Enabling IKE

By default, IKE is enabled on all the interfaces of your router. To enable IKE if it has been disabled, issue the following command from global configuration mode:

 Router(config)# crypto isakmp enable 

If you do not want to use IKE to automatically establish the IPSec tunnel, you can use the no form of the command to globally disable IKE. However, you can still configure IPSec manually if you leave IKE globally enabled.