In order to configure a LAN-to-LAN tunnel between the Cisco VPN 3000 Concentrator and the Sonicwall TZ170, complete these steps on the Cisco VPN 3000 Concentrator:
On the Cisco VPN 3000 Concentrator, choose Configuration > System > Tunneling Protocols > IPSec > IKE Proposals > Modify in order to create an Internet Key Exchange (IKE) proposal.
Choose Configuration > System > Tunneling Protocols > IPSec > IKE Proposals.
Choose created proposal in the last step and click Activate in order to activate the IKE proposal.
Choose Configuration > System > Tunneling Protocols > IPSec LAN-to-LAN.
Click on Add.
Set up an IPsec tunnel called To_Sonicwall with the IP address of the Sonicwall as the peer. For the Preshared Key, choose the actual key. Under Authentication, choose Proposal, and choose DES or 3DES for encryption. Choose the IKE proposal from step 1 and choose the Local and Remote networks.
Choose Configuration > Policy Management > Traffic Management > Security Associations > Modify and verify that Perfect Forward Secrecy is disabled and leave the IPsec Time Lifetime at the default 28,800 seconds.