword with tunnel protection ipsec profile?

If not use it in both tunnel

MHM

[tvotna]

This is a wrong recommendation. If point-to-point SVTI or GRE tunnels have different tunnel destinations, "shared" keyword in the "tunnel protection ipsec profile <name>" should not be used .

Collect conditional IKEv1/IKEv2 debugs to begin with.