Tunneling Alternatives

As an alternative to IPSec encapsulation, you can try setting tunnel encapsulation to GRE or UDP. Remember, using GRE or UDP encapsulation is useful for troubleshooting, but these encapsulation methods do not provide as much protection as IPSec with encryption.

Using GRE or UDP means that data will be sent in the clear and is NOT recommended for production use across insecure links.