Hello Ravishankar
If your tunnel is going down after the tunnel mode ipsec ipv4 command, it may be due to a missing or incorrect configuration somewhere in the setup. There is no easy way to determine what this may be, you will have to perform some troubleshooting steps to determine why this is happening. Ensure that your configs on both devices are set correctly. You can also use some debug commands to determine the reason why the tunnel interface is going down. Some of these include:
- debug crypto isakmp
- debug crypto ipsec
- debug crypto engine
Some additional show commands that can help you out include:
Let us know how you get along, and inform us of your findings so that we can help you further.
I hope this has been helpful!
Laz